General description

Hippocampal sclerosis, also known as mesial temporal sclerosis, is the most frequent pathological finding associated with intractable temporal lobe epilepsy. It is characterized by a shrunken and hardened hippocampus, histologically displaying neuronal loss and glial proliferation. While all hippocampal regions may be affected, the dentate gyrus, and the CA1, CA4, and to a lesser extent CA3 sections are primarily involved.

These alterations are mainly observed in the hilus of the dentate gyrus and the CA1 and CA3 pyramidal cell layers. Various morphological and cytochemical changes accompany mesial temporal sclerosis, particularly within the dentate gyrus. These include selective loss of inhibitory interneurons, abnormal axon sprouting, reorganization of neurotransmitter receptors, alterations in second messenger systems, and hyperexcitability of granule cells. The histological hallmarks of the condition are neuronal cell loss, gliosis, and sclerosis.