How localized is localization-related epilepsy?

Abstract

The most common localization-related epilepsy is temporal lobe epilepsy (TLE). Traditionally, TLE has been considered a localized disorder given the focal mesial temporal onset of seizures, hippocampal atrophy and sclerosis, and therapeutic response to focal resection of the anteromedial temporal lobe. However, there is growing evidence of more diffuse anatomic and functional abnormalities. Patients with TLE exhibit dysfunction of the anterior temporal lobe (e.g., memory formation and naming), but they also can exhibit abnormal cognitive functions not associated with focal dysfunction of the anterior temporal lobes. The reason for these unanticipated cognitive findings is becoming clearer. MRI studies have provided evidence for reduced volumes in multiple brain regions in TLE including extrahippocampal temporal, frontal, parietal, and occipital lobes, and diverse subcortical structures, which involve not only the hippocampus and parahippocampal gyrus, but also the thalamus, caudate, amygdala, and cerebellum.1 Diffuse abnormalities of the cortical mantle also occur, including markers of gray matter complexity and thickness in temporal lobe and in extratemporal regions ipsilateral and contralateral to the side of temporal lobe seizure onset.2 Positron …