Title
DELINEATION OF SEIZURE ONSET, SEIZURE SPREAD, AND NORMAL BRAIN ACTIVITY BY FUNCTIONAL MAGNETIC RESONANCE IMAGING (fMRI).

Authors
J. Hirsch^1,2, K. Kim^1,2, J.D. Victor², N Relkin², K.M. Lee^1,2, D.R. Moreno¹. Dept of Neurology¹, MSKCC; Dept. of Neurology and Neuroscience, Cornell U Med College², NY, NY 10021.

A 16 year old right handed female with a congenital malformation in the right posterior frontal lobe and a seizure disorder participated in a functional imaging study to identify sensorimotor areas. One of the patient's typical sensory seizures occurred during one of the runs. This enabled us to localize fMRI signals associated with the onset of a spontaneous seizure, its progression, and the relationship to normally activated motor cortex. Images were acquired on a 1.5-telsa scanner (GE) equipped for echoplanar imaging with an in plane resolution of 1.56 X 1.56 mm. 16 contiguous slices were acquired each 4.7 mm thick. There was minimal movement artifact which was further reduced by alignment of the images prior to a voxel-by-voxel statistical analysis. The fMRI signals associated with the seizure were first observed in an area adjacent to the normal motor activity. MR signal amplitudes exceeded the normal functional activity by as much as a factor of 5. A sequential time analysis (6 sec intervals) revealed both local spreading of the onset focus and the emergence of subsequent foci first in the ipsilateral prefrontal areas, and the mesial surface areas. These were followed by activity in the homologous regions of the opposite hemisphere suggesting that the generalization followed a specific pattern of functional connectivity. These findings are the first to co-localize eloquent motor activity and seizure activity, and to quantify the onset, progression pattern, time course, and relative MR amplitudes of the seizure event.

Supported by EY7977 (JV), C.V. Starr Foundation (NR), Morris Foundation (KK).