Gamma Knife radiosurgery in the treatment of abducens nerve schwannomas: a retrospective study.

OBJECTIVE Of the intracranial schwannomas, those arising from the vestibular nerves are the most common. Abducens nerve (AN) schwannomas are very rare, and there is limited literature on their optimal management. Therapeutic options include surgery and/or stereotactic radiosurgery. The aim of this study was to evaluate the role of Gamma Knife radiosurgery (GKRS) in these sixth cranial nerve (CN) schwannomas. METHODS The authors performed a retrospective analysis of patients who had undergone GKRS for intracranial tumors at their institute in the period from 2003 to 2010. Inclusion criteria were as follows: isolated AN paresis on presentation, a lesion along the course of the sixth CN, and imaging features characteristic of a schwannoma. Patients with other CN deficits and neurofibromatosis Type 2 were excluded. Symptomatic improvement was defined as the resolution of or an improvement in diplopia noted on a subjective basis or as an improvement in lateral eyeball excursion noted objectively on follow-up. A reduction in tumor volume by at least 20%, as noted by comparing the pre- and post-GKRS images, was deemed significant. RESULTS Six patients with a mean age of 37.1 years (range 17-55 years) underwent primary GKRS. There were 2 prepontine cistern, 3 cavernous sinus, and 1 cisterno-cavernous tumor. The mean duration of symptoms was 6.1 months (range 3-12 months). The mean tumor volume was 3.3 cm3 (range 1.5-4.8 cm3). The mean tumor margin radiation dose was 12.5 Gy (range 12-14 Gy), while the median margin dose was 12 Gy (50% isodose line). The median number of isocenters used was 5 (range 4-8). The brainstem received an average 8.35-Gy radiation dosage (range 5.5-11 Gy). The mean follow-up duration was 44.3 months (range 24-78 months). Symptoms remained stable in 1 patient, improved in 3, and resolved in 2 (total improvement 83%). Magnetic resonance imaging at the last follow-up showed a stable tumor size in 3 patients (50%) and a reduction in the other 3. Thus, the tumor control rate achieved was 100%. No new CN deficits were noted. CONCLUSIONS Abducens nerve schwannomas are rare intracranial tumors. They can be cavernous, cisternal, or cisterno-cavernous in location. Excellent tumor control rates and symptomatic improvement can be achieved with GKRS, which appears to be a safe and effective, minimally invasive modality for the treatment of such lesions. Therefore, it is reasonable to consider GKRS as the initial treatment of choice for this rare pathology. Long-term follow-up will be essential for further recommendations.

Cavernous sinus hemangioma: a fourteen year single institution experience.

Cavernous sinus hemangioma (CSH) is a rare extra-axial vascular neoplasm that accounts for 2% to 3% of all cavernous sinus tumors. Their location, propensity for profuse bleeding during surgery, and relationship to complex neurovascular structures are factors which present difficulty in excising these lesions. The authors describe their experience of 22 patients with CSH over 14 years at a tertiary care center. Patients were managed with microsurgical resection using a purely extradural transcavernous approach (13 patients) and with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden) (nine patients). Retrospective data analysis found headache and visual impairment were the most common presenting complaints, followed by facial hypesthesia and diplopia. All but one patient had complete tumor excision in the surgical series. Transient ophthalmoparesis (complete resolution in 6-8 weeks) was the most common surgical complication. In the GKRS group, marked tumor shrinkage (>50% tumor volume reduction) was achieved in two patients, slight shrinkage in five and no change in two patients, with symptom improvement in the majority of patients. To our knowledge, we describe one of the largest series of CSH managed at a single center. Although microsurgical resection using an extradural transcavernous approach is considered the treatment of choice in CSH and allows complete excision with minimal mortality and long-term morbidity, GKRS is an additional tool for treating residual symptomatic lesions or in patients with associated comorbidities making surgical resection unsuitable.

Outcome after decompressive craniectomy in patients with dominant middle cerebral artery infarction: A preliminary report.

INTRODUCTION: Life-threatening, space occupying, infarction develops in 10-15% of patients after middle cerebral artery infarction (MCAI). Though decompressive craniectomy (DC) is now standard of care in patients with non-dominant stroke, its role in dominant MCAI (DMCAI) is largely undefined. This may reflect the ethical dilemma of saving life of a patient who may then remain hemiplegic and dysphasic. This study specifically addresses this issue. MATERIALS AND METHODS: This retrospective analysis studied patients with DMCAI undergoing DC. Patient records, operation notes, radiology, and out-patient files were scrutinized to collate data. Glasgow outcome scale (GOS), Barthel index (BI) and improvement in language and motor function were evaluated to determine functional outcome. RESULTS: Eighteen patients between 22 years and 72 years of age were included. 6 week, 3 month, 6 month and overall survival rates were 66.6% (12/18), 64% (11/17), 62.5% (10/16) and 62.5% (10/16) respectively. Amongst ten surviving patients with long-term follow-up, 60% showed improvement in GOS, 70% achieved BI score >60 while 30% achieved full functional independence. In this group, motor power and language function improved in 9 and 8 patients respectively. At last follow-up, 8 of 10 surviving patients were ambulatory with (3/8) or without (5/8) support. Age <50 years corresponded with better functional outcome amongst survivors (P value -0.0068). CONCLUSION: Language and motor outcomes after DC in patients with DMCAI are not as dismal as commonly perceived. Perhaps young patients (<50 years) with DMCAI should be treated with the same aggressiveness that non-DMCAI is currently dealt with.

Monitored gradual occlusion of the internal carotid artery followed by ligation for giant internal carotid artery aneurysms.

OBJECTIVE: To demonstrate a technique of gradual monitored occlusion of the internal carotid artery (ICA) followed by ligation for giant aneurysms as an option for balloon test occlusion followed by permanent ligation of ICA. MATERIALS AND METHODS: Authors retrospectively analyzed 27 patients with giant and complex ICA aneurysms who underwent carotid artery ligation between January 2001 and December 2010. Clinical presentation included headache, vision loss and diplopia. There were 19 patients with cavernous aneurysm, 5 supraclinoid, 1 ophthalmic, 1 petrous segment and 1 cervical segment aneurysm located extracranially. All demonstrated good cross-circulation. Selverstone clamp was used for gradual occlusion of the ICA over 72 h under closed observation in the intensive care unit. RESULTS: Six patients developed hemiparesis in the postoperative period. Improvement occurred in one patient over two to three weeks while the remaining five patients had residual hemiparesis. One patient developed malignant MCA infarct for which decompressive craniectomy had to be done. There was no mortality in the present series. CONCLUSIONS: Gradual monitored occlusion and ICA ligation may be a simple, safe alternative procedure to clipping in surgically inaccessible and complex aneurysms, especially for surgeons with limited experience. Cross circulation study is an absolute requisite for carotid ligation.

Outcome after delayed Oberlin transfer in brachial plexus injury.

BACKGROUND: Nerve transfers following traumatic brachial plexus injuries are infrequently operated on after 6 months of injury because myoneural degeneration may set in before nerve regeneration can occur. An exception may lie in transferring healthy donor nerve fascicles directly onto an injured recipient nerve close to the motor point. This is especially true of the Oberlin transfer in which ulnar nerve fascicle(s) are transferred onto the damaged nerve to the biceps. OBJECTIVE: This retrospective observational study evaluated the outcome of the Oberlin transfer on bicipital power in patients with upper trunk/C5,6,7 root level injuries operated on after 6 months of injury. METHODS: Using a standard infraclavicular exposure, the musculocutaneous nerve was followed to its branch to the biceps. Distal to this, the ulnar nerve was skeletonized and a constituent motor fascicle was transferred onto the nerve to biceps. Medical Research Council (MRC) motor power grading was assessed every 3 months following surgery. Patients with a follow-up less than 12 months were excluded. RESULTS: Nine patients operated on after an average of 12.2 months (range, 7-24 months) following injury qualified for the study. At an average follow-up of 26.7 months (range, 12-41 months), all patients had ≥ 2/5 biceps power. Seven patients (77.8%) had useful biceps function ≥ 3/5 MRC score. A single patient operated on 24 months after injury gained 4/5 MRC biceps power. CONCLUSION: The Oberlin transfer is a useful salvage procedure in patients presenting after 6 months of a brachial plexus injury.

Extraventricular neurocytomas: a morphological and histogenetic consideration. A study of six cases.

AIMS: Various molecular markers have been used for diagnosis, management and prognostication of gliomas. Neurocytomas are close morphological mimics of oligodendrogliomas. While combined 1p/19q deletion has been used as a molecular signature of oligodendroglial tumours, it has also been variably reported to occur in neurocytomas, especially those in extraventricular locations (EVN). In recent studies, presence of IDH1 mutation has shown immense prognostic significance in glial tumours including oligodendrogliomas, but its role in neurocytoma pathogenesis remains unexplored. In this study, EVN cases were analysed for histomorphological features, IDH1 mutation using an antibody for specifically detecting mutant IDH1 protein, and 1p/19q deletion by fluorescence in situ hybridisation (FISH) assay. RESULTS: Over a period of 10 years (2000-2009), 60 cases of neurocytoma were diagnosed, of which six were EVN. These six cases were assessed for histomorphology, IDH1 mutation and 1p/19q deletion. Five cases showed atypical histological features. While none showed mIDH1, four of the five atypical cases harboured 1p/19q deletion either in isolation or in combination. The only case which was well-differentiated (typical) did not show 1p/19q loss. CONCLUSIONS: EVNs are more commonly associated with aggressive histological features. IDH1 mutations, although frequent in oligodendrogliomas, are not seen in EVN. However, similar to oligodendrogliomas, 1p/19q deletion is found in these tumours. Thus, a potential histogenetic link between oligodendrogliomas and EVN remains debatable. This molecular alteration may also have prognostic connotations, being associated with atypical morphological features. Due to the rarity of these tumours, multicentric pooling of larger studies is needed to have an insight into the impact of these molecular aberrations on their biological behaviour.

Loss of heterozygosity on chromosome 10q in glioblastomas, and its association with other genetic alterations and survival in Indian patients.

BACKGROUND: Glioblastoma multiforme (GBM) is the most common malignant central nervous system neoplasm. Loss of heterozygosity (LOH) on chromosome 10q in these tumors has been found to show variable association with prognosis. AIM: To evaluate LOH 10q status in cases of GBM, and to correlate these results with patient characteristics, other genetic alterations, and survival. MATERIAL AND METHODS: Fresh tumor tissue and blood samples were obtained for 25 cases of GBM diagnosed over a 2-year period. LOH 10q assay was performed on blood and tumor DNA by a PCR-based method using four microsatellite markers. TP53 mutation analysis and fluorescence in situ hybridization for epidermal growth factor receptor (EGFR) were performed. Histopathology was reviewed and clinical data were analyzed. RESULTS: LOH 10q was identified in 17 of 25 cases (68%). Losses were frequent with markers D10S1765 (12/20 informative cases; 60%) and D10S587 (12/17 informative cases; 70.5%) in the regions of 10q23.3 and 10q26.1, respectively. D10S540 for 10q25.1 showed LOH in 4/12 informative cases (33.3%) and D10S1770 for 10q26-ter in none of the 25 cases. LOH with D10S1765 at the PTEN gene locus was found to correlate with overall LOH 10q status (P = 0.001). LOH 10q was more common in patients older than 40 years (16/19, 84.2%) than in those below (1/6, 16.7%) (P = 0.006). One of three pediatric patients included demonstrated LOH 10q. Survival rates for patients with LOH were lower than for patients with retained heterozygosity. CONCLUSION: LOH 10q is a frequent genetic abnormality in GBM in Indian patients, is seen more frequently in older adults, and its presence is associated with shorter survival. The single best marker to determine LOH 10q status is D10S1765 at the PTEN region.

Intraoperative pulse and blood pressure recordings of neurosurgeons: a pilot study of cardiovascular performance.

BACKGROUND: Although hemodynamic changes in anesthetized patients remain well documented, no study has quantified the effect of operating stress on the neurosurgeon. OBJECTIVE: We present a study of intraoperative (IOP) pulse and blood pressure (BP) recordings obtained from neurosurgeons and compare them with rest and exercise values. METHODS: This prospective, single-blind comparative analysis used an ambulatory BP device to record IOP, rest and exercise BP, and pulse. The Student t test and chi test were used for statistical analysis. RESULTS: Five neurosurgeons performed 10 aneurysm clippings and 1 vestibular schwannoma excision. The average IOP pooled systolic, diastolic, and mean BPs and pulse rates were 140, 103, and 116 mm Hg and 94 bpm, respectively. Corresponding rest and exercise values were 116, 75, and 89 mm Hg and 76 bpm and 130, 99, and 109 mm Hg and 128 bpm, respectively. Average IOP mean and diastolic BPs were significantly elevated compared with rest readings (P = .032, P = .023). Episodes of severe IOP BP (systolic BP/diastolic BP > 180/110 mm Hg) accounted for 28% of all readings and were significantly increased over rest values (P < .001). The incidence of abnormal IOP BP (systolic BP/diastolic BP > 140/90 mm Hg) was also significantly greater than exercise and rest values (P < .001). CONCLUSION: Neurosurgery can induce a significant hemodynamic stress malresponse in the operating surgeon that appears to be greater than that induced by vigorous exercise. The correlation of this occupational hazard to long-term health and longevity remains to be studied.

Tumor control and hearing preservation after Gamma Knife radiosurgery for vestibular schwannomas in neurofibromatosis type 2.

To analyze the effect of Gamma Knife radiosurgery (GKS) on tumor control and hearing preservation rates in patients with vestibular schwannomas (VS) in a setting of neurofibromatosis type 2 (NF 2), a retrospective study was carried out at a tertiary-level referral Gamma Knife unit. Dose plans, pre- and postoperative radiology, and follow-up clinical records of patients with NF 2 who had undergone GKS for VS using a Leksell Gamma Knife (Elekta Instruments AB, Stockholm, Sweden) model B unit from 1997 to 2008 were reviewed. Thirty patients with 54 VS underwent GKS. The average age of the cohort was 29 years (range 10-56 years). Twenty-four patients had bilateral VS. The commonest clinical presentation was hearing loss and tinnitus. Primary GKS was given to 36 tumors, while 18 tumors received it as an adjunct to surgery. Average tumor size was 3.7 cc (range 0.1-13.3 cc). A median 12 Gy prescription dose (range 10-15 Gy) was administered at the 50% isodose (range 42-50%) to cover on average 91.5% of the tumor. Eighteen patients were available for clinical, 14 patients for radiological, and 5 patients (with useful hearing) for audiometric follow-up at an average of 26.6 months. The tumor control rate was 87.5% in this series (33.3% tumor regression), while hearing preservation was noted in 66.7% of cases. One patient developed worsening of facial function. GKS for VS provides satisfactory tumor control and hearing preservation in patients with NF 2. Long-term follow-up will determine future recommendations.

Use of spontaneous ventilation to monitor the effects of posterior fossa surgery in the sitting position.

We describe the successful excision, guided by spontaneous ventilation, of a cervico-medullary hemangioblastoma in a 22-year-old female in the sitting position. A balanced anesthesia technique comprising an oxygen, nitrous oxide, sevoflurane, fentanyl and vecuronium mixture was used. Apart from routine monitors, electroencephalographic spectral entropy monitoring was used to determine the depth of anesthesia and transesophageal echocardiography for detection of venous air embolism. The patient remained in spontaneous ventilation for 235min during tumor excision. The intraoperative and postoperative course were uneventful. The patient recovered without any major neurological deficit.