Update: Abdominal pseudocyst

Abdominal pseudocyst

Abdominal pseudocyst (APC) is a distal catheter site-specific failure in patients treated with ventriculoperitoneal shunts.


Few studies with more than 10 patients have been reported.

It is well known in children but uncommon in adults.


The pathogenesis of pseudocysts remains unclear, it is attributed to an inflammatory response, usually the result of infection and nonspecific inflammatory processes.

Diverse predisposing factors have been proposed such as previous abdominal surgeries, multiple VPS revisions, history of necrotizing enterocolitis.


The wall is composed of fibrous tissue without an epithelial lining and is filled with cerebrospinal fluid. Debris is identified in the majority of the fluid collections.

The pseudocyst can either move freely within the peritoneal cavity or adhere to small-bowel loops, the serosal surface of solid organs, the parietal peritoneum, or small-bowel loops. The latter would explain why some bowel loops may become engulfed when the pseudocyst increases in size or why the pseudocyst may be prone to torsion.


The cerebrospinal fluid (CSF) is being poorly or not absorbed across the serosa and results in an increased pressure within the APC, reducing forward pressure gradient and shunt malfunction.

Pediatric patients commonly present with symptoms of elevated intracranial pressure and abdominal pain, whereas adults predominantly present with abdominal signs only.

Familiarity with these types of shunt failure is essential for neurologists and pediatricians because they are often the first to evaluate and triage these patients 1) 2).


They are seen as a thin-walled cystic mass around the shunt tip. Ultrasonography or CT can indicate the definitive diagnosis.

Ultrasonography proved to be the method of choice in the diagnosis of VPS abdominal complications, especially CSF pseudocyst.

Well defined hypoechoic / anechoic cystic mass with tip of VP shunt within it

Pressure effects on adjacent organs if mass is huge

Multiple septae may form chronically

Debris and internal echoes are seen if the mass is infected


May show a small or massive , loculated cyst like structure in the peritoneal cavity at the distal tip of VP shunt

Measurement of attenuation values with CT characterizes the contents as water attenuation and demonstrates the relationships of portions of the shunt catheter with the pseudocyst.

In case of IH signs, a cerebral CT scan can be performed to evaluate the ventricular distension and to check the shunt position 3).

Differential diagnosis

Possible differential considerations include

Mesenteric abscess



Cystic lymphangioma

Cystic mesothelioma

Mesenteric cyst

Benign cystic teratoma

Cystic spindle cell tumour

Pancreatic pseudocyst

Enteric duplication cyst

Omental cyst

It may be difficult to differentiate seroma, urinoma, abscess, lymphocele, and cerebrospinal fluid on the basis of imaging findings alone. Fine-needle aspiration with ultrasound or CT guidance has a high diagnostic yield 4).

Gastroenterological surgeons should be aware of this possible complication, and this complication should be considered during differential diagnosis of an acute abdomen complaint 5)


Whenever suspected it should be confirmed by imaging, followed by open exploration and repositioning of the shunt 6).

In case of suspected infection, the VPS is removed and replaced by an external ventricular drain. Antibiotics are started and adjusted to the results of the CSF culture. If there is no direct sign of infection, only the distal catheter is externalized and antibiotics are introduced until infection is treated. Depending on the peritoneal absorption state, the distal catheter is replaced in the abdominal cavity or in the atrium, the pleural space or the gallbladder if there is no suitable place for repositioning. If the peritoneal state allows it, a laparoscopic procedure is recommended to avoid peritoneal adhesion formation increasing the recurrence rate of CSF pseudocyst 7).


Various methods to process the cyst have been described in the medical literature, but the recurrence rate remains elevated (25-100%). Then the probability of an infection without any clinical sign has to be considered.

Case series


One hundred thirty-eight patients were treated for hydrocephalus, and 112 patients received a peritoneal catheter during the follow-up. An APC was diagnosed in 14 (12.5%) patients, and 28 revisions were needed for its treatment. The rate of shunt infection in patients with APC was 50%, but bacterial examination of the pseudofluid culture revealed infection in only 3 patients. Age at first surgical procedure, type of first surgical procedure, and etiology of hydrocephalus were not associated with APC diagnosis. APC recurred in 4 patients. These patients had a catheter repositioning directly into the peritoneum as first surgical treatment. No recurrences were observed in patients with shunt externalization or replacement of the peritoneal catheter.

An APC is a major long-term complication after ventriculoperitoneal shunt treatment. Although a sterile inflammatory response cannot be excluded completely, our results favor the hypothesis of low-level shunt infection. In both cases, the surgical consequences are the same. An infected APC should be treated as a shunt infection. Uninfected patients can be treated with shunt externalization and replacement of only the peritoneal catheter 8).


In a retrospective analysis of 4 cases diagnosed to have abdominal pseudo cyst following VP shunt between 2008 and 2013. All the four cases were suspected clinically and diagnosis was confirmed by abdominal ultrasonography.

In three patients, the cyst was multilocular and of varying size. Fourth one had a unilocular cyst at the lower end of VP shunt. All the four patients had features of varying degree raised intracranial pressure and a two patients had abdominal signs also. All the patients needed open exploration. Cyst fluid was drained and partial to complete excision of the cyst was done along with the repositioning of the shunt in abdominal cavity in three patients and exteriorization of shunt in one patient. Patients were followed for any further complication over a period of 1-year 9).

Four unique cases of abdominal pseudocyst formation. The first patient initially presented with a right upper quadrant pseudocyst. Shunt was externalized and the distal end was revised with placement of catheter on the opposite side. He developed another pseudocyst within 5 months of shunt revision and developed another shunt failure.

The second patient had a history of shunt revisions and a known pseudocyst, presented with small bowel obstruction, and underwent laparotomy for the lysis of adhesions with improvement in his symptoms. After multiple readmissions for the same problem, it was thought that the pseudocyst was causing gastric outlet obstruction and his VP shunt was converted into a ventriculopleural shunt followed by percutaneous drainage of his pseudocyst.

The third patient developed hydrocephalus secondary to cryptococcal meningitis. He developed abdominal pain secondary to an abdominal pseudocyst, which was drained percutaneously with relief of symptoms.

The fourth patient had a history of multiple shunt revisions and a previous percutaneous pseudocyst drainage that recurred with cellulitis and abscess secondary to hardware infection.

Abdominal pseudocysts are a rare but important complication of VP shunt placement. Treatment depends on etiology, patient presentation, and clinical manifestations. Techniques for revision include distal repositioning of peritoneal catheter, revision of catheter into pleural space or right atrium, or removal of the shunt completely 10).


A 31-year-old female, in which a large abdominal pseudocyst was developed 1 year after insertion of a ventriculoperitoneal shunt for hydrocephalus. The abdominal CT scan and the ultrasonographical evaluation of the abdomen showed a well defined, cystic mass lesion with a volume of 50 cm3, in the recessus hepato-renal. The peritoneal tip of the shunt was located within the mass lesion. A distal externalization of the peritoneal catheter without excision of the pseudocyst was performed. Cerebrospinal fluid culture demonstrated a Staphylococcus epidermidis infection and adequate antibiotic treatment was administrated. The previous symptoms improved 4 weeks later and a new catheter was placed intraperitoneally in a different quadrant. The postoperative course was uneventful. They suggest that chronic inflammation or subclinical peritonitis is a predisposing factor for this complication 11).


64 cases of APC were found in 36 patients. The records were then reviewed for the presence of infection, history of necrotizing enterocolitis, prior abdominal surgery, and treatment performed. Of the cases of APC, 46 were primary and 18 were recurrent. A history of prior abdominal surgery other than shunt revision was found in 47% of patients and a history of necrotizing enterocolitis was found in 19% of patients. The average number of prior shunt revisions was 4.1 per patient. Shunt infection as defined by positive cultures of either cerebrospinal fluid or abdominal fluid was present in only 23% of cases of APC. A history of prior shunt infection was present in 30% of patients. Infection was treated by shunt removal, external ventricular drainage, and appropriate antibiotics. After the infection was cleared or if no infection was present, treatment consisted of: (1) repositioning the distal catheter into the peritoneum, (2) repositioning the distal catheter into the pleural space, the atrium, or the gallbladder, (3) exploratory laparotomy with lysis of adhesions and repositioning the peritoneal catheter, (4) APC aspiration only, or (5) shunt removal or disconnection. Because of the complexity of APC management, we analyzed the outcomes of our cases and outlined an algorithm to simplify this process 12).


Rainov et al., report on 14 cases of sonographically diagnosed abdominal pseudocysts, an incidence of pseudocyst formation of 4.5%. The most common presentation of the paediatric patients is with symptoms of elevated intracranial pressure and abdominal pain, whereas the adults have predominantly local abdominal signs. Diagnosis is readily made with ultrasonography. Predisposing factors for pseudocyst formation are multiple shunt revisions and infection. Microscopically, the pseudocysts consist of fibrous tissue without epithelial lining. The treatment involves surgical removal of the catheter with or without excision of the pseudocyst wall and placement of a new catheter intraperitoneally in a different quadrant or an intra-atrial shunt. Recurrences are rare, especially under appropriate medical treatment of infection. In this series, microbiologically proven infection was present in 30% of the cases 13).


Five cases of children with abdominal complications of VP shunts (four pseudocysts and one umbilical granuloma with spontaneous drainage of CSF) 14).

Case reports


A 30-year-old woman with abdominal distension, vomiting and confusion caused by her developing an abdominal CSF pseudocyst, 13 years after her last shunt revision 15)


In 1999, a 50-year-old woman underwent ventriculoperitoneal (VP) shunt surgery for hydrocephalus after subarachnoid hemorrhage. She was hospitalized for fever and recurrent systemic seizures in November 2006. Head computed tomography (CT) showed only old changes. The seizures and fever were controlled by medicinal therapy. However, in December, her consciousness level suddenly decreased, and she showed progressive lower abdominal distension. Head CT showed marked ventriculomegaly, and abdominal CT showed a giant cystic mass at the shunt-tube tip in the lower abdominal cavity. Because thick pus was aspirated from the intra-abdominal mass, we diagnosed the patient with acute obstructive hydrocephalus due to an infected abdominal pseudocyst. Laparotomy and direct cyst drainage were performed, and antibiotic therapy against Streptococcus, the causative pathogen, was administered. The VP shunt tube was replaced. The postoperative course was uneventful, and postoperative CT showed hydrocephalus improvement and no pseudocyst recurrence. Abdominal pseudocysts, which are rare after VP shunt surgeries, usually occur after the subacute postoperative course in younger cerebral hemorrhagic cases. The case was quite rare because the cyst developed in the chronic phase in an older patient and was caused by streptococcal infection. The cyst components should be examined before cyst drainage when choosing surgical strategies 16)

A 14-year-old patient, known to have a VPS as intraventricular hemorrhage treatment, presenting cephalalgia, vomiting, apathy, and an indurate abdominal mass without fever. The first abdominal CSF pseudocyst diagnosis had been established 3 months earlier. Abdominal ultrasounds confirmed a large homogeneous cyst with the shunt tip within the pseudocyst. Cerebral CT revealed an increased ventricular size. An exploratory laparotomy with cyst aspiration, lysis of adhesions, excision of cystic walls, and repositioning of the peritoneal catheter was performed.

No antibiotics were initiated given that the cultures were negative 17).

A case of a 4-month-old girl with shunted hydrocephalus who presented with shunt failure from a suspected abdominal pseudocyst that was found to be a fetal ovarian cyst is reported 18).


Chick JF, Chauhan NR, Mullen KM, Kamdar NV, Khurana B. Teaching NeuroImages: massive abdominal CSFoma. Neurology. 2013 Mar 26;80(13):e146. doi: 10.1212/WNL.0b013e318289705e. PubMed PMID: 23530158 19).

A 22-year-old man who was admitted because of diffuse abdominal distention. A VPS was placed 21 years earlier to treat hydrocephalus secondary to spina bifida. Abdominal computed tomography (CT) revealed a homogeneous low-density fluid collection adjacent to the VPS catheter tip, causing stomach obstruction. Thus a peritoneal pseudocyst around VPS was suspected and emergency laparotomy was performed. The large mass was localized in the left upper abdomen between the stomach and mesentery of the transverse colon, exactly at the omental bursa. The cystic mass was opened and 1500 ml of clear fluid was drained; the distal end of the VPS was repositioned outside the mass. Thus, an abdominal cerebrospinal fluid pseudocyst as a complication of VPS was diagnosed 20).


A nineteen year-old female with a VP shunt who presented with only abdominal distension suggestive of a full-term pregnancy. Abdominal CT studies subsequently established a diagnosis of APC. A total of 12.7L of fluid was drained laparoscopically, and the VP shunt was eventually revised into a ventriculo-atrial shunt. Because adult patients often present years after their VP shunt procedures with only abdominal complaints, the diagnosis of APC relies on detailed history taking and a strong clinical suspicion 21).

A 13-year-old girl with a VP shunt presented with progressive abdominal distention, pain and vomiting. The shunt was inserted at infancy for congenital hydrocephalus. A shunt infection was treated with externalization of the shunt, antibiotics and subsequent shunt replacement. At the age of four, the shunt was revised for a distal malfunction. Nine years later, abdominal CT and ultrasound demonstrated large multiseptated cysts. The shunt was externalized and 1.8 L of sterile, xanthochromic peritoneal fluid was drained. The cerebrospinal fluid was clear, colorless, acellular and sterile with normal protein and glucose levels. Two days later, the distal portion of the shunt was replaced back into the pleural cavity. Five months later a pleural effusion formed. Thoracentesis was performed and there was no evidence of infection. The shunt was subsequently converted to a ventriculoatrial system. The patient has remained well for over 3.5 years 22).


Pernas JC, Catala J. Case 72: Pseudocyst around ventriculoperitoneal shunt. Radiology. 2004 Jul;232(1):239-43. PubMed PMID: 15220507. 23).


Browd SR, Gottfried ON, Ragel BT, Kestle JR. Failure of cerebrospinal fluid shunts: part II: overdrainage, loculation, and abdominal complications. Pediatr Neurol. 2006 Mar;34(3):171-6. Review. PubMed PMID: 16504785.
2) , 15)

Anwar R, Sadek AR, Vajramani G. Abdominal pseudocyst: a rare complication of ventriculoperitoneal shunting. Pract Neurol. 2017 Jun;17(3):212-213. doi: 10.1136/practneurol-2016-001579. Epub 2017 Feb 9. PubMed PMID: 28183984.
3) , 7) , 17)

Laurent P, Hennecker JL, Schillaci A, Scordidis V. [Abdominal CSF pseudocyst recurrence in a 14-year-old patient with ventricular-peritoneal shunt]. Arch Pediatr. 2014 Aug;21(8):869-72. doi: 10.1016/j.arcped.2014.05.019. Epub 2014 Jul 2. French. PubMed PMID: 24997061.

Tamura A, Shida D, Tsutsumi K. Abdominal cerebrospinal fluid pseudocyst occurring 21 years after ventriculoperitoneal shunt placement: a case report. BMC Surg. 2013 Jul 8;13:27. doi: 10.1186/1471-2482-13-27. PubMed PMID: 23834856; PubMed Central PMCID: PMC3710075.
6) , 9)

Hamid R, Baba AA, Bhat NA, Mufti G, Mir YA, Sajad W. Post ventriculoperitoneal shunt abdominal pseudocyst: Challenges posed in management. Asian J Neurosurg. 2017 Jan-Mar;12(1):13-16. doi: 10.4103/1793-5482.145539. PubMed PMID: 28413525; PubMed Central PMCID: PMC5379787.

Gmeiner M, Wagner H, van Ouwerkerk WJR, Senker W, Holl K, Gruber A. Abdominal Pseudocysts and Peritoneal Catheter Revisions: Surgical Long-Term Results in Pediatric Hydrocephalus. World Neurosurg. 2018 Jan 9. pii: S1878-8750(18)30072-X. doi: 10.1016/j.wneu.2018.01.032. [Epub ahead of print] PubMed PMID: 29325961.

Kashyap S, Ghanchi H, Minasian T, Dong F, Miulli D. Abdominal pseudocyst as a complication of ventriculoperitoneal shunt placement: Review of the literature and a proposed algorithm for treatment using 4 illustrative cases. Surg Neurol Int. 2017 May 10;8:78. doi: 10.4103/2152-7806.206007. eCollection 2017. PubMed PMID: 28584681; PubMed Central PMCID: PMC5445654.

Birbilis T, Kontogianidis K, Matis G, Theodoropoulou E, Efremidou E, Argyropoulou P. Intraperitoneal cerebrospinal fluid pseudocyst. A rare complication of ventriculoperitoneal shunt. Chirurgia (Bucur). 2008 May-Jun;103(3):351-3. PubMed PMID: 18717287.

Mobley LW 3rd, Doran SE, Hellbusch LC. Abdominal pseudocyst: predisposing factors and treatment algorithm. Pediatr Neurosurg. 2005 Mar-Apr;41(2):77-83. PubMed PMID: 15942277.

Rainov N, Schobess A, Heidecke V, Burkert W. Abdominal CSF pseudocysts in patients with ventriculo-peritoneal shunts. Report of fourteen cases and review of the literature. Acta Neurochir (Wien). 1994;127(1-2):73-8. Review. PubMed PMID: 7942187.

Bryant MS, Bremer AM, Tepas JJ 3rd, Mollitt DL, Nquyen TQ, Talbert JL. Abdominal complications of ventriculoperitoneal shunts. Case reports and review of the literature. Am Surg. 1988 Jan;54(1):50-5. Review. PubMed PMID: 3276260.

Tomiyama A, Harashina J, Kimura H, Ito K, Honda Y, Yanai H, Iwabuchi S. An Intra-Abdominal Pseudocyst around a Ventriculoperitoneal Shunt due to Streptococcus Infection 7 Years after Shunt Surgery. Surg Res Pract. 2014;2014:898510. doi: 10.1155/2014/898510. Epub 2014 Jan 5. PubMed PMID: 25379565; PubMed Central PMCID: PMC4208502.

Calayag M, Malone CC, Drake B, Chavhan G, Rutka JT. Fetal ovarian cyst mimicking a CSF pseudocyst in the setting of shunt failure. J Neurosurg Pediatr. 2014 Oct 24:1-3. [Epub ahead of print] PubMed PMID: 25343733.

Chick JF, Chauhan NR, Mullen KM, Kamdar NV, Khurana B. Teaching NeuroImages: massive abdominal CSFoma. Neurology. 2013 Mar 26;80(13):e146. doi: 10.1212/WNL.0b013e318289705e. PubMed PMID: 23530158.

Tamura A, Shida D, Tsutsumi K. Abdominal cerebrospinal fluid pseudocyst occurring 21 years after ventriculoperitoneal shunt placement: a case report. BMC Surg. 2013 Jul 8;13:27. doi: 10.1186/1471-2482-13-27. PubMed PMID: 23834856; PubMed Central PMCID: PMC3710075.

Wang B, Hasadsri L, Wang H. Abdominal cerebrospinal fluid pseudocyst mimicking full-term pregnancy. J Surg Case Rep. 2012 Jul 1;2012(7):6. doi: 10.1093/jscr/2012.7.6. PubMed PMID: 24960731; PubMed Central PMCID: PMC3649563.

Yuh SJ, Vassilyadi M. Management of abdominal pseudocyst in shunt-dependent hydrocephalus. Surg Neurol Int. 2012;3:146. doi: 10.4103/2152-7806.103890. Epub 2012 Nov 27. PubMed PMID: 23230527; PubMed Central PMCID: PMC3515935.

Pernas JC, Catala J. Case 72: Pseudocyst around ventriculoperitoneal shunt. Radiology. 2004 Jul;232(1):239-43. PubMed PMID: 15220507.

Update: Bariatric surgery for idiopathic intracranial hypertension

Bariatric surgery for idiopathic intracranial hypertension

Bariatric surgery (BS) has been suggested as idiopathic intracranial hypertension treatment (IIH) associated with morbid obesity.



A systematic review and meta-analyses of surgical and non-surgical studies in 2017:

Bariatric surgery achieved 100% papilloedema resolution and a reduction in headache symptoms in 90.2%. Non-surgical methods offered improvement in papilloedema in 66.7%, visual field defects in 75.4% and headache symptoms in 23.2%. Surgical BMI decrease was 17.5 vs. 4.2 for non-surgical methods.

Whilst both bariatric surgery and non-surgical weight loss offer significant beneficial effects on IIH symptomatology, future studies should address the lack of prospective and randomised trials to establish the optimal role for these interventions 1).


A comprehensive literature search was conducted using the following databases: MEDLINE, EMBASE, PubMed, Scopus, Web of Sciences, and the Cochrane Library. No restrictions were placed on these searches, including the date of publication.

A total of 85 publications were identified, and after initial appraisal, 17 were included in the final review. Overall improvement in symptoms of IIH after bariatric surgery was observed in 60 of the 65 patients observed (92%). Postoperative lumbar puncture opening pressure was shown to decrease by an average of 18.9 cmH2O in the 12 patients who had this recorded.

Bariatric surgery for weight loss is associated with alleviation of IIH symptoms and a reduction in intracranial pressure. Furthermore, an improvement was observed in patients where conventional treatments, including neurosurgery, were ineffective. Further prospective randomized studies with control groups and a larger number of participants are lacking within the published studies to date. There is, therefore, a strong rationale for the use of bariatric surgery in individuals with IIH for the effective treatment of this condition, as well as the efficacy of weight loss for various other obesity co-morbidities 2).


Fridley et al. published in 2011 a review:

Eleven relevant publications (including 6 individual case reports) were found, reporting on a total of 62 patients. The Roux-en-Y gastric bypass was the most common bariatric procedure performed. Fifty-six (92%) of 61 patients with recorded postoperative clinical history had resolution of their presenting IIH symptoms following bariatric surgery. Thirty-four (97%) of 35 patients who had undergone pre- and postoperative funduscopy were found to have resolution of papilledema postoperatively. Eleven (92%) of 12 patients who had undergone pre- and postoperative formal visual field testing had complete or nearly complete resolution of visual field deficits, and the remaining patient had stabilization of previously progressive vision loss. In 13 patients both pre- and postoperative CSF pressures were recorded, with an average postoperative pressure decrease of 254 mm H(2)O. Changes in weight loss and body mass index varied depending on the reported postoperative follow-up interval.

The published Class IV evidence suggests that bariatric surgery may be an effective treatment for IIH in obese patients, both in terms of symptom resolution and visual outcome. Prospective, controlled studies are necessary for better elucidation of its role 3).

In a study Roth et al. describe a high rate of overdrainage (OD) seen in patients following shunts and BS.

Patients with IIH that undergo shunt surgery and BS (not concomitantly) may suffer from OD symptoms, necessitating multiple shunt revisions, and valve upgrades. Despite BS being a valid primary treatment for some patients with IIH, among shunted patients, BS may not lead to resolution of IIH-related symptoms and patients may remain shunt-dependent 4).

Hoang et al. present a report of 3 patients with adolescent-onset IIH that was treated at the Duke University in whom bariatric surgery was pursued successfully. The patients had previously undergone CSF shunting at ages 12, 15, and 23 years. They were shunt dependent for a collective average of 3.3 years prior to bariatriwc surgery. All patients reported “low-pressure” or postural headaches after bariatric surgery that correlated with dramatic reduction in their weight. Two of the 3 patients had their shunts removed and continued to be shunt free 1.5 years later at last follow-up; the third patient remained shunt dependent with the pressure set at 200 mm H2O. Given the significant complications inherent to multiple shunt revisions, earlier intervention for weight loss, including bariatric surgery, in these patients might have prevented complications and the associated health care burden. The authors recommend a multidisciplinary approach for IIH treatment with early consideration for weight loss interventions in select patients 5).

Findings support the notion that caloric restriction represents an important mechanism to explain the very early anti-diabetic effects observed after bariatric surgery. However, exclusion of the upper gastrointestinal tract also provides further metabolic improvements, possibly mediated by gastrointestinal hormonal responses and altered postprandial glucose absorption 6).

Case reports


A 46-year-old woman presented at our service with idiopathic intracranial hypertension that had been diagnosed two years earlier, which had led to chronic refractory headache and an estimated 30% loss of visual acuity, associated with bilateral papilledema. She presented partial improvement of the headache with acetazolamide, but the visual loss persisted. Her intracranial pressure was 34 cmH2O. She presented a body mass index of 39.5 kg/m2, also associated with high blood pressure. Computed tomography of the cranium with endovenous contrast did not show any abnormalities. She underwent Roux-en-Y gastric bypass with uneventful postoperative evolution. One month following surgery, she presented a 24% excess weight loss. An ophthalmological examination revealed absence of visual loss and remission of the papilledema. There were no new episodes of headache following the surgery. There was also complete resolution of high blood pressure. The intracranial pressure decreased to 24 cmH2O, six months after the surgery 7).


Manfield JH, Yu KK, Efthimiou E, Darzi A, Athanasiou T, Ashrafian H. Bariatric Surgery or Non-surgical Weight Loss for Idiopathic Intracranial Hypertension? A Systematic Review and Comparison of Meta-analyses. Obes Surg. 2017 Feb;27(2):513-521. doi: 10.1007/s11695-016-2467-7. Review. PubMed PMID: 27981458; PubMed Central PMCID: PMC5237659.


Handley JD, Baruah BP, Williams DM, Horner M, Barry J, Stephens JW. Bariatric surgery as a treatment for idiopathic intracranial hypertension: a systematic review. Surg Obes Relat Dis. 2015 Nov-Dec;11(6):1396-403. doi: 10.1016/j.soard.2015.08.497. Epub 2015 Aug 12. Review. PubMed PMID: 26499350.


Fridley J, Foroozan R, Sherman V, Brandt ML, Yoshor D. Bariatric surgery for the treatment of idiopathic intracranial hypertension. J Neurosurg. 2011 Jan;114(1):34-9. doi: 10.3171/2009.12.JNS09953. Epub 2010 Jan 22. Review. PubMed PMID: 20095788.


Roth J, Constantini S, Kesler A. Over-drainage and persistent shunt-dependency in patients with idiopathic intracranial hypertension treated with shunts and bariatric surgery. Surg Neurol Int. 2015 Dec 8;6(Suppl 27):S655-60. doi: 10.4103/2152-7806.171230. eCollection 2015. PubMed PMID: 26713173; PubMed Central PMCID: PMC4683795.


Hoang KB, Hooten KG, Muh CR. Shunt freedom and clinical resolution of idiopathic intracranial hypertension after bariatric surgery in the pediatric population: report of 3 cases. J Neurosurg Pediatr. 2017 Sep 29:1-6. doi: 10.3171/2017.6.PEDS17145. [Epub ahead of print] PubMed PMID: 28960170.


Michaud A, Grenier-Larouche T, Caron-Dorval D, Marceau S, Biertho L, Simard S, Richard D, Tchernof A, Carpentier AC. Biliopancreatic diversion with duodenal switch leads to better postprandial glucose level and beta cell function than sleeve gastrectomy in individuals with type 2 diabetes very early after surgery. Metabolism. 2017 Sep;74:10-21. doi: 10.1016/j.metabol.2017.06.005. Epub 2017 Jun 21. PubMed PMID: 28764844.


Cazzo E, Gestic MA, Utrini MP, Mendonça Chaim FD, Mendonça Chaim FH, Cândido EC, da Silveira Jarolavsky LB, de Almeida AMN, Pareja JC, Chaim EA. Bariatric surgery as a treatment for pseudotumor cerebri: case study and narrative review of the literature. Sao Paulo Med J. 2017 May 29:0. doi: 10.1590/1516-3180.2016.0305060117. [Epub ahead of print] PubMed PMID: 28562736.

Update: Cryptococcal meningitis

Cryptococcal meningitis

Cryptococcosis is a fungal infection caused by Cryptococcus spp. that enters the body via inhalation, which mainly invades the lungs and central nervous system.

Two types of fungus can cause cryptococcal meningitis (CM). They are called Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C.gattii). This disease is rare in healthy people. CM is more common in people who have compromised immune systems, such as people who have AIDS.

Cryptococcal meningitis may have long-term morbidity and requires a permanent cerebrospinal fluid shunt.

see Cryptococcus neoformans ventriculoperitoneal shunt infection.

see Cryptococcal choroid plexitis.

Clinical features

Cryptococcal meningitis are usually subacute or chronic in nature. HIV-infected patients may have minimal or nonspecific symptoms. Common symptoms are as follows:






Normal or mildly elevated temperature

Nausea and vomiting (with increased intracranial pressure)

Fever and stiff neck (with an aggressive inflammatory response; less common)

Blurred vision, photophobia, and diplopia

Hearing defects, seizures, ataxia, aphasia, and choreoathetoid movements

After lung and CNS infection, the next most commonly involved organs in disseminated cryptococcosis include the skin, the prostate, and the medullary cavity of bones. Cutaneous manifestations (10-15% of cases) are as follows:

Papules, pustules, nodules, ulcers, or draining sinuses

Umbilicated papules in patients with AIDS

Cellulitis with necrotizing vasculitis in organ transplant recipients

Other less common forms of cryptococcosis include the following:

Optic neuritis or endophthalmitis





Renal abscess


Adrenal involvement.


The workup in patients with suspected cryptococcosis includes the following:

Cutaneous lesions: Biopsy with fungal stains and cultures

Blood: Fungal culture, cryptococcal serology, and cryptococcal antigen testing

Cerebrospinal fluid: India ink smear, fungal culture, and cryptococcal antigen testing

Urine and sputum cultures, even if renal or pulmonary disease is not clinically evident

In AIDS patients with cryptococcal pneumonia, culture of bronchoalveolar lavage washings

With possible CNS cryptococcosis, especially in patients who present with focal neurologic deficits or a history compatible with slowly progressive meningitis, consider obtaining a computed tomography or magnetic resonance imaging scan of the brain prior to performing a lumbar puncture. If a mass lesion is identified, do not perform a lumbar puncture to obtain spinal fluid; rather, consult a neurosurgeon for an alternative procedure.

With pulmonary cryptococcosis, radiographic findings in patients who are asymptomatic and immunocompetent may include the following:

Patchy pneumonitis

Granulomas ranging from 2-7 cm

Miliary disease similar to that in tuberculosis.


Treatment of cryptococcal meningitis consists of three phases: induction, consolidation, and maintenance. Effective induction therapy requires potent fungicidal drugs (amphotericin B and flucytosine), which are often unavailable in low-resource, high-endemicity settings. As a consequence, mortality is unacceptably high. Wider access to effective treatment is urgently required to improve outcomes. For human immunodeficiency virus-infected patients, judicious management of asymptomatic cryptococcal antigenemia and appropriately timed introduction of antiretroviral therapy are important 1).

Case series


A study aimed to evaluate the risk factors and create a predictive model for permanent shunt treatment in cryptococcal meningitis patients. This was a retrospective analytical study conducted at Khon Kaen University. The study period was from January 2005 to December 2015.

They enrolled all adult patients diagnosed with cryptococcal meningitis. Risk factors predictive for permanent shunting treatment were analyzed by multivariate logistic regression analysis. There were 341 patients diagnosed with cryptococcal meningitis. Of those, 64 patients (18.7%) were treated with permanent shunts. There were three independent factors associated with permanent shunt treatment. The presence of hydrocephalus had the highest adjusted OR at 56.77. The resulting predictive model for permanent shunt treatment (y) is (-3.85) + (4.04 × hydrocephalus) + (2.13 × initial CSF opening pressure (OP) > 25 cm H2O) + (1.87 × non-HIV). In conclusion, non-HIV status, initial CSF OP greater than or equal to 25 cm H2O, and the presence of hydrocephalus are indicators of the future necessity for permanent shunt therapy 2).


In Japan, most cases of cryptococcosis are caused by Cryptococcus neoformans(C. neoformans). Until now, only three cases which the infectious agent was Cryptococcus neoformans var. gattii(C. gattii)have been reported. As compared with cryptococcosis caused by C. neoformans, which is often observed in immunocompromised hosts, cryptococcosis caused by C. gattii occurs predominantly in immunocompetent hosts and is resistant to antifungal drugs. Here, we report a case of refractory cerebral cryptococcoma that was successfully treated by surgical resection of the lesions. A 33-year-old man with no medical history complained of headache, hearing disturbance, and irritability. Pulmonary CT showed a nodular lesion in the left lung. Cerebrospinal fluid examination with Indian ink indicated cryptococcal meningitis, and PCR confirmed infection with C. gattii. C. gattii is usually seen in the tropics and subtropics. Since this patient imported trees and soils from abroad to feed stag beetles, parasite or fungal infection was, as such, suspected. Although he received 2 years of intravenous and intraventricular antifungal treatment, brain cryptococcomas were formed and gradually increased. Because of the refractory clinical course, the patient underwent surgical resection of the cerebral lesions. With continuation of antifungal drugs for 6 months after the surgeries, Cryptococcus could not be cultured from cerebrospinal fluid, and no lesions were seen on MR images. If cerebral cryptococcosis responds poorly to antifungal agents, surgical treatment of the cerebral lesion should be considered. 3).


Sloan DJ, Parris V. Cryptococcal meningitis: epidemiology and therapeutic options. Clin Epidemiol. 2014 May 13;6:169-82. doi: 10.2147/CLEP.S38850. eCollection 2014. Review. PubMed PMID: 24872723; PubMed Central PMCID: PMC4026566.


Phusoongnern W, Anunnatsiri S, Sawanyawisuth K, Kitkhuandee A. Predictive Model for Permanent Shunting in Cryptococcal meningitis. Am J Trop Med Hyg. 2017 Aug 14. doi: 10.4269/ajtmh.17-0177. [Epub ahead of print] PubMed PMID: 28820702.


Inada T, Imamura H, Kawamoto M, Sekiya H, Imai Y, Tani S, Adachi H, Ishikawa T, Mineharu Y, Asai K, Ikeda H, Ogura T, Shibata T, Beppu M, Agawa Y, Shimizu K, Sakai N, Kikuchi H. [Cryptococcus Neoformans Var. Gattii meningoencephalitis with cryptococcoma in an immunocompetent patient successfully treated by surgical resection]. No Shinkei Geka. 2014 Feb;42(2):123-7. Japanese. PubMed PMID: 24501185.

Update: Cerebrospinal fluid shunt complication

see Lumboperitoneal shunt complication.

see Ventriculoperitoneal shunt complication.

Ventricular shunts for pediatric hydrocephalus continue to be plagued with high failure rates. Reported risk factors for shunt failure are inconsistent and controversial. The raw or global shunt revision rate has been the foundation of several proposed quality metrics.

The most common problems related to cerebrospinal fluid shunt are shunt obstruction, shunt infection and shunt overdrainage. The incidence of shunt complications is higher when less time has elapsed since the previous shunt surgery. Nearly all shunt patients end up with one or multiple reoperations. Thorough history, head scan (ultrasound, CT or MRI) and plain x-ray (shunt series) are the corner stones when reviewing shunt problems.

Wong et al. performed a PubMed search using search terms “cerebral shunt,” “cerebrospinal fluid shunt,” “CSF shunt,” “ventriculoperitoneal shunt,” “cerebral shunt AND complications,” “cerebrospinal fluid shunt AND complications,” “CSF shunt AND complications,” and “ventriculoperitoneal shunt AND complications.” Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to be included to maximize the range of rates of occurrence for the adverse events reported. RESULTS: In this review of the neurosurgery literature, the reported rate of mechanical malfunction ranged from 8% to 64%. The use of programmable valves has increased but remains of unproven benefit even in randomized trials. Infection was the second most common complication, with the rate ranging from 3% to 12% of shunt operations. A meta-analysis that included 17 randomized controlled trials of perioperative antibiotic prophylaxis demonstrated a decrease in shunt infection by half (OR 0.51, 95% CI 0.36-0.73). Similarly, use of detailed protocols including perioperative antibiotics, skin preparation, and limitation of OR personnel and operative time, among other steps, were shown in uncontrolled studies to decrease shunt infection by more than half. Other adverse events included intraabdominal complications, with a reported incidence of 1% to 24%, intracerebral hemorrhage, reported to occur in 4% of cases, and perioperative epilepsy, with a reported association with shunt procedures ranging from 20% to 32%. Potential management strategies are reported but are largely without formal evaluation.

Surgery for CSF shunt placement or revision is associated with a high complication risk due primarily to mechanical issues and infection. Concerted efforts aimed at large-scale monitoring of neurosurgical complications and consistent quality improvement within these highlighted realms may significantly improve patient outcomes 1).


Shunt dysfunction

Shunt overdrainage

see Shunt overdrainage.

Solid noninfectious growing mass

Shunt-related craniocerebral disproportion.

Slit ventricle syndrome and secondary craniosynostosis are late-onset complications after shunt placement these 2 conditions occasionally occur together.

see Tension pneumocephalus after shunt insertion.

The results of shunt testing are helpful in many circumstances, such as the initial choice of shunt and the evaluation of the shunt when its dysfunction is suspected 2).

Shunting procedures for syringomyelia have been criticized due to the inconsistent long-term outcomes.

This is largely the result of small volume flow at a very low-pressure profile leading to occlusion or malfunction of the shunts.


Patients have reported anecdotally on noises associated with their shunts 4).


Radionuclide shuntogram is important in the evaluation of cerebrospinal fluid shunt complications such as mechanical failure, malpositioning, pseudocyst, or overdrainage. Bermo et al present a case of congenital hydrocephalus and posterior fossa cyst with multiple shunt procedures and revisions with breakage of the proximal tube of the ventriculoperitoneal shunt but preserved CSF drainage through the patent fibrous tract. Careful correlation with SPECT/CT images helped confirm the breakage and exclude CSF leak outside of the tract, which was suspected on planar images 3).



Case series


Kaestner et al. from the Department of Neurosurgery, Klinikum Kassel, Germany, identified all patients who had been treated or followed in our neurosurgical department within a 15-year period from January 2000 up to the end of 2014. After approval of the local ethics committee all patients who were cognitively intact were explored by a questionnaire and by personal interview about acoustic phenomena related to their shunts.

Three hundred forty-seven patients were eligible for the survey, and 260 patients completed the questionnaire. Twenty-nine patients (11.2%) reported on noises raised by their shunts. All of them experienced short-lasting noises while changing body posture, mainly from a horizontal to an upright position, or while reclining the head. Most of the patients reported on soft sounds, but loud and even very loud noises occurred in some patients. Seventy-six percent of the patients were not bothered by these noises as they considered it as a normal part of the therapy or as proof that the shunt device was functioning. Modern valves with gravitational units are prone to produce noises in young adults, but nearly all valve types can evoke noises.

Noises caused by a shunt do occur in a considerable number of patients with shunts. One should be aware of this phenomenon, and these patients must be taken seriously 5).


Rossi et al undertook a study to determine risk factors for shunt revision within their own patient population.

In this single-center retrospective cohort study, a database was created of all ventricular shunt operations performed at the authors’ institution from January 1, 2010, through December 2013. For each index shunt surgery, demographic, clinical, and procedural variables were assembled. An “index surgery” was defined as implantation of a new shunt or the revision or augmentation of an existing shunt system. Bivariate analyses were first performed to evaluate individual effects of each independent variable on shunt failure at 90 days and at 180 days. A final multivariate model was chosen for each outcome by using a backward model selection approach.

There were 466 patients in the study accounting for 739 unique (“index”) operations, for an average of 1.59 procedures per patient. The median age for the cohort at the time of the first shunt surgery was 5 years (range 0-35.7 years), with 53.9% males. The 90- and 180-day shunt failure rates were 24.1% and 29.9%, respectively. The authors found no variable-demographic, clinical, or procedural-that predicted shunt failure within 90 or 180 days.

In this study, none of the risk factors that were examined were statistically significant in determining shunt failure within 90 or 180 days. Given the negative findings and the fact that all other risk factors for shunt failure that have been proposed in the literature thus far are beyond the control of the surgeon (i.e., nonmodifiable), the use of an institution’s or individual’s global shunt revision rate remains questionable and needs further evaluation before being accepted as a quality metric 6).


A study aims to review the imaging findings of distal (thoracic and abdominal) complications related to ventriculo-peritoneal (VP), ventriculo-pleural (VPL), and ventriculo-atrial (VA) cerebrospinal fluid (CSF) shunt catheter placement. Institution review board-approved single-center study of patients with thoracic and abdominal CSF catheter-related complications on cross-sectional imaging examinations over a 14-year period was performed. Clinical presentation, patient demographics, prior medical history, and subsequent surgical treatment were recorded. The presence or absence of CSF catheter-related infection and/or acute hydrocephalus on cross-sectional imaging was also recorded. There were 81 distal CSF catheter-related complications identified on 47 thoracic or abdominal imaging examinations in 30 patients (age 5-80 years, mean 39.3 years), most often on CT (CT = 42, MRI = 1, US = 4). Complications included 38 intraperitoneal and 11 extraperitoneal fluid collections. Extraperitoneal collections included nine abdominal wall subcutaneous (SC) pseudocysts associated with shunt migration and obesity, an intrapleural pseudocyst, and a breast pseudocyst. There were also two large VPL-related pleural effusions, a fractured catheter in the SC tissues, and a large VA shunt thrombus within the right atrium. Ten patients (33.3 %) had culture-positive infection from CSF or shunt catheter samples. Ten patients (33.3 %) had features of temporally related acute or worsening hydrocephalus on neuroimaging. In four of these patients, the detection of thoracic and abdominal complications on CT preceded and predicted the findings of acute hydrocephalus on cranial imaging. Thoracic and abdominal complications of CSF shunts, as can be identified on CT, include shunt infection and/or obstruction, may be both multiple and recurrent, and may be predictive of concurrent acute intracranial problems 7).


From January 1999 to December 2006, Korinek et al., conducted a prospective surveillance program for all neurosurgical procedures including reoperations and infections. Patients undergoing CSF shunt placement were retrospectively identified among patients labeled in the database as having a shunt as a primary or secondary intervention. Revisions of shunts implanted in another hospital or before the study period were excluded, as well as lumbo- or cyst-peritoneal shunts. Shunt complications were classified as mechanical dysfunction or infection. Follow-up was at least 2 years. Potential risk factors were evaluated using log-rank tests and stepwise Cox regression models.

During the 8-year surveillance period, a total of 14 275 patients underwent neurosurgical procedures, including 839 who underwent shunt placement. One hundred nineteen patients were excluded, leaving 720 study patients. Mechanical dysfunction occurred in 124 patients (17.2%) and shunt infection in 44 patients (6.1%). These 168 patients required 375 reoperations. Risk factors for mechanical dysfunction were atrial shunt, greater number of previous external ventriculostomies, and male sex; risk factors for shunt infection were previous CSF leak, previous revisions for dysfunction, surgical incision after 10 am, and longer operating time.

Shunt surgery still carries a high morbidity rate, with a mean of 2.2 reoperations per patient in 23.3% of patients. Our risk-factor data suggest methods for decreasing shunt-related morbidity, including peritoneal routing whenever possible and special attention to preventing CSF leaks after craniotomy or external ventriculostomy 8).

Case reports

James et al. describe 3 children who presented with progressively enlarging skin-covered solid masses over the shunt catheter in the neck/clavicular region. The authors reviewed the clinical, laboratory, pathological, radiographic, and follow-up data for all 3 patients and reviewed the literature on the subject. The patients had no clinical evidence of an infectious process. Surgical exploration revealed that masses were surrounding and encasing the shunt tubing to which they were strongly attached. Pathological studies of the tissues demonstrated varying degrees of exuberant chronically inflamed granulation tissues, interstitial fibrosis, and dystrophic calcification. One patient had associated thinning of the skin overlying the mass and subsequently developed ulceration. No infectious organisms were observed. The cerebrospinal fluid aspirates from the shunts did not yield any organisms. There has been no recurrence of the masses. The presence of a growing mass over the shunt tube in the neck or the chest region without clinical evidence of infection does not indicate that the mass should be treated with antibiotics and complete shunt removal. Rather, the mass can be cured by extirpation and with “bypass” new shunt tubing locally 9).


Wong JM, Ziewacz JE, Ho AL, Panchmatia JR, Bader AM, Garton HJ, Laws ER, Gawande AA. Patterns in neurosurgical adverse events: cerebrospinal fluid shunt surgery. Neurosurg Focus. 2012 Nov;33(5):E13. doi: 10.3171/2012.7.FOCUS12179. Review. PubMed PMID: 23116093.


Chari A, Czosnyka M, Richards HK, Pickard JD, Czosnyka ZH. Hydrocephalus shunt technology: 20 years of experience from the Cambridge Shunt Evaluation Laboratory. J Neurosurg. 2014 Jan 3. [Epub ahead of print] PubMed PMID: 24405071.


Bermo M, Leung AS, Matesan M. A Case of Discontinued Proximal Limb of a Ventriculoperitoneal Shunt With Patent Fibrous Tract. Clin Nucl Med. 2016 Feb 24. [Epub ahead of print] PubMed PMID: 26914568.


Kaestner S, Fraij A, Deinsberger W, Roth C. I can hear my shunt-audible noises associated with CSF shunts in hydrocephalic patients. Acta Neurochir (Wien). 2017 Apr 14. doi: 10.1007/s00701-017-3179-z. [Epub ahead of print] PubMed PMID: 28411322.


Kaestner S, Fraij A, Deinsberger W, Roth C. I can hear my shunt-audible noises associated with CSF shunts in hydrocephalic patients. Acta Neurochir (Wien). 2017 Jun;159(6):981-986. doi: 10.1007/s00701-017-3179-z. Epub 2017 Apr 14. PubMed PMID: 28411322.


Rossi NB, Khan NR, Jones TL, Lepard J, McAbee JH, Klimo P Jr. Predicting shunt failure in children: should the global shunt revision rate be a quality measure? J Neurosurg Pediatr. 2016 Mar;17(3):249-59. doi: 10.3171/2015.5.PEDS15118. Epub 2015 Nov 6. PubMed PMID: 26544083.


Bolster F, Fardanesh R, Morgan T, Katz DS, Daly B. Cross-sectional imaging of thoracic and abdominal complications of cerebrospinal fluid shunt catheters. Emerg Radiol. 2015 Nov 26. [Epub ahead of print] PubMed PMID: 26610766.


Korinek AM, Fulla-Oller L, Boch AL, Golmard JL, Hadiji B, Puybasset L. Morbidity of ventricular cerebrospinal fluid shunt surgery in adults: an 8-year study. Neurosurgery. 2011 Apr;68(4):985-94; discussion 994-5. doi: 10.1227/NEU.0b013e318208f360. PubMed PMID: 21221037.


James HE, Postlethwait RA, Sandler ED. Solid noninfectious growing masses over cerebrospinal fluid shunts: report of 3 cases. J Neurosurg Pediatr. 2015 Jan 30:1-4. [Epub ahead of print] PubMed PMID: 25634820.

Callosal Angle

Ideally the angle should be measured on a coronal image perpendicular to the anterior commissureposterior commissure (AC-PC) plane at the level of the posterior commissure 1) 2).


The shapes of the ventricles, the ventricular index and a callosal angle of 110 degrees or less provided supporting evidence of obstruction in a study. Recognition of an obstructive element in ventricular dilatation following head injury is important, since in a small carefully selected group of patients a ventricular shunting operation may favourably affect recovery 3).

Measuring the Callosal angle (CA) helps in differentiating INPH patients from Alzheimer’s disease (AD) and normally aged subjects4).

In iNPH, Evans’ index, which indicates external enlargement, is not appropriate for evaluating ventricular enlargement; alternatively, the size of cerebral ventricles estimated by coronal sections can be used 5).

The callosal angle has been proposed as a useful marker of patients with idiopathic normal pressure hydrocephalus (iNPH) 6).

It is helpful in distinguishing these patients from those with ex-vacuo ventriculomegaly.

A small callosal angle, wide temporal horns, and occurrence of disproportionately enlarged subarachnoid space hydrocephalus are common in patients with idiopathic normal pressure hydrocephalus and were significant predictors of a positive shunt outcome. These noninvasive and easily assessed radiologic markers could aid in the selection of candidates for shunt surgery 7).


In general patients with iNPH have smaller angles than those with ventriculomegaly from atrophy or normal controls.

A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80°.

In one study, symptomatic iNPH patients who responded to shunting had a significantly smaller mean preoperative callosal angle (59° (95% CI 56°-63°)) compared with those who did not respond (68° (95% CI 61°-75°)).

CA and Evans Index (EI) may serve as a screening tool to help the radiologist differentiate patients with NPH from patients without NPH, which would allow for designation of patients for further volumetric assessment 8).

Simple linear regression analyses demonstrated that presurgical high-convexity tightness, callosal angle, and Sylvian fissure dilation were significantly associated with the 1-year changes in the clinical symptoms. A multiple linear regression analysis demonstrated that presurgical high-convexity tightness alone predicted the improvement of the clinical symptoms 1 year after surgery 9).

In a retrospective cohort study, Kojoukhova et al evaluated brain CT or MRI scans of 390 patients with suspected iNPH. Based on a 24-h intraventricular pressure monitoring session, patients were classified into a non-NPH (n = 161) or probable iNPH (n = 229) group. Volumes of cerebrospinal fluid compartments (lateral ventricles, sylvian and suprasylvian subarachnoid spaces and basal cisterns) were visually assessed. Disproportionally enlarged subarachnoid spaces, flow void, white matter changes, medial temporal lobe atrophy and focally dilated sulci were evaluated. Moreover, we measured quantitative markers: Evans’ index (EI), the modified cella media index, mean width of the temporal horns and callosal angle.


Virhammar J, Laurell K, Cesarini KG et-al. The callosal angle measured on MRI as a predictor of outcome in idiopathic normal-pressure hydrocephalus. J. Neurosurg. 2014;120 (1): 178-84. doi:10.3171/2013.8.JNS13575

Ishii K, Kanda T, Harada A et-al. Clinical impact of the callosal angle in the diagnosis of idiopathic normal pressure hydrocephalus. Eur Radiol. 2008;18 (11): 2678-83. doi:10.1007/s00330-008-1044-4

Hawkins TD, Lloyd AD, Fletcher GI, Hanka R. Ventricular size following head injury: a clinico-radiological study. Clin Radiol. 1976 Jul;27(3):279-89. PubMed PMID: 1086181.

Ishii K, Kanda T, Harada A, Miyamoto N, Kawaguchi T, Shimada K, Ohkawa S, Uemura T, Yoshikawa T, Mori E. Clinical impact of the callosal angle in the diagnosis of idiopathic normal pressure hydrocephalus. Eur Radiol. 2008 Nov;18(11):2678-83. doi: 10.1007/s00330-008-1044-4. Epub 2008 May 24. PubMed PMID: 18500524.

Naruse H, Matsuoka Y. [Post-operative improvement of 14 cases who were considered iNPH despite Evans’ index of 0.3 or less]. No Shinkei Geka. 2013 Jan;41(1):25-30. Japanese. PubMed PMID: 23269252.

Cagnin A, Simioni M, Tagliapietra M, Citton V, Pompanin S, Della Puppa A, Ermani M, Manara R. A Simplified Callosal Angle Measure Best Differentiates Idiopathic-Normal Pressure Hydrocephalus from Neurodegenerative Dementia. J Alzheimers Dis. 2015;46(4):1033-8. doi: 10.3233/JAD-150107. PubMed PMID: 26402630.

Virhammar J, Laurell K, Cesarini KG, Larsson EM. Preoperative prognostic value of MRI findings in 108 patients with idiopathic normal pressure hydrocephalus. AJNR Am J Neuroradiol. 2014 Dec;35(12):2311-8. doi: 10.3174/ajnr.A4046. Epub 2014 Jul 10. PubMed PMID: 25012669.

Miskin N, Patel H, Franceschi AM, Ades-Aron B, Le A, Damadian BE, Stanton C, Serulle Y, Golomb J, Gonen O, Rusinek H, George AE; Alzheimer’s Disease Neuroimaging Initiative.. Diagnosis of Normal-Pressure Hydrocephalus: Use of Traditional Measures in the Era of Volumetric MR Imaging. Radiology. 2017 May 10:161216. doi: 10.1148/radiol.2017161216. [Epub ahead of print] PubMed PMID: 28498794.

Narita W, Nishio Y, Baba T, Iizuka O, Ishihara T, Matsuda M, Iwasaki M, Tominaga T, Mori E. High-Convexity Tightness Predicts the Shunt Response in Idiopathic Normal Pressure Hydrocephalus. AJNR Am J Neuroradiol. 2016 Jun 30. [Epub ahead of print] PubMed PMID: 27365329.

Update: Idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus (iNPH) is a progressive neurodegenerative disease in the elderly with enlarged ventricles and normal or slightly elevated cerebrospinal fluid pressure, clinically characterized by an insidious onset and gradual progression of impairments of gait, balance, cognition, with urinary incontinence 1).


Normal Pressure Hydrocephalus first became recognized on March 10, 1964 as a distinct medical syndrome by Salomón Hakim, M.D., Ph.D.

The classic triad of magnetic apraxia, urinary incontinence, and dementia remain relevant into the 21(st) century as being the basis for symptomatic diagnosis and predicting potential benefit from ventriculoperitoneal shunting, though they have been greatly augmented by the addition of modern neuroimaging, particularly MRI.

Modern criteria recognize a wider range of diagnostic criteria, and new positive and negative prognostic indicators for treatment benefit have been discovered, though the mainstay remains initial drainage of a large volume of cerebrospinal fluid and monitoring for clinical improvement. Even with our advances in understanding both primary and secondary normal pressure hydrocephalus, diagnosis, management, and counseling remain challenging in this disorder 2).


In people over 65 years old, pooled prevalence obtained from specific population studies was 1.3%, almost 50-fold higher than that inferred from door-to-door surveys of dementia or Parkinsonism. Prevalence may be even higher in assisted-living and extended-care residents, with up to 11.6% of patients fulfilling the criteria for suspected iNPH and 2.0% of patients showing permanent improvement after cerebrospinal fluid (CSF) diversion. The only prospective population-based survey that reported iNPH incidence estimated 1.20 cases/1000 inhabitants/year, 15-fold higher than estimates obtained from studies based on hospital catchment areas. The incidence of shunt surgery for iNPH and SRiNPH obtained from incident cases of hospital catchment areas appears to be fewer than two cases and one case/100,000 inhabitants/year, respectively. Unfortunately, there is no population-based study reporting the real values for these two parameters.

iNPH appears to be extremely under-diagnosed. Properly designed and adequately powered population based studies are required to accurately characterize this disease’s epidemiology 3).

The prevalence of iNPH is high—for example, in Japan among people older than 65, the prevalence is between 0.5% and 2.9% 4)and the syndrome is both underdiagnosed and undertreated.


It is recommended that INPH be classified into probable, possible, and unlikely categories. It is hope that these criteria will be widely applied in clinical practice and will promote greater consistency in patient selection in future clinical investigations involving INPH 5).



All patients with idiopathic normal pressure hydrocephalus (INPH) who underwent shunting in Sweden in 2008-2010 were compared to age- and sex-matched population-based controls. Inclusion criteria were age 60-85 years and no dementia. The 10 most important vascular risk factor (VRFs) and cerebrovascular and peripheral vascular disease were prospectively assessed using blood samples, clinical examinations, and standardized questionnaires. Assessed VRFs were hypertension, hyperlipidemia, diabetes, obesity, psychosocial factors, smoking habits, diet, alcohol intake, cardiac disease, and physical activity.

In total, 176 patients with INPH and 368 controls participated. Multivariable logistic regression analysis indicated that hyperlipidemia (odds ratio [OR] 2.380; 95% confidence interval [CI] 1.434-3.950), diabetes (OR 2.169; 95% CI 1.195-3.938), obesity (OR 5.428; 95% CI 2.502-11.772), and psychosocial factors (OR 5.343; 95% CI 3.219-8.868) were independently associated with INPH. Hypertension, physical inactivity, and cerebrovascular and peripheral vascular disease were also overrepresented in INPH. Moderate alcohol intake and physical activity were overrepresented among the controls. The population-attributable risk percentage was 24%.

The findings confirm that patients with INPH have more VRFs and lack the protective factors present in the general population. Almost 25% of cases of INPH may be explained by VRFs. This suggests that INPH may be a subtype of vascular dementia. Targeted interventions against modifiable VRFs are likely to have beneficial effects on INPH 6).

Although the exact pathogenesis of NPH is unknown, many possible causes have been postulated, including cerebrovascular ischemia. Studies have demonstrated that periventricular blood flow and cerebrovascular autoregulation are reduced.

It is also thought that biomechanical changes, such as the combination of tissue distortion caused by ventricular dilation, CSF and interstitial fluid stasis, and impaired autoregulation may result in failure of drainage of neurotoxic compounds such as amyloid-b.

Increased CSF stroke volume through the aqueduct has also been demonstrated in the NPH population despite normal CSF pressures. The reaction of the cerebral mantle to all or some of these processes is poorly understood. It is thought that white matter tract connections serving the cortex could be disrupted in a variety of ways, including disconnection, swelling, stretching, and compression. Therefore, it is possible that some types of disruption may be more tolerable (i.e., more reversible) than others.

Only a few studies have seized the opportunity to reevaluate the theories of pathogenesis of NPH using developments in imaging techniques.

The disorders of Alzheimer disease, vascular dementia and normal pressure hydrocephalus are all causes of dementia in the elderly population. It is often the case that it is clinically very difficult to tell these diseases apart. All three forms of dementia share the same risk factors, which for the most part are vascular risk factors. Bateman proposes that there is an underlying vascular pathophysiology behind these conditions, which is related to the strength of the pulse waves induced in the craniospinal cavity by the arterial vascular tree. It is proposed the manifestation of the dementia in any one patient is dependant on the way that the pulsations interact with the brain and its venous and perivascular drainage. This interaction is predominately dependant on the compliance of the craniospinal cavity and the chronicity of the increased pulse wave stress 7).

Experimental animal model

Kaolin was injected bilaterally into the subarachnoid space overlying the cranial convexities in 20 adult rats. Magnetic resonance imaging (MRI) was obtained by using an 11.7 T scanner at 14, 60, 90, and 120 days after kaolin injection. Locomotor, gait, and cognitive evaluations were performed independently. Kaolin distribution and the associated inflammatory and fibrotic responses were histologically analyzed.

Evans index of ventriculomegaly showed significant progressive growth in ventricular size over all time points examined. The greatest enlargement occurred within the first 2 months. Evans index also correlated with the extent of kaolin distribution by MRI and by pathological examination at all time points. First gait changes occurred at 69 days, anxiety at 80, cognitive impairment at 81, and locomotor difficulties after 120 days. Only locomotor deterioration was associated with Evans index or the radiological evaluation of kaolin extension. Inflammatory/fibrotic response was histologically confirmed over the cranial convexities in all rats, and its extension was associated with ventricular size and with the rate of ventricular enlargement.

Kaolin injected into the subarachnoid space over the cerebral hemispheres of adult rats produces an inflammatory/fibrotic response leading in a slow-onset communicating hydrocephalus that is initially asymptomatic. Increased ventricular size eventually leads to gait, memory, and locomotor impairment closely resembling the course of human adult chronic hydrocephalus 8).


Disturbed cerebrospinal fluid (CSF) dynamics are part of the pathophysiology of normal pressure hydrocephalus (NPH).

A study investigated the contribution of established CSF dynamic parameters to mean pulse amplitude (AMP), a prognostic variable defined as mean amplitude of cardiac-related intracranial pressure pulsations during 10 min of lumbar infusion test, with the aim of clarifying the physiological interpretation of the variable. AMP(mean) and CSF dynamic parameters were determined from infusion tests performed on 18 patients with suspected NPH. Using a mathematical model of CSF dynamics, an expression for AMP(mean) was derived and the influence of the different parameters was assessed. There was high correlation between modelled and measured AMP(mean) (r = 0.98, p < 0.01). Outflow resistance and three parameters relating to compliance were identified from the model. Correlation analysis of patient data confirmed the effect of the parameters on AMP(mean) (Spearman’s ρ = 0.58-0.88, p < 0.05). Simulated variations of ±1 standard deviation (SD) of the parameters resulted in AMP(mean) changes of 0.6-2.9 SD, with the elastance coefficient showing the strongest influence. Parameters relating to compliance showed the largest contribution to AMP(mean), which supports the importance of the compliance aspect of CSF dynamics for the understanding of the pathophysiology of NPH 9).

Clinical Features

Elderly presenting with gait abnormality, cognitive decline, and urinary incontinence, with enlarged ventricles of the brain but normal or slightly elevated cerebrospinal fluid (CSF) pressure 10) 11).

Postural stability in NPH is predominantly affected by deficient vestibular functions, which did not improve after spinal tap test. Conditions which improved best were mainly independent from visual control and are based on proprioceptive functions 12).

The natural course of iNPH is symptom progression over time, with worsening in gait, balance and cognitive symptoms. This deterioration is only partially reversible.

Currently there is no pathological hallmark for iNPH 13).

It is frequently present with cerebral vasculopathy; significantly increased prevalence of cardiovascular disease iNPH patients, which provide evidence that cardiovascular disease is involved as an exposure in the development of iNPH 14).

Idiopathic normal pressure hydrocephalus (iNPH) may present, besides the classic triad of symptoms, extrapiramidal parkinsonian like movement disorders.



There is no accurate test for diagnosing normal pressure hydrocephalus or for screening for patients who will benefit from shunt surgery.

Shunting is possibly effective in iNPH (96% chance subjective improvement, 83% chance improvement on timed walk test at 6 months) (3 Class III). Serious adverse event risk was 11% (1 Class III). Predictors of success included elevated Ro (1 Class I, multiple Class II), impaired cerebral blood flow reactivity to acetazolamide (by SPECT) (1 Class I), and positive response to either external lumbar drainage (1 Class III) or repeated lumbar punctures. Age may not be a prognostic factor (1 Class II). Data are insufficient to judge efficacy of radionuclide cisternography or aqueductal flow measurement by MRI.

There is limited Class I evidence that impaired cerebral blood flow (CBF) reactivity to acetazolamide is a predictor of successful CSF shunting, but single photon emission computed tomography (SPECT) is not a practical screening tool for NPH.


There remains a lack of consensus about the role of individual imaging modalities in characterizing specific features of the condition and predicting the success of CSF shunting. Variability of clinical presentation and imperfect responsiveness to shunting are obstacles to the application of novel imaging techniques. Few studies have sought to interpret imaging findings in the context of theories of NPH pathogenesis 15).

Although attempts at predictive methodology, such as highvelocity aqueductal flow rate measurement on MRI, have achieved widespread acceptance in clinical practice, there is no Class I evidence (only 1 Class II study and 2 Class III studies) available to support this 16).


NPH is characterized by an ongoing periventricular neuronal dysfunction seen on MRI as periventricular hyperintensity (PVH). Clinical improvement after shunt surgery is associated with CSF changes indicating a restitution of axonal function. Other biochemical effects of shunting may include increased monoaminergic and peptidergic neurotransmission, breakdown of blood brain barrier function, and gliosis 17).

An MRI-based diagnostic scheme used in a multicenter prospective study (Study of Idiopathic Normal Pressure Hydrocephalus on Neurological Improvement [SINPHONI]) appears to suggest that features of disproportionately enlarged subarachnoid-space hydrocephalus (DESH) are meaningful in the evaluation of NPH 18).


In a retrospective cohort study, Kojoukhova et al evaluated brain CT or MRI scans of 390 patients with suspected iNPH. Based on a 24-h intraventricular pressure monitoring session, patients were classified into a non-NPH (n = 161) or probable iNPH (n = 229) group. Volumes of cerebrospinal fluid compartments (lateral ventricles, sylvian and suprasylvian subarachnoid spaces and basal cisterns) were visually assessed. Disproportionally enlarged subarachnoid spaces, flow void, white matter changes, medial temporal lobe atrophy and focally dilated sulci were evaluated. Moreover, we measured quantitative markers: Evans’ index (EI), the modified cella media index, mean width of the temporal horns and callosal angle.

iNPH was more likely in patients with severe volumetric disproportion between the suprasylvian and sylvian subarachnoid spaces than in those without disproportion (OR 7.5, CI 95 % 4.0-14.1, P < 0.0001). Mild disproportion (OR 2.6, CI 95 % 1.4-4.6, P = 0.001) and narrow temporal horns (OR per 1 mm 0.91, CI 95 % 0.84-0.98, P = 0.014) were also associated with an iNPH diagnosis. Other radiological markers had little association with the iNPH diagnosis in the final combined multivariate model. Interestingly, EI was higher in non-NPH than iNPH patients (0.40 vs. 0.38, P = 0.039). Preoperative radiological markers were not associated with shunt response.

Visually evaluated disproportion was the most useful radiological marker in iNPH diagnostics. Narrower temporal horns also supported an iNPH diagnosis, possibly since atrophy was more pronounced in the non-NPH than iNPH group 19).

The Evans index is useful as a marker of ventricular volume and thus has been proposed as a helpful biomarker in the diagnosis of normal pressure hydrocephalus (NPH)

Unfortunately it is a very rough marker of ventriculomegaly, and varies greatly depending on the location and angle of the slice.

As such Evans’ index has little role to play in day-to-day reporting.

Phase contrast magnetic resonance imaging

Psychomotor Tasks

Although gait is the primary indicator for treatment candidacy and outcome, additional monitoring tools are needed. Line Tracing Test (LTT) and Serial Dotting Test (SDT), two psychomotor tasks, have been introduced as potential outcome measures20).

Lumbar infusion test

Cerebrospinal fluid tap test

Cerebrospinal fluid tap test (CSF-TT), are often used in practice to provide further predictive value in detecting suitable patients for shunting.

Pressure recording

see Idiopathic normal pressure hydrocephalus intracranial pressure monitoring


Alzheimer disease (AD)-related pathology was assessed in cortical biopsy samples of 111 patients with idiopathic normal-pressure hydrocephalus. Alzheimer disease hallmark lesions amyloid beta (Aβ) and hyperphosphorylated tau protein (HPtau)-were observed in 47% of subjects, a percentage consistent with that for whole-brain assessment reported postmortem in unselected cohorts. Higher-immunostained area fraction of AD pathology corresponded with lower preoperative mini mental state examination scores. Concomitant Aβ and HPtau pathology, reminiscent of that observed in patients with AD, was observed in 22% of study subjects. There was a significant correlation between Aβ-immunostained area fraction in tissue and Aβ42 (42-amino-acid form of Aβ) in cerebrospinal fluid (CSF). Levels of Aβ42 were significantly lower in CSF in subjects with concomitant Aβ and HPtau pathology compared with subjects lacking pathology. Moreover, a significant correlation between HPtau-immunostained area fraction and HPtau in CSF was noted. Both HPtau and total tau were significantly higher in CSF in subjects with concomitant Aβ and HPtau pathology compared with subjects lacking pathology. The 42-amino-acid form of Aβ (Aβ42) and HPtau in CSF were the most significant predictors of the presence of AD pathology in cortical biopsies. Long-term follow-up studies are warranted to assess whether all patients with idiopathic normal-pressure hydrocephalus with AD pathology progress to AD and to determine the pathologic substrate of idiopathic normal-pressure hydrocephalus 21).

Differential diagnosis

Secondary normal pressure hydrocephalus (NPH) does indeed exist and should be differentiated from iNPH based on outcome as well as clinical, pathophysiological, and epidemiological characteristics but should not be considered as a separate entity. Evaluation of patients with NPH to identify a known cause is recommended because the response to treatment varies considerably. Although clinical presentation is often the same, a multitude of primary etiologies can lead to the development of sNPH. The most common etiologies of sNPH include SAH, traumatic brain injury, intracranial malignancies, meningitis, and stroke. Further studies are required to investigate differences in management and outcome among the diverse etiologies of sNPH 22).

In Alzheimer’s disease (AD) patients, diffuse aggregates of amyloid-β (Aβ) and neurofibrillary hyperphosphorylated tau are detected in the neocortex of the brain, while similar accumulation of Aβ is also detected in iNPH.

Apolipoprotein E (APOE4) affects the Aβ deposition in the brain of iNPH and AD patients in a similar manner 23).

APOE4 is not a risk factor for iNPH and does not predict the response to shunt. Data further support the view that the iNPH syndrome is a distinct dementing disease 24).


Shunt surgery has been established as the only durable and effective treatment for idiopathic normal pressure hydrocephalus

To maximise the benefits of shunt treatment, surgery should be performed soon after diagnosis 25).

The results of a prospective multicentre study on patients with iNPH diagnosed solely on clinical and radiological criteria support shunt surgery in patients presenting with symptoms and signs and MRI findings suggestive of iNPH 26).


Endoscopic third ventriculostomy

The only randomized trial of endoscopic third ventriculostomy (ETV) for idiopathic normal pressure hydrocephalus (iNPH) compares it to an intervention which is not a standard practice (VP shunting using a non-programmable valve). The evidence from this study is inconclusive and of very low quality. Clinicians should be aware of the limitations of the evidence. There is a need for more robust research on this topic to be able to determine the effectiveness of ETV in patients with iNPH 27).



Subdural collections, shunt malfunction, and postoperative seizures constituted the most frequent complications 28).

see Shunt overdrainage in idiopathic normal pressure hydrocephalus.

Case series


Twelve of 56 patients with NPH-like symptoms presented with morphological aqueductal stenosis (AS) (21.4 %). Patent aqueduct and non-patent aqueduct groups had similar values of mean opening lumbar pressure (8.2 vs. 8.1 mmHg), and mean opening pulse amplitude (3.1 vs. 2.9 mmHg). Mean pressure in the plateau stage (28.6 vs. 23.2 mmHg), and mean pulse amplitude in the plateau stage (12.5 vs. 10.6 mmHg) were higher in the patent aqueduct group. These differences were not statistically significant. Only Rout was significantly higher in the patent aqueduct group (13.6 vs. 10.1 mmHg/ml/min). One-third of NPH patients with AS presented Rout >12 mmHg/ml/min.

No differences in mean pressure or pulse amplitude during basal and plateau epochs of the lumbar infusion test in NPH patients were detected, regardless of aqueductal patency. However, Rout was significantly higher in patients with patent aqueduct 29).

Bir et al., retrospectively reviewed the clinical notes of 2001 patients with adult-onset hydrocephalus who presented to Louisiana State University Health Sciences Center within a 25-year span. Significant differences between the groups were analyzed by a chi-square test; p < 0.05 was considered significant.

The overall mean (± SEM) incidence of adult hydrocephalus in this population was 77 ± 30 per year, with a significant increase in incidence in the past decade (55 ± 3 [1990-2003] vs 102 ± 6 [2004-2015]; p < 0.0001). Hydrocephalus in a majority of the patients had a vascular etiology (45.5%) or was a result of a tumor (30.2%). The incidence of hydrocephalus in different age groups varied according to various pathologies. The incidence was significantly higher in males with normal-pressure hydrocephalus (p = 0.03) or head injury (p = 0.01) and higher in females with pseudotumor cerebri (p < 0.0001). In addition, the overall incidence of hydrocephalus was significantly higher in Caucasian patients (p = 0.0002) than in those of any other race.

Knowledge of the demographic variations in adult-onset hydrocephalus is helpful in achieving better risk stratification and better managing the disease in patients. For general applicability, these results should be validated in a large-scale meta-analysis based on a national population database 30).

A detailed screening process included neurological, neurosurgical and neuropsychological evaluations, followed by cerebrospinal fluid (CSF) tap test (TT) and resistance outflow (Ro) measurement. Outcome was evaluated through the Japanese NPH grading scale-revised (JNPHGSR) and the motor (third) section of the Unified Parkinson’s Disease Rating Scale (UPDRS-m). Friedman’s analysis of variance with Wilcoxon post-hoc test was used to evaluate the difference in JNPHGSR and UPDRS-m scores between pre-treatment and follow-up (12 months) in the two groups, while Kruskal-Wallis statistic and post-hoc Mann-Whitney test was used to compare the change in JNPHGSR and UPDRS-m scores between the two groups.

32/54 (59%) patients (mean age 73.2) screened in 36 months met the inclusion criteria, but only 30 were enrolled (two refused surgery), 15 in each group. Preoperative 123I-Ioflupane-cerebral SPECT (DaTSCAN) revealed striatal dopaminergic deficit in 14/30 patients (46.5%). At the final 12 months follow-up, both groups improved JNPHGSR and UPRDS-m scores. The UPDRS-m score improvement was significant in both groups, but greater in group A (p0.003); JNPHGSR score improvement was similar in the two groups.

iNPH associated with parkinsonism may be a frequent finding. In these cases, patients may benefit from VP shunt plus dopamine oral therapy 31).

From 2008 to 2013, consecutive patients diagnosed with INPH based on clinical and radiological criteria were included in a single-centre study. All patients received programmable-valve ventriculoperitoneal shunts. Outcome measures were assessed at baseline, 3, 6 and 12months post-operatively. Outcomes included gait time and scores on the Unified Parkinson’s Disease Rating Scale part III (UPDRS-III), the Addenbrooke’s Cognitive Examination Revised (ACE-R) and the Mini-Mental State Examination (MMSE). Thresholds for improvements were set a priori as ⩾20% decrease in gait time, ⩾10point decrease in UPDRS-III score, ⩾5point increase in ACE-R score and ⩾2point increase in MMSE score at last follow-up. The proportion of patients improving varied between measures, being gait time (60%), UPDRS-III (69%), MMSE (63%), and ACE-R (56%). Overall, improvement in at least one outcome measure was observed in 85% of patients and 38% improved in gait time, UPDRS-III score and cognitive scores. Only 15% of patients experienced no improvement on any measure. This study demonstrates that the majority of INPH patients can sustain improvements in multiple symptoms up to 12months after shunting 32).


A study included 29 patients with a mean age of 73.9 years; 62.1% were male and 65.5% had hypertension. Clinical improvement (complete or partial) was observed in 58% after one year and in 48% by the end of the follow-up period (mean follow-up time was 37.8 months). Older age, presence of hypertension, and surgery-related complications were more prevalent in the group responding poorly to treatment. One patient died, 20.7% experienced severe complications, and 69% were dependent (mRS ≥ 3) by the end of the follow-up period. Age at diagnosis was independently associated with poorer clinical response at one year and a higher degree of dependency by the end of follow-up.

Symptomatic benefits offered by VPS were partial and transient; treatment was associated with a high complication rate and poor functional outcomes in the long term, especially in the oldest patients 33).


Fifty-one patients were included after confirmation of the diagnosis by extensive clinical and diagnostic investigations. Surgery included ventriculoatrial or ventriculoperitoneal shunting with differential pressure valves in the majority of patients. For each of the cardinal symptoms, postoperative outcome was assessed separately with the Krauss Improvement Index, yielding a value between 0 (no benefit) and 1 (optimal benefit) for the overall outcome.

Mean age at surgery was 70.2 years (range, 50-87 years). Thirty patients were women, and 21 were men. Short-term (18.8 +/- 16.6 months) follow-up was available for 50 patients. The Krauss Improvement Index was 0.66 +/- 0.28. Long-term (80.9 +/- 51.6 months) follow-up was available for 34 patients. The Krauss Improvement Index was 0.64 +/-0.33. Twenty-nine patients died during the long-term follow-up at a mean age of 75.8 years (range, 55-95 years). The major causes of death were cardiovascular disorders: cardiac failure (n = 7) and cerebral ischemia (n = 12). Other causes were pneumonia (n = 2), acute respiratory distress syndrome (n = 1), pulmonary embolism (n = 1), cancer (n = 2), renal failure (n = 1), and unknown (n = 3). There was no shunt-related mortality.

Idiopathic normal pressure hydrocephalus patients may benefit from shunting over the long term when rigorous selection criteria are applied. Shunt-related mortality is negligible. The main cause of death is vascular comorbidity 34).

1) Hakim S, Adams RD. The special clinical problem of symptomatic hydrocephalus with normal cerebrospinal fluid pressure. Observations on cerebrospinal fluid hydrodynamics. J Neurol Sci. 1965 Jul-Aug;2(4):307-27. PubMed PMID: 5889177.
2) Finney GR. Normal pressure hydrocephalus. Int Rev Neurobiol. 2009;84:263-81. doi: 10.1016/S0074-7742(09)00414-0. Review. PubMed PMID: 19501723.
3) Martín-Láez R, Caballero-Arzapalo H, López-Menéndez LÁ, Arango-Lasprilla JC, Vázquez-Barquero A. Epidemiology of Idiopathic Normal Pressure Hydrocephalus: A Systematic Review of the Literature. World Neurosurg. 2015 Jul 13. pii: S1878-8750(15)00871-2. doi: 10.1016/j.wneu.2015.07.005. [Epub ahead of print] Review. PubMed PMID: 26183137.
4) Iseki C, Kawanami T, Nagasawa H, Wada M, Koyama S, Kikuchi K, Arawaka S, Kurita K, Daimon M, Mori E, Kato T. Asymptomatic ventriculomegaly with features of idiopathic normal pressure hydrocephalus on MRI (AVIM) in the elderly: a prospective study in a Japanese population. J Neurol Sci. 2009 Feb 15;277(1-2):54-7. doi: 10.1016/j.jns.2008.10.004. Epub 2008 Nov 5. PubMed PMID: 18990411.
5) Relkin N, Marmarou A, Klinge P, Bergsneider M, Black PM. Diagnosing idiopathic normal-pressure hydrocephalus. Neurosurgery. 2005 Sep;57(3 Suppl):S4-16; discussion ii-v. Review. PubMed PMID: 16160425.
6) Israelsson H, Carlberg B, Wikkelsö C, Laurell K, Kahlon B, Leijon G, Eklund A, Malm J. Vascular risk factors in INPH: A prospective case-control study (the INPH-CRasH study). Neurology. 2017 Jan 6. pii: 10.1212/WNL.0000000000003583. doi: 10.1212/WNL.0000000000003583. [Epub ahead of print] PubMed PMID: 28062721.
7) Bateman GA. Pulse wave encephalopathy: a spectrum hypothesis incorporating Alzheimer’s disease, vascular dementia and normal pressure hydrocephalus. Med Hypotheses. 2004;62(2):182-7. PubMed PMID: 14962623.
8) Jusué-Torres I, Jeon LH, Sankey EW, Lu J, Vivas-Buitrago T, Crawford JA, Pletnikov MV, Xu J, Blitz A, Herzka DA, Crain B, Hulbert A, Guerrero-Cazares H, Gonzalez-Perez O, McAllister JP 2nd, Quiñones-Hinojosa A, Rigamonti D. A Novel Experimental Animal Model of Adult Chronic Hydrocephalus. Neurosurgery. 2016 Nov;79(5):746-756. PubMed PMID: 27759679.
9) Qvarlander S, Malm J, Eklund A. CSF dynamic analysis of a predictive pulsatility-based infusion test for normal pressure hydrocephalus. Med Biol Eng Comput. 2014 Jan;52(1):75-85. doi: 10.1007/s11517-013-1110-1. Epub 2013 Oct 23. PubMed PMID: 24151060.
10) Hakim S, Adams RD (1965) The special clinical problem of symptomatic hydrocephalus with normal cerebrospinal fluid pressure. Observations on cerebrospinal fluid hydrodynamics. J Neurol Sci 2: 307–327.
11) Adams RD, Fischer CM, Hakim S, Ojemann RG, Sweet WH (1965) Symptomatic occult hydrocephalus with “normal” cerebrospinal-fluid pressure. A treatable syndrome. N Engl J Med 273: 117–126.
12) Abram K, Bohne S, Bublak P, Karvouniari P, Klingner CM, Witte OW, Guntinas-Lichius O, Axer H. The Effect of Spinal Tap Test on Different Sensory Modalities of Postural Stability in Idiopathic Normal Pressure Hydrocephalus. Dement Geriatr Cogn Dis Extra. 2016 Sep 27;6(3):447-457. PubMed PMID: 27790243; PubMed Central PMCID: PMC5075737.
13) Leinonen V, Koivisto AM, Savolainen S, Rummukainen J, Sutela A, et al. (2012) Post-mortem findings in 10 patients with presumed normal-pressure hydrocephalus and review of the literature. Neuropathol Appl Neurobiol 38: 72–86.
14) Eide PK, Pripp AH. Increased prevalence of cardiovascular disease in idiopathic normal pressure hydrocephalus patients compared to a population-based cohort from the HUNT3 survey. Fluids Barriers CNS. 2014 Aug 19;11:19. doi: 10.1186/2045-8118-11-19. eCollection 2014. PubMed PMID: 25180074; PubMed Central PMCID: PMC4150119.
15) Keong NC, Pena A, Price SJ, Czosnyka M, Czosnyka Z, Pickard JD. Imaging normal pressure hydrocephalus: theories, techniques, and challenges. Neurosurg Focus. 2016 Sep;41(3):E11. doi: 10.3171/2016.7.FOCUS16194. PubMed PMID: 27581307.
16) Halperin JJ, Kurlan R, Schwalb JM, Cusimano MD, Gronseth G, Gloss D: Practice guideline: Idiopathic normal pressure hydrocephalus: Response to shunting and predictors of response: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology. Neurology 85:2063–2071, 2015
17) Tullberg M, Blennow K, Månsson JE, Fredman P, Tisell M, Wikkelsö C. Ventricular cerebrospinal fluid neurofilament protein levels decrease in parallel with white matter pathology after shunt surgery in normal pressure hydrocephalus. Eur J Neurol. 2007 Mar;14(3):248-54. PubMed PMID: 17355543.
18) Hattori T, Ito K, Aoki S, Yuasa T, Sato R, Ishikawa M, et al: White matter alteration in idiopathic normal pressure hydrocephalus: tract-based spatial statistics study. AJNR Am J Neuroradiol 33:97–103, 2012
19) Kojoukhova M, Koivisto AM, Korhonen R, Remes AM, Vanninen R, Soininen H, Jääskeläinen JE, Sutela A, Leinonen V. Feasibility of radiological markers in idiopathic normal pressure hydrocephalus. Acta Neurochir (Wien). 2015 Oct;157(10):1709-18; discussion 1719. doi: 10.1007/s00701-015-2503-8. Epub 2015 Jul 21. PubMed PMID: 26190755.
20) Rossetti MA, Piryatinsky I, Ahmed FS, Klinge PM, Relkin NR, Salloway S, Ravdin LD, Brenner E, Malloy PF, Levin BE, Broggi M, Gavett R, Maniscalco JS, Katzen H. Two Novel Psychomotor Tasks in Idiopathic Normal Pressure Hydrocephalus. J Int Neuropsychol Soc. 2016 Mar;22(3):341-9. doi: 10.1017/S1355617715001125. Epub 2016 Jan 28. PubMed PMID: 26817685.
21) Elobeid A, Laurell K, Cesarini KG, Alafuzoff I. Correlations Between Mini-Mental State Examination Score, Cerebrospinal Fluid Biomarkers, and Pathology Observed in Brain Biopsies of Patients With Normal-Pressure Hydrocephalus. J Neuropathol Exp Neurol. 2015 May;74(5):470-479. PubMed PMID: 25868149.
22) Daou B, Klinge P, Tjoumakaris S, Rosenwasser RH, Jabbour P. Revisiting secondary normal pressure hydrocephalus: does it exist? A review. Neurosurg Focus. 2016 Sep;41(3):E6. doi: 10.3171/2016.6.FOCUS16189. PubMed PMID: 27581318.
23) Laiterä T, Paananen J, Helisalmi S, Sarajärvi T, Huovinen J, Laitinen M, Rauramaa T, Alafuzoff I, Remes AM, Soininen H, Haapasalo A, Jääskeläinen JE, Leinonen V, Hiltunen M. Effects of Alzheimer’s Disease-Associated Risk Loci on Amyloid-β Accumulation in the Brain of Idiopathic Normal Pressure Hydrocephalus Patients. J Alzheimers Dis. 2016 Oct 11. [Epub ahead of print] PubMed PMID: 27802227.
24) Pyykkö OT, Helisalmi S, Koivisto AM, Mölsä JA, Rummukainen J, Nerg O, Alafuzoff I, Savolainen S, Soininen H, Jääskeläinen JE, Rinne J, Leinonen V, Hiltunen M. APOE4 predicts amyloid-β in cortical brain biopsy but not idiopathic normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry. 2012 Nov;83(11):1119-24. doi: 10.1136/jnnp-2011-303849. PubMed PMID: 22955176.
25) Andrén K, Wikkelsø C, Tisell M, Hellström P. Natural course of idiopathic normal pressure hydrocephalus. J Neurol Neurosurg Psychiatry. 2013 Nov 29. doi: 10.1136/jnnp-2013-306117. [Epub ahead of print] PubMed PMID: 24292998.
26) Klinge P, Hellström P, Tans J, Wikkelsø C; European iNPH Multicentre Study Group. One-year outcome in the European multicentre study on iNPH. Acta Neurol Scand. 2012 Sep;126(3):145-53. doi: 10.1111/j.1600-0404.2012.01676.x. Epub 2012 May 10. PubMed PMID: 22571428.
27) Tudor KI, Tudor M, McCleery J, Car J. Endoscopic third ventriculostomy (ETV) for idiopathic normal pressure hydrocephalus (iNPH). Cochrane Database Syst Rev. 2015 Jul 29;7:CD010033. doi: 10.1002/14651858.CD010033.pub2. Review. PubMed PMID: 26222251.
28) Black PM. Idiopathic normal-pressure hydrocephalus. Results of shunting in 62 patients. J Neurosurg. 1980 Mar;52(3):371-7. PubMed PMID: 7359191.
29) González-Martínez EL, Santamarta D. Does aqueductal stenosis influence the lumbar infusion test in normal-pressure hydrocephalus? Acta Neurochir (Wien). 2016 Oct 11. PubMed PMID: 27730385.
30) Bir SC, Patra DP, Maiti TK, Sun H, Guthikonda B, Notarianni C, Nanda A. Epidemiology of adult-onset hydrocephalus: institutional experience with 2001 patients. Neurosurg Focus. 2016 Sep;41(3):E5. doi: 10.3171/2016.7.FOCUS16188. PubMed PMID: 27581317.
31) Broggi M, Redaelli V, Tringali G, Restelli F, Romito L, Schiavolin S, Tagliavini F, Broggi G. Normal pressure hydrocephalus and parkinsonism: preliminary data on neurosurgical and neurological treatment. World Neurosurg. 2016 Mar 9. pii: S1878-8750(16)00408-3. doi: 10.1016/j.wneu.2016.03.004. [Epub ahead of print] PubMed PMID: 26970480.
32) Shaw R, Everingham E, Mahant N, Jacobson E, Owler B. Clinical outcomes in the surgical treatment of idiopathic normal pressure hydrocephalus. J Clin Neurosci. 2016 Feb 27. pii: S0967-5868(15)00717-1. doi: 10.1016/j.jocn.2015.10.044. [Epub ahead of print] PubMed PMID: 26935749.
33) Illán-Gala I, Pérez-Lucas J, Martín-Montes A, Máñez-Miró J, Arpa J, Ruiz-Ares G. Long-term outcomes of adult chronic idiopathic hydrocephalus treated with a ventriculo-peritoneal shunt. Neurologia. 2015 Dec 31. pii: S0213-4853(15)00230-3. doi: 10.1016/j.nrl.2015.10.002. [Epub ahead of print] English, Spanish. PubMed PMID: 26749191.
34) Mirzayan MJ, Luetjens G, Borremans JJ, Regel JP, Krauss JK. Extended long-term (> 5 years) outcome of cerebrospinal fluid shunting in idiopathic normal pressure hydrocephalus. Neurosurgery. 2010 Aug;67(2):295-301. doi: 10.1227/01.NEU.0000371972.74630.EC. PubMed PMID: 20644414.

Update: Transient obstructive hydrocephalus


While obstructive hydrocephalus is a relatively common and potentially life-threatening condition, transient obstructive hydrocephalus is a rare condition in adults.


Transient obstruction of cerebrospinal fluid (CSF) flow through the ventricular system has been reported to result from systemic causes such as lead and carbon monoxide poisoning as well as CNS infections and meningitis 1).

Previous case reports have also described spontaneous resolution of obstructive hydrocephalus after intraventricular hemorrhage (IVH) in neonates and adults.

Transient acute hydrocephalus after spontaneous intracranial bleeding in adults 2).

Obstructive hydrocephalus with deterioration of consciousness from a ruptured arteriovenous malformation (AVM) requires urgent decompression, but also vigilance during the preoperative stage in case of rare spontaneous resolution 3).

The acute phase in a cerebellar infarction may become complicated with transient obstructive hydrocephalus, subsequent intracranial hypertension, and the need for surgical management. Although many patients respond well to medical treatment, clinical findings and neuroimaging methods must be considered to determine whether the hydrocephalus can be surgically treated in a timely fashion.

In fourteen patients, six required surgery for hydrocephalus management. Three of the cases had an endoscopic third ventriculostomy without complications, the rest were managed conservatively. As an average, patency was re-established in the aqueduct three months post ictus.

Management of obstructive hydrocephalus in the acute phase of a cerebellar stroke must be individualized. In cases with transient obstructive hydrocephalus, endoscopic third ventriculostomy is a good surgical treatment option that avoids the risks of a long-term ventricular shunt 4).

Case reports


Two cases of transient obstructive hydrocephalus caused by obstruction of mesencephalic duct in patients that presented with altered consciousness which resolved spontaneously in a few hours5).

A 66-year-old male was admitted with sudden onset right-sided hemiparesia. CT demonstrated a hematoma on the left basal ganglia with extension to all ventricles. The following day, the patient’s neurological status progressed to coma and developed bilateral pyramidal signs. MRI demonstrated obstructive hydrocephalus and acute diffuse infarction accompanied by elevation of the CC. On the same day there was improvement in his neurological status with significant decrease in ventricular size and complete resolution of the clot in the third ventricle. The mechanism of signal abnormalities is probably related with the neural compression of the CC against the falx. Presumably, the clot causing obstruction in the third ventricle dissolved or decayed by the help of fibrinolytic activity of CSF, which was raised after IVH and caused spontaneous improvement of hydrocephalus. Bilateral neurological symptoms suggest diffuse axonal damage and normalization of the intracranial pressure should be performed on the early onset of clinical detorioration in order to prevent axonal injury 6).


A 33-year-old man with a previously diagnosed Spetzler-Martin Grade 5 arteriovenous malformation presented with severe headache, which was found to be due to IVH. Forty hours after presentation he developed significant obstructive hydrocephalus due to the thrombus migrating to the cerebral aqueduct, and a ventriculostomy placement was planned. However, shortly thereafter his headache began to improve spontaneously. Within 4 hours after onset the headache had completely resolved, and an interval head CT scan revealed resolution of hydrocephalus.

In patients with IVH, acute obstructive hydrocephalus can develop at any time after the ictus. Though a delayed presentation of acute but transient obstructive hydrocephalus is unusual, it is important to be aware of this scenario and ensure that deterioration secondary to thrombus migration and subsequent obstructive hydrocephalus do not occur 7).

Transient obstructive hydrocephalus following traumatic brain injury 8).


Transient obstructive hydrocephalus by intraventricular fat migration after surgery of the posterior fossa 9).


A 86-year-old man with right frontal stroke developed obstructive hydrocephalus caused by blood in the cerebral aqueduct. The patient had sudden and immediate clinical improvement and a repeated head computed tomography (CT) scan showing spontaneous resolution of hydrocephalus. Spontaneous resolution of obstructive hydrocephalus is possible when the cause is minimal blood in the cerebral aqueduct without any blood in the fourth ventricle 10).


Spontaneous resolution of acute hydrocephalus without aspiration of cerebral fluid is rare. In a neonate born at full term this has only been reported once before. Abubacker et al., report on one further case that was caused by intraventricular haemorrhage (IVH). The probable mechanism is resolution of the acute haemorrhage in the region of the aqueduct, resulting in resolution of the hydrocephalus itself. The importance of considering conservative management of acute hydrocephalus in the clinically stable neonate is emphasised 11).


A 64-year-old woman presented with headache. Computerized tomography (CT) scan revealed hydrocephalus with tiny blood clots in the left foramen of Monro and in the aqueduct. Six hours after the onset, the signs and symptoms disappeared spontaneously. The second CT showed improvement of the hydrocephalus with migration of the clot into the i.v. ventricle. Aqueductal trapping and releasing of the clot formed by bleeding from the choroid plexus located in the left foramen of Monro was suspected for the origin of the transient hydrocephalus 12).


Acute transient hydrocephalus in carbon monoxide poisoning: a case report 13).


In the Sultanate of Oman acute lead encephalopathy in neonates is common. Brain oedema in acute lead encephalopathy occurs predominantly in the cerebellar vermis and may act as a midline posterior fossa mass, occluding the fourth ventricle. The resultant transient obstructive hydrocephalus may need emergency drainage of cerebro-spinal fluid. The hydrocephalus is transient as vermis oedema subsides with medical treatment. Two such cases are reported and discussed 14).


Spontaneous resolution of acute hydrocephalus. A case report 15).


One and a half years old boy was admitted with vomiting and somnolence four days after head injury. The first CT scans taken on admission showed high density areas in the prepontine and ambient cisterns and in the aqueduct. The lateral and third ventricles were dilated, while the fourth ventricle was normal. On the 2nd hospital day he was nearly asymptomatic. The second CT scans done seven days after injury no longer revealed the high density areas and the ventricular dilatation. Vomiting is one of the most important signs for intracranial mass lesions after head injury. But children often vomit even without having mass lesions, and CT scan is useful for evaluation of such cases. In our case, vomiting was probably due to aqueductal obstruction by a small clot resulting acute hydrocephalus, as revealed by CT scans. This case suggested that transient obstructive hydrocephalus must be taken into consideration as one of causes for posttraumatic vomiting 16).

1) Dubey AK, Rao KL. Pathology of post meningitic hydrocephalus. Indian J Pediatr. 1997 Nov-Dec;64(6 Suppl):30-3. Review. PubMed PMID: 11129878.
2) Hou K, Zhu X, Sun Y, Gao X, Zhao J, Zhang Y, Li G. Transient acute hydrocephalus after spontaneous intracranial bleeding in adults. World Neurosurg. 2016 Dec 31. pii: S1878-8750(16)31418-8. doi: 10.1016/j.wneu.2016.12.103. [Epub ahead of print] PubMed PMID: 28049036.
3) Inamura T, Kawamura T, Inoha S, Nakamizo A, Fukui M. Resolving obstructive hydrocephalus from AVM. J Clin Neurosci. 2001 Nov;8(6):569-70. PubMed PMID: 11683609.
4) Ramos-Zuñiga R, Jiménez-Guerra R. Rational management of transient obstructive hydrocephalus secondary to a cerebellar infarct. Minim Invasive Neurosurg. 2006 Oct;49(5):302-4. PubMed PMID: 17163345.
6) Kaymakamzade B, Eker A. Acute infarction of corpus callosum due to transient obstructive hydrocephalus. Neurol Neurochir Pol. 2016 Jul-Aug;50(4):280-3. doi: 10.1016/j.pjnns.2016.03.005. PubMed PMID: 27375144.
7) Lusis EA, Vellimana AK, Ray WZ, Chicoine MR, Jost SC. Transient Obstructive Hydrocephalus due to Intraventricular Hemorrhage: A Case Report and Review of Literature. J Clin Neurol. 2013 Jul;9(3):192-5. doi: 10.3988/jcn.2013.9.3.192. PubMed PMID: 23894243; PubMed Central PMCID: PMC3722471.
8) García Iñiguez JP, Madurga Revilla P, Palanca Arias D, Monge Galindo L, López Pisón FJ. [Transient obstructive hydrocephalus following traumatic brain injury]. An Pediatr (Barc). 2013 Jun;78(6):413-4. doi: 10.1016/j.anpedi.2012.09.022. Spanish. PubMed PMID: 23141931.
9) Zairi F, Arikat A, Allaoui M, Assaker R. Transient obstructive hydrocephalus by intraventricular fat migration after surgery of the posterior fossa. Acta Neurochir (Wien). 2012 Feb;154(2):303-4. doi: 10.1007/s00701-011-1258-0. PubMed PMID: 22207488.
10) Yaghi S, Hinduja A. Spontaneous resolution of obstructive hydrocephalus from blood in the cerebral aqueduct. Clin Pract. 2011 Apr 7;1(1):e15. doi: 10.4081/cp.2011.e15. Review. PubMed PMID: 24765269; PubMed Central PMCID: PMC3981214.
11) Abubacker M, Bosma JJ, Mallucci CL, May PL. Spontaneous resolution of acute obstructive hydrocephalus in the neonate. Childs Nerv Syst. 2001 Feb;17(3):182-4. PubMed PMID: 11305774.
12) Nomura S, Orita T, Tsurutani T, Kajiwara K, Izumihara A. Transient hydrocephalus due to movement of a clot plugging the aqueduct. Comput Med Imaging Graph. 1997 Nov-Dec;21(6):351-3. PubMed PMID: 9690009.
13) Prabhu SS, Sharma RR, Gurusinghe NT, Parekh HC. Acute transient hydrocephalus in carbon monoxide poisoning: a case report. J Neurol Neurosurg Psychiatry. 1993 May;56(5):567-8. PubMed PMID: 8505654; PubMed Central PMCID: PMC1015023.
14) Sharma RR, Chandy MJ, Lad SD. Transient hydrocephalus and acute lead encephalopathy in neonates and infants. Report of two cases. Br J Neurosurg. 1990;4(2):141-5. PubMed PMID: 2357283.
15) Braitman RE, Friedman M. Spontaneous resolution of acute hydrocephalus. A case report. Clin Pediatr (Phila). 1982 Dec;21(12):757-8. PubMed PMID: 7140131.
16) Sasaki O, Furusawa Y, Takahara Y. [Transient obstructive hydrocephalus of an infant following mild head injury (author’s transl)]. No Shinkei Geka. 1981;9(3):407-9. Japanese. PubMed PMID: 7242826.