Browsing by Author "Nair, S"

Now showing 1 - 20 of 71
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    A biodegradable in situ injectable hydrogel based on chitosan and oxidized hyaluronic acid for tissue engineering applications
    (CARBOHYDRATE POLYMERS, 2011) Nair, S; Remya, NS; Remya, S; Nair, PD
    An "in situ" biodegradable gel consisting of chitosan, glycerol phosphate (GP) and oxidized hyaluronic acid (HDA) were synthesised and characterized This is a two component hydrogel system where chitosan neutralized with GP resulted in instantaneous gelling when combined with HDA. The gels are cytocompatible and could be freeze dried to form porous scaffolds. The percentage porosity of the freeze-dried chitosan hyaluronic acid dialdehyde gels (CHDA) increased with increasing oxidation. Fibroblast cells seeded onto CHDA porous scaffolds adhered, proliferated and produced ECM components on the scaffold. Chondrocytes encapsulated in CHDA gels retained their viability and specific phenotypic characteristics. The gel material is hence proposed as a scaffold and encapsulating material for tissue engineering applications. (C) 2011 Elsevier Ltd. All rights reserved.
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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 during pregnancy: Report of two cases and review of literature
    (ACTA NEUROCHIRURGICA, 2001)
    Though infrequent, acoustic neurinomas have been described during pregnancy and represent a therapeutic challenge for excision without producing any problem for the mother and the foetus. First Author experienced two cases of acoustic neurinomas presenting during pregnancy. One patient presented in the terminal stages of the third trimester of pregnancy and underwent caesarean section, followed by retromastoid craniectomy and excision of the rumour. Operative management of the pregnancy and tumour in the same sitting has not been reported in the literature. Second patient who presented during 2nd trimester of pregnancy, was operated on for the tumour and had a successful continuance of pregnancy. Details of the management are discussed and the relevant literature reviewed. In addition to causing aggravation of symptoms, the larger size and increased vascularity of these rumours during pregnancy, makes them more vulnerable to acute bleeding, which in turn may initiate new or exacerbate pre-existing symptoms, as noted in one of the cases presented in this report.
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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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    Anaplastic ganglioglioma: case report and review of the literature
    (BRITISH JOURNAL OF NEUROSURGERY, 1998)
    A 10-year-old girl underwent radical decompression of a right temporal tumour extending to the insular cortex which proved to be a differentiated ganglioglioma. One year later, she presented with a bleeding right frontal tumour extending to the insula, the histology of which showed it to be the anaplastic variant of ganglioglioma. She underwent postoperative radiotherapy but died 6 months after the second operation. Anaplastic ganglioglioma is a rare variant of ganglioglioma and progression of the latter to anaplastic ganglioglioma is an extremely rare occurrence. The literature regarding ganglioglioma is reviewed.
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    Atypical meningioma: A clinicopathological analysis
    (NEUROLOGY INDIA, 2000) Joseph, E; Sandhyamani, S; Rao, MB; Nair, S; Radhakrishnan, VV
    In this retrospective study, 382 operated cases of meningiomas were reviewed, 32 cases (8.3%) were histopathologically classified as atypical meningioma, The anatomical locations and histological features in all the thirty-two cases were correlated with their recurrence rates and biological behaviour. The overall recurrence rate for atypical meningioma within two years was 28% as compared to 9.3% in benign meningiomas. It is being emphasized that an accurate histopathological interpretation of atypical meningioma is essential for predicting the recurrence, biological behavior as well as postoperative management modalities.
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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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    Calcification in vestibular schwannoma: Report of two cases and review of the literature
    (NEUROLOGY INDIA, 2011) Gopalakrishnan, CV; Shrivastava, A; Nair, S
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    Central Neurocytomas: A Review of an Institutional Series of 33 Cases
    (NEUROSURGERY QUARTERLY, 2012) Menon, GR; Patil, A; Abraham, M; Nair, S
    Objective: Neurocytomas (NCs) comprise a rare but distinct clinicopathologic entity, often with a benign course. Our operative series of 33 patients with NCs attempts to review the clinical characteristics of this rare entity. Method: Retrospective analysis of the case records of all the patients with central NCs operated since January 2000. The following prognostic factors were analyzed for statistical significance: age, sex, location, extent of resection, and the histopathologic grade. Results: The study group included 33 patients with a mean age of 28.87 years (range, 9 to 55 y) and with a male preference (M: F = 20: 13). Increased intracranial headache was the predominant presenting complaint (27/33; 81.8%), followed by gait imbalance, memory deficits, weakness, and seizures. At the first surgery, gross total removal could be achieved only in 16 cases (48.84%). The majority (26/33; 78.78%) were typical NCs and 7 were atypical NCs. Of the 17 patients with residual lesions, only 4 patients showed an increase in the size of the residue and only 2 of them had symptomatic recurrence requiring repeat surgery. Of the 16 patients who underwent radical excision, 4 had recurrence, 1 requiring repeat surgery. Three of the atypical NCs recurred in spite of gross total resection. We had 5 perioperative mortalities, all related to tumor bleeding and postoperative brain swelling. One child with a recurrent fourth ventricular NC expired after adjuvant chemotherapy. Of the remaining 27 patients, 25 patients had a Glasgow outcome score (GOS) of 5 and 2 were in GOS 3 at the end of a mean follow-up period of 4.63 years (range 2 to 11 y). Conclusions: Central NCs are unique tumors of neuronal origin with strong histologic resemblance to other intraventricular tumors of glial origin. NCs are vascular tumors, and their radical removal can be challenging. Although radical surgery is the treatment of choice, they are slow growing, and subtotal resections also provide long-term symptom-free survival even for atypical lesions.
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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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    Changing characteristics of a colloid cyst of the third ventricle
    (NEURORADIOLOGY, 1999)
    We describe extremely unusual radiological characteristics in a colloid cyst of the third ventricle, where the cyst became dense and its size decreased following a cerebrospinal fluid diversion procedure. Such a course of events has been reported in colloid cysts only twice in the literature.
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    Chiari and duraplasty Response
    (JOURNAL OF NEUROSURGERY, 2012) Menon, G; Bahuleyan, B; Nair, S
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    Clinical and polysomnographic predictors of severe obstructive sleep apnea in the South Indian population
    (ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2016) Sreedharan, SE; Agrawal, P; Rajith, RS; Nair, S; Sarma, SP; Radhakrishnan, A
    Background: With the emergence of lifestyle diseases in epidemic proportions, obstructive sleep apnea (OSA) is being increasingly recognized in less developed countries as well. Aim: We sought to study the demographic, clinical, and polysomnographic (PSG) predictors of OSA severity in a cohort of South Indian patients. Materials and Methods: Consecutive patients with PSG proven OSA [apnea hypopnea index (AHI) >= 5/h] were prospectively recruited. The study period was from January 2012 to December 2012. Demographic data, history of vascular risk factors, substance abuse, sleep quality, snoring, and witnessed apneas were collected using a structured pro forma. In addition, PSG variables such as AHI, sleep latency and efficiency, duration of slow wave and rapid eye movement (REM) sleep, and other parameters were collected. Correlations between AHI severity and clinical and PSG parameters were done. Results: There were 152 (119 males and 33 females) subjects with a mean age of 53.8 years and body mass index (BMI) of 29.31. Mean AHI was 36.2/h (range: 5.1-110) and 66 subjects had severe OSA. Around 12% had the presenting complaint as insomnia, mainly of sleep maintenance. Of the subjects, 35% had witnessed apneas and 67% had excessive daytime sleepiness (EDS); 40% of patients had >= 2 risk factors. PSG parameters showed short sleep onset latency with a high arousal index. Mean apnea duration was 24.92 s. We found that age >55 years, BMI > 25 kg/m(2), witnessed apneas, EDS, hypertension, dyslipidemia, reduced slow wave sleep duration, mean apnea duration > 20 s, and desaturation index > 10/h correlated well with OSA severity while the arousal index, sleep latency and efficiency, and exposure to smoking and alcohol showed no association. Conclusions: Older subjects with witnessed apneas are likely to have more severe OSA. Even though overall sleep architecture was similar between the groups, severe OSA had shorter slow wave sleep, longer apneas, and higher nocturnal hypoxemia.
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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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    Diagnostic Value of Ga-68 PSMA-11 PET/CT Imaging of Brain Tumors-Preliminary Analysis
    (CLINICAL NUCLEAR MEDICINE, 2017) Sasikumar, A; Joy, A; Pillai, MRA; Nanabala, R; Anees, KM; Jayaprakash, PG; Madhavan, J; Nair, S
    Objective: To evaluate the feasibility of using Ga-68 PSMA-11 PET/CT for imaging brain lesions and its comparison with F-18-FDG. Methods: Ten patients with brain lesions were included in the study. Five patients were treated cases of glioblastoma with suspected recurrence. F-18-FDG and Ga-68 PSMA-11 brain scans were done for these patients. Five patients were sent for assessing the nature (primary lesion/metastasis) of space occupying lesion in brain. They underwent whole body F-18-FDG PET/CT scan and a primary site elsewhere in the body was ruled out. Subsequently they underwent Ga-68 PSMA-11 brain PET/CT imaging. Target to background ratios (TBR) for the brain lesions were calculated using contralateral cerebellar uptake as background. Results: In five treated cases of glioblastoma with suspected recurrence the findings of Ga-68 PSMA-11 PET/CT showed good correlation with that of F-18-FDG PET/CT scan. Compared to the F-18-FDG, Ga-68 PSMA-11 PET/CT showed better visualization of the recurrent lesion (presence/absence) owing to its significantly high TBR. Among the five cases evaluated for lesion characterization glioma and atypical meningioma patients showed higher SUVmax in the lesion with Ga-68 PSMA-11 than with F-18-FDG and converse in cases of lymphoma. TBR was better with Ga-68 PSMA PET/CT in all cases. Conclusion: Ga-68 PSMA-11 PET/CT brain imaging is a potentially useful imaging tool in the evaluation of brain lesions. Absence of physiological uptake of Ga-68 PSMA-11 in the normal brain parenchyma results in high TBR values and consequently better visualization of metabolically active disease in brain.
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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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    Evaluation of the established non-MHC multiple sclerosis loci in an Indian population
    (MULTIPLE SCLEROSIS, 2011) Pandit, L; Ban, M; Sawcer, S; Singhal, B; Nair, S; Radhakrishnan, K; Shetty, R; Misri, Z; Hegde, S; Bhat, IG
    Background: Multiple sclerosis (MS) is a chronic demyelinating neurodegenerative disorder with a strong genetic component. Objective: The prevalence of MS in India is low compared with white populations of Northern European descent. Methods: In order to ascertain whether disease susceptibility genes are the same across different populations, we completed the first investigation in the Indian MS population of 15 MS loci outside of the major histocompatibility (MHC) region that were previously identified and validated with MS susceptibility through genome-wide association and replication studies in white populations. Results: In total, 197 Indian patients and 197 unrelated controls were analyzed. The most associated single nucleotide polymorphism (SNP) within this study was rs6897932 in the IL7R gene, which showed a strong protective effect in this data set (rs 6897932, OR = 0.5543, 95% CI = 0.37-0.78, p = 0.0009727). Two other SNPs were nominally associated with MS in this dataset, namely CLEC16A rs 12708716 (p = 0.0082, OR = 1.478, 95% CI = 1.106-1.975) and CD226 rs763361 (p = 0.03971, OR = 1.353, CI = 1.014-1.805). For the majority of the remaining SNPs (7/14), the trend for association was in the same direction as in previous studies in the white population. Conclusions: Although the power of this study was limited, our preliminary data suggest that disease susceptibility genes in MS in the Indian population may be similar to those of western populations.
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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.