ICTAL BRAIN IMAGING IN PRESURGICAL EVALUATION OF PATIENTS WITH MEDICALLY INTRACTABLE COMPLEX PARTIAL SEIZURES

At the Indiana University Medical Center, 99 patients with medically i ntractable complex partial seizures (MI-CPS) had presurgical evaluatio n with subsequent anterior temporal lobectomy. The majority of the pat ients had single photon emission tomography (SPECT) performed interict ally as well as during an actual epileptic seizure (ictal scan). Decre ased regional cerebral perfusion (rCP) was seen in 54/94 (57%) of the interictal scans corresponding to the eventual site of the surgery. Ho wever, ictal scans provided a higher yield; increased rCP in the tempo ral lobe during an actual seizure was observed in 60/82 (73%) concorda nt to the side of surgery. SPECT is a useful, noninvasive method of lo calizing the epileptiform focus in patients with MI-CPS considered for resective surgery. Both interictal and ictal SPECT need to be perform ed; combined interictal hypoperfusion and ictal hyperperfusion in the same focal area are unique to epileptogenic lesions. Ictal SPECT studi es can be performed in the majority of patients during the period of c ontinuous video/EEG monitoring with only a little additional effort. C ombining the results of functional brain imaging (interictal and ictal SPECT, PET) with clinical semiology of seizures, surface and sphenoid al EEG, magnetic resonance imaging and other non-invasive tests, anter ior temporal lobectomy can be recommended in approximately two-thirds of the patients without resorting to potentially dangerous intracrania l EEG monitoring.