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Clinicopathological correlations also show correlation with ILAE subtype and pre-operative
memory36. Different HS subtypes may be detectable with high field MRI37.

Subfield Severity of neuronal loss

Dentate gyrus 0-2 0-1 0-2 0-1
CA4 2 0-1 1-2 0
CA3 0-2 0-1 0-1 0
CA2 0-2 0-1 0-1 0
CA1 2 1-2 0-1 0
Subiculum 0 0 0 0
Classification HS ILAE type 1 HS ILAE type 2 HS ILAE type3 No HS

Previous Classical/Total/ CA1 End folium No HS
Severe predominant HS
terminologies HS sclerosis or CA4

predominant

Table. ILAE Classification for hippocampal sclerosis (HS) 2013. Semi-quantitative microscopic
examination based on formalin-fixed, paraffin-embedded surgical specimen (4–7 µm section thickness),
haematoxylin and eosin staining, cresyl-violet combined with Luxol-fast blue staining (CV/LFB; Figure
1), GFAP immunohistochemistry (Figure 3) and NeuN immunohistochemistry (recommended; Figure 4).
The scoring system refers to neuronal cell loss (NeuN staining) and is defined for Subiculum and CA1 to
CA4 as following: 0 = No obvious neuronal loss or moderate astrogliosis only; 1 = Neuronal loss and
gliosis (GFAP) is moderate or patchy is patchy more or less than moderate; 2 = severe neuronal loss
(majority of neurons lost) and fibrillary astrogliosis. Scores for the Dentate Gyrus (DG): granule cell layer
is normal (score = 0), dispersed (score 1; can be focal) or shows severe granule cell loss (score 2; can be
focal) (Blumcke et al, 2013). The ILAE subtypes are shown in the diagram below; pyramidal neurones of
hippocampal subfields and subiculum are shown in red, granule cells in blue and astrocytosis in green
(taken from Thom 201438).