Peri-Ictal SPECT in presurgical evaluation of epilepsy patients

Epilepsy surgery has become a valuable treatment option for patients with medically refractory focal epilepsy rendering 70-80% seizure free and providing them with the opportunity of Leading satisfactory lives. Successful surgical treatment relies on an accurate localization of brain region where the seizures originate, the so-called epileptogenic zone. In a significant number of patients, however, the epileptogenic zone cannot be localized adequately. Thus, invasive techniques which carry significant risks have to be applied or the patient is denied the opportunity of surgical cure. Thus, the development of novel techniques in the presurgical evaluation of epilepsy patients is warranted. The goal of the present research project is to determine the role of ictal SPECT - a non- invasive technique - in the presurgical evaluation of epilepsy patients. Ictal SPECT offers the unique possibility to visualize the dynamic functional changes of regional cerebral blood flow associated with focal seizures and thus yields valuable information for the localization of the epileptogenic zone. Specifically, the following questions will be investigated: 1. Lateralization accuracy and prognostic value of ictal SPECT in patients with uni- and bitemporal interracial spikes on scalp-EEG. 2. Correlation of ictal SPECT with clinical seizure symptomatology as documented on prolonged video-EEG- monitoring in order to elucidate the mechanisms underlying ictal symptoms like impairment of consciousness, experiential phenomena, ictal vomiting and unilateral eye lid blinking. 3. Correlation of ictal SPECT with ictal EEG changes in order to study propagation pathways of epileptic discharges. 4. Time evolution of rCBF changes as studied with Peri-Ictal SPECT in order to elucidate the poorly understood mechanisms involved in the transition from the interictal to the ictal state. 5. Correlation of postictal SPECT with transient postictal functional deficits like postictal paresis, postictal aphasia and postictal neuropsychological deficits as well as postictal EEG changes to study the mechanisms underlying these deficits. 6. Postsurgical SPECT studies in order to study functional recovery of lateral temporal neocortex and contralateral mesiotemporal structures after successful epilepsy surgery. 7. Postictal psychosis. We will perform EEG recordings and SPECT during episodes of postictal psychosis in order to study its underlying mechanisms. Thus, our research project should significantly improve the exact localization of the epileptogenic zone in the presurgical evaluation of epilepsy patients. Furthermore, new insights in the basic mechanisms of human focal epilepsy and brain function in general will be provided.