Browsing by Author "Radhakrishnan, A"

Now showing 1 - 20 of 45
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    A clinician's dilemma: Sturge-Weber syndrome 'without facial nevus'!!
    (ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2013) Jagtap, SA; Srinivas, G; Radhakrishnan, A; Harsha, KJ
    Sturge-Weber syndrome (SWS) is a rare, sporadic neurocutaneous syndrome characterized by a classical triad of facial port wine nevus, ipsilateral leptomeningeal angiomatosis (LAM) and glaucoma. The incidence of SWS is 1/50,000 live births, although it is more often underreported. The incidence of SWS without facial nevus is not known, although very few patients without facial nevus have been reported. In these patients, the diagnosis of SWS is made by the findings of computed tomography, magnetic resonance imaging, and histopathology. Here, we report three patients with SWS from our cohort of 28 patients with SWS without facial nevus and discuss their clinical profile and outcome.
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    A Potential Biomarker in Amyotrophic Lateral Sclerosis: Can Assessment of Brain Iron Deposition with SWI and Corticospinal Tract Degeneration with DTI Help?
    (AMERICAN JOURNAL OF NEURORADIOLOGY, 2016) Sheelakumari, R; Madhusoodanan, M; Radhakrishnan, A; Ranjith, G; Thomas, B
    BACKGROUND AND PURPOSE: Iron-mediated oxidative stress plays a pivotal role in the pathogenesis of amyotrophic lateral sclerosis. This study aimed to assess iron deposition qualitatively and quantitatively by using SWI and microstructural changes in the corticospinal tract by using DTI in patients with amyotrophic lateral sclerosis. MATERIALS AND METHODS: Seventeen patients with amyotrophic lateral sclerosis and 15 age- and sex-matched controls underwent brain MR imaging with SWI and DTI. SWI was analyzed for both signal-intensity scoring and quantitative estimation of iron deposition in the anterior and posterior banks of the motor and sensory cortices and deep gray nuclei. The diffusion measurements along the corticospinal tract at the level of pons and medulla were obtained by ROI analysis. RESULTS: Patients with amyotrophic lateral sclerosis showed reduced signal-intensity grades in the posterior bank of the motor cortex bilaterally. Quantitative analysis confirmed significantly higher iron content in the posterior bank of the motor cortex in patients with amyotrophic lateral sclerosis. In contrast, no significant differences were noted for the anterior bank of the motor cortex, anterior and posterior banks of the sensory cortex, and deep nuclei. Receiver operating characteristic comparison showed a cutoff of 35g Fe/g of tissue with an area under the curve of 0.78 (P = .008) for the posterior bank of the motor cortex in discriminating patients with amyotrophic lateral sclerosis from controls. Fractional anisotropy was lower in the pyramidal tracts of patients with amyotrophic lateral sclerosis at the pons and medulla on either side, along with higher directionally averaged mean diffusivity values. The combination of SWI and DTI revealed an area under the curve of 0.784 for differentiating patients with amyotrophic lateral sclerosis from controls. CONCLUSIONS: Measurements of motor cortex iron deposition and diffusion tensor parameters of the corticospinal tract may be useful biomarkers for the diagnosis of clinically suspected amyotrophic lateral sclerosis.
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    Alpha coma evolving into spindle coma in a case of acute fulminant hepatic failure: What does it signify?
    (ANNALS OF INDIAN ACADEMY OF NEUROLOGY, 2010) Das, A; Cherian, A; Dash, GK; Radhakrishnan, A
    A 44-year-old male developed acute fulminant hepatic failure of unknown etiology and expired within four days. His serial electroencephalograms (EEGs) showed diffuse background slowing on day one, which evolved into "alpha coma" and later into "spindle coma" over the ensuing two days. Such EEG transition is hitherto undescribed in patients with hepatic encephalopathy and gives fresh insight into the etiopathogenesis of specific EEG patterns in diffuse encephalopathy.
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    An audit of the predictors of outcome in status epilepticus from a resource-poor country: a comparison with developed countries
    (EPILEPTIC DISORDERS, 2016) Hassan, H; Rajiv, KR; Menon, R; Menon, D; Nair, M; Radhakrishnan, A
    Aim. Status epilepticus is a neurological emergency with significant morbidity and mortality. This study describes the clinical profile, treatment, and predictors of outcome of status epilepticus in a tertiary referral centre in a developing country and aims to highlight the similarities and differences from data available from the western world. Methods. A retrospective analysis of data of patients treated for status epilepticus was conducted from prospectively maintained records, between January 2000 and September 2010. The demographic data, clinical profile and investigations (including neuroimaging and EEG), aetiology, treatment, and outcomes were studied and compared with data available from the western world. Results. The analysis included 108 events in 84 patients. A single episode of status epilepticus was treated in 72 patients (86%) and multiple status epilepticus events, ranging from two to six per patient, were managed in 12 patients (14%). Mean age was 24.1 +/- 20.3 years and 63% were males. The types of status epilepticus included convulsive status in 98 (90.7%), non-convulsive status in seven (6.5%), and myoclonic status in three (2.8%). The majority of events (60%) were remote symptomatic, 16% were acute symptomatic, 16% were of unexplained aetiology, and 8% were progressive symptomatic. In 85 events (79%), status epilepticus could be aborted with first and second-line drugs. The remaining 23 events (21%) progressed to refractory status epilepticus, among which, 13 (56%) were controlled with continuous intravenous midazolam infusion. Case fatality rate was 11%, neurological sequelae were reported in 22%, and 67% returned to baseline. Acute symptomatic status, older age, altered sensorium at the time of admission, and delayed hospitalisation were predictors of poor outcome. Conclusions. Aetiologywas the most important determinant of outcome of status epilepticus, as in reports from the western world, with remote symptomatic aetiology secondary to gliosis being the most common. Treatment delay was frequent and adversely affected the outcome.
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    CAN SPIKE VOLTAGE TOPOGRAPHY PREDICT THE ICTAL PATTERNS IN TEMPORAL LOBE EPILEPSY?
    (EPILEPSIA, 2011) Parameswaran, S; Radhakrishnan, A; Radhakrishnan, K
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    Can transcranial magnetic stimulation be used to evaluate patients with narcolepsy?
    (NEUROLOGICAL SCIENCES, 2013) Vijayakumari, AA; Khan, FR; Varma, RP; Radhakrishnan, A
    Narcolepsy is a rare, chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy and other manifestations of dissociated rapid eye movement in sleep. We assessed the utility of transcranial magnetic stimulation (TMS) as an objective tool to elucidate the cortical excitability changes and also to analyze its role in assessing the treatment efficacy in narcolepsy. Eight patients with narcolepsy under our regular follow-up from 2000 to 2009 at our Sleep disorder clinic were chosen. All of them underwent polysomnography, multiple sleep latency tests and TMS. Resting motor threshold (RMT), cortical silent period (CSP) and central motor conduction time (CMCT) were assessed using TMS in both drug-na < ve and post-treatment states. Eight controls were also subjected to all the three investigations. Appropriate statistical methods were used. The mean RMT (%) pre-treatment was higher in narcolepsy patients than that in controls, and it normalized following treatment. CSP and CMCT were unaffected in narcolepsy patients as compared to controls. This study shows that the cortical excitability is significantly low in narcolepsy patients. This motor cortex hypoexcitability becomes normal with the institution of treatment, pari passu with the control of symptoms. In future, TMS may be considered as an effective tool for documenting the treatment efficacy in patients with narcolepsy.
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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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    Clinico-radiological spectrum and outcome in idiopathic hypertrophic pachymeningitis
    (JOURNAL OF THE NEUROLOGICAL SCIENCES, 2015) Dash, GK; Thomas, B; Nair, M; Radhakrishnan, A
    Objective: To elucidate the clinico-radiological features, treatment response and outcome of a large cohort of patients (n = 20) with idiopathic hypertrophic pachymeningitis (IHP) and to examine if any of these features could differentiate between IHP and secondary causes of hypertrophic pachymeningitis (SHP). Methods: 20 patients with IHP diagnosed between 1998 and 2009 formed the study cohort. We adopted a validated clinical score to quantitatively assess and document their neurological disability and to compare their pre- and post-treatment outcomes. Appropriate statistical analysis was done to look for any clinical and/or radiological features to differentiate IHP from SHP. Results: Out of the twenty eight consecutive patients with pachymeningitis, 20 were having IHP and 8 were having SHP (Tuberculosis-5, Sarcoidosis-2, Wegener's granulomatosis-1). In IHP, headache and visual symptoms dominated the clinical symptomatology (80% and 75%). In MRI, the peripheral pattern of contrast enhancement was more common with IHP (p = 0.03). The posterior falx and tentorium showing a hypointense center ("fibrosis") and enhancing periphery ("active inflammation") together mimicking "Eiffel-by-night" sign was found to be more commonly associated with IHP (60% vs 12.5%, p = 0.03). Biopsy was done in 9 patients. At a mean follow-up of 51 months (range 24-144 months), the mean pretreatment clinical score improved from 6.55 to 1.80 in 20 patients with IHP (p < 0.001). Conclusions: Our data on the largest cohort of patients with IHP would shed light into its dinico-radiological spectrum, treatment and outcome. The prognosis is satisfactory if managed appropriately. We have highlighted the role of MRI in differentiating between IHP and other causes of SHP. (C) 2015 Published by Elsevier B.V.
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    Corpora amylacea in refractory mesial temporal lobe epilepsy: Clinicopathological correlations
    (EPILEPSIA, 2006) Radhakrishnan, A; Joseph, C; Radhakrishnan, VV; Radhakrishnan, K; Sharma, PS
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    Correlation between anatomic landmarks and fMRI in detection of the sensorimotor cortex in patients with structural lesions
    (Acta Radiol. 2013, 2013-07) Hingwala, D; Thomas, B; Radhakrishnan, A; Nair, SN; Kesavadas, C
    BACKGROUND: Structural lesions in/near the sensorimotor cortex may cause distortion/obscuration of the anatomic landmarks. PURPOSE: To compare the localization of the sensorimotor cortex using anatomical landmarks and fMRI in the clinical setting in patients with structural lesions in/near the central sulcus. MATERIAL AND METHODS: We analyzed the anatomic and fMRI data of 68 consecutive patients (42 tumors, 15 gliotic lesions, 11 focal cortical dysplasias [FCD]) who underwent MRI to assess the relationship of these lesions to the sensorimotor cortex. Anatomical data was analyzed on conventional two- and three-dimensional sequences. BOLD fMRI was performed with block design hand/leg or lip movement paradigm and general linear model was used for detecting the activated cortex. fMRI was considered as a valid method for identifying the sensorimotor cortex based on previously reported literature. RESULTS: The sensorimotor cortex could not be identified with anatomical landmarks in 9/68 (13.2%) patients. fMRI detected activation in areas different from that predicted by anatomical landmarks in 11/68 (16.2%) cases. This occurred in 5/42 (11.9%) tumors, 6/15 (40%) gliotic lesions, and 0/11 (0%) FCDs. The kappa value for concordance between fMRI and anatomic landmarks was 0.883 overall, 1.0 for tumors, 0.721 for gliotic lesions, and in none of the patients with focal cortical dysplasias. CONCLUSION: In patients with lesions that obscure normal cerebral landmarks, fMRI supplies the information that is not available from the anatomic images. In patients with landmarks that can be recognized, the location of the rolandic cortex may be misjudged in some cases if functional imaging is not used. Anatomic landmarks may not correlate with the area of functional activation in gliotic lesions and tumors. Determining the risk of a postoperative neurologic defect from surgery is likely to be more reliable with functional imaging than with conventional anatomic imaging.
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    Cost-effective utilization of SPECT for the presurgical evaluation of refractory epilepsy
    (JOURNAL OF THE NEUROLOGICAL SCIENCES, 2009) Rathore, C; Radhakrishnan, A; Kesavdas, C; Sarma, PS; Radhakrishnan, K
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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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    ELECTROCLINICAL PREDICTORS OF OUTCOME IN WEST SYNDROME & ITS RELATIONSHIP TO TRACTOGRAPHIC ABNORMALITIES
    (EPILEPSIA, 2015) Menon, R; Sundar, A; Nair, JS; Radhakrishnan, A; Thomas, B; Thomas, S
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    Epilepsy with myoclonic absences: Electroclinical characteristics in a distinctive pediatric epilepsy phenotype
    (EPILEPSY & BEHAVIOR, 2016) Zanzmera, P; Menon, RN; Karkare, K; Soni, H; Jagtap, S; Radhakrishnan, A
    Purpose: The purpose of this article was to study the electroclinical characteristics and seizure outcome of children with epilepsy with myoclonic absences (EMA). Method: In this descriptive cohort study, we reviewed clinical records of patients who met the criteria for EMA. Each patient's demographic data, birth/developmental history, seizure semiology/pattern, antiepileptic drugs (AED), clinical examination, video-electroencephalography (VEEG), and neuroimaging data were reviewed. Response to AED and change in seizure frequency/pattern on follow-up were noted. Responders were defined by seizure freedom/>50%.reduction.in seizure frequency on follow-up. Result: Twelve children were diagnosed with EMA between 2008 and 2013 [50% male; mean age of onset: 3.5 years]. Main seizure types were the characteristic myoclonic absences (100%) and generalized tonic-clonic seizures (42%). Ictal correlate on VEEG was 3- to 3.5-Hz spike-and-wave discharges (82%) and fast recruiting bifrontal rhythm (25%). One patient had specific MRI abnormalities. Mean duration of follow-up was 23.9 months. Seizure frequency had significantly improved on follow-up (p = 0.005), and at last follow-up, nine patients were in the responder group: four seizure-free for at least 1 year, two with >90%, and three with >50% reduction in seizure frequency. The number of AED reduced significantly between initial visit and last follow-up among responders. Two patients on follow-up developed different seizure patterns, with generalized tonic and complex partial seizures. One responder expired because of unprovoked generalized convulsive status epilepticus. Conclusion: This cohort, the largest from the Indian subcontinent on the rare syndrome of EMA, suggests mild heterogeneity in a seemingly homogenous electroclinical phenotype. Clinical semiology while unique may demonstrate focality and variable ictal patterns. Most patients respond to either valproate monotherapy or valproate-lamotrigine combination; however, the prognosis remains guarded. The seizures of a minority of patients remain drug-refractory and may evolve into tonic or complex partial seizures. (C) 2016 Elsevier Inc. All rights reserved.