UTILITY OF INTERICTAL SPECT OF RCBF FOR FOCAL DIAGNOSIS OF THE EPILEPTOGENIC ZONE(S)

With Single Photon Emission Computed Tomography (SPECT) of regional ce rebral bloodflow (rCBF) ictally and interictally, regional changes of rCBF can be detected in many cases with medically intractable complex partial seizures. Interictal SPECT shows abnormal rCBF in the epilepto genic temporal lobe in 40% to 85% of the patients. A critical survey o f the methodological problems considering isotopes, scanners, data ana lysis and patient population is presented here as well as a few semiqu antitative studies including our own. It is concluded, that SPECT of r CBF is a useful, non-invasive method of localizing the epileptogenic z one in patients with severe partial focal epilepsy. Ictal SPECT of rCB F has a higher predictive value and is more sensitive than interictal studies for localization of the seizure focus. Interictal SPECT using a high-resolution system obtains an almost as high frequency of locali zation of the focus. With low resolution scanners, a minor frequency i s observed. Both interictal and ictal SPECT recordings should be obtai ned for localization of the epileptogenic focus in presurgical cases a s interictal hypoperfusion and ictal hyperperfusion demonstrated in th e same focal area are highly characteristic of a seizure focus.