REDUCED GABA(A) RECEPTOR DENSITY CONTRALATERAL TO A POTENTIALLY EPILEPTOGENIC MRI ABNORMALITY IN A PATIENT WITH COMPLEX PARTIAL SEIZURES

Imaging cerebral GABA(A) receptor density (GRD) with single-photon emi ssion tomography (SPET) and iodine-123 iomazenil is highly accurate in lateralizing epileptogenic foci in patients with complex partial seiz ures of temporal origin. Limited knowledge exists on how iomazenil SPE T compares with magnetic resonance imaging (MRI) in this regard, We pr esent a patient with complex partial seizures in whom MRI had identifi ed an arachnoid cyst anterior to the tip of the left temporal lobe, Co ntralaterally to this structural abnormality, inter ictal electroencep halography (EEG) performed after sleep deprivation disclosed an interm ittent frontotemporal dysrhythmic focus with slow and sharp waves. On iomazenil SPET images GRD was significantly reduced in the right tempo ral lobe and thus contralaterally to the MRI abnormality, but ipsilate rally to the pathological EEG findings. These data suggest that iomaze nil SPET may significantly contribute to the presurgical evaluation of epileptic patients even when MRT identifies potentially epileptogenic structural lesions.