Browsing by Author "Abraham, M"

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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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    Anesthesia for craniotomy in a patient with previous paralytic polio
    (JOURNAL OF CLINICAL ANESTHESIA, 2008) Suneel, PR; Sinha, PK; Unnikrishnan, KP; Abraham, M
    Poliomyelitis remains endemic in many developing nations. Patients may develop residual muscle weakness in one or more, limbs after an attack of poliomyelitis in childhood. We report an adult patient who presented for right temporal cortical grid placement. He had childhood poliomyelitis and, while showing no evidence of postpolio syndrome, demonstrated excessive sensitivity to nondepolarizing muscle relaxants and developed prolonged muscle weakness during the postoperative period. (c) 2008 Elsevier Inc. All rights reserved.
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    Anesthesia management of awake craniotomy performed under asleep-awake-asleep technique using laryngeal mask airway: Report of two cases
    (NEUROLOGY INDIA, 2008) Vitthal, GS; Sreedhar, R; Abraham, M
    Asleep-awake-asleep technique of anesthesia is used during awake craniotomy with or without securing airway. We assessed this technique using laryngeal mask airway (LMA) in two patients. Patients underwent awake craniotomy for epilepsy surgery and the removal of a frontotemporal glioma. After anesthesia induction, airway was secured using LMA. Anesthesia was maintained using oxygen, nitrous oxide and sevoflurane, supplemented with an infusion of propofol and remifentanil. Twenty minutes before corticography, anesthesia was discontinued and LMA removed. Both patients were awake and cooperative during the neurological assessment and surgery on eloquent areas. The LMA was reinserted before the closure of the dura and remained in place until the end of surgery. Both patients had no recall of events under anesthesia, although experienced mild pain and discomfort during awake phase of surgery. Both expressed complete satisfaction over the anesthetic management. Asleep-awake-asleep technique using LMA offers airway protection. The painful aspect of surgery can be performed under anesthesia, hence minimizing the duration of stress and pain. Patients remained awake and cooperative throughout the time of neurological testing.
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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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    Calcified neurocysticercosis lesions and antiepileptic drug-resistant epilepsy: A surgically remediable syndrome?
    (EPILEPSIA, 2013) Rathore, C; Thomas, B; Kesavadas, C; Abraham, M; Radhakrishnan, K
    PurposeIn contrast to the well-recognized association between acute symptomatic seizures and neurocysticercosis, the association between antiepileptic drug (AED)-resistant epilepsy and calcified neurocysticercosis lesions (CNLs) is poorly understood. We studied the association between AED-resistant epilepsy and CNLs, including the feasibility and outcome of resective surgery. MethodsFrom the prospective database maintained at our epilepsy center, we reviewed the data of all patients with AED-resistant epilepsy who underwent presurgical evaluation from January 2001 to July 2010 and had CNL on imaging. We used clinical, neuroimaging, and interictal, ictal, and intracranial electroencephalography (EEG) findings to determine the association between CNL and epilepsy. Suitable candidates underwent resective surgery. Key FindingsForty-five patients fulfilled the inclusion criteria. In 17 patients, CNL was proven to be the causative lesion for AED-resistant epilepsy (group 1); in 18 patients, CNL was associated with unilateral hippocampal sclerosis (HS; group 2); and in 10 patients, CNLs were considered as incidental lesions (group 3). In group 1 patients, CNLs were more common in frontal lobes (12/17), whereas in group 2 patients, CNLs were more commonly located in temporal lobes (11/18; p=0.002). Group 2 patients were of a younger age at epilepsy onset than those in group 1 (8.97.3 vs. 12.6 +/- 6.8years, p=0.003). Perilesional gliosis was more common among patients in group 1 when compared to group 3 patients (12/17 vs. 1/10; p=0.006). Fifteen patients underwent resective surgery. Among group 1 patients, four of five became seizure-free following lesionectomy alone. In group 2, four patients underwent anterior temporal lobectomy (ATL) alone, of whom one became seizure-free; five underwent ATL combined with removal of CNL (two of them after intracranial EEG and all of them became seizure-free, whereas one patient underwent lesionectomy alone and did not become seizure-free. SignificanceIn endemic regions, although rare, CNLs are potential cause for AED-resistant and surgically remediable epilepsy, as well as dual pathology. Presence of perilesional gliosis contributes to epileptogenicity of these lesions. For those patients with CNL and HS, resection of both lesions favors better chance of seizure-free outcome.
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    CALCIFIED NEUROCYSTICERCUS LESIONS (CNL) AND DRUG RESISTANT EPILEPSY: SURGICALLY REMEDIABLE SYNDROME?
    (EPILEPSIA, 2013) Rathore, C; Thomas, B; Kesavadas, C; Abraham, M; Radhakrishnan, K
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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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    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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    Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy
    (EPILEPSY RESEARCH, 2015) James, JS; Radhakrishnan, A; Thomas, B; Madhusoodanan, M; Kesavadas, C; Abraham, M; Menon, R; Rathore, C; Vilanilam, G
    Purpose: Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population. Methods: DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively. Results: Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 +/- 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 +/- 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 +/- 2.03 mm (range: 26.4-32.8 mm) and was 28.92 +/- 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was <= 38 mm on the right and <= 35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs. Conclusions: DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability. (C) 2014 Elsevier B.V. All rights reserved.
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    DOES ACUTE ELECTROCORTICOGRAPHY PREDICTS SEIZURE OUTCOME FOLLOWING ANTERIOR TEMPORAL LOBECTOMY?
    (EPILEPSIA, 2009) Rekalakunta, C; Rathore, C; Nayak, D; Abraham, M; Radhakrishnan, A; Radhakrishnan, K
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    Does F-18 FDG-PET substantially alter the surgical decision-making in drug-resistant partial epilepsy?
    (EPILEPSY & BEHAVIOR, 2015) Menon, RN; Radhakrishnan, A; Parameswaran, R; Thomas, B; Kesayadas, C; Abraham, M; Vilanilam, G; Sarma, SP
    Objective: There is a dearth of information on the critical utility of positron emission tomography (PET) in choosing candidates for epilepsy surgery especially in resource-poor countries where it is not freely available. This study aimed to critically analyze the utility of FDG-PET in the presurgical evaluation and surgical selection of patients with DRE based on the results obtained through its use in our comprehensive epilepsy program. Methods: From 2008 to 2012, 117 patients with drug-resistant epilepsy underwent F-18 fluoro-deoxy-glucose (FDG) PET in our center. We utilized their data to audit the utility of PET in choosing/deferring patients for surgery. Results: Of the 117 patients (age: 5-42 years) who underwent F-18 FDG-PET, 64 had normal MRI, and 53 had lesions. Electroclinical data favored temporal ictal onset in 48 (41%), extratemporal in 60 (51.3%), and uncertain lobar localization in 9 (7.7%). The topography of PET hypometabolism was localizing in 53 (45.3%), lateralizing in 12 (10.3%), and 52 (44.4%) had either normal or discordant results. In the nonlesional group, focal hypometabolism was concordant to the area of ictal onset in 27 (41.5%) versus 38 (58.5%) in the lesional group (p = 0.002). Greater concordance was noted in temporal lobe epilepsy (TLE) (78.0%) as compared to extratemporal epilepsy (ETPE) (28.6%) (p < 0.001). Positron emission tomography was more concordant in patients with mesial temporal sclerosis than in those with other lesions (82.8% versus 50%) (p = 0.033). Positron emission tomography helped in surgical decision-making in 68.8% of TLE and 23.3% of ETPE cases. Overall, 37 patients (31.6%) were directly selected for resective surgery based on PET results. Conclusions: Positron emission tomography, when utilized judiciously, remained an ancillary tool in the surgical selection of one-third of patients with drug-resistant partial epilepsy, although its utility as an independent tool is not very promising. (C) 2015 Elsevier Inc. All rights reserved.
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    Early resective surgery causes favorable seizure outcome in malformations of cortical development
    (EPILEPSY RESEARCH, 2016) Radhakrishnan, A; Menon, R; Menon, D; Singh, A; Radhakrishnan, N; Vilanilam, G; Abraham, M; Thomas, B; Kesavadas, C; Varma, RP; Thomas, SV
    Purpose: We analyzed consecutive cases of a large cohort of the spectrum of malformations of cortical development (MCDs) including focal cortical dysplasias (FCDs) who underwent presurgical evaluation through our epilepsy program from January 2000-December 2010. We analyzed factors predicting surgical candidacy, predictors of seizure outcome and reasons for deferring surgery. Methods: 148 patients with MCD underwent detailed presurgical evaluation and 69 were operated. MCD was diagnosed based on characteristic findings in MRI and re-confirmation by histopathology in operated patients. Post-operative seizure outcome of non-operated and operated patients were assessed every 3 and 12 months and yearly intervals. Multivariate analysis and backward step-wise logistic regression analyzed factors predicting seizure outcome. Kaplan-Meier analysis predicted seizure-free survival rates. Results: 66.67% patients were seizure-free and aura-free at last follow-up. On multivariate logistic regression, the predictors of seizure freedom in operated MCDs were completeness of resection (odds ratio 8.2; 95% CI 1.43-64.96, p = 0.01), shorter duration of epilepsy (odds ratio 1.19, 95% CI 1.02-1.39, p = 0.02), and absence of spikes in post-operative EEG at one year (odds ratio 4.2; 95% CI 2.52-16.6; p <0.002). In FCD sub-group, shorter duration of epilepsy (11.1 versus 16.1 years, p = 0.03), absence of secondary generalized seizures (p = 0.05), absence of spikes in post-operative EEG on seventh day (p = 0.009) and one year (p = 0.002) were associated with favorable seizure outcome. Conclusion: Majority of patients with MCD and refractory epilepsy when operated early remains seizure free. Shorter duration of epilepsy is the single most important pre-operative variable and absence of spikes in post-operative EEG, predicts a long-term favorable seizure outcome. (c) 2016 Elsevier B.V. All rights reserved.
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    Genetic and epigenetic mechanisms in the development of arteriovenous malformations in the brain
    (CLINICAL EPIGENETICS, 2016) Thomas, JM; Surendran, S; Abraham, M; Rajavelu, A; Kartha, CC
    Vascular malformations are developmental congenital abnormalities of the vascular system which may involve any segment of the vascular tree such as capillaries, veins, arteries, or lymphatics. Arteriovenous malformations (AVMs) are congenital vascular lesions, initially described as "erectile tumors," characterized by atypical aggregation of dilated arteries and veins. They may occur in any part of the body, including the brain, heart, liver, and skin. Severe clinical manifestations occur only in the brain. There is absence of normal vascular structure at the subarteriolar level and dearth of capillary bed resulting in aberrant arteriovenous shunting. The causative factor and pathogenic mechanisms of AVMs are unknown. Importantly, no marker proteins have been identified for AVM. AVM is a high flow vascular malformation and is considered to develop because of variability in the hemodynamic forces of blood flow. Altered local hemodynamics in the blood vessels can affect cellular metabolism and may trigger epigenetic factors of the endothelial cell. The genes that are recognized to be associated with AVM might be modulated by various epigenetic factors. We propose that AVMs result from a series of changes in the DNA methylation and histone modifications in the genes connected to vascular development. Aberrant epigenetic modifications in the genome of endothelial cells may drive the artery or vein to an aberrant phenotype. This review focuses on the molecular pathways of arterial and venous development and discusses the role of hemodynamic forces in the development of AVM and possible link between hemodynamic forces and epigenetic mechanisms in the pathogenesis of AVM.
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    Intracalvarial schwannoma: A case report with review of literature
    (NEUROLOGY INDIA, 2014) Amita, R; Sandhyamani, S; Abraham, M; Nair, S; Praveen, A; Kapilamoorthy, TR
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    MAPPING AND VOLUMETRY OF HESCHL'S GYRUS BY VBM AIDS IN PLANNING TEMPORAL LOBE RESECTION IN PATIENTS WITH "TLE WITH AUDITORY AURA"
    (EPILEPSIA, 2015) Radhakrishnan, A; James, JS; Sundar, A; Thomas, B; Menon, R; Vilanilam, C; Abraham, M
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    MAPPING AND VOLUMETRY OF HESCHL'S GYRUS BY VOXEL BASED MORPHOMETRY AIDS IN PLANNING TEMPORAL LOBE RESECTION IN PATIENTS WITH "TLE WITH AUDITORY AURA"
    (EPILEPSIA, 2013) Radhakrishnan, A; James, JS; Madhusoodanan, M; Thomas, B; Kesavadas, C; Abraham, M; Radhakrishnan, K
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    MECHANICAL THROMBECTOMY IN ACUTE ISCHEMIC STROKE: INDIAN EXPERIENCE AT A TERTIARY CARE CENTER
    (INTERNATIONAL JOURNAL OF STROKE, 2016) Nagesh, C; Jayadevan, ER; Kumar, S; Sylaja, PN; Sajith, S; Sreedharan, SE; Abraham, M
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    Pediatric gliosarcoma of thalamus
    (NEUROLOGY INDIA, 2012) Neelima, R; Abraham, M; Kapilamoorthy, TR; Hingwala, DR; Radhakrishnan, VV
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    Petroclival Meningiomas: Institutional Experience of 119 cases
    (13TH ASIAN-AUSTRALASIAN CONGRESS OF NEUROLOGICAL SURGEONS (AACNS), 2012) Nair, S; Gopalakrishnan, CV; Vikas, V; Abraham, M; Rao, RM; Menon, G; George, V; Easwer, HV; Sudhir, JK; Amit, D
    A retrospective analysis of 119 cases of petroclival-premeatal meningiomas surgically managed in their institute from 1st Jan 1990 till 14th November 2011 was carried out to see the outcome with various approaches. While the tumor resection was carried through an anterolateral/ lateral route in 32(27%), it was through a combined posterior subtemporal /pre or trans-sigmoid (posterior petrosal) in 24(20%) & retrosigmoid supra-paracerebellar route in 55 cases (46%). In three cases with extra cranial extension to infratemporal area, a modified Fisch approach was used. Five patients who were in poor clinical condition had only a CSF diversionary procedure. The percentage of these tumors operated by conventional retrosigmoid route has increased in the later part of the series thus proving that in many of these tumors without significant middle fossa extension, it is not necessary to use complex and time consuming skull base approaches which in themselves can cause morbidity. The tumor could be radically removed in 79 patients (66%), subtotally in 26 (22%) and decompression only in 9). Six patients had tumor excision in two stages. There was an operative mortality of 8.4% (10 cases). Out of the 85 patients on long term follow up 56 are independent. Six out of the eight patients who had symptomatic recurrence were re-operated.
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    Posterior Inferior Cerebellar Artery Aneurysms: Operative Strategies Based on a Surgical Series of 27 Patients
    (TURKISH NEUROSURGERY, 2014) Viswanathan, GC; Menon, G; Nair, S; Abraham, M
    AIM: Posterior inferior cerebellar artery (PICA) aneurysms are uncommon. The natural history and management of these aneurysms remains poorly understood. Surgical treatment of PICA aneurysms is challenging in view of their close neurovascular relationship. MATERIAL and METHODS: Data relating to clinical presentation, radiological findings, operative approaches and outcomes were analyzed in 27 consecutive patients surgically treated for PICA aneurysms in a single hospital between January 1991 and December 2010. RESULTS: Headache was the most common presentation (100%) followed by gait ataxia (14.8%) and lower cranial nerve dysfunction (7.4%). SAH was seen in 20 patients, intraventricular hemorrhage in 22 patients, and 3 had evidence of intracerebellar hematoma. Eighteen aneurysms were located proximally and 9 were located distally. The 25 saccular and 2 fusi-saccular aneurysms were secured by direct clipping (24 cases) or aneurysmorrhaphy (3 cases) using a far-lateral suboccipital (without condylar resection) or midline/ paramedian suboccipital approach. Overall outcome at the time of hospital discharge was excellent or good in 88.9% of the patients. CONCLUSION: PICA aneurysms, by virtue of their rarity and strategic location pose a unique technical challenge. Depending on the PICA segment affected, variations in the surgical corridor and clipping strategy were major contributors to good outcomes.