Dysplasia Type Ia, Ib and Hippocampal Sclerosis: Is Reelin the Missing Link?

Abnormal radial and/or tangential cortical lamination in the temporal lobe cortex associated to Hippocampal Sclerosis (HS) is now classified as focal cortical dysplasia (FCD) type IIIa in the current ILAE FCD classification. In these cases, the temporal cortex may show architectural abnormalities or hypertrophic neurons outside layer V. Five variants of FCD type IIIa have been recognized: HS with architectural abnormalities in the temporal lobe; HS with Temporal Lobe Sclerosis (TLS), HS with TLS and heterotopic neurons in subcortical white matter, HS with TLS and small “lentiform” heterotopias in subcortical white matter; and HS without TLS but with small “lentiform” subcortical heterotopias [1]. One of these types of histological features is frequently found in specimens of patients with temporal lobe epilepsy.