Abstracts

Patients with early onset epilepsy often show language reorganization to the right hemisphere. There is debate whether reorganization of language functions occurs in homologous regions of the right hemisphere or if reorganization occurs more diffusely, outside traditional language areas. We examined the hypothesis that reorganization of frontal language processing functions occurs in right homologues of Broca[apos]s area., We studied13 epilepsy patients (mean age 18.1 yrs; mean age seizure onset 10.3 yrs) and 17 healthy controls (mean age 25.2 yrs). All patients had a left seizure focus, had 1.5T structural MRI, and vEEG. All had atypical language (right or mixed dominance based on visual review of 4 language fMRI paradigms performed at 3T: auditory category decision, listening, reading, and an auditory description decision task (ADDT). Seven patients had left hemisphere stroke (MCA), 1 had left hemisphere dysplasia, and 4 had normal structural MRIs. All healthy controls were right handed and left hemisphere dominant for language. We compared point maxima of activation in inferior frontal gyrus (IFG) for ADDT (EPI BOLD; block design, experimental condition - deciding whether a description of a named object is correct ([ldquo]A large grey animal is an elephant[rdquo]); control condition - reverse speech with tone decision). Individual fMRI data sets were analyzed using SPM2. In addition, a group activation map was computed for the controls. The Euclidean distance was then computed from each participant[apos]s point maxima to the group point maxima right homologue (x[sub]0, [/sub]y[sub]0[/sub], z[sub]0[/sub]) using [radic][(x-x[sub]0[/sub])² + (y-y[sub]0[/sub])² + (z-z[sub]0[/sub])²]. A between groups t-test was performed on the distances and location found for patients and controls., The group maxima for controls was -44, 32, 18 (Left IFG, MNI coordinates). The mean distance of individual maxima from the group mean for controls was 13.09 mm ([plusmn]5.81) and for patients, from the right homologue, was 16.69 mm ([plusmn]8.39). The t-test between the controls and patients distances[apos] was not significant. We found no significant distances in any particular direction (x, y, or z)., Re-organization of [ldquo]expressive[rdquo] language to the right hemisphere occurs in the homologue to Broca[apos]s area. We did not find evidence for activation outside this area., (Supported by R01 NS44280 [amp] Clinical Epilepsy Section NINDS, NIH.)