Surgical strategy for refractory epilepsy secondary to porencephaly: ictal SPECT may obviate the need for intracranial electroencephalography. Patient series

BACKGROUND: Surgical treatment of intractable epilepsy caused by porencephaly can be difficult because of poorly localizing or lateralizing electroclinical findings. The authors aimed to determine whether noninvasive evaluations are sufficient in these patients. OBSERVATIONS: Eleven patients were included in this study. The porencephalic cyst was in the left middle cerebral artery (MCA) area in 9 patients, the left posterior cerebral artery area in 1 patient, and the bilateral MCA area in 1 patient. Interictal electroencephalography (EEG) revealed multiregional, bilateral, interictal epileptiform discharges in 5 of 11 patients. In 6 of 10 patients whose seizures were recorded, the ictal EEG was nonlateralizing. Nine patients underwent ictal single-photon emission computed tomography (SPECT), which revealed lateralized hyperperfusion in 8 of 9 cases. Fluorodeoxyglucose positron emission tomography (FDG-PET) was useful for identifying the functional deficit zone. No patient had intracranial EEG. The procedure performed was hemispherotomy in 7 patients, posterior quadrant disconnection in 3 patients, and occipital disconnection in 1 patient. A favorable seizure outcome was achieved in 10 of 11 patients without the onset of new neurological deficits. LESSONS: Ictal SPECT was useful for confirming the side of seizure origin when electroclinical findings were inconclusive. Thorough noninvasive evaluations, including FDG-PET and ictal SPECT, enabled curative surgery without intracranial EEG. Seizure and functional outcomes were favorable.