Browsing by Author "Vilanilam, G"

Now showing 1 - 4 of 4
  • Item
    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.
  • Item
    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.
  • Item
    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.
  • Item
    Surgery for "Long-term epilepsy associated tumors (LEATs)": Seizure outcome and its predictors
    (Clin Neurol Neurosurg, 2016-02) Radhakrishnan, A; Abraham, M; Vilanilam, G; Menon, R; Menon, D; Kumar, H; Cherian, A; Radhakrishnan, N; Kesavadas, C; Thomas, B; Sarma, SP; Thomas, SV
    Objectives: “Long-term epilepsy associated tumors (LEATs)” by definition are tumors primarily causing drug-resistant seizures for two years or more. They include low-grade glial and glioneuronal tumors with normal life expectancy. We studied a large cohort of patients with LEATs who underwent surgery through our epilepsy program. Patients & methods: From 1998–2011, 105 patients with LEATs underwent surgery in our center. We utilized their data archived in a prospective registry to evaluate their electro-clinical-imaging characteristics affecting the long-term seizure outcome. Results: Of 105patients (age 3–50 years),meanage at surgery was 20 years andmeanpre-surgicalduration of epilepsy was 10.9 years. 66 (62.8%) had secondary generalized seizures. 82 had temporal tumors, 23 had extra temporal (13 frontal, 3 parietal, 2 occipital and 5 multilobar lesions) and four had associated hippocampal sclerosis. The interictal discharges and ictal onset were concordant to the lesion in 82 (78%) and 98 (93%) patients respectively. Lesionectomy and/or adjoining corticectomy or temporal lobectomy was done. Ganglioglioma was the most dominant pathological substrate in 61 (58%). During a mean follow-up of 7.5 years (range 3–16 years), 78/105 (74.2%) were seizure-free and 45 (57.4%) were totally off drugs. Secondary generalized seizures (p-0.02), temporal location of tumor (p-0.008) and spikes in third month post-operative EEG (p-0.03) caused unfavorable seizure outcome. A pre-surgical duration of epilepsy of more than 6.6 years caused less than optimal surgical outcome Conclusions: Early surgery should be considered a priority in LEATs. Presence of secondary generalized seizures is the single most important predictor of a poor seizure outcome