Neuropathologic and clinical features of human medial temporal lobe epilepsy

Background and purpose: There is recent evidence of various types of morphological changes in the hippocampus of a rodent model of medial temporal lobe epilepsy (mTLE). However, little is known about such changes in humans. We examined the histological changes [i.e., neuronal loss, cell genesis, and granule cell dispersion (GCD)] in surgical hippocampal specimens taken from patients with mTLE.

Methods: Nissl staining, and nestin and Prox1 immunohistochemistry were performed on human hippocampal specimens obtained from patients with medically intractable mTLE, thus allowing the analysis of neuronal loss, cell genesis, and GCD, respectively. We also assessed the correlations between clinical parameters and the histopathologic findings.

Results: The degree of cell genesis in the granule cell layer was significantly correlated with the severity of GCD, history of childhood febrile seizures, and frequent generalized seizures. Cell genesis was not correlated with cell death, age at seizure onset, duration of epilepsy, or the mean frequency of all seizures.

Conclusions: Our results indicate that cell genesis in the dentate gyrus of patients with mTLE is associated with GCD and is influenced by the presence of febrile seizures during childhood and the frequency of episodes of generalized seizures.