Browsing by Author "Nair, S."
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Item Adult medulloblastoma: Clinical profile and treatment results of 18 patients(JOURNAL OF CLINICAL NEUROSCIENCE, 2008)The objective of this article is to examine the clinicoradiological features and surgical outcomes of adult patients (>16 years) with medulloblastoma. An attempt was made to identify the predictors of poor outcome and assess patterns of relapse and to compare these with pediatric medulloblastoma. Retrospective case record analyses were performed on 18 adults (> 16 years) and 79 children (< 16 years) operated upon after January 1990, who had at least 5 years of follow-up. The following variables were assessed by bivariate analyses: age, location of the lesion, brainstem invasion, extent of excision and histological subtype. Statistical analysis was performed using chi-square test, Fischer's exact test and Student's t-test. Results revealed there was no gender preference. The tumor was located in the vermis in 12 patients (66.6%) and in the cerebellar hemisphere in six (16.6%). Calcification was observed in two cases (11.1%) and hydrocephalus was seen in six (33.3%). MRI evidence of brainstem infiltration was seen in three patients (16.6%). Total excision was achieved in 13 cases (72.2%), near total excision in four (22.2%) and subtotal excision in one. Major complications included fresh cranial nerve deficits in four patients (22.2%), hemiparesis and gait unsteadiness in three (16.6%), mutism in one and meningitis in two. All patients underwent adjuvant radiotherapy in the form of craniospinal irradiation with a posterior fossa boost. On follow-up, 11 patients (61.1%) were observed to have recurrence and all were located in the posterior fossa. All 11 subsequently underwent chemotherapy. Two patients had reoperation for residual/recurrent lesions causing raised intracranial symptoms. Five-year follow-up data showed that 10 patients (55.5%) were alive, five (27.7%) had died while three (16.6%) were lost to follow-up. In spite of recent advances in management, patients with medulloblastoma still have a poor prognosis. However, adults fared better than children. Vermian location had a better outcome in adults, but not in children. Desmoplastic variant histology was not observed to be a significant prognostic factor in the adult group while brain stem invasion carried a poor prognosis. (c) 2007 Elsevier Ltd. All rights reserved.Item Bilateral thalamic lesions(BRITISH JOURNAL OF NEUROSURGERY, 2010)Objective. Bilateral thalamic lesions are rare and relatively obscure neoplasms. We present our experience with nine cases of bilateral thalamic lesions and attempt to analyse them in the background of available literature.Materials and methods. Retrospective analyses of the case records of 9 cases of bilateral thalamic lesions treated in our department since January 2002, which have a minimum of 1 year follow-up.Results. The study group included four males and five females with a mean age of 14.6 years (5 years to 29 years). Seven of these patients had radiological evidence of bilateral thalamic lesions at presentation and 2 patients had involvement of the opposite thalamus at a later stage of the disease. All patients except one presented with raised intracranial pressure symptoms. Focal motor deficits (4/9), behavioral and memory disturbances (3/9) were the other major presenting symptoms. Biopsy confirmation was possible in six patients and histopathology was suggestive of low grade fibrillary astrocytoma in all six patients. Seven patients required CSF diversion procedure for associated hydrocephalus. Eight of our nine patients underwent radiotherapy. On last follow-up, 3 patients were clinically stable with images suggestive of arrested disease, four patients had evidence of progressive disease both clinically and radiologically and there were two recorded cases of mortality.Conclusion. Primary bilateral thalamic lesions have characteristic neuroradiological properties and are distinct from unilateral thalamic tumours with bilateral progression. Almost all of these lesions on histology prove to be gliomas but decompressive surgery is seldom feasible. Surgical intervention is limited to biopsy and CSF diversion for hydrocephalus. Bilateral thalamic lesions remain unresponsive to adjuvant therapy and generally carry a poor prognosis.Item Childhood and adolescent meningiomas: a report of 38 cases and review of literature(ACTA NEUROCHIRURGICA, 2009)The aim is to study the clinical, radiological and pathological features of childhood and adolescent meningiomas and analyse outcome prognosticators.A retrospective analysis of the case records of patients less than 20 years of age operated for a meningioma in our institute since 1982 was performed. The variables analysed included age, sex, presentation, associated neurofibromatosis (NF), imaging characteristics, extent of resection and histopathology.The study group included 20 males and 18 females with a mean age of 15.53 years. Eleven children (28.9%) had evidence of NF of whom three had NF2 with bilateral vestibular schwannomas. The common presenting symptoms were seizures (76.3%), raised intracranial tension (71%), and focal neurological deficits (39.4%). The location of the operated tumours were as follows: ten skull base (24.4%), ten falx/parasagittal (24.4%), eight spinal (19.5%), five convexity (12.2%), three posterior fossa (7.3%), three intraventricular (7.3%) and two optic nerve sheath (4.9%). Two children (4.9%) had cystic meningiomas. Grade I excision was achieved only in twenty tumours (48.8%). On histopathology, thirty (73.2%) were grade I, nine (21.9%) were grade II and two (4.9%) were grade III meningiomas. Seven tumours recurred of which six were located at the skull base. During the mean follow up period of 4.74 years, the majority, 32 (84.2%) had a good outcome and five (13.2%) had a poor outcome. One child (2.6%) expired due to post-operative sepsis.Childhood meningiomas are uncommon but not rare lesions with a marginal male predominance. Absence of large series with long follow up precludes any definite conclusions on the clinical course and outcome. Uniform observations made in different series including ours, include a higher incidence of the skull base location and tumours with atypical histopathology. Favourable prognostic factors include younger age (< than 10 years), superficial location, total excision and absence of neurofibromatosis. Location and extent of excision appear to be more important than histopathology grade in predicting outcome.Item Dissecting intracranial aneurysms presenting as subarachnoid haemorrhage: report of two cases and review of literature(BRITISH JOURNAL OF NEUROSURGERY, 2008)Subarachnoid haemorrhage due to intracranial non-traumatic dissecting aneurysms is rare. Most of the published reports refer to dissecting aneurysms in the vertebrobasilar territory. Anterior circulation dissecting aneurysms are rare and their pathogenesis, clinical features, angiographic findings and management are a matter of debate. Management of patients with intracranial arterial dissection is unclear. Unlike the well-established proximal occlusion and trapping approaches to vertebral artery dissections, choices of interventions for anterior circulation and basilar dissecting aneurysms are limited, and most reports have been limited to wrapping techniques for arterial wall reinforcement. The role of anticoagulation therapy in the presence of subarachnoid haemorrhage is also a matter of debate. As no clear-cut guidelines are available, treatment should be tailored to the individual patient. We describe two cases of intracranial dissecting aneurysms, which presented as subarachnoid haemorrhage (SAH) and discuss the management issues.Item Fungal infections of the central nervous system in HIV-negative patients: Experience from a tertiary referral center of South India(ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2010)Objective: To describe the clinical, radiological, and cerebrovascular fluid (CSF) findings and the outcome of microbiologically or histopathologically proven fungal infections of the central nervous system (CNS) in HIV-negative patients. Methodology and Results: We identified definite cases of CNS mycosis by screening the medical records of our institute for the period 2000-2008. The clinical and imaging details and the outcome were abstracted from the medical records and entered in a structured proforma. There were 12 patients with CNS mycosis (i.e., 2.7% of all CNS infections treated in this hospital); six (50%) had cryptococcal infection, three (25%) had mucormycosis, and two had unclassified fungal infection. Four (33%) of them had diabetes as a predisposing factor. The common presentations were meningoencephalitis (58%) and polycranial neuritis (41%). Magnetic resonance imaging revealed hydrocephalus in 41% and meningeal enhancement in 25%, as well as some unusual findings such as subdural hematoma in the bulbocervical region, carpeting lesion of the base of the skull, and enhancing lesion in the cerebellopontine angle. The CSF showed pleocytosis (66%), hypoglycorrhachia (83%), and elevated protein levels (100%). The diagnosis was confirmed by meningocortical biopsy (in three cases), paranasal sinus biopsy (in four cases), CSF culture (in three cases), India ink preparation (in four cases), or by cryptococcal polysaccharide antigen test (in three cases). Out of the ten patients for whom follow-up details were available, six patients recovered with antifungal medications (amphotericin B, 1 mg/kg/day for the minimum period of 6 weeks) and/or surgical treatment. Four patients expired (only one of them had received antifungal therapy). Conclusions: Most patients with CNS mycosis recover with appropriate therapy, but the diagnosis and management of these rare infections remains a challenge to clinicians.Item Glioma grading: sensitivity, specificity, positive and negative predictive values of diffusion and perfusion imaging(JOURNAL OF NEURO-ONCOLOGY, 2009)Purpose The purpose of our study was to determine the statistical significance of thresholds of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC) and ADC ratios in grading cerebral gliomas. Materials and methods In this retrospective study, 51 patients with histopathologically confirmed primary cerebral gliomas who had undergone conventional MR imaging, dynamic contrast-enhanced T2*-weighted perfusion MR imaging and diffusion MR imaging were included. A retrospective blinded analysis of the imaging findings including the perfusion and diffusion parameters was done. The rCBV measurements were obtained from regions of maximum perfusion. Minimum ADC values were obtained from the region of maximum hypointensity within the tumor and from the corresponding opposite white matter. Tumor grade determined with the two methods were then compared with the histopathologic grade. Mann-Whitney tests were performed to compare the DWI and PWI between tumor types. Receiver operating characteristic analyses were performed to determine optimum thresholds for tumor grading and also to calculate the sensitivity, specificity, PPV, and NPV for identifying high-grade gliomas. Results Statistical analysis demonstrated a threshold value of 2.91 for rCBV to provide sensitivity, specificity, PPV, and NPV of 94.7, 93.75, 90.0, and 96.8%, respectively, in determining high-grade gliomas. An ADC value of 98.50 mm(2)/s was defined as a threshold below which tumors were classified as high-grade gliomas and a sensitivity, specificity, PPV, and NPV of 90, 87.1, 81.81 and 93.10% respectively, were obtained. Significant differences were noted in the rCBV ratios, ADC and ADC ratios between low- and high-grade gliomas (P < 0.0001). Conclusion Combining PWI and DWI with conventional MR imaging increases the accuracy of pre-operative imaging grading of glial neoplasms. The rCBV measurements had the most superior diagnostic performance in predicting glioma grade. Absolute ADC values or ADC ratios were also helpful in preoperative grading of gliomas. Threshold values can be used in a clinical setting to evaluate tumors preoperatively for histologic grade and provide a means for guiding treatment and predicting postoperative patient outcome.Item Intracranial Intradural Aneurysmal Bone Cyst: A Unique Case(PEDIATRIC NEUROSURGERY, 2009)Aneurysmal bone cyst (ABC) of the skull is exceedingly rare. We report a unique case of an intradural ABC without bone involvement presenting with raised intracranial pressure. The patient was a 14-year-old boy who presented with headache, vomiting and right focal seizure. Imaging showed a large multicystic left frontal lesion without any evidence of bone involvement. The lesion adherent to an intact sphenoid wing dura was completely excised. The histopathology report was consistent with an ABC. This case represents the first report of an ABC without involvement of the skull bones or any evidence of dural erosion. The possible mechanism of origin at this unusual location is hypothesized. Copyright (C) 2009 S. Karger AG, BaselItem Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannomas from meningioma(AMERICAN JOURNAL OF NEURORADIOLOGY, 2008)BACKGROUND AND PURPOSE: Vestibular schwannomas (VS may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.MATERIALS AND METHODS: In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.RESULTS: There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).CONCLUSION: Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA, meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.Item Meningiomas of the Lateral Ventricle-A Report of 15 cases(BRITISH JOURNAL OF NEUROSURGERY, 2009)Lateral ventricular meningiomas are rare tumours that pose considerable surgical challenge. This study attempts to analyse some of the important clinical features of these tumours and review technical considerations in surgery for lateral ventricular meningiomas. A retrospective analysis of the case records of patients with lateral ventricular meningiomas operated in our institute since 1998 with a minimum of one year follow up was done. The variables analysed included age, sex, clinical presentation, imaging characteristics, histopathology and operative details. Outcome was analysed using the Glasgow outcome score (GOS). Fifteen patients with a mean age of 40.6 years formed the study group. A female preponderance was observed (M:F 5:10). Raised intracranial pressure was the predominant symptom at presentation (10/15; 66%) followed by visual field deficits (6/15; 40%) and contralateral motor deficits (5/15; 33.3%). One patient presented with evidence of intratumoural bleed. The tumour was on the right side in 7 patients and on the left side in 8 patients. The lesion was located in the trigone of the lateral ventricle in 13 patients and in the body of the ventricle in two. The tumours were excised through a parietooccipital approach in 11 (73.33%) patients and through a middle temporal gyrus approach in 4 (26.66%).The tumour recurred in 2 patients, both tumours being histologically fibroblastic variants. Fresh operative complications included motor deficits in 3, contralateral homonymous hemianopia in 2, dysphasia in 1, refractory seizures in 2 and loculated hydrocephalus in one. We had no operative mortality. At last follow-up for 10 patients were in GOS 5, two were in GOS 4 and three in GOS 3. Lateral ventricular meningiomas are difficult tumours to operate. Total surgical excision through a superior parietal lobule or middle temporal gyrus approach is possible in most cases with minimal morbidity.Item Precoronal, Paramedian Minicraniotomy: A Minimal Access Approach for Microsurgical, Transcallosal, Transforaminal Removal of Colloid Cysts of the Third Ventricle(MINIMALLY INVASIVE NEUROSURGERY, 2008)Objective: Microsurgical excision of colloid cysts of the third ventricle is accomplished along the transcallosal or the transfrontal routes. In the transcallosal approach, venous tributaries of the superior sagittal sinus can often act as an impediment to entry into the interhemispheric fissure for accessing the corpus callosum. We propose a paramedian minicraniotomy anterior to the coronal suture for removing colloid cysts via the transcallosal approach as veins are relatively rare in this area.Methods: A triangular minicraniotomy was designed with each side measuring 3 cm based on the midline in the precoronal area of the frontal bone on the right side. Nineteen cases of symptomatic colloid cysts of the third ventricle whose diagnoses were proven by CT and/or MRI were subjected to microsurgery in the period from June 2004 to May 2007. Following the minicraniotomy the cysts were removed utilizing the transcallosal transforaminal route.Results: Venous tributaries crossing the inter-hemispheric fissure were seen in 2 patients and these could be avoided to access the corpus callosum. Complete excision could be achieved in all cases. All patients had a good outcome although one patient had transient left lower limb weakness. The mean operating time was 163 minutes, while the mean duration of stay in the intensive care unit and hospitalization were 1.35 days and 3.73 days, respectively.Conclusion: The pre-coronal, paramedian minicraniotomy is safe and effective for the total excision of colloid cysts of the third ventricle. As a minimal access approach, it needs only a short duration of postoperative hospitalized care.Item Proposed diagnostic criteria for intracranial infectious aneurysms(JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY, 2008)Background: We propose a set of criteria for diagnosis of intracranial infectious aneurysm (IA). The proposed diagnostic criteria contain a mandatory criterion ( demonstration of intracranial aneurysm by neuroimaging) and 12 supportive criteria drawn from three domains. Domain A encompasses infection, such as infective endocarditis, meningitis, cavernous sinus thrombophlebitis or orbital cellulitis. Domain B encompasses angiographic features of the aneurysm, such as multiplicity, distal location, fusiform shape, change in size or appearance of new aneurysm at follow-up angiogram. Domain C encompasses other features, such as age,45 years, recent history of fever, lumbar puncture or cerebral haemorrhage. Each criterion is given 1 point and the sum under each domain (A(sum), B(sum) and C(sum)) and total score are calculated.Methods: We evaluated these criteria in 25 patients with confirmed IA and in another 111 consecutive patients with non-infectious aneurysm. The sensitivity, specificity and receiver operator characteristic (ROC) curves were calculated for these cohorts.Results: The highest ROC was for total score (0.997). A total score of 3 had high sensitivity (96%) and specificity (100%), as well as a positive predictive value of 100% and negative predictive value of 99.4%. A total score of 2 had high sensitivity ( 100%) but low specificity ( 87.4%). Other combinations had lower ROC areas, sensitivities and specificities.Conclusion: Diagnosis of IA would be clinically compelling if three or more of the proposed supportive criteria are satisfied, or clinically probable if two proposed supportive criteria are satisfied apart from the mandatory criteria.Item Rosai-Dorfman disease mimicking chronic subdural hematoma(JOURNAL OF CLINICAL NEUROSCIENCE, 2008)Rosai-Dorfman disease (RDD) otherwise known as simus histiocytosis with massive lymphadenopathy is an uncommon benign systemic histio-proliferative disease characterised by massive lymphadenopathy particularly in the head and neck region and is often associated with extra-nodal involvement. We report a case in which RDD was mistaken for a chronic subdural hematoma and surgery was attempted. (C) 2007 Elsevier Ltd. All rights reserved.Item Subfrontal gangliocytoma masquerading as olfactory groove meningioma(BRITISH JOURNAL OF NEUROSURGERY, 2009)We describe a rare case of an unusually located gangliocytoma. The conventional magnetic resonance imaging (MRI) appearance was suggestive of an olfactory groove meningioma. However, advanced MRI sequences (diffusion-weighted imagingDWI; perfusion MRI; susceptibility-weighted imagingSWI; MR spectroscopyMRS) revealed features more consistent with a glial neoplasm.Item Item Symptomatic granular cell tumour of the pituitary(BRITISH JOURNAL OF NEUROSURGERY, 2008)Granular cell tumours (GCT) and pituicytomas are rare tumours seen in the sellar suprasellar region which are believed to arise from either the infundibulum or the posterior lobe of the pituitary gland. Whether they are two distinct lesions or represent one single pathological entity remains a matter of debate. We report the case of a 42-year-old male with a granular cell neoplasm of the sellar suprasellar region and attempt to discuss the controversies shrouding this distinct clinicopathological entity.Item Telovelar approach: technical issues for large fourth ventricle tumors(CHILDS NERVOUS SYSTEM, 2007)Objects Fourth ventricle is conventionally accessed via resection of the part of the vermis for total excision of the tumors at the expense of significant morbidity. Numerous avenues have been identified to minimize the morbidity; some of which include transforaminal, subtonsillar, telovelar approaches, etc. These approaches are devised on the basis that accurate dissection along the natural avascular planes will avoid injury to the important structures in this area minimizing morbidity. We attempt to emphasize the technique of telovelar approach and the problems encountered while employing this technique for excision of large fourth ventricle tumors.Material and methods Fifteen patients with fourth ventricle tumors were operated during January to September 2005 at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fourteen of these cases were medulloblastomas, and one was ependymoma. All the patients were operated in prone oblique position via telovelar approach.Conclusion Clear understanding of the normal anatomy will help in meticulous dissection and will result in reduced morbidity. Significant incidence of postoperative ataxia and mutism is seen with this approach in large tumors, and this can be avoided by staged dissection of the uvulotonsillar cleft.