Abstracts

Functional neuroimaging is a powerful tool for focus detection in partial epilepsies. As increased neuronal activation during a seizure might be accompanied by a relative increase in perfusion, measuring these changes is an accepted method for localizing the epileptogenic focus. Ictal SPECT is a standard technique but requires inpatient monitoring and trained personnel. Perfusion CT is a possible tool for measuring cerebral blood perfusion. Since patients presenting with convulsive status epilepticus, change in mental status, or seizures undergo emergency CT, the goal of this study was to investigate whether perfusion changes detected by CT are helpful during an emergency diagnostic workup. The study included 7 women and 10 men (mean age 44 years, range 22-74 years) presenting within 2 hours after an epileptic seizure. The patients underwent non-contrast and contrast enhanced CT of the brain. Asymmetry indices for cerebral perfusion over homologus brain areas were calculated for the standard perfusion parameters (rCBV, rCBF, MTT) with a commercially available software package. Sixteen patients underwent routine EEG. All EEGs were analyzed visually and surface voltage maps were computed and compared with the region of increased or decreased cerebral perfusion. In 4 patients, regional hyperperfusion was present during non-convulsive status epilepticus and correlated with the ictal EEG and the clinical semiology suggesting that it represented the area of ictal onset. In 6 patients postictal focal slowing of the EEG correlated with regional hypoperfusion. Postictal perfusion studies and EEG were normal in seven patients presenting with a first epileptic seizure.[table1] However, further prospective studies are needed to further elucidate the potential value of this method. Regional ictal hyperperfusion can be detected by perfusion CT in patients with nonconvulsive status epilepticus. The perfusion patterns may further help to differentiate between other etiologies.