SPECT and Localized Proton MRS of Epilepsy in Children with Cortical Dysplasia

Abstract

70 PLATFORM AND POSTER SESSIONSbarrier (BBB) in the left hemisphere by injection of a hyperosmolar solution of mannitol into the left internal carotid artery, following an intravenous injection of bicuculline methiodide. Both hemispheres were then observed from an axial view before and after the induction of seizures by using the three-dimensional chemical shift imaging (CSI) technique. Proton CSI data were obtained from a 40 x 40 mmz FOV, divided into an 8 x 8 matrix, by using water suppression, fat suppression, and outer volume suppression, thus creating a metabolic map. The opening of the BBB was confirmed as a transient increase in signal intensity in the left hemisphere on T,-weighted MR images.Results: Neither the intravenous injection of bicuculline methiodide nor the transient opening of the BBB alone caused seizure activity. The rats developed tonic-clonic seizures after the transient opening of the BBB after injection of bicuculline methiodide. The left hemisphere showed periodic spikes on the scalp EEG -15 min after the opening. Metabolic images showed an accumulation of lactate in the left cerebral hemisphere at 1 and 3 h after seizure induction. Metabolic images of lactate, however, detected no abnormalities in the hemisphere 24 h after the seizure. No clear concurrent changes in the NAA map were observed in this study. The cerebellar hemispheres showed no changes of either the lactate or NAA metabolic images.Conclusions: We found a transient accumulation of lactate in the cerebral hemisphere due to abnormal neuronal excitation after its evocation with bicuculline methiodide. The metabolic maps were obtained in vivo with a noninvasive procedure. We suggest that lactate can be a reversible indicator for NMR metabolic mapping, showing the focus of abnormal neuronal excitation in the acute stages of clinical seizures. Purpose: Changes of regional cerebral blood flow (rCBF) in patients with epilepsy with cerebral cortical malformations (CCMs) were studied interictally and ictally, and compared with rCBF in patients with other epileptogenic lesions. Regional Cerebral Blood Flow in Patients withMethods: The interictal and ictal rCBF of 66 patients with medically intractable partial seizures with CCMs, identified by magnetic resonance imaging (MRI; 63 cases) or histological study of surgically resected specimens (33 cases) or both were measured by using single photon emission computed tomography (SPECT). The CCMs were classified into cortical dysplasia in 40 patients (34 intralobular and six multilobular), heterotopia in 16 patients (seven double cortex, six subcortical, and three periventricular/subependymal), polymicrogyria in six patients (two bilateral perisylvian polymicrogyria, two unilateral schizencephaly, and two focal polygyric anomaly), hemimegalencephaly in two patients, and pachygyria in two patients. Among the 63 patients with symptomatic partial epilepsy, the localization of their epileptogenic foci was identified in 54 patients (26 frontal, 14 temporal, five occipital, two parietal, and sev...