Postictal SPECT in Epileptic Versus Nonepileptic Seizures

Abstract

Despite advances in video-electroencephalogram (EEG) technology, in many patients distinguishing epileptic seizures from nonepileptic seizures (NES) remains a challenge. Reliable methods to make this distinction are needed. In a pilot study, we performed postictal and interictal single photon emission computed tomography (SPECT) in 22 patients undergoing video-EEG monitoring who had altered responsiveness during an episode. Eleven had seizures, defined as episodes associated with EEG seizure patterns or postictal prolactin (PRL) elevations greater than 1.5 times the highest interictal baseline PRL; 11 had NES. Among the 11 seizures, postictal SPECT was abnormal in seven (regions of hypoperfusion in six and hyperperfusion in one) and normal in four. In six cases (55%), the interictal and postictal SPECT changed. Among the 11 NES cases, postictal SPECT was abnormal in three cases (all hypoperfusion abnormalities) and normal in eight cases. In no case did the interictal and postictal SPECT change. This small sample revealed a trend toward greater hypometabolism (postictal versus interictal) on SPECT for epileptic seizures compared to NES (p < 0.12). There were postictal SPECT changes in two of five seizures unassociated with postictal PRL elevation. Prolactin was elevated in two cases unassociated with change on SPECT. Comparision of postictal to interictal SPECT may help distinguish epileptic seizures from NES. Results from SPECT may also help identify epileptic seizures unassociated with PRL elevation.