Epilepsy research
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Direct brain stimulation is an emerging treatment of epilepsy especially in patients that are not candidates for epilepsy surgery. Several different approaches of brain stimulation in epilepsy have been developed: stimulation is applied to interrupt epileptic networks in subcortical structures or a stimulus is directly applied to the seizure onset zone. Scheduled stimulation targets mainly subcortical structures like the anterior thalamic nucleus or the centromedian nucleus of the thalamus. ⋯ An automated implanted device for seizures detection and stimulation has been developed and shown to be safe for human use. A large clinical trial is currently ongoing. In conclusion, the optimal target and mode of stimulation for the treatment of epilepsy remains under investigation and requires large and costly controlled trials.
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Functional magnetic resonance imaging (fMRI) is commonly used to localize brain function, but its utility in the clinical setting remains unclear. Subdural electrode implantation provides opportunities to correlate the spatial relationship of the blood oxygen level-dependent (BOLD) response to areas defined by extraoperative electrical stimulation mapping (ESM) in patients undergoing staged epilepsy surgery. 4 subjects underwent pre-operative fMRI using the analogous paradigms to those used for ESM to delineate language and motor function. Coregistration of the pre-operative MRI to a post-operative CT and MRI scan was performed in order to assess the spatial relationship between the BOLD response and the location of electrode contacts used for ESM while accounting for brain shift. fMRI was accurate in predicting the location of motor cortex with sensitivity and negative predictive value (NPV) of 1.0. ⋯ Despite this, sensitivity and specificity were .47 and .76, respectively (T score 2.5, p<.01 corrected FDR) with PPV and NPV of .40 and .77, respectively. Sensitivity for predicting areas within 1cm of ESM-defined language sites was higher at .82 with an NPV of .94. The results indicate that fMRI is clinically useful for lateralizing language and the localizing motor cortex. fMRI localizes language less accurately, but it may be useful in estimating the region of ESM-induced deficit in areas away from the base of the frontal and temporal bone.
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Intra-operative electrocorticography (ECoG) is useful in epilepsy surgery to delineate margins of epileptogenic zone, guide resection and evaluate completeness of resection in surgically remediable intractable epilepsies. The study evaluated 157 cases (2000-2008). The preoperative evaluation also included ictal SPECT (122) and PET in 32 cases. ⋯ The improvement in ECoG correlated significantly with clinical improvement [Sensitivity: 100% (95% CI; 96-100%); specificity: 68.3% (95% CI; 51.8-81.4%); positive predictive value: 89.9% (95% CI, 83.1-94.3%); negative predictive value: 100% (95% CI, 85-100%)]. The level of agreement was 91.72% (kappa: 0.76). Concluding, pre and post resection ECoG correlated with its grade of severity and clinical outcome.