Spike-Triggered f MRI in Reading Epilepsy and Benign Epilepsy with Centrotemporal Spikes

Abstract

Neurology 2003;60:415-421 OBJECTIVE: To determine the origin of epileptiform activity in reading epilepsy (RE) and the association between these regions and regions activated by reading, and to assess brain morphometry in these areas. METHODS: In two subjects with RE, EEG was recorded inside the three tesla MRI while subjects read silently. Spike-triggered fMRI images were compared to base-line. In a second fMRI study, 30 seconds of silent reading was compared to visual fixation. Morphometry of these areas was assessed using curvilinear surface reconstruction. Left central sulcal patterns in three subjects with RE were compared to three subjects with idiopathic generalized epilepsy (IGE) and 12 normal controls. RESULTS: One subject with RE showed spike-related activity (17 spikes) in the left precentral gyrus, and bilaterally in the central sulcus and globus pallidus. The other showed no definite activation owing to low spike numbers (4 spikes). In both subjects, the block reading task recruited normal visual and language areas including the left posterior middle frontal gyrus. Two subjects with RE showed an unusual gyrus branching anteriorly off the left central sulcus. A similar sulcal pattern was seen in none of the subjects with IGE and only 1 of 12 controls. CONCLUSION: Spike activity overlapped with reading activity in the left middle frontal gyrus, a structure recruited during working memory cognitive tasks. The authors postulate that, because of a local structural anomaly, the spikes of reading epilepsy spread from working memory areas into adjacent motor cortex, activating a cortical subcortical circuit. Epilepsia 2003;44(2):200-204 OBJECTIVE: We performed spike triggered functional MRI (fMRI) in a 12 year old girl with Benign Epilepsy with Centro-temporal Spikes (BECTS) and left-sided spikes. Our aim was to demonstrate the cerebral origin of her interictal spikes. METHODS: EEG was recorded within the 3 Tesla MRI. Whole brain fMRI images were acquired, beginning 2-3 seconds after spikes. Baseline fMRI images were acquired when there were no spikes for 20 seconds. Image sets were compared with the Student's t-test. RESULTS: Ten spike and 20 baseline brain volumes were analysed. Focal activiation was seen in the inferior left sensorimotor cortex near the face area. The anterior cin-gulate was more active during baseline than spikes. CONCLUSIONS: Left sided epileptiform activity in this patient with BECTS is associated with fMRI activation in the left face region of the somatosensory cortex, which would be consistent with the facial sensorimotor involvement in BECT seizures. The presence of BOLD signal change in other regions raises the possibility that the scalp recorded field of this patient with BECTs may reflect electrical change in more than one brain region. COMMENTARY