Browsing by Author "Menon, G"

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    A retrospective study of primary cerebellar glioblastoma multiforme in adults
    (JOURNAL OF CLINICAL NEUROSCIENCE, 2012) Gopalakrishnan, CV; Dhakoji, A; Nair, S; Menon, G; Neelima, R
    Primary cerebellar glioblastoma multiforme (GBM) is a rare tumour in adults that accounts for less than 1% of all patients with GBM. In view of their rarity, the pathogenesis and prognosis of cerebellar GBM are not yet completely understood. The aim of this study was to retrospectively analyse patients with primary cerebellar GBM treated in our institute over a period of 10 years. Data from the case records of five adult patients with cerebellar GBM was evaluated and their outcome was assessed. We observed local failure in patients who reported back with recurrence. The presence of brainstem infiltration was a significant factor influencing progression-free survival. The overall prognosis was worse than for patients with supratentorial GBM. In view of their rarity, a meta-analysis is required to assess the pathogenesis and prognostic factors affecting overall survival in patients with cerebellar GBM. (C) 2012 Elsevier Ltd. All rights reserved.
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    Acoustic neurinomas: Facial nerve preservation in large and giant tumors - a personal series of over 600 cases
    (13TH ASIAN-AUSTRALASIAN CONGRESS OF NEUROLOGICAL SURGEONS (AACNS), 2012) Nair, S; Gopalakrishnan, CV; Vikas, V; Sudhi Jr; Abraham, M; Menon, G; Easwer, HV; Krishnakumar; George, V; Amit, D
    The goal of vestibular schwannoma surgery has changed over years from preserving patient's life to total or near total excision with functional facial nerve preservation and with hearing preservation in selected cases. These tumours can be unilateral or bilateral, can be purely intracanalicular or intra-extracanalicular, can have varied sizes, can be purely solid or cystic with or without intratumoral bleed, can be vascular or avascular, can have extensive pial breaching with peritumoral edema, can be medially impacted into brainstem with extension across midline or laterally impacted into the petrous bone with involvement of cochlea, can be polylobular, can extend superiorly upto the ambient cistern or inferiorly below foramen magnum, may or may not have extratumoral arachnoid cap and may or may not be associated with hydrocephalus. Each of these poses different problems for the operating surgeon. Sometimes optimal bone removal may itself be complicated by large emissary veins or a highly placed jugular bulb. Over a thirteen and a half year period from 1st February 1998 to 14thNovember 2011, 610 cases of large and giant vestibular schwannomas were operatively managed with an operative mortality of <1% (6 cases). There were 63 patients (10.3%) of cystic vestibular schwannomas and 21 cases of bilateral vestibular schwannomas. Twelve patients of cystic schwannomas presented with imaging evidence of bleed. All the patients were operated by retrosigmoid route in the lateral position. A retrospective analysis of 100 consecutively operated cases was undertaken to compare the clinical presentation and surgical outcome for giant tumors (size >4.5 cm in any dimension on radiological imaging) as opposed to tumors of smaller sizes (large: 2.5 to 4.5 cm & small: <2.5 cm). While 25 patients in the study group had giant tumors, it was large in 72 and small in the remaining three. The incidence of preoperative hearing loss, trigeminal nerve involvement and cerebellar signs were almost identical in the giant and the large tumor groups. But the incidence of preoperative facial paresis, lower cranial nerve involvement and hydrocephalus was significantly more in the giant group. All the patients were operated by retrosigmoid approach in the lateral position. Excepting 5 patients (2 giant & 3 large), where only a sub / near total removal was done, all the remaining had total excision of the lesion. While anatomical preservation of seventh nerve could be achieved in 90% of the large tumors, it was only 60% in the giant category. Mean hospital stay was 18 and 15 days for giant and large group respectively. Acoustic neurinomas of all sizes can be operated by retromastoid approach alone with gratifying results. The technical issues of operative management with particular emphasis on extra-arachnoid dissection in preserving facial nerve is highlighted.
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    Advanced magnetic resonance imaging with histopathological correlation in papillary tumor of pineal region: Report of a case and review of literature
    (NEUROLOGY INDIA, 2010) Vaghela, V; Radhakrishnan, N; Radhakrishnan, VV; Menon, G; Kesavadas, C; Thomas, B
    Papillary tumors of the pineal region are recently described as rare mass lesions with limited literature available on their natural history and imaging features. Magnetic resonance imaging (MRI) including perfusion, diffusion, and spectroscopic features were described in an 18-year-old girl with papillary tumor of pineal region. A well-defined, T1 hyperintense and contrast-enhancing mass lesion was noted in pineal region with few cystic spaces within. Solid portion of lesion showed minimal diffusion restriction with average apparent diffusion coefficient of 0.812 x 10(-3) mm(2)/s: on MR spectroscopy elevated myo-inositol peak with reduced N-acetylaspartate and elevated choline in the tumor. On perfusion study there was significantly high relative cerebral blood volume (rCBV) (6-9 times) and relative cerebral blood flow (rCBF). Our findings agree with previous descriptions of cystic areas with T1 hyperintense appearance of this tumor but very high level of tumor perfusion, diffusion restriction, and presence of myo-inositol peak are important imaging findings and may correlate with the recent reports of high tumor recurrence in these cases.
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    Advanced magnetic resonance imaging with histopathological correlation in papillary tumor of pineal region: report of a case and review of literature.
    (Neurology India, 2010)
    Papillary tumors of the pineal region are recently described as rare mass lesions with limited literature available on their natural history and imaging features. Magnetic resonance imaging (MRI) including perfusion, diffusion, and spectroscopic features were described in an 18-year-old girl with papillary tumor of pineal region. A well-defined, T1 hyperintense and contrast-enhancing mass lesion was noted in pineal region with few cystic spaces within. Solid portion of lesion showed minimal diffusion restriction with average apparent diffusion coefficient of 0.812 Chi 10 -3 mm 2 /s; on MR spectroscopy elevated myo-inositol peak with reduced N-acetylaspartate and elevated choline in the tumor. On perfusion study there was significantly high relative cerebral blood volume (rCBV) (6-9 times) and relative cerebral blood flow (rCBF). Our findings agree with previous descriptions of cystic areas with T1 hyperintense appearance of this tumor but very high level of tumor perfusion, diffusion restriction, and presence of myo-inositol peak are important imaging findings and may correlate with the recent reports of high tumor recurrence in these cases.
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    BEYOND THE LEARNING CURVE IN EPILEPSY SURGERY: THE INSTITUTIONAL AND INDIVIDUAL PERSPECTIVE
    (EPILEPSIA, 2011) Vilanilam, GC; Abraham, M; Menon, G; Rao, RM; Nair, S; Radhakrishnan, K
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    Cerebellar hemisphere, an uncommon location for pleomorphic xanthoastrocytoma and lipidized glioblastoma multiformis
    (NEUROLOGY INDIA, 2003)
    Lipidized glioblastoma multiformis (LGB) and pleomorphic xanthoastrocytoma (PXA) are often supratentorial in location and occur in the second to fourth decade. This report presents two young patients, one having LGB and the other having PXA in the cerebellum. Histological differentiation between LGB and PXA is discussed.
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    Cerebrospinal fluid rhinorrhea and acquired anterior basal encephalocoele in a patient with colloid cyst of the third ventricle
    (NEUROLOGY INDIA, 2010) Deepak, KS; Kesavadas, C; Kapilamoorthy, TR; Menon, G
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    Chiari and duraplasty Response
    (JOURNAL OF NEUROSURGERY, 2012) Menon, G; Bahuleyan, B; Nair, S
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    Clinical and electroencephalographic correlates of breach activity
    (AMERICAN JOURNAL OF ELECTRONEURODIAGNOSTIC TECHNOLOGY, 1999) Radhakrishnan, K; Chandy, D; Menon, G; Sarma, S
    In order to define the EEG spectrum and the prevalence of breach activity, as well as the factors contributing to its genesis, we studied 50 patients with surgically induced skull defects. We observed breach activity in 32 (64%) patients. Focally enhanced alpha, beta, and mu rhythms with or without decreased amplitude of eye movement artifacts were the EEG findings encountered in our patients. The amplitude asymmetry never exceeded a factor of 3 or more. Of the variables compared between patients with and without breach activity, only the time between surgery and the EEG recording correlated positively with the development of breach activity. The delay in the development of breach activity may indicate that breach activity is not due solely to the discontinuity of bone. The development of meningocortical adhesions and gliosis could contribute to the pathogenesis of breach activity.
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    Colloid Cyst: Institutional Experience of 293 Cases
    (13TH ASIAN-AUSTRALASIAN CONGRESS OF NEUROLOGICAL SURGEONS (AACNS), 2012) Nair, S; Menon, G; Easwer, HV; Abraham, M; Vikas, V; Krishnakumar; Gopalakrishnan, CV; George, V; Sudhir, J
    Aim: To analyze the clinical presentation, surgical outcome of 293 cases of colloid cysts surgically managed over a period of 32 years beginning January 1980 to September 2011. Methods: Age range was between 9 to 66 years. Raised ICP headache was the most common initial presenting symptom in 74% followed by visual blurring in 7%, memory disturbance in 5.3%, intermittent headaches in 7.6%, drop attacks, gait unsteadiness in 3.4% and incidental in five patients (2%). Imaging with CT scan done showed the cyst to be hyperdense in 69%, isodense in 28% and hypodense in 4% of patients. Shorter duration of symptoms correlated with MRI T2W hyperintensity changes. While an interhemispheric transcallosal approach was used in 271, it was trans-cortical in 22 (endoscope assisted in 6 & endoscopically in 2). Results: Out of the 271 patients operated through the transcallosal approach, the cyst was removed through transforaminal route in 226, interforniceal rote in 24, subchoroidal in 14 and suprachoroidal in seven. Twenty-two patients underwent emergency surgery. Twenty-eight patients had CSF diversionary procedure (14 patients referred with preoperative shunt done elsewhere and 14 required postoperative CSF diversions). Complications included impaired memory in 35, hemiplegia/ hemiparesis in 8 and seizures in twelve. There was an operative mortality of 1% (3 cases). Eight patients had symptomatic recurrence of which 6 had total excision at first surgery. Conclusions: These potentially life threatening lesions can be removed safely through the interhemispheric transcallosal approach. Periodic follow-up with MR imaging is necessary as recurrence can occur even after apparent total excision.
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    Computing the difference between life and death: Prerupture blood flow analysis of a fatal aneurysm bleed
    (NEUROLOGY INDIA, 2016) Sudhir, BJ; Reddy, JB; Menon, G; Jayachandran, T
    Although hemodynamics plays a key role in the genesis, expansion, and rupture of an aneurysm, quantified hemodynamic parameters for comparison have not been standardized for predicting the risk of rupture of intracranial aneurysms. Computational fluid dynamics is being increasingly used in near-realistic, patient-specific simulation of blood flow in intracranial aneurysms. A simulation was carried out on the computed tomography (CT) angiogram image of a patient harboring a giant internal carotid artery aneurysm. Since the CT angiogram was performed a few hours before the fatal rupture of the aneurysm, the study could give an insight into the hemodynamics of the aneurysm that tipped it to rupture. Wall shear stress, pressure distribution, and flow streamlines were obtained using computational methods. These objective results could form the basis of reference for future studies employing simulation techniques for predicting aneurysmal rupture.
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    Dissecting intracranial vertebral artery aneurysms
    (NEUROLOGY INDIA, 2001)
    Dissecting aneurysms of the intracranial arteries are exceedingly rare vascular lesions that can produce acute cerebral or brain stem infarction in young healthy adults. They carry a high mortality rate. Two cases of dissecting vertebral artery aneurysms that presented with bleed, were successfully operated by trapping and excision of the dissecting segment. Both dissecting aneurysms were located distal to PICA origin. Both the patients developed post operative lower cranial nerve paresis and one developed lateral medullary syndrome, which improved subsequently. Dissecting aneurysms presenting with bleed should be surgically managed by trapping and excising the involved segment sparing the PICA origin or by interventional radiological techniques. Revascularisation procedures should be considered in addition to trapping of the main vertebral segment if PICA is involved in the trapped segment. The diagnostic and therapeutic difficulties associated with dissecting vertebral artery aneurysms and the controversies regarding their management have been reviewed.
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    Extraventricular neurocytoma, a comprehensive review
    (ACTA NEUROCHIRURGICA, 2014) Patil, AS; Menon, G; Easwer, HV; Nair, S
    Extra ventricular neurocytoms (EVN) are a rare parenchymal brain tumour distinct from central neurocytomas. This review attempts to analyze a series of seven cases of EVN from a single institute against the background of available literature. Retrospective analysis of the clinical manifestation, pathological features, imaging findings, microsurgical treatment effectiveness and progression free survival of seven cases of EVN operated between 2000-2012. The study group included five females and two males in the age group 7-65 years (mean 30.71 yrs). The distribution of the lesion was as follows Lobar 4, Cerebellum 1, Pineal 1, spinal 1. The duration of clinical symptoms ranged from three months to seven years and the presentation was site and size specific. Cystic Changes (71 %), perilesional oedema (57 %) and heterogeneous contrast enhancement (85.7 %), and calcification (42 %) were a few distinct imaging characteristics. Increased perfusion correlated with atypical histology in two patients. Surgical resection remains the main management strategy for longer outcome and patients with STR + RT and GTR had comparable follow-up. Extremes of age and atypical histological features were adverse prognostic factors. EVN are rare tumors with either glial or neuronal differentiation or a potential for atypical changes. Both, GTR and STR combined with RT, offer reasonably good outcome with overall comparable survival. The available literature of EVN is limited, larger series with long term follow-ups are needed to dictate the management protocol. The role of adjuvant therapy is still debatable and needs further validation.
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    Factors Predicting the Need for Cerebrospinal Fluid Diversion following Posterior Fossa Tumor Surgery in Children
    (PEDIATRIC NEUROSURGERY, 2012) Gopalakrishnan, CV; Dhakoji, A; Menon, G; Nair, S
    Background: No consensus exists regarding the management of hydrocephalus in children with posterior fossa tumors before, during or after surgery. In the present study we analyze the factors that predispose to persistent hydrocephalus and the need for a postoperative cerebrospinal fluid (CSF) diversion procedure. Methods: Pediatric patients who underwent surgery for posterior fossa tumors with hydrocephalus at our hospital were reviewed to evaluate the need for a postoperative CSF diversion procedure. Patients having undergone CSF diversion preoperatively were excluded from the study group. The case records of 84 patients were reviewed. The factors evaluated included age at diagnosis, duration of symptoms, severity of preoperative hydrocephalus, tumor size, tumor location, tumor histology, extent of tumor resection and postoperative complications that could be related to CSF circulation disorders. Results: At the time of presentation, 80/84 (95.2%) patients had symptomatic hydrocephalus; 25/84 (29.8%) patients required a CSF diversion procedure in the postoperative period. Children presenting with symptom duration of less than 3 months had a significantly higher requirement for postoperative CSF diversion in comparison to those with longer symptomatology (p = 0.016). Evan's index and frontal and occipital horn ratio on preoperative imaging were found to correlate closely with the need for postoperative shunt (p = 0.001 and p < 0.001, respectively). The requirement for shunt was statistically higher in patients with midline tumors in comparison to laterally placed lesions (p = 0.04) and in children with medulloblastoma (p < 0.001) and ependymoma (p = 0.016) as the tumor subtypes. Children who underwent intraoperative external ventricular drainage (EVD) had a shunt insertion rate of 39.6% compared with 16.7% of those who did not have an EVD (p < 0.001). Patients with meningitis and pseudomeningocele in the postoperative period had a statistically significant higher risk of shunt requirement (p = 0.008 and p = 0.016, respectively). The mean age at diagnosis and the extent of tumor resection did not correlate with the need for CSF diversion. Conclusion: The fact that less than one-third of patients require a CSF diversion after posterior fossa tumor resection refutes the role of prophylactic endoscopic third ventriculostomy. Awareness regarding the factors that can predict persistent postoperative hydrocephalus is essential for the surgeon during patient counseling and surgical planning, and also in deciding the intensity of postoperative clinical and radiological monitoring. Copyright (c) 2012 S. Karger AG, Basel
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    False aneurysm of cavernous carotid artery and carotid cavernous fistula: Complications following transsphenoidal surgery
    (NEUROLOGY INDIA, 2003)
    We present two cases of carotid-injury during transsphenoidal surgery for pituitary adenoma. While in one of the cases it resulted in the formation of a false aneurysm of cavernous carotid artery, in the other patient, a carotid cavernous fistula (CCF) formed. The false aneurysm was managed by surgical trapping- and the patient had an uneventful recovery. The CCF was initially managed with balloon embolization. The balloon got deflated and resulted in a false aneurysm with persistent CCF. This was occluded with Guglielmi Detachable Coils (GDC). The management options are discussed and relevant literature is reviewed. We emphasize the importance of an early cerebral angiography to know the status of the injured carotid artery and formation of false aneurysm / fistula.
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    Germinoma of the basal ganglia: A case report and review of literature
    (NEUROLOGY INDIA, 2002) Elizabeth, J; Menon, G; Nair, S; Bhattacharya, RN; Radhakrishnan, VV
    Germ cell tumors of extrapineal region are extremely uncommon. The clinicopathological features of germinoma in the left basal ganglia, in a 21 year old male are presented in this report. Post-operative radiotherapy is advocated, in view of the good radiosensitivity of these tumors.
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    Immediate postoperative death due to hypothalamic injury following surgery for craniopharyngioma
    (JOURNAL OF CLINICAL NEUROSCIENCE, 2009) Bahuleyan, B; Menon, G; Nair, S
    Autonomic disturbances due to hypothalamic injury that result in postoperative death are rare complications following surgery for craniopharyngioma. We discuss the case of a child who died due to hypothalamic injury following radical excision of a multi-compartmental craniopharyngioma. Mechanisms and clinical manifestations of hypothalamic injury and ways to avoid this fatal complication are discussed. (C) 2008 Elsevier Ltd. All rights reserved.
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    Intramedullary spinal cord glial tumours: Management philosophy and surgical outcome
    (MINIMALLY INVASIVE NEUROSURGERY AND MULTIDISCIPLINARY NEUROTRAUMATOLOGY, 2006) Nair, S; Menon, G; Rao, BRM; Rajesh, BJ; Muthurethinam, T; Mathew, A; Easwer, HV; Bhattacharya, RN
    A retrospective analysis of 88 consecutive cases of intramedullary glial tumours, which constituted 58% of 149 cases of intramedullary lesions surgically managed over a 22-year period, is presented. Fifty-six astrocytomas and 32 ependymomas formed the group, which comprised 55 males and 33 females. While majority of the astrocytomas were in the cervical or cervicodorsal location (70%), it was almost equally distributed between the cervical and conus regions in 23 cases of ependymomas. The management philosophy has changed over the years from biopsy to total removal for ependymomas and a generous inside out decompression in case of astrocytomas. While only a biopsy or decompression was done in 35 of the earlier patients of astrocytomas a radical removal (subtotal in 18 and total in 3) could be achieved in 21 of our recent patients. We could achieve total resection in all the last 17 patients of ependymomas. Low grade astrocytomas radically removed and all ependymomas were not given radiotherapy. Out of the 39 patients of astrocytomas who are in follow up, 13 have improved, 19 remaining static and 7 have deteriorated. While only three of the 25 patients of ependymomas on long term follow up have deteriorated 18 have improved and 6 are remaining static. Conclusion: Although total resection of ependymomas have become a procedure with good functional results in most hands, a radical resection can be achieved with long term stabilisation of neurological deficits in majority of astrocytomas.
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    Kissing anterior communicating artery aneurysms: Diagnostic dilemma and management issues
    (JOURNAL OF POSTGRADUATE MEDICINE, 2011) Baldawa, SS; Menon, G; Nair, S
    Kissing aneurysms are unusual and relatively rare types of multiple intracranial arterial aneurysms. When located on the anterior communicating artery (ACoA), kissing aneurysms pose considerable diagnostic difficulty on preoperative conventional angiogram. Special angiographic views or 3D rotational angiogram are needed to make the correct diagnosis and to avoid interpreting them as multilobed or bilobed saccular aneurysms on preoperative conventional angiogram. Treatment of these aneurysms, either by clipping or coiling, needs to be individualized. Unique problems which need to be addressed during surgical clipping are high risk of rupture due to dense adhesions between the kissing aneurysms, requirement of at least two clips in a narrow working area, the aneurysm that needs to be clipped first and interference of the first clip with application of subsequent clips. The authors present a case of a 63-year-old male who had kissing ACoA aneurysms managed successfully by clipping.
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    Kissing anterior communicating artery aneurysms: diagnostic dilemma and management issues.
    (Journal of postgraduate medicine, 2011)
    Kissing aneurysms are unusual and relatively rare types of multiple intracranial arterial aneurysms. When located on the anterior communicating artery (ACoA), kissing aneurysms pose considerable diagnostic difficulty on preoperative conventional angiogram. Special angiographic views or 3D rotational angiogram are needed to make the correct diagnosis and to avoid interpreting them as multilobed or bilobed saccular aneurysms on preoperative conventional angiogram. Treatment of these aneurysms, either by clipping or coiling, needs to be individualized. Unique problems which need to be addressed during surgical clipping are high risk of rupture due to dense adhesions between the kissing aneurysms, requirement of at least two clips in a narrow working area, the aneurysm that needs to be clipped first and interference of the first clip with application of subsequent clips. The authors present a case of a 63-year-old male who had kissing ACoA aneurysms managed successfully by clipping.