1. Neurologia, Orszagos Pszichiatriai es Neurologiai Intezet, Hüvösvölgyi ut 116, Budapest, 1021 Hungary.
A 28-year-old woman with temporal lobe epilepsy underwent presurgical evaluation. Scalp-EEG showed non-localizing seizure patterns. MRI revealed a right hippocampal sclerosis. Ictal HMPAO-SPECT showed a marked left temporal hyperperfusion. Video-EEG monitoring with foramen ovale electrodes (FOE) showed an initial seizure pattern which appeared in the right FOE and which shifted to the left 8 s after clinical onset. Three years after a right temporal lobectomy, the patient is seizure-free. In conclusion, although the ictal SPECT suggested a left temporal seizure focus, the intracranial EEG and the postoperative seizure-freedom confirmed the right-sidelocation of the epileptogenic region. A rapid right-left seizure spread explains the mechanism of falsely lateralizing ictal SPECT.