ICTAL AND INTERICTAL ECD-SPECT FOR FOCUS LOCALIZATION IN EPILEPSY

Forty-one ECD (Technetium-99m-ethyl cysteinate dimer) SPECT investigat ions were undertaken in the course of a presurgical diagnostic work-up in 23 patients with pharmacoresistant focal epilepsy. In 21 patients, both an ictal and interictal SPECT were conducted. In the patients re ceiving ictal SPECT the tracer was injected between 7 and 30 s after t he seizure onset. Of the interictal SPECTs 17 of 23 showed focal hypop erfusion which was consistent in 17 cases (74%) with the area of the e lectrophysiological focus (EF) and 6 patients had a normal interictal SPECT. Of the ictal SPECTs 18 of 21 (86%) showed regional hyperperfusi on, 18 of them in the same location as the EE. Ictal SPECT showed a hy poperfusion similar to that in interictal SPECT in another 3 patients. In these cases seizure duration was short (28-54 s), so that the trac er reached the brain postictally. Our results show that ictal ECD-SPEC T is an effective method for demonstrating an epileptogenic focus. Pos sible reasons for false-negative ictal SPECT results are discussed.