Abstracts

Rationale: Patients with medically refractory partial seizures who are candidates for resective epilepsy surgery frequently undergo language mapping as to minimize resection of eloquent cortex. Unique representation of language in Epilepsy patients especially these with childhood onset of seizures may alter the surgical approach. Methods: We used a large array 148 channel biomagnetometer (4D Neuroimaging)and tasks tapping receptive (word recognition) and expressive(verb generation,picture naming) language mapping paradigms on 6 Medically Refractory Resective Epilepsy Candidates and 12 controls.Language activations were assessed utilizing standard methods with Single Equivalent Current Dipole (SECD)that clustered in time and brain space. A laterality index(LI) was calculated on SECD meeting criteria [(L-R)/(L R)] for each patient.Neuropschological testing was performed on all patients. 4/6 had angio-WADA and direct cortical stimulations. Healthy controls (N=12) underwent an MEG study with a word recognition language paradigm. Language activation was similarly assessed with SECD fits and calculation of LI. Results: Of the six epilepsy patients 5/6 showed right hemispheric or bilateral language dominance for receptive language. In contrast 10/12 of control patients showed left hemispheric or bilateral dominance for receptive language. Expressive language was left hemispheric in all the epilepsy patients. Age of seizure onset had a range of 18 months-17 years. Conclusions: Receptive and Expressive language may have divergent hemispheric dominance in patients with Medically Refractory Epilepsy with childhood and adolescent onset of seizures. The right sided receptive language hemispheric dominance in epilepsy patients may have implications for surgical planning as well as emphasize the need to separately assess both receptive and expressive language in these patients. MEG with multiple language tasks can be used non-invasively to assess language in both hemispheres A larger cohort of patients is needed as to substantiate these preliminary findings.