Synonyms:
a.k.a. mesial temporal sclerosis a.k.a. Amon’s horn sclerosis a.k.a. hippocampal sclerosis
Diagnosis:
Pathology is the gold standard, but MRI is very sensitive
Pathology:
Gold standard
Atrophy, white discolouration of the hippocampal formation, enlarged temporal horn of the lateral ventricle. Fornix atrophy.
Microscopically: loss of neurons (pyramidal & dentate layer) in CA1 (Sommer sector) & CA4 (end-folium). Discontinuity of dentate granular layer. Astrocytic gliosis. Atrophy of white matter efferents (alveus & fimbria).
Findings on investigations:
MRI
- Hippocampal sclerosis: atrophy on T1, high signal on T2, decreased hippocampal volume
EEG:
- Absolute interictal spike frequency = or >60spikes/hr is associated with poor surgical outcome, if <60spikes/hr it’s associated with good surgical outcome for amygldalohippocampectomy.