Category Archives: Operative Neurosurgery

Hyponatremia Following Transsphenoidal Surgery

Epidemiology

Delayed hyponatremia following transsphenoidal surgery is a known complication, with a peak incidence of 4-7 days post-operatively 1) 2) 3).

It is a common cause of hospital readmission, due to fluid retention resulting in reduction of plasma sodium concentration below physiologic levels 4).


In a database of 466 consecutive patients who underwent endoscopic transsphenoidal surgery at a tertiary care center between April 2006 and July 2014 was reviewed for 30-day causes for readmission, length of stay, level of care required, and average cost.

Twenty-nine readmissions were identified within the study period, indicating a 30-day readmission rate of 6.2%. Among all patients, rates of 30-day readmission were 2.1% for epistaxis, 1.5% for hyponatremia, 0.9% for cerebrospinal fluid leak, and 1.7% for other medical conditions. Average cost per readmission ranged from $6011 for hyponatremia to $24,613 for cerebrospinal fluid leak 5).

Etiology

The development of Delayed Symptomatic Hyponatremia (DSH) after transsphenoidal surgery has been ascribed mostly to elevations in the secretion of ADH following mechanical manipulation of the pituitary gland, or less frequently as a result of excessive urinary excretion of salt resulting in cerebral salt wasting syndrome (CSWS) 6).

Patients with Cushing’s disease were at a significantly higher risk than other patients to experience DSH 7) 8).

Clinical features

Patients can present with a range of symptoms, from minor nausea, vomiting headache to confusion, and in severe cases, seizures and death 9).

Management

Close symptom monitoring may be a reasonable alternative to routine screening 10).

Age, gender, tumor size, rate of decline of blood sodium, and Cushing disease are potential predictors of Delayed Symptomatic Hyponatremia (DSH) (defined as serum sodium level <135 mEq/L with associated symptoms) after postoperative day 3. By identifying patients at high risk for DSH, preventative efforts can be implemented in the perioperative setting to reduce the incidence of potentially catastrophic hyponatremia following transsphenoidal surgery 11).

Modern skull base surgeons suggest that improved visualization and identification provided by the endoscope can lead to greater visualization and reduced trauma to the posterior pituitary gland 12) 13) 14).

Systematic review

A systematic search of the literature was conducted using MEDLINE/PUBMED, EMBASE, and Cochrane databases. Inclusion criteria were 1) case series with at least 10 cases reported, 2) adult patients who underwent eTSS or mTSS for pituitary tumors, and 3) reported occurrence of Delayed Symptomatic Hyponatremia (DSH) (defined as serum sodium level <135 mEq/L with associated symptoms) after postoperative day 3. Data were analyzed using CMA V.3 Statistical Software (2014).

Ten case series satisfied the inclusion criteria for a total of 2947 patients. Various factors including age, gender, cerebrospinal fluid leak, and tumor size were investigated as potential predictors of DSH. DSH event rates for both mTSS and eTSS fell between around 4 and 12 percent and included a variety of proposed predictors.

Age, gender, tumor size, rate of decline of blood sodium, and Cushing disease are potential predictors of DSH. By identifying patients at high risk for DSH, preventative efforts can be implemented in the perioperative setting to reduce the incidence of potentially catastrophic hyponatremia following transsphenoidal surgery 15).

Case series

2017

Data from before and after delayed hyponatremia (DH) care pathway implementation were retrospectively reviewed. Patient demographics and clinical characteristics were compared. Readmission causes, clinical pathway failures, sodium trends, and symptoms were evaluated.

Before the DH care pathway implementation, 229 (55%) patients were treated (group 1); afterward, 188 (45%) were treated (group 2). Baseline characteristics were equivalent between groups, except for glucocorticoid supplementation, which was higher in group 2. The incidence of detected DH was significantly lower in group 1 (16/229, 7%) than group 2 (29/188, 15%) ( P = .006) likely due to the impact of routine screening in group 2. Ten group 1 patients (4%) were readmitted for hyponatremia and 6 (3%) were managed as outpatients. Eleven group 2 patients (6%) were readmitted and 17 (9%) were managed as outpatients. Readmission rates between groups were similar ( P = .49). Patients readmitted with severe hyponatremia experienced symptoms ≥24 h before presentation. The protocol failed to prevent readmission because outpatient management for mild or moderate DH (n = 4) failed, sodium levels precipitously declined after normal screening (n = 3), and severe hyponatremia developed after scheduled screenings were missed (n = 3).

Although more DH patients were identified after care pathway implementation, readmission rates were not reduced and clinical outcomes were not changed. Because DH onset timing varies, some patients have highly acute presentation, and most readmitted patients develop symptoms before reaching their sodium nadir, close symptom monitoring may be a reasonable alternative to routine screening 16).


Of 303 patients who had transsphenoidal surgery, 27 (8.9%) were readmitted within 30 days. Most of the 27 (15 [55.6%]) had delayed hyponatremia. Other causes were diabetes insipidus (4 [14.8%]), adrenal insufficiency (2 [7.4%]), and cerebrospinal fluid leak, epistaxis, cardiac arrhythmia, pneumonia, urinary tract infection, and hypoglycemia (1 each [3.7%]). Outpatient sodium screening was performed as needed. In cases of hyponatremia, the mean postoperative day of readmission was day 8 (range, 6-12 days) and the mean serum sodium was 119 mmol/L (range, 111-129 mmol/L). Numerous patient and surgical factors were examined, and no specific predictors of readmission were identified. We developed an outpatient care pathway for managing hyponatremia with the goal of improving readmission rates.

This study establishes a quality benchmark for readmission rates after transsphenoidal surgery for pituitary lesions and identifies delayed hyponatremia as the primary cause. Implementation of an outpatient care pathway for managing hyponatremia may improve readmission rates 17).

2013

A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130-134 mEq/L), moderate (125-129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics. RESULTS: Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = -0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality. CONCLUSIONS: Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified 18).

2011

Kinoshita et al. evaluated (i) the incidence of post-operative hyponatremia (serum Na levels ≤ 135 mEq/L) and the emergence of hyponatremic symptoms, and assessed (ii) the risk factors under a uniform protocol of i.v. infusion with steroid and electrolyte fluid. We examined 88 consecutive operated patients (female: 60; male: 28) with pituitary adenoma. Apart from reconfirming the effects of the purported risk factors, we focused on the degree of serum Na decline on post-operative hyponatremia. Although remained stable during early post-operative period (4 days after surgery), the serum Na levels subsequently decreased after post-operative day 4 in 81 of 88 cases (92.0%). Of 88 patients, 27 (30.7%) and 9 (10.2%) cases suffered from hyponatremia, and developed hyponatremic symptoms. Interestingly, the degree of serum Na levels decline (from pre-operative levels) indicated a useful independent risk factor for monitoring hyponatremic symptoms (p = 0.006) and the degree of decline tended to be greater in elder patients (> 60 years) (p = 0.0346). Serum Na levels should be monitored from, at least, post-operative day 7 to detect early development of hyponatremia. Special attention and recovery effort should be given to elder patients with marked serum Na level decline after surgery 19).

2008

The incidence and risk factors of symptomatic and asymptomatic hyponatremia were investigated in 94 patients who underwent transsphenoidal surgery and serum sodium level monitoring between January 2002 and December 2006. The records were retrospectively reviewed to determine the incidence and risk factors (age and sex, tumor size, endocrinologic findings) of hyponatremia. Postoperatively, the serum sodium levels of the patients were measured at least once within 2 or 3 days. Hyponatremia was found in 17 of the 94 patients, of whom 7 became symptomatic. The mean sodium level of symptomatic patients with hyponatremia at diagnosis was 123.5 mEq/l, compared with 129.8 mEq/l of asymptomatic patients. The serum sodium levels began to fall on mean postoperative day 7 and reached nadir on mean day 8. All 17 patients with hyponatremia were treated with mild fluid restriction. Four symptomatic patients with severe hyponatremia were treated with 3% hypertonic saline infusion in addition to fluid restriction. One symptomatic patient with severe hyponatremia was treated with fluid restriction only. All patients recovered within 5 days of management. Sex, tumor type, and tumor size did not correlate with development of delayed hyponatremia, but patients aged >/=50 years were more likely to develop hyponatremia. Postoperative hyponatremia after transsphenoidal surgery is more common than previously reported and may lead to fatal complications. Therefore, all patients should undergo serum electrolyte level monitoring regularly for at least 1 or 2 weeks after transsphenoidal surgery 20).

2007

Patients who underwent transsphenoidal surgery at the University of Southern California University Hospital between 1997 and 2004 had serum sodium levels drawn on an outpatient basis on postoperative Day 7. Patient records were retrospectively reviewed to determine the incidence of, and risk factors for, symptomatic and asymptomatic hyponatremia. Two hundred forty-one patients had routine serum sodium levels drawn as outpatients on postoperative Day 7. Twenty-three percent of these patients were found to be hyponatremic (Na < or =135 mEq/L). The overall incidence rate of symptomatic hyponatremia in the 241 patients was 5%. The majority of hyponatremic patients (80%) remained asymptomatic, whereas 20% became symptomatic. In patients with symptomatic hyponatremia, the mean sodium level at diagnosis was 120.5 mEq/L, compared with 128.4 mEq/L in asymptomatic, hyponatremic patients (p < 0.0001). Female patients were more likely to develop hyponatremia than male patients (33% compared with 22%, p < 0.03). Fifty-two percent of patients who had transient diabetes insipidus (DI) early in their postoperative course subsequently developed hyponatremia, compared with 21% of those who did not have DI (p < 0.001). Patient age, tumor type, and tumor size did not correlate with development of delayed hyponatremia. Outpatients with moderately and severely low sodium levels were 5 and 12.5 times more likely, respectively, to be symptomatic than were patients with mild hyponatremia.

Delayed hyponatremia occurs more frequently than was previously suspected in patients who have undergone transsphenoidal surgery, especially in female patients and those who have previously had transient DI. The majority of hyponatremic patients remain asymptomatic. Obtaining a serum sodium value on an outpatient basis 1 week after pituitary surgery is helpful in recognition, risk stratification, and subsequent intervention, and may prevent potentially serious complications 21).

1999

1571 patients with pituitary adenomas (238 Cushing’s disease, 405 acromegaly, 534 hormonally inactive adenomas, 358 prolactinoma, 23 Nelson’s syndrome, and 13 thyrotropinoma) were daily examined within a 10-day postoperative inpatient observation period. Prevalence of patterns of polyuria (> 2500 ml) and oliguria/hyponatraemia (< 132 mmol/l) were surveyed as well as predictors of postoperative morbidity. RESULTS: 487 patients (31%) developed immediate postoperative hypotonic polyuria, 161 patients (10%) showed prolonged polyuria and 37 patients (2.4%) delayed hyponatraemia. A biphasic (polyuria-hyponatraemia) and triphasic (polyuria-hyponatraemia-polyuria) pattern was seen in 53 (3.4%) and 18 (1.1%) patients, respectively. Forty-one patients (2.6%) displayed immediate postoperative (day 1) hyponatraemia. Altogether, 8.4% of patients developed hyponatraemia at some time up to the 10th day postoperative, with symptomatic hyponatraemia in 32 patients (2.1%). Risk analysis showed that patients with Cushing’s disease had a fourfold higher risk of polyuria than patients with acromegaly and a 2.8-fold higher risk for postoperative hyponatraemia. Younger age, male sex, and intrasellar expansion were associated with a higher risk of hypotonic polyuria, but this was not considered clinically relevant.

The analysis illustrates that disturbances in osmoregulation resulting in polyuria and pertubations of serum sodium concentration are of very high prevalence and need observation even after selective transsphenoidal surgery for pituitary adenomas, especially in patients with Cushing’s disease22).

1995

To clarify the frequency, presentation, and outcome of this poorly understood complication, Taylor et al. reviewed the database of 2297 patients who underwent transsphenoidal pituitary surgery between February 1971 and June 1993. Of 53 patients (2.3%) treated for symptomatic hyponatremia, 11 were excluded (2 received arginine vasopressin within 24 hours, 1 had untreated hypothyroidism, 4 had untreated adrenal insufficiency, and 4 had incomplete records). The remaining 42 patients (1.8%), 11 men and 31 women aged 21 to 79 years, presented 4 to 13 days (mean, 8 d) postoperatively with nausea and vomiting (20 patients), headache (18 patients), malaise (12 patients), dizziness (4 patients), anorexia (2 patients), and seizures (1 patient). Hyponatremia was unrelated to sex, age, adenoma type, tumor size, or glucocorticoid tapering. Although the clinical picture in our patients is consistent with SIADH, this was not supported by the antidiuretic hormone levels, which were normal or low-normal in the two patients in whom they were measured, suggesting the possibility that low serum sodium may not reflect SIADH. In all patients, hyponatremia resolved within 6 days (mean, 2 d); treatment consisted of salt replacement and mild fluid restriction in 37 patients and fluid restriction only in 4 (treatment unknown in 1). Delayed hyponatremia after transsphenoidal resection of pituitary adenoma is not as rare as previously thought, nor is it necessarily associated with SIADH or with hypoadrenalism during glucocorticoid tapering 23).

1) , 21)

Zada G, Liu CY, Fishback D, Singer PA, Weiss MH. Recognition and management of delayed hyponatremia following transsphenoidal pituitary surgery. J Neurosurg. 2007 Jan;106(1):66-71. PubMed PMID: 17236489.

2) , 7) , 22)

Hensen J, Henig A, Fahlbusch R, Meyer M, Boehnert M, Buchfelder M. Prevalence, predictors and patterns of postoperative polyuria and hyponatraemia in the immediate course after transsphenoidal surgery for pituitary adenomas. Clin Endocrinol (Oxf). 1999 Apr;50(4):431-9. PubMed PMID: 10468901.

3) , 6)

Kelly DF, Laws ER, Jr., Fossett D. Delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. Report of nine cases. J Neurosurg. 1995;83(2):363-367.

4)

Bohl MA, Ahmad S, Jahnke H, et al. Delayed Hyponatremia Is the Most Common Cause of 30-Day Unplanned Readmission After Transsphenoidal Surgery for Pituitary Tumors. Neurosurgery. 2015.

5)

Hendricks BL, Shikary TA, Zimmer LA. Causes for 30-Day Readmission following Transsphenoidal Surgery. Otolaryngol Head Neck Surg. 2016 Feb;154(2):359-65. doi: 10.1177/0194599815617130. Epub 2015 Nov 17. PubMed PMID: 26577772.

8)

Sane T, Rantakari K, Poranen A, Tahtela R, Valimaki M, Pelkonen R. Hyponatremia after transsphenoidal surgery for pituitary tumors. The Journal of clinical endocrinology and metabolism. 1994;79(5):1395-1398.

9)

Whitaker SJ, Meanock CI, Turner GF, et al. Fluid balance and secretion of antidiuretic hormone following transsphenoidal pituitary surgery. A preliminary series. Journal of neurosurgery. 1985;63(3):404-412.

10) , 16)

Bohl MA, Ahmad S, White WL, Little AS. Implementation of a Postoperative Outpatient Care Pathway for Delayed Hyponatremia Following Transsphenoidal Surgery. Neurosurgery. 2017 Apr 25. doi: 10.1093/neuros/nyx151. [Epub ahead of print] PubMed PMID: 28449052.

11) , 15)

Cote DJ, Alzarea A, Acosta MA, Hulou MM, Huang KT, Almutairi H, Alharbi A, Zaidi HA, Algrani M, Alatawi A, Mekary RA, Smith TR. Predictors and Rates of Delayed Symptomatic Hyponatremia after Transsphenoidal Surgery: A Systemastic Review. World Neurosurg. 2016 Apr;88:1-6. doi: 10.1016/j.wneu.2016.01.022. Epub 2016 Jan 22. PubMed PMID: 26805685.

12)

Ammirati M, Wei L, Ciric I. Short-term outcome of endoscopic versus microscopic pituitary adenoma surgery: a systematic review and meta-analysis. J Neurol Neurosurg Psychiatry. 2013;84(8):843-849.

13)

Gao Y, Zhong C, Wang Y, et al. Endoscopic versus microscopic transsphenoidal pituitary adenoma surgery: a meta-analysis. World J Surg Oncol. 2014;12(94).

14)

Cavallo LM, Dal Fabbro M, Jalalod’din H, et al. Endoscopic endonasal transsphenoidal surgery. Before scrubbing in: tips and tricks. Surg Neurol. 2007;67(4):342-347.

17)

Bohl MA, Ahmad S, Jahnke H, Shepherd D, Knecht L, White WL, Little AS. Delayed Hyponatremia Is the Most Common Cause of 30-Day Unplanned Readmission After Transsphenoidal Surgery for Pituitary Tumors. Neurosurgery. 2016 Jan;78(1):84-90. doi: 10.1227/NEU.0000000000001003. PubMed PMID: 26348011.

18)

Hussain NS, Piper M, Ludlam WG, Ludlam WH, Fuller CJ, Mayberg MR. Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors. J Neurosurg. 2013 Dec;119(6):1453-60. doi: 10.3171/2013.8.JNS13411. Epub 2013 Sep 20. PubMed PMID: 24053496.

19)

Kinoshita Y, Tominaga A, Arita K, Sugiyama K, Hanaya R, Hama S, Sakoguchi T, Usui S, Kurisu K. Post-operative hyponatremia in patients with pituitary adenoma: post-operative management with a uniform treatment protocol. Endocr J. 2011;58(5):373-9. Epub 2011 Apr 5. PubMed PMID: 21467692.

20)

Lee JI, Cho WH, Choi BK, Cha SH, Song GS, Choi CH. Delayed hyponatremia following transsphenoidal surgery for pituitary adenoma. Neurol Med Chir (Tokyo). 2008;48(11):489-92; discussion 492-4. PubMed PMID: 19029775.

23)

Taylor SL, Tyrrell JB, Wilson CB. Delayed onset of hyponatremia after transsphenoidal surgery for pituitary adenomas. Neurosurgery. 1995 Oct;37(4):649-53; discussion 653-4. Review. PubMed PMID: 8559292.

Book: Color Atlas of Brainstem Surgery

Color Atlas of Brainstem Surgery

Color Atlas of Brainstem Surgery

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The highly complex specialty of brainstem surgery requires many years of study, a focus on precision, and a passionate dedication to excellence to prepare the neurosurgeon for navigating significant anatomic challenges. Although the brainstem is technically surgically accessible, its highly eloquent structure demands rigorous surgical decision-making. An in-depth understanding of brainstem and thalamic anatomy and the safe entry zones used to access critical areas of the brainstem is essential to traversing the brainstem safely and successfully.

This remarkable, one-of-a-kind atlas draws on the senior author’s decades of experience performing more than 1,000 surgeries on the brainstem, thalamus, basal ganglia, and surrounding areas. Its content is organized by anatomic region, enabling readers to study separate subdivisions of the brainstem, each of which has its own unique anatomic and surgical considerations. From cover to cover, the atlas provides readers with technical guidance on approach selection, the timing of surgery, and optimization of outcomes-elucidated by more than 1700 remarkable color illustrations, dissections, clinical images, and line drawings.

Key Highlights

  • Beautifully detailed, highly sophisticated brain slices and dissections by Kaan Yagmurlu, who trained under the internationally renowned neuroanatomist and neurosurgeon Albert Rhoton Jr.
  • Color illustrations clearly labeled with callouts and other indicators of foci of interest delineate multiple safe entry zones to the brainstem
  • More than 50 detailed patient cases highlight each patient’s history of previous neurological disorders, presenting symptoms, preoperative imaging, diagnosis, the planned surgical approach, patient positioning, intraoperative and postoperative imaging, and outcome
  • Seven animations and more than 50 surgical videos elucidate approach selection, anatomy, and surgical outcomes of thalamic region and brainstem lesions

This illuminating atlas provides insights into the complexities of the hallowed halls of the brainstem. Neurosurgeons and neurosurgical residents alike who glean knowledge from the clinical pearls throughout each section will no doubt become more adept surgeons, to the ultimate benefit of their patients.


Product Details

  • Published on: 2017-04-15
  • Original language: English
  • Dimensions: 12.30″ h x 1.30″ w x 9.40″ l,
  • Binding: Hardcover
  • 416 pages

Book: Innovative Neuromodulation

Innovative Neuromodulation
From Academic Press

Innovative Neuromodulation

List Price: $99.95

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Innovative Neuromodulation serves as an extensive reference that includes a basic introduction to the relevant aspects of clinical neuromodulation that is followed by an in-depth discussion of the innovative surgical and therapeutic applications that currently exist or are in development.

This information is critical for neurosurgeons, neurophysiologists, bioengineers, and other proceduralists, providing a clear presentation of the frontiers of this exciting and medically important area of physiology. As neuromodulation remains an exciting and rapidly advancing field―appealing to many disciplines―the editors’ initial work (Essential Neuromodulation, 2011) is well complemented by this companion volume.

  • Presents a comprehensive reference on the emerging field of neuromodulation that features chapters from leading physicians and researchers in the field
  • Provides commentary for perspectives on different technologies and interventions to heal and improve neurological deficits
  • Contains 300 full-color pages that begin with an overview of the clinical phases involved in neuromodulation, the challenges facing therapies and intraoperative procedures, and innovative solutions for better patient care

Product Details

  • Published on: 2017-02-14
  • Original language: English
  • Dimensions: 9.25″ h x 6.25″ w x 1.00″ l,
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Editorial Reviews

From the Back Cover

Edited by two prominent clinical experts in the field, Innovative Neuromodulation 1e will serve as an extensive reference that includes a basic introduction to the relevant aspects of clinical neuromodulation followed by in-depth discussion of the innovative surgical and therapeutic applications that currently exist or are being developed at present. This information contained is critical for neurosurgeons, neurophysiologists, bioengineers, and other proceduralists, providing a clear presentation of the frontiers of this exciting and medically important area of physiology.

As neuromodulation remains an exciting and rapidly advancing field, appealing to many disciplines, the editors’ initial volume (Essential Neuromodulation, 2011) will be well complemented by this companion volume. Innovative Neuromodulation stands on its own, capturing the up-to-date advances and inspiration that currently grip the field.

About the Author
Jeff Arle, MD, PhD, FAANS
Dr. Arle is currently the Associate Chief of Neurosurgery at Beth Israel Deaconess Medical Center in Boston, the Chief of Neurosurgery at Mt. Auburn Hospital in Cambridge, and an Associate Professor of Neurosurgery at Harvard Medical School. He received his BA in Biopsychology from Columbia University in 1986 and his MD and PhD from the University of Connecticut in 1992. His dissertation work for his doctorate in Biomedical Sciences was in computational modeling in the Cochlear Nucleus. He then went on to do a residency in neurosurgery at the University of Pennsylvania, incorporating a double fellowship in movement disorder surgery and epilepsy surgery under Drs. Patrick Kelly, Ron Alterman, and Werner Doyle, finishing in 1999.

He edited the companion text Essential Neuromodulation with Dr. Shils, the first edition published by Elsevier in 2011. He has now practiced in the field of functional neurosurgery for 17 years and is experienced in all areas of neuromodulation from deep brain stimulators to vagus nerve, spinal cord, peripheral nerve, and motor cortex stimulators, contributing frequent peer-reviewed publications and numerous chapters to the literature on many aspects of the neuromodulation field. He currently serves as an associate editor at the journals Neuromodulation and Neurosurgery, is the co-chair of the Research and Scientific Policy Committee for the International Neuromodulation Society, and is on the Board of Directors for the International Society for Intraoperative Neurophysiology. His longstanding research interests are in the area of computational modeling in the understanding and improved design of devices used in neuromodulation treatments.

Jay L. Shils, Ph.D., D.ABNM, FASNM, FACNS is the director of intra-operative neurophysiology and associate professor in anesthesiology at Rush University Medical center in Chicago, IL. He received his Bachelor of Science degree in electrical engineering from Syracuse University, and both his masters and PhD in Bio-Engineering at The University of Pennsylvania investigating higher order signal extraction and processing techniques on human EEG data to investigate interactions in the visual system and in epilepsy.

He began his work in the field of intraoperative neurophysiology in 1995 specializing in single unit recordings during surgery for movement disorders in the department of Neurology at the University of Pennsylvania School of medicine. Dr. Shils’ research interests include investigating methods for improving real-time intraoperative neurophysiologic techniques as well as theoretical research in neuromodulation mechanisms of action. Dr. Shils has published over 30 peer reviewed papers and multiple chapters on intraoperative neurophysiologic surgical technique, post-operative management of movement disorders patients, and computational modeling as related to neuromodulation effects on various neural circuits. He is the co-editor of two books: “Neurophysiology in Neurosurgery: A modern approach” with Dr. Vedran Deletis; and “Essential Neuromodulation” with Dr. Jeffrey E. Arle. Prior to going to graduate school Dr. Shils was an electrical engineer at the Electric Boat division of General Dynamics where he was involved in various modifications to existing electrical systems.

Dr. Shils is the past President of the International Society for Intraoperative Monitoring and was the founding secretary of the society. He is a past board member of and past chairman for the American Society of Neurophysiologic Monitoring ethics committee and is the 2106/2017 president of the ASNM. He is an associate editor for the Journal of Neurosurgery and Journal of Clinical Neurophysiology.

Update: Microvascular decompression for trigeminal neuralgia

Microvascular decompression (MVD) via lateral suboccipital approach is the standard surgical intervention for trigeminal neuralgia (TN).

Outcome

It has proven to be the most successful and durable surgical approach for trigeminal neuralgia (TN).

However, not all patients with TN manifest unequivocal neurovascular compression (NVC). Furthermore, over time patients with an initially successful MVD manifest a relentless rate of TN recurrence.

It does not achieve 100 % cure rate. Re-exploration of the posterior fossa may carry increased risk over first-time MVD and is not always successful, so other treatments are needed.

Case series

2017

Clinical characteristics, intraoperative findings, and postoperative curative effects were analyzed in 72 patients with trigeminal neuralgia who were treated by microvascular decompression. The patients were divided into arterial and venous compression groups based on intraoperative findings. Surgical curative effects included immediate relief, delayed relief, obvious reduction, and invalid result. Among the 40 patients in the arterial compression group, 32 had immediate pain relief of pain (80.0%), 5 cases had delayed relief (12.5%), and 3 cases had an obvious reduction (7.5%). In the venous compression group, 12 patients had immediate relief of pain (37.5%), 13 cases had delayed relief (40.6%), and 7 cases had an obvious reduction (21.9%). During 2-year follow-up period, 6 patients in the arterial compression group experienced recurrence of trigeminal neuralgia, but there were no recurrences in the venous compression group. Simple artery compression was followed by early relief of trigeminal neuralgia more often than simple venous compression. However, the trigeminal neuralgia recurrence rate was higher in the artery compression group than in the venous compression group 1).

2016

Indocyanine green videoangiography was performed in 17 TN patients undergoing microvascular decompression.

von Eckardstein et al., focused on whether ICG angiography is helpful in determining the site of conflict, particularly when not directly visible via the microscope, and whether fluorescence is strong enough to shine through the nerve obliterating the direct view of the compressing vessel.

In four patients, the site of conflict was immediately apparent after opening the cerebellopontine cistern, and ICG angiography did not provide the neurosurgeon with additional information. In another two patients, imaging quality and fluorescence were too poor. Of the remaining 11 patients with a hidden site of nerve-vessel conflict, ICG angiography was found to be helpful in anticipating the site of compression and the course of the artery in 7 patients, particularly in regard to the so-called shining-through effect through fiber bundles of the thinned nerve. Of all the patients, 88% reported at least improvement or cessation of their symptoms, including all of the patients with a shine-through effect.

ICG angiography could be a helpful adjunct in decompressing the trigeminal nerve and can guide the surgeon to the nerve-vessel conflict. Intensity of the fluorescence is powerful enough to shine through thinned and splayed trigeminal nerve fiber bundles 2).


A retrospective review of patient records from 1998 to 2015 identified a total of 942 patients with TN and 500 patients who underwent MVD. After excluding several cases, 306 patients underwent MVD as their first surgical intervention and 175 patients underwent subsequent MVD. Demographics and clinicopathological data and outcomes were obtained for analysis.

In patients who underwent subsequent MVD, surgical intervention was performed at an older age (55.22 vs 49.98 years old, p < 0.0001) and the duration of symptoms was greater (7.22 vs 4.45 years, p < 0.0001) than for patients in whom MVD was their first surgical intervention. Patients who underwent initial MVD had improved pain relief and no improvement in pain rates compared with those who had subsequent MVD (95.8% and 4.2% vs 90.3% and 9.7%, respectively, p = 0.0041). Patients who underwent initial MVD had significantly lower rates of facial numbness in the pre- and postoperative periods compared with patients who underwent subsequent MVD (p < 0.0001). The number of complications in both groups was similar (p = 0.4572).

The results demonstrate that patients who underwent other procedures prior to MVD had less pain relief and a higher incidence of facial numbness despite rates of complications similar to patients who underwent MVD as their first surgical intervention 3).

2015

A retrospective analysis of clinical data was performed in 99 patients who underwent MVD from May 2012 to June 2015. The outcome data from 27 MVD operations for 27 patients aged 70-80 years (mean 74.6 years) were compared with 72 MVD operations with 72 patients aged 25-69 years (mean 55.7 years). Preoperative comorbidities were recorded and postoperative worsening comorbidities and non-neurological complications were evaluated at discharge. Efficacy of the surgery and neurological complications were evaluated in July 2015.

No decrease in activity of daily living was found in any patient. Complete pain relief without medication was achieved in 77.8% and partial pain relief in 14.8% in the elderly group, and 83.3% and 9.7%, respectively, in the non-elderly group (p=0.750). Permanent neurological complication was not observed in the elderly group, whereas Vth nerve and VIIIth nerve complications were observed in the non-elderly group. Rates of preoperative multiple comorbidities and of cardiovascular comorbidity were significantly higher in the elderly group (p<0.01). Worsening comorbidity and new pathology at discharge were mainly hypertension in both groups, but glaucoma attack and asthma attack were observed in the elderly group. All pathologies were successfully managed.

MVD for elderly patients with TN can be achieved safely with careful perioperative management. Information of comorbidity should be shared with all staff involved in the treatment, who should work as a team to avoid worsening comorbidity. The possibility of unpredictable events in the elderly patients should always be considered 4).


Since 2004, there were a total of 51 patients with TIC and 12 with HS with available MRI scans. All patients underwent preoperative MRI to rule out non-surgical etiologies for facial pain and facial spasm, and confirm vascular compression. Follow-up after surgery was 13±22 months for the patients with TIC and 33±27 months for the patients with HS.

There were 45 responders to MVD in the TIC cohort (88%), with a Visual analog scale (VAS) of 1±3. All patients with HS responded to MVD between 25 and 100%, with a mean of 75±22%. Wound complications occurred in 10% of patients with MVD for TIC, and 1 patient reported hearing loss after MVD for HS, documented by audiogram. The congruence rate between the preoperative MRI and operative findings of vascular compression was 84% in TIC and 75% in HS.

MVD is an effective and safe modality of treatment for TIC and HS. In addition to ruling out structural lesions, MRI can offer additional information by highlighting vascular loops associated with compressions. On conventional scans as obtained here, the resolution of MRI was congruent with operative findings in 84% in TIC and 75% in HS. This review emphasizes that the decision to undertake MVD in TIC or HS should be based on clinical diagnosis and not visualization of a compressing vessel by MRI. Conversely, the presence of a compressing vessel by MRI demands perseverance by the surgeon until the nerve is decompressed 5).


The trigeminal nerve was sectioned into 5 zones. Zone 1, 2, 3, 4 was located at the rostral, caudal, ventral, and dorsal part of the nerve root entry zone (REZ) respectively, and zone 5 was located at the distal of the nerve root. This study contained 86 patients with trigeminal neuralgia underwent microvascular decompression. Every zone was exposed through preoperative imaging. During the operation, offending vessels were explored from zone 1 to zone 5, and different decompression techniques were used for different types of vessels.

Through zone exploration, the sensitivity of preoperative imaging was 96.5% and specificity was 100%. Location of the neurovascular conflict was in the zone 1 in 53.5% of the patients, zone 2 in 32.6%, zone 3 in 45.3%, zone 4 in 29.1%, and zone 5 in 34.9%. In total, 2 zones were both involved in 59.3%, and 3 zones were involved in 18.6%. All offending arteries were moved away and interposed with Teflon sponge. Offending veins of 11 patients were too small to interpose, and coagulated and cut was adopted. The other offending veins were interposed with wet gelatin and Teflon sponge, respectively 6).

2014

Lee et al. performed a retrospective review of cases of TN Type 1 (TN1) or Type 2 (TN2) involving patients 18 years or older who underwent evaluation (and surgery when indicated) at Oregon Health & Science University between July 2006 and February 2013. Surgical and imaging findings were correlated.

The review identified a total of 257 patients with TN (219 with TN1 and 38 with TN2) who underwent high-resolution MRI and MR angiography with 3D reconstruction of combined images using OsiriX. Imaging data revealed that the occurrence of TN1 and TN2 without NVC was 28.8% and 18.4%, respectively. A subgroup of 184 patients underwent surgical exploration. Imaging findings were highly correlated with surgical findings, with a sensitivity of 96% for TN1 and TN2 and a specificity of 90% for TN1 and 66% for TN2. Conclusions Magnetic resonance imaging detects NVC with a high degree of sensitivity. However, despite a diagnosis of TN1 or TN2, a significant number of patients have no NVC. Trigeminal neuralgia clearly occurs and recurs in the absence of NVC 7).

2002

A study comprises 42 cases of trigeminal neuralgia that underwent operation with endoscopic-assisted microvascular decompression between October 1992 and October 1998. This study was performed in the Ear, Nose, and Throat Department, Nord Hospital, in Marseille, France. The decompression was performed by means of a minimally invasive retrosigmoid approach without a cerebellar retractor. The cerebellopontine angle was then explored by a 30-degree endoscope that gives a panoramic view of this space, with clear visualization of the trigeminal nerve from the pons to Meckel’s cave, allowing for the identification of the precise location of the site of the conflict. Microvascular decompression was performed under the microscope by separating the offending vessel from the trigeminal nerve; separation was maintained by the insertion of a piece of Teflon.

The site of conflict was detected at the root entry zone of the nerve in 35 patients (83.3%) and at Meckel’s cave in 7 patients (16.7%). In 32 cases (76.2%), the type of contact between the vessel and the nerve was of the simple type (1 vessel coming in contact with the nerve in a single point); in 6 cases (14.3%), it was a multiple type (2 vessels touching the nerve in the same point); and in 4 cases (9.5%), it was a nutcracker type (2 vessels compressing the nerve between them). After at least 1-year follow-up and a single operation (cases that required a second operation for revision were considered failures), a successful result was obtained in 31 cases (73.8%), and an improvement was obtained in 4 cases (9.5%). The operation was a failure or early recurrence occurred in 7 cases (16.7%). Postoperative complications were rare. A cerebrospinal fluid leak occurred in only 1 case (2.4%) and was subsequently treated with lumbar puncture and a compressive bandage.

The minimally invasive retrosigmoid endoscopic-assisted microvascular decompression is an acceptable treatment of primary trigeminal neuralgia. Endoscopy provides a unique way to explore the cerebellopontine angle and to identify the exact location of the neurovascular conflict 8).


1) Shi L, Gu X, Sun G, Guo J, Lin X, Zhang S, Qian C. After microvascular decompression to treat trigeminal neuralgia, both immediate pain relief and recurrence rates are higher in patients with arterial compression than with venous compression. Oncotarget. 2017 Jan 20. doi: 10.18632/oncotarget.14765. [Epub ahead of print] PubMed PMID: 28122347.
2) von Eckardstein KL, Mielke D, Akhavan-Sigari R, Rohde V. Enlightening the Cerebellopontine Angle: Intraoperative Indocyanine Green Angiography in Microvascular Decompression for Trigeminal Neuralgia. J Neurol Surg A Cent Eur Neurosurg. 2016 Sep 23. PubMed PMID: 27704490.
3) Theodros D, Rory Goodwin C, Bender MT, Zhou X, Garzon-Muvdi T, De la Garza-Ramos R, Abu-Bonsrah N, Mathios D, Blitz AM, Olivi A, Carson B, Bettegowda C, Lim M. Efficacy of primary microvascular decompression versus subsequent microvascular decompression for trigeminal neuralgia. J Neurosurg. 2016 Jul 15:1-7. [Epub ahead of print] PubMed PMID: 27419826.
4) Amagasaki K, Watanabe S, Naemura K, Shono N, Nakaguchi H. Safety of microvascular decompression for elderly patients with trigeminal neuralgia. Clin Neurol Neurosurg. 2015 Dec 31;141:77-81. doi: 10.1016/j.clineuro.2015.12.019. [Epub ahead of print] PubMed PMID: 26765772.
5) Hitchon PW, Zanaty M, Moritani T, Uc E, Pieper CL, He W, Noeller J. Microvascular decompression and MRI findings in trigeminal neuralgia and hemifacial spasm. A single center experience. Clin Neurol Neurosurg. 2015 Oct 22;139:216-220. doi: 10.1016/j.clineuro.2015.10.012. [Epub ahead of print] PubMed PMID: 26519891.
6) Feng BH, Zheng XS, Liu M, Wang XQ, Wang XH, Ying TT, Li ST. Microvascular Decompression for Trigeminal Neuralgia: Zone Exploration and Decompression Techniques. J Craniofac Surg. 2015 Oct 21. [Epub ahead of print] PubMed PMID: 26501973.
7) Lee A, McCartney S, Burbidge C, Raslan AM, Burchiel KJ. Trigeminal neuralgia occurs and recurs in the absence of neurovascular compression. J Neurosurg. 2014 May;120(5):1048-54. doi: 10.3171/2014.1.JNS131410. Epub 2014 Feb 7. PubMed PMID: 24506241.
8) El-Garem HF, Badr-El-Dine M, Talaat AM, Magnan J. Endoscopy as a tool in minimally invasive trigeminal neuralgia surgery. Otol Neurotol. 2002 Mar;23(2):132-5. PubMed PMID: 11875338.

Virtual reality in neurosurgery

Virtual reality (VR), sometimes referred to as immersive multimedia, is a computer-simulated environment that can simulate physical presence in places in the real world or imagined worlds. Virtual reality can recreate sensory experiences, including virtual taste, sight, smell, sound, touch, etc.

Chan et al., highlights a selection of recent developments in research areas related to virtual reality simulation, including anatomic modeling, computer graphics and visualization, haptics, and physics simulation, and discusses their implication for the simulation of neurosurgery 1).


Medicine and surgery are turning towards simulation to improve on limited patient interaction during residency training. Many simulators today utilize virtual reality with augmented haptic feedback with little to no physical elements.

To optimize the learning exercise, it is essential that both visual and haptic simulators are presented to best present a real-world experience. Many systems attempt to achieve this goal through a total virtual interface.

Bova et al., approach has been to create a mixed-reality system consisting of a physical and a virtual component. A physical model of the head or spine is created with a 3-dimensional printer using deidentified patient data. The model is linked to a virtual radiographic system or an image guidance platform. A variety of surgical challenges can be presented in which the trainee must use the same anatomic and radiographic references required during actual surgical procedures.

Using the aforementioned techniques, they have created a ventriculostomy simulators, percutaneous radiofrequency trigeminal rhizotomy, and spinal instrumentation.

The system has provided the residents an opportunity to understand and appreciate the complex 3-dimensional anatomy of the 3 neurosurgical procedures simulated. The systems have also provided an opportunity to break procedures down into critical segments, allowing the user to concentrate on specific areas of deficiency 2).


Shakur et al., developed a real-time augmented reality simulator for percutaneous trigeminal rhizotomy using the ImmersiveTouch platform. Ninety-two neurosurgery residents tested the simulator at American Association of Neurological Surgeons Top Gun 2014. Postgraduate year (PGY), number of fluoroscopy shots, the distance from the ideal entry point, and the distance from the ideal target were recorded by the system during each simulation session. Final performance score was calculated considering the number of fluoroscopy shots and distances from entry and target points (a lower score is better). The impact of PGY level on residents’ performance was analyzed.

Seventy-one residents provided their PGY-level and simulator performance data; 38% were senior residents and 62% were junior residents. The mean distance from the entry point (9.4 mm vs 12.6 mm, P = .01), the distance from the target (12.0 mm vs 15.2 mm, P = .16), and final score (31.1 vs 37.7, P = .02) were lower in senior than in junior residents. The mean number of fluoroscopy shots (9.8 vs 10.0, P = .88) was similar in these 2 groups. Linear regression analysis showed that increasing PGY level is significantly associated with a decreased distance from the ideal entry point (P = .001), a shorter distance from target (P = .05), a better final score (P = .007), but not number of fluoroscopy shots (P = .52).

Because technical performance of percutaneous rhizotomy increases with training, they proposed that the skills in performing the procedure in there virtual reality model would also increase with PGY level, if this simulator models the actual procedure. The results confirm this hypothesis and demonstrate construct validity 3).


Alaraj et al., developed a real-time sensory haptic feedback virtual reality aneurysm clipping simulator using the ImmersiveTouch platform. A prototype middle cerebral artery aneurysm simulation was created from a computed tomographic angiogram. Aneurysm and vessel volume deformation and haptic feedback are provided in a 3-dimensional immersive virtual reality environment. Intraoperative aneurysm rupture was also simulated. Seventeen neurosurgery residents from 3 residency programs tested the simulator and provided feedback on its usefulness and resemblance to real aneurysm clipping surgery.

Residents thought that the simulation would be useful in preparing for real-life surgery. About two-thirds of the residents thought that the 3-dimensional immersive anatomic details provided a close resemblance to real operative anatomy and accurate guidance for deciding surgical approaches. They thought the simulation was useful for preoperative surgical rehearsal and neurosurgical training. A third of the residents thought that the technology in its current form provided realistic haptic feedback for aneurysm surgery.

Neurosurgical residents thought that the novel immersive VR simulator is helpful in their training, especially because they do not get a chance to perform aneurysm clippings until late in their residency programs 4).


Lemole et al., use the ImmersiveTouch (ImmersiveTouch, Inc., Chicago, IL) virtual reality platform, developed at the University of Illinois at Chicago, to simulate the task of ventriculostomy catheter placement as a proof-of-concept. Computed tomographic data are used to create a virtual anatomic volume.

Haptic feedback offers simulated resistance and relaxation with passage of a virtual three-dimensional ventriculostomy catheter through the brain parenchyma into the ventricle. A dynamic three-dimensional graphical interface renders changing visual perspective as the user’s head moves. The simulation platform was found to have realistic visual, tactile, and handling characteristics, as assessed by neurosurgical faculty, residents, and medical students.

They developed a realistic, haptics-based virtual reality simulator for neurosurgical education. The first module recreates a critical component of the ventriculostomy placement task. This approach to task simulation can be assembled in a modular manner to reproduce entire neurosurgical procedures 5).


1) Chan S, Conti F, Salisbury K, Blevins NH. Virtual reality simulation in neurosurgery: technologies and evolution. Neurosurgery. 2013 Jan;72 Suppl 1:154-64. doi: 10.1227/NEU.0b013e3182750d26. PubMed PMID: 23254804.
2) Bova FJ, Rajon DA, Friedman WA, Murad GJ, Hoh DJ, Jacob RP, Lampotang S, Lizdas DE, Lombard G, Lister JR. Mixed-reality simulation for neurosurgical procedures. Neurosurgery. 2013 Oct;73 Suppl 1:138-45. doi: 10.1227/NEU.0000000000000113. PubMed PMID: 24051877.
3) Shakur SF, Luciano CJ, Kania P, Roitberg BZ, Banerjee PP, Slavin KV, Sorenson J, Charbel FT, Alaraj A. Usefulness of a Virtual Reality Percutaneous Trigeminal Rhizotomy Simulator in Neurosurgical Training. Neurosurgery. 2015 Sep;11 Suppl 3:420-5; discussion 425. doi: 10.1227/NEU.0000000000000853. PubMed PMID: 26103444.
4) Alaraj A, Luciano CJ, Bailey DP, Elsenousi A, Roitberg BZ, Bernardo A, Banerjee PP, Charbel FT. Virtual reality cerebral aneurysm clipping simulation with real-time haptic feedback. Neurosurgery. 2015 Mar;11 Suppl 2:52-8. doi: 10.1227/NEU.0000000000000583. PubMed PMID: 25599200; PubMed Central PMCID: PMC4340784.
5) Lemole GM Jr, Banerjee PP, Luciano C, Neckrysh S, Charbel FT. Virtual reality in neurosurgical education: part-task ventriculostomy simulation with dynamic visual and haptic feedback. Neurosurgery. 2007 Jul;61(1):142-8; discussion 148-9. Review. PubMed PMID: 17621029.

Venous sinus stenting for idiopathic intracranial hypertension


Trials suggest that venous sinus stenting offers both comparable rates of efficacy – with improved papilledema in 97% of patients, resolved headache in 83%, and improved visual acuity in 78% .

Patients whose sight is threatened by medically refractory IIH must often consider invasive procedures to control their disease. Venous sinus stenting may offer equal efficacy and lower failure and complication rates than traditional surgical approaches such as optic nerve sheath fenestration and cerebrospinal fluid diversion 3).

Videos

Reviews

2017

A systematic review of the surgical treatment of IIH was carried out. Cochrane Library, MEDLINE and EMBASE databases were systematically searched from 1985 to 2014 to identify all relevant manuscripts written in English. Additional studies were identified by searching the references of retrieved papers and relative narrative reviews.

Forty-one (41) studies were included (36 case series and 5 case reports), totalling 728 patients. Three hundred forty-one patients were treated with optic nerve sheath fenestration (ONSF), 128 patients with lumboperitoneal shunting (LPS), 72 patients with ventriculoperitoneal shunting (VPS), 155 patients with venous sinus stenting and 32 patients with bariatric surgery. ONSF showed considerable efficacy in vision improvement, while CSF shunting had a superior headache response. Venous sinus stenting demonstrated satisfactory results in both vision and headache improvement along with the best complication profile and low relapse rate, but longer follow-up periods are needed. The complication rate of bariatric surgery was high when compared to other interventions and visual outcomes have not been reported adequately. ONSF had the lowest cost.

No surgical modality proved to be clearly superior to any other in IIH management. However, in certain contexts, a given approach appears more justified. Therefore, a treatment algorithm has been formulated, based on the extracted evidence of this review. The traditional treatment paradigm may need to be re-examined with sinus stenting as a first-line treatment modality 4).

2015

Kanagalingam et al., review the role of cerebral venous sinus stenting in the management of patients with medically refractory pseudotumor cerebri. Although long- term studies are needed in this field, the current reports indicate a favorable outcome for preventing vision loss and symptom control 5).

2013

In 2013, a review of the literature was performed which identified patients with IIH treated with venous sinus stenting. The procedural data and outcomes are presented. A total of 143 patients with IIH (87% women, mean age 41.4 years, mean body mass index 31.6 kg/m(2)) treated with venous sinus stenting were included in the analysis. Symptoms at initial presentation included headache (90%), papilledema (89%), visual changes (62%) and pulsatile tinnitus (48%). There was a technical success rate of 99% for the stent placement procedure with a total of nine complications (6%). At follow-up (mean 22.3 months), 88% of patients experienced improvement in headache, 97% demonstrated improvement or resolution of papilledema, 87% experienced improvement or resolution of visual symptoms and 93% had resolution of pulsatile tinnitus. In patients with IIH with focal venous sinus stenosis, endovascular stent placement across the stenotic sinus region represents an effective treatment strategy with a high technical success rate and decreased rate of complications compared with treatment modalities currently used 6).


Teleb et al., aimed to review all published cases and case series of dural sinus stenting for IIH, with analysis of patient presenting symptoms, objective findings (CSF pressures, papilledema, pressure gradients across dural sinuses), follow-up of objective findings, and complications.

A Medline search was performed to identify studies meeting pre-specified criteria of a case report or case series of patients treated with dural sinus stent placement for IIH. The manuscripts were reviewed and data was extracted.

A total of 22 studies were identified, of which 19 studies representing 207 patients met criteria and were included in the analysis. Only 3 major complications related to procedure were identified. Headaches resolved or improved in 81% of patients. Papilledema improved the (172/189) 90%. Sinus pressure decreased from an average of 30.3 to 15 mm Hg. Sinus pressure gradient decreased from 18.5 (n=185) to 3.2 mm Hg (n=172). Stenting had an overall symptom improvement rate of 87%.

Although all published case reports and case series are nonrandomized, the low complication and high symptom improvement rate make dural sinus stenting for IIH a potential alternative surgical treatment. Standardized patient selection and randomization trials or registry are warranted 7).

Case series

2017

Seventeen patients underwent dural venous sinus stenting (DVSS). Average pre- and post-intervention pressure gradients were 23.06 and 1.18 mmHg, respectively (p < 0.0001). Sixteen (94%) noted improvement in headache, fourteen (82%) had visual improvement and all (100%) patients had improved main symptom. Of 11 patients with optical coherence tomography, 8 showed decreased RNFL thickness and 3 remained stable; furthermore, these 11 patients had improved vision with improved papilledema in 8, lack of pre-existing papilledema in 2 and stable, mild edema in 1 patient.

This series of patients with dural sinus stenosis demonstrated improvement in vision and reduction in RNFL thickness. DVSS appears to be a useful treatment for IIH patients with dural sinus stenosis 8).

2016

Ten patients for whom medical therapy had failed were prospectively followed. Ophthalmological examinations were assessed, and patients with venous sinus stenosis on MR angiography proceeded to catheter angiography, venography with assessment of pressure gradient, and ICP monitoring. Patients with elevated ICP measurements and an elevated pressure gradient across the stenosis were treated with stent placement. RESULTS All patients had elevated venous pressure (mean 39.5 ± 14.9 mm Hg), an elevated gradient across the venous sinus stenosis (30.0 ± 13.2 mm Hg), and elevated ICP (42.2 ± 15.9 mm Hg). Following stent placement, all patients had resolution of the stenosis and gradient (1 ± 1 mm Hg). The ICP values showed an immediate decrease (to a mean of 17.0 ± 8.3 mm Hg), and further decreased overnight (to a mean of 8 ± 4.2 mm Hg). All patients had subjective and objective improvement, and all but one improved during follow-up (median 23.4 months; range 15.7-31.6 months). Two patients developed stent-adjacent stenosis; retreatment abolished the stenosis and gradient in both cases. Patients presenting with papilledema had resolution on follow-up funduscopic imaging and optical coherence tomography (OCT) and improvement on visual field testing. Patients presenting with optic atrophy had optic nerve thinning on follow-up OCT, but improved visual fields. CONCLUSIONS For selected patients with IIH and venous sinus stenosis with an elevated pressure gradient and elevated ICP, venous sinus stenting results in resolution of the venous pressure gradient, reduction in ICP, and functional, neurological, and ophthalmological improvement. As patients are at risk for stent-adjacent stenosis, further follow-up is necessary to determine long-term outcomes and gain an understanding of venous sinus stenosis as a primary or secondary pathological process behind elevated ICP 9).


El Mekabaty et al., retrospectively reviewed a prospectively maintained database spanning December 2011 to May 2015 of all patients with idiopathic intracranial hypertension who were screened for possible venous sinus stenting, including only patients who received a stent, noting symptomatic improvements, changes in opening lumbar puncture pressure, demographic characteristics, and any subsequent intervention after stent placement. Fisher’s exact test and logistic regression were used to test each of seven potential predictors for retreatment. RESULTS: There were eight revisions in 31 patients (25.8%). Among Caucasians, 8.0% required a revision compared with 100% of African-Americans (p<0.001). The c-index for race was 0.857. Body mass index (BMI) was also a significant predictor of revision (p=0.031): among class III obese patients the revision rate was 46.2% compared with 16.7% among class I and II obese patients and 0% among overweight to normal weight patients.

BMI was a significant predictor of revision, suggesting that higher BMI may have a higher risk of revision. The small number of African-Americans in the study makes interpretation of the practical significance of the revision rate in these patients uncertain. None of the other studied factors was statistically significant. 10).


A written informed consent approved by the Weill Cornell institutional review board was signed and obtained from the study participants. Thirty-seven consecutive patients with IIH and venous sinus stenosis who were treated with venous sinus stenting between Jan.2012-Jan.2016 were prospectively evaluated. Patients without pulsatile tinnitus were excluded. Tinnitus severity was categorized based on “Tinnitus Handicap Inventory” (THI) at pre-stent, day-0, 1-month, 3-month, 6-month, 12-month, 18-month and 2-year follow-up. Demographics, body-mass index (BMI), pre and post VSS trans-stenotic pressure gradient were documented. Statistical analysis performed using Pearson’s correlation, Chi-square analysis and Fischer’s exact test.

29 patients with a mean age of 29.5±8.5 years M:F = 1:28. Median (mean) THI pre and post stenting were: 4 (3.7) and 1 (1) respectively. Median time of tinnitus resolution post VSS was 0-days. There was significant improvement of THI (Δ Mean: 2.7 THI [95% CI: 2.3-3.1 THI], p<0.001) and transverse-distal sigmoid sinus gradient (Δ Mean: -15.3 mm Hg [95% CI: 12.7-18 mm Hg], p<0.001) post-stenting. Mean follow-up duration of 26.4±9.8 months (3-44 months). VSS was feasible in 100% patients with no procedural complications. Three-patients (10%) had recurrent sinus stenosis and tinnitus at mean follow-up of 12 months (6-30 months).

Venous sinus stenting is an effective treatment for pulsatile tinnitus in patients with IIH and venous sinus stenosis 11).

2013

Fields et al reviewed all cases of dural stents for IIH. Eligibility criteria included medically refractory IIH with documented papilledema and dural venous sinus stenosis of the dominant venous outflow system (gradient ≥10 mm Hg).

Fifteen cases (all women) of mean age 34 years were identified. All had failed medical therapy and six had failed surgical intervention. Technical success was achieved in all patients without major periprocedural complications. The mean preprocedural gradient across the venous stenosis was reduced from 24 mm Hg before the procedure to 4 mm Hg after the procedure. Headache resolved or improved in 10 patients. Papilledema resolved in all patients and visual acuity stabilized or improved in 14 patients. There were no instances of restenosis among the 14 patients with follow-up imaging.

In this small case series, dural sinus stenting for IIH was performed safely with a high degree of technical success and with excellent clinical outcomes. These results suggest that angioplasty and stenting for the treatment of medically refractory IIH in patients with dural sinus stenosis warrants further investigation as an alternative to LPS, VPS and ONSF 12).


1) , 4) Kalyvas AV, Hughes M, Koutsarnakis C, Moris D, Liakos F, Sakas DE, Stranjalis G, Fouyas I. Efficacy, complications and cost of surgical interventions for idiopathic intracranial hypertension: a systematic review of the literature. Acta Neurochir (Wien). 2017 Jan;159(1):33-49. doi: 10.1007/s00701-016-3010-2. Review. PubMed PMID: 27830325.
2) Dinkin MJ, Patsalides A. Venous Sinus Stenting for Idiopathic Intracranial Hypertension: Where Are We Now? Neurol Clin. 2017 Feb;35(1):59-81. doi: 10.1016/j.ncl.2016.08.006. Review. PubMed PMID: 27886896.
3) Chaudhry S, Bryant TK, Peeler CE. Venous sinus stenting in idiopathic intracranial hypertension: a safer surgical approach? Curr Opin Ophthalmol. 2016 Nov;27(6):481-485. Review. PubMed PMID: 27585210.
5) Kanagalingam S, Subramanian PS. Cerebral venous sinus stenting for pseudotumor cerebri: A review. Saudi J Ophthalmol. 2015 Jan-Mar;29(1):3-8. doi: 10.1016/j.sjopt.2014.09.007. Review. PubMed PMID: 25859134; PubMed Central PMCID: PMC4314570.
6) Puffer RC, Mustafa W, Lanzino G. Venous sinus stenting for idiopathic intracranial hypertension: a review of the literature. J Neurointerv Surg. 2013 Sep 1;5(5):483-6. doi: 10.1136/neurintsurg-2012-010468. Review. PubMed PMID: 22863980.
7) Teleb MS, Cziep ME, Lazzaro MA, Gheith A, Asif K, Remler B, Zaidat OO. Idiopathic Intracranial Hypertension. A Systematic Analysis of Transverse Sinus Stenting. Interv Neurol. 2013;2(3):132-143. PubMed PMID: 24999351; PubMed Central PMCID: PMC4080637.
8) Smith KA, Peterson JC, Arnold PM, Camarata PJ, Whittaker TJ, Abraham MG. A case series of dural venous sinus stenting in idiopathic intracranial hypertension: association of outcomes with optical coherence tomography. Int J Neurosci. 2017 Feb;127(2):145-153. PubMed PMID: 26863329.
9) Liu KC, Starke RM, Durst CR, Wang TR, Ding D, Crowley RW, Newman SA. Venous sinus stenting for reduction of intracranial pressure in IIH: a prospective pilot study. J Neurosurg. 2016 Dec 23:1-8. doi: 10.3171/2016.8.JNS16879. [Epub ahead of print] PubMed PMID: 28009240.
10) El Mekabaty A, Obuchowski NA, Luciano MG, John S, Chung CY, Moghekar A, Jones S, Hui FK. Predictors for venous sinus stent retreatment in patients with idiopathic intracranial hypertension. J Neurointerv Surg. 2016 Dec 13. pii: neurintsurg-2016-012803. doi: 10.1136/neurintsurg-2016-012803. [Epub ahead of print] PubMed PMID: 27965382.
11) Boddu S, Dinkin M, Suurna M, Hannsgen K, Bui X, Patsalides A. Resolution of Pulsatile Tinnitus after Venous Sinus Stenting in Patients with Idiopathic Intracranial Hypertension. PLoS One. 2016 Oct 21;11(10):e0164466. doi: 10.1371/journal.pone.0164466. PubMed PMID: 27768690; PubMed Central PMCID: PMC5074492.
12) Fields JD, Javedani PP, Falardeau J, Nesbit GM, Dogan A, Helseth EK, Liu KC, Barnwell SL, Petersen BD. Dural venous sinus angioplasty and stenting for the treatment of idiopathic intracranial hypertension. J Neurointerv Surg. 2013 Jan 1;5(1):62-8. doi: 10.1136/neurintsurg-2011-010156. PubMed PMID: 22146571.

A New Way into the Brain

The traditional way to reach a deep-seated lesion within the brain is through an open craniotomy. While this route is effective at accomplishing the primary goal of accessing the tumor, it’s littered with collateral damage, says Johns Hopkins Hospital neurosurgeon Kaisorn Chaichana.

Assistant Professor of Neurosurgery, Oncology, and Otolaryngology

“It usually requires a big incision, a big opening in the skull, a big opening in the dura,” he says. “As we dissect downward, we’re compromising the white matter the whole time.” The end result, he adds, is substantial blood loss, long hospital stays, long recovery times and an increased risk of damage to brain structures, which can cause neurological deficits.

Enter the minimally invasive tubular retractor, a device that Chaichana has recently incorporated into many of the procedures he’s performed to help mitigate these issues. With a tubular diameter slightly less than a nickel, this retractor allows for less invasive brain surgery by using an obturator with an atraumatic tip to push white matter away instead of cutting it.

During procedures that use this device, Chaichana and his colleagues typically rely on MRI with diffusion tensor imaging data gathered before surgery to guide an interoperative navigation system. Using these data to pinpoint the location of a lesion, the surgeons make a small opening about the size of a silver dollar through the scalp, skull and dura. They then insert the tubular retractor between white matter tracts directly over the tumor.

Once the obdurator is in place, the surgeons can remove an inner metal insert, leaving behind an inner clear sheath. The surgery is performed with an exoscope—a small camera that hovers over the surgical field—and tools to go within the device. Using this protocol, Chaichana and his colleagues can resect entire tumors with minimal disruption to the surrounding brain structures.

This approach is particularly valuable for tumors in eloquent locations, Chaichana says. Treating these tumors using traditional surgical methods would increase the result in motor, language or visual field deficits because of the large dissection of the critical brain matter. However, in the 30 cases he’s already treated using this device over the past year, these functions have been largely preserved. These patients have also had shorter surgeries, significantly less blood loss, shorter hospital stays and quicker recoveries, he adds.

Because of its host of benefits, Chaichana says, he expects that use of this device will grow throughout this field over time.

“With this approach, we can offer patients the same great results as an open resection,” he says, “while also giving them a much greater chance of preserving their neurological function and quality of life.”