Focus localization in patients with partial epilepsy with 99Tcm-HMPAO SPECT under continuous surface EEG monitoring

Our study was aimed at determining the validity of 99Tcm-HMPAO single photon emission computed tomography (SPECT) in the localization of the epileptogenic focus by correlating this diagnostic method with other auxiliary investigations such as surface EEG and X-ray transmission computed tomography (CT). Twenty-eight patients with partial epilepsy and spontaneous memory complaints were assessed with a 21-channel EEG recorded during psychometric evaluation of the memory complaints and with a 12-channel EEG during 99Tcm-HMPAO SPECT. No significant agreement was observed for total focus localization by the two EEGs, CT or SPECT. The EEGs were highly reproducible. Frontal and temporal pathology on CT resulted in frontal and temporal cold spots on SPECT on the same side in six patients. In addition, SPECT demonstrated frontal, temporal or posterior temporal-inferior parietal cold spots in nine patients without accompanying pathology on CT. It is concluded that CT and SPECT may provide complementary anatomical and functional information, respectively, to the EEG. Furthermore, SPECT may be complementary to CT in visualizing functional deficits without an anatomical correlate. The value of SPECT studies in partial epilepsy may be improved by increasing the resolution of the SPECT system and by simultaneous EEG monitoring.