Update: Spinal arachnoid cyst

Spinal arachnoid cyst

Epidemiology

Almost always dorsal, most common in the thoracic spine.

Most are extradural and these are sometimes referred to as arachnoid diverticula – these may be associated with kyphoscoliosis in juveniles or with spinal dysraphism.

Etiology

Intradural arachnoid cysts may be congenital or may follow infection or trauma.

Clinical features

Usually asymptomatic, even if large.

Differential diagnosis

Vith a ventral cyst, consider a neurenteric cyst.

Treatment

When indicated, treatment options include:

1. percutaneous procedures: may be done under MRI 1). or CT guidance. CT guidance usually requires use of intrathecal contrast to delineate the cyst

A. needle aspiration.

B. needle fenestration.

2. open surgical resection or fenestration

Case report

Takahashi et al. describe the case of a high cervical, intradural extramedullary cyst located anterior to the spinal cord in a 13-year-old boy. The lesion was fenestrated percutaneously by using real-time magnetic resonance (MR) imaging guidance and a local anesthetic agent. The patient’s symptom, severe exercise-induced headache, immediately resolved after treatment. Nine months later, complete disappearance of the cyst was confirmed on MR imaging and computerized tomography myelography. Magnetic resonance imageing-guided fenestration can be considered a minimally invasive option for intradural cystic lesions 2).

1) , 2) Takahashi S, Morikawa S, Egawa M, Saruhashi Y, Matsusue Y. Magnetic resonance imaging-guided percutaneous fenestration of a cervical intradural cyst. Case report. J Neurosurg. 2003 Oct;99(3 Suppl):313-5. PubMed PMID: 14563151.

Update: Pallidotomy

Pallidotomy

Indications

Pallidotomy is an alternative to deep brain stimulation for the treatment of the involuntary movements known as dyskinesias which can become a problem in people with Parkinson disease after long-term treatment with levodopa — a condition known as levodopa-induced dyskinesia.

It is also sometimes used in alternative to deep brain stimulation to treat difficult cases of essential tremor.

Unilateral posteroventral pallidotomy can be effective at reducing Parkinsonism, but is associated with impaired language learning (if performed on the dominant hemisphere) or impaired visuospatial contructional ability (if performed on the non-dominant hemisphere). It can also impair executive functions.

Bilateral pallidotomy will not reduce Parkisonistic symptoms but will cause severe apathy and depression along with slurred unintelligable speech, drooling, and pseudobulbar palsy.

Pallidotomy has long been an accepted procedure and the indications for this surgery, in the opinion of the responding centers of a survey of current practice in North America (1996), were rated on a scale of 1 (poor) to 4 (excellent) and demonstrated dyskinesia as the best indication (median = 4); on-off fluctuations, dystonia, rigidity, and bradykinesia as good indications (median = 3); and freezing, tremor and gait disturbance as fair indications (median = 2). Most centers used MRI alone (50%) or in combination with CT scan (n = 6) or ventriculopathy (n = 5) to localize the target. The median values of pallidal coordinates were: 2 mm anterior to the midcommissural point 21 mm lateral to the midsagittal plane and 5 mm below the intercommissural line. Microrecording was performed by half of the centers (n = 14) and half of the remaining centers were considering starting it (n = 7). Main criteria used to define the target included the firing pattern of spontaneous neuronal discharges (n = 13) and the response to joint movement (n = 10). Most centers performed motor (n = 26) and visual (n = 23) macrostimulation. Twenty four centers performed test lesions using median values of 55 degrees C temperatures for 30 s. Final lesions consisted of 3 permanent lesions placed 2 mm apart, each lesion created with median values of 75 degrees C temperatures for 1 minute. Median hospital stay was 2 days 1).

1) Favre J, Taha JM, Nguyen TT, Gildenberg PL, Burchiel KJ. Pallidotomy: a survey of current practice in North America. Neurosurgery. 1996 Oct;39(4):883-90; discussion 890-2. PubMed PMID: 8880789.

Update: Intraventricular oligodendroglioma

Intraventricular oligodendroglioma (IVO)

J.Sales-Llopis

Neurosurgery Department, University Hospital Son Dureta, Palma de Mallorca, Spain

Oligodendrogliomas usually arise in the cerebral hemispheres, less frequently they are found in the cerebellar hemispheres and very rarely they adopt an intraventricular location.

Epidemiology

Intraventricular oligodendroglioma remains a rare diagnosis, with high-grade/anaplastic IVO being an even rarer subtype.

Types

These lesions vary in regard to tumor grading and clinical presentation, as compared with their intraparenchymal counterparts.

see Anaplastic intraventricular oligodendroglioma.

Clinical Features

They occur in the younger age, an interval between clinical onset and diagnosis or operation is shorter, and initial symptoms are most often limited to those of increased intracranial pressure, although the patient may occasionally present mild organic dementia, callosal disconnection syndrome, and/or mild gait ataxia 1).

Diagnosis

Analysis of the clinical and CT characteristics of 11 cases in the literature and eight new examples revealed specific radiographic features, which included the presence of an anterior, midline mass within the lateral ventricles composed of clumped calcifications within a dense, enhancing matrix.

Hydrocephalus is a constant feature, and these tumors present with signs of increased intracranial pressure. Eighteen of the 19 cases were benign and all were pure oligodendrogliomas, without admixture of other cellular elements.

Intraventricular oligodendrogliomas can be distinguished from other intraventricular lesions by fairly specific CT characteristics. 2)3).

Angiography showed slightly increased vascularity in the mass, and displacement of subependymal veins near the tumor 4).

Magnetic resonance imaging proved to be most useful as a radiologic diagnostic procedure 5)

Outcome

Intraventricular oligodendrogliomas grow slowly and are associated with prolonged survival but, due to their location, are difficult to remove and frequently require shunting. Subsequently developing symptoms, including herniation and death, are more frequently associated with complications related to hydrocephalus than with tumor growth.

The ability to recognize them is helpful in prognosis, and awareness of associated complications related to hydrocephalus may assist in the long-term survival of affected patients 6).

Differential diagnosis

Oligodendrogliomas of the lateral ventricle are rare but should be included in the differential diagnosis of intraventricular tumors near the foramen of Monro 7).

The possibility of central neurocytoma should be considered in all young patients including children presenting with an intraventricular lesion. Definitive diagnosis requires electron microscopic and immunohistochemical studies 8).

Case reports

1979

Two cases of primary intraventricular oligodendrogliomas which were successfully removed by a transventricular approach using microtechniques are presented 9).

1985

Two cases of primary intraventricular oligodendrogliomas are presented. Total excisions of well-demarcated large tumors in the lateral ventricle were successfully performed in young women by means of a frontal transventricular approach. An evaluation by computed tomography and positron emission tomography was attempted to obtain definite diagnosis of not only the location of the tumor but also the histologic grade of malignancy 10).

1986

Ng et al. report two cases 11).


Martinez-Lage et al. report a case of a ventricular oligodendroglioma associated with a cortical arteriovenous malformation. The patient presented with subarachnoid hemorrhage. Computed tomographic scan showed an intraventricular hyperdense lesion, mimicking a hematoma. Angiography revealed a superficial arteriovenous malformation in the right parietal lobe, unrelated to ventricular cavities. Both lesions were treated during the same operation 12).

1987

Two cases of oligodendroglioma primarily involving the lateral ventricle are reported in female patients, aged 29 and 19, respectively, with sole complaints of an increased intracranial pressure.

The tumor was radically removed via a parafalcine transcallosal approach without causing any persistent neurological deficits 13).

1992

A 39-year-old woman harbouring a primary oligodendroglioma of the left lateral ventricle was treated by subtotal removal of the tumour through a left frontal transcortical transventricular approach. The clinical, radiological and surgical details of the case are presented in correlation with the current data on oligodendrogliomas. Benefits of postoperative irradiation are stressed 14).

1996

Romero et al. describe two cases of intraventricular oligodendroglioma.

Case No. 1: 18-year old woman with a clinical history of headache, vertigo and dizziness of 6 months duration. Central Nervous System imaging revealed a right lateral ventricle tumor.

Case No. 2: 38 year old man with a chief complaint of positional headache and visual impairment. C.N.S. imaging showed a third ventricular lesion15).

1) , 5) , 13) Nioka H, Nakasu S, Nakasu Y, Matsuda M, Handa J. [Oligodendroglioma of the lateral ventricle–report of 2 cases and a review]. No Shinkei Geka. 1987 Feb;15(2):201-5. Japanese. PubMed PMID: 3561685.
2) , 6) Dolinskas CA, Simeone FA. CT characteristics of intraventricular oligodendrogliomas. AJNR Am J Neuroradiol. 1987 Nov-Dec;8(6):1077-82. PubMed PMID: 3120535.
3) , 4) , 7) Hasuo K, Fukui M, Tamura S, Yasumori K, Uchino A, Nakagaki H, Ogawa H, Nagasaka S, Masuda K. Oligodendrogliomas of the lateral ventricle: computed tomography and angiography. J Comput Tomogr. 1987 Oct;11(4):376-82. PubMed PMID: 3443012.
8) Yuen ST, Fung CF, Ng TH, Leung SY. Central neurocytoma: its differentiation from intraventricular oligodendroglioma. Childs Nerv Syst. 1992 Oct;8(7):383-8. PubMed PMID: 1458495.
9) Markwalder TM, Huber P, Markwalder RV, Seiler RW. Primary intraventricular oligodendrogliomas. Surg Neurol. 1979 Jan;11(1):25-8. PubMed PMID: 451839.
10) Kikuchi K, Kowada M, Mineura K, Uemura K. Primary oligodendroglioma of the lateral ventricle with computed tomographic and positron emission tomographic evaluations. Surg Neurol. 1985 May;23(5):483-8. PubMed PMID: 3872482.
11) Ng SH, Lui CC, Wai YY, Liu YH, Tsai CC, Chen L. Primary intraventricular oligodendroglioma–report of two cases. Changgeng Yi Xue Za Zhi. 1986 Mar 20;9(1):33-40. PubMed PMID: 3454696.
12) Martinez-Lage JF, Poza M, Esteban JA, Sola J. Subarachnoid hemorrhage in the presence of a cerebral arteriovenous malformation and an intraventricular oligodendroglioma: case report. Neurosurgery. 1986 Jul;19(1):125-8. PubMed PMID: 3748333.
14) Tekkok IH, Ayberk G, Saglam S, Onol B. Primary intraventricular oligodendroglioma. Neurochirurgia (Stuttg). 1992 Mar;35(2):63-6. PubMed PMID: 1603222.
15) Romero Z, Mora-La Cruz E, Cardozo J. [Intraventricular oligodendroglioma. Description of 2 cases]. Invest Clin. 1996 Mar;37(1):51-9. Review. Spanish. PubMed PMID: 8920031.

Magnetic resonance neurography first description

Magnetic resonance neurography (MRN) is the direct imaging of nerves in the body by optimizing selectivity for unique MRI water properties of nerves. It is a modification of magnetic resonance imaging. This technique yields a detailed image of a nerve from the resonance signal that arises from in the nerve itself rather than from surrounding tissues or from fat in the nerve lining. Because of the intraneural source of the image signal, the image provides a medically useful set of information about the internal state of the nerve such as the presence of irritation, nerve swelling (edema), compression, pinch or injury. Standard magnetic resonance images can show the outline of some nerves in portions of their courses but do not show the intrinsic signal from nerve water. Magnetic resonance neurography is used to evaluate major nerve compressions such as those affecting the sciatic nerve (e.g. piriformis syndrome), the brachial plexus nerves (e.g. thoracic outlet syndrome), the pudendal nerve, or virtually any named nerve in the body. A related technique for imaging neural tracts in the brain and spinal cord is called magnetic resonance tractography or diffusion tensor imaging.

History

We have made cross-sectional image “neurograms” in which peripheral nerve has a greater signal intensity than that of other tissue. Neurographic images of the rabbit forelimb were obtained using a spin-echo magnetic resonance imaging (MRI) technique that combines fat suppression and diffusion weighting. After fat suppression the nerve shows up in relative isolation and is brighter than the surrounding tissue due to its longer T2 relaxation time of approximately 50 ms compared to approximately 27 ms for muscle. The addition of pulsed gradients for diffusion weighting of the MR signal further enhances the intensity of the nerve signal relative to that of surrounding muscle tissue. The greater diffusional anisotropy of nerve tissue (D parallel/D perpendicular = 3.1) compared to that of muscle (D parallel/D perpendicular = 1.9) allows further enhancement of the nerve by a subtraction of two diffusion-weighted images, one with the gradients oriented parallel and one with the gradients oriented perpendicular to the nerve orientation. We show that by manipulation of the MRI parameters, either echo time or pulsed gradient strength, the nerves can be made to show up as the most intense feature. This verifies the feasibility of generating three-dimensional “neurographic” images, analogous to angiograms, but which demonstrate the peripheral nerve tracts in apparent isolation 1).

1) Howe FA, Filler AG, Bell BA, Griffiths JR. Magnetic resonance neurography.Magn Reson Med. 1992 Dec;28(2):328-38. PubMed PMID: 1461131.

Update: Neurocysticercosis

Twenty-six patients with cysticercosis of the brain parenchyma were treated with the antihelmintic agent praziquantel (50 mg per kilogram of body weight daily for 15 days). During treatment a strong inflammatory reaction occurred, as evidenced by increased protein and cells in the cerebrospinal fluid. This finding correlated with headache, exacerbation of neurologic symptoms, and edema and inflammation around cystic lesions. After three months of treatment all patients had improved clinically, and 13 (50 per cent) were asymptomatic. The total number of cysts on CT scans had decreased from 152 at the beginning of treatment to 51, and the mean diameter of cysts was reduced by 72 per cent. CT scans showed improvement in 25 of the 26 patients, with total remission of all cysts in nine. Seventeen control patients followed with CT studies for a mean of 9 +/- 2 months had no spontaneous remission of lesions, and in many cases the scans showed worsening during the observation period. Our results indicate that praziquantel is effective in cysticercosis of the brain parenchyma.


Sotelo J, Escobedo F, Rodriguez-Carbajal J, Torres B, Rubio-Donnadieu F. Therapy of parenchymal brain cysticercosis with praziquantel. N Engl J Med. 1984 Apr 19;310(16):1001-7. PubMed PMID: 6708975.

Update: Chiari Type 1

In a series of 71 patients, pain was the commonest symptom (69% of patients); other symptoms included weakness (56%), numbness (52%), and unsteadiness (40%). The presenting physical signs consisted of a foramen magnum compression syndrome (22%), central cord syndrome (65%), or a cerebellar syndrome (11%). Myelography was performed in 69 patients, and was the most useful investigation. Only 23% of plain radiographs were abnormal. In addition to tonsillar descent, the operative findings included arachnoid adhesions (41%) and syringomyelia (32%). All patients underwent suboccipital craniectomy and C1-3 laminectomy. Respiratory depression was the most frequent postoperative complication (14%), and one patient died from sleep apnea. Early postoperative improvement of both symptoms (82%) and signs (70%) was followed by later relapse in 21% of patients, showing an initial benefit following surgery. None of the patients with a cerebellar syndrome deteriorated, whereas 56% of patients with evidence of foramen magnum compression and 66% of those with a central cord syndrome maintained their initial improvement. The authors conclude that posterior fossa decompression appears to benefit some patients, although a significant proportion might be expected to relapse within 2 to 3 years after operation, depending upon the presenting syndrome 1)

1) Paul KS, Lye RH, Strang FA, Dutton J. Arnold-Chiari malformation. Review of 71 cases. J Neurosurg. 1983 Feb;58(2):183-7. PubMed PMID: 6848674.

Taylor-Haughton line revisited

Taylor Haughton line

In 1900 Taylor and Haughton described a technique to define a line on the scalp directly above the central fissure 1)

1. Draw a Nasion-Inion line ( Nasion – Just below Glabella and Inion -External Occipital protruberance)

2. Divide the Nasion-Inion line in to 25%, 50% and 75%

3. Bregma is the point between the 25% and 50% points and Lambda is at 75% point

4. Sylvian fissure is drawn from the orbitotemporal angle (A point of depressin where eyebrow ends) to the 75% point on naso-inion line.

5. Draw a line perpendicular to the root of the zygoma starting at preauricular point

6. Central sulcus is drawn from 54% point on naso-inion line to the point where the sylvian line cuts the perpendicular line

The Taylor-Haughton line was used to identify the central fissure in computed tomography (CT) images. Radiopaque catheters are placed on the scalp on either side of the Taylor-Haughton line prior to CT imaging. The accuracy of the Taylor-Haughton line for identifying the central fissure was also investigated in cadaver brains. The Taylor-Haughton line provides a good approximation of the location of the rolandic fissure 2)

1) Taylor EH,Haughton WS.Some recent researchers on the topography of the convolutions andfissures of thebrain.Trans R Acad Med Ireland 1900;18:511-522
2) Taylor AJ, Haughton VM, Syvertsen A, Ho KC. Taylor-Haughton line revisited. AJNR Am J Neuroradiol. 1980 Jan-Feb;1(1):55-6. PubMed PMID: 6779590.