SPECT IN THE LOCALIZATION OF EXTRATEMPORAL AND TEMPORAL SEIZURE FOCI

The yield ofictal, postictal, and interictal SPECT was compared in the localisation of seizure foci in 177 patients with partial epilepsy. I n 119 patients with known unilateral temporal lobe epilepsy ictal SPEC T (97% correct localisation) was superior to postictal SPECT (71% corr ect), which was better than interictal studies (48% correct). Similarl y, in cases of known or suspected extratemporal epilepsy the yield of ictal SPECT studies was high (92%). By contrast, the yield of posticta l studies was much lower (46%) and usually only very early postictal s tudies were diagnostic. Interictal SPECT was of little value. The accu racy of ictal in localising temporal lobe is now well established. Ext ratemporal seizures are often brief and difficult to localise. This re port shows that ictal SPECT also has a high diagnostic yield in a wide range of extratemporal epilepsies. The brevity of many extratemporal seizures means that true ictal SPECT examinations can be difficult to achieve, but the high diagnostic yield justifies the special organisat ional effort needed to obtain such studies.