Selective medial temporal volume reduction in the hippocampus of patients with idiopathic generalized tonic-clonic seizures

Background: Different subtypes of idiopathic generalized epilepsy may indicate different mechanisms and outcomes, suggesting that it is necessary to use a 'pure sample' of a single subtype. Methods: A volumetric study, in conjunction with cognition assessments, was performed in a pure sample of patients with idiopathic generalized tonic clonic seizures (IGE-GTCS; 15 males and 15 females) matched with normal control subjects (15 males and 17 females). The volumetric measurements were focused on the hippocampus and its surrounding structures, including the amygdala, the parahippocampal gyrus, the entorhinal cortex and the perirhinal cortex. The Wechsler Adult Intelligence Scale-Revised in China was administered to assess cognitive status. Results: A volume reduction was found only in the hippocampus, with a more severe effect on the left side than the right side. The total number and frequency of seizures had significant negative correlations with multiple cognitive measures. Furthermore, the hippocampal volume reduction was significantly correlated with some aspects of cognitive impairment. Conclusion: These findings suggest that compared with the other medial temporal structures, the hippocampus may be more vulnerable to the neuropathology of IGE-GTCS. The observation that cognitive deterioration was correlated with an increased frequency and total number of seizures highlights the critical importance of preventing seizures from recurrence. (C) 2014 Elsevier B.V. All rights reserved.