Abstracts

OBJECTIVE: Functional magnetic resonance imaging (fMRI) of the motor cortex is a potentially powerful tool in the pre-operative planning of surgical procedures in the Rolandic region. Little is known about the patterns of fMRI activation associated with various pathologic lesions (such as cortical displasia) in that region or their relation to functional deficits before or after surgical intervention. ??METHODS: 20 Controls and 30 Patients (with rolandic pathologies: 10 vascular malformations, 10 congential cortical abnormalities, 10 tumors) were studied using fMRI with a hand motor paradigm. 24/30 patients had intractable epilepsy for a mean duration of 12 years. Changes in position or amplitude of the fMRI motor activation on the lesion side were compared with the activation pattern obtained in the contralateral side. A classification scheme based on hemispheric (a)symmetry, mass effect, and plasticity was used to compare maps between subjects, and relative to hand motor dexterity and or weakness. Grade 0 (A.B.C) = no plasticity effect. Grade 1 (A.B.C) = plasticity effect. ??RESULTS: There was 89.5% inter-observer agreement on classification of fMRI activation patterns. Displacement of activation by mass effect was more likely with tumors. True plasticity (different cortical area of activation) was observed in cases of congenital cortical abnormalities (cortical displasia), while various patterns of fMRI activation were associated with vascular malformations. Baseline neurologic deficits were more frequent with increasing mass effect or in association with plasticity. 50% of epileptogenic cortical malformations were classified as Grade 1.B, showing recruitment of additional homolateral regions in addition to asymmetry of activity ??CONCLUSION: Congenital cortical malformations suggested a much higher level of reorganization of the motor hand area compared to vascular malformations or tumors. The classification scheme appears to provide an excellent mean for classifying patients according to their motor-fMRI. Future studies will address risks of surgical intervention and patterns of functional recovery in relation to baseline fMRI grading.