Mesial temporal sclerosis and M1 occlusion

Case contributed by A.Prof Frank Gaillard



Patient Data

Age: 50
Gender: Male

The right hippocampus is reduced in volume, and has increased signal intensity and loss of internal structure or consistent with the diagnosis of right-sided mesial temporal sclerosis. No abnormality grey-white differentiation identified.

The left hippocampus is normal. Prominence of the cerebellar sulci suggest long-standing epilepsy treatment effects.

Review of the MRA shows truncation of the right M1 segment with a small vessel showing some residual flow towards M2 branches. An abdominal leash of vessels is identified in the position of the lenticulostriate, presumably collaterals. Fetal posterior communicating of the left internal carotid. The left vertebral is dominant. 


  1. Right-sided mesial temporal sclerosis
  2. Blocked M1 segment on the right with lenticulostriate collaterals

Case Discussion

Note that this patient has right sided moya moya pattern, with the underlying etiology of the M1 occlusion uncertain, but most probably not moya moya disease. This poses additional surgical risks during surgery and raises the question of if and when to bypass the M1 occlusion. 




The sections of neocortex show disturbance of cortical lamination with a haphazard arrangement of enlarged dysmorphic neurons in many areas with overlapping of neuronal nuclei. Areas in
which there is persistence of a columnar arrangement of neurons are also noted. Occasional large neurons are identified in the molecular layer. No balloon neurons are seen. A moderate number of neurons is seen in white matter. Myelination is normal. There is no evidence of tumor. The features are of cortical dysplasia - ILAE Type IIa

In addition to the dysplastic features in the cortex, there are several aggregates of small caliber arterial vascular structures in the sub-arachnoid and Virchow-Robbin spaces. Many of these show mural hyalinization and excessively folded elastic laminae. No vessel thromboses are seen. These features are unusual and may represent small collateral channels. It is noted that imaging showed occlusion of the proximal right middle cerebral artery and the appearances raised the possibility of Moya Moya disease or phenomenon. The small arterial vessels with excessively folded elastic laminae are consistent with that condition. No ischemic changes are seen in cerebral cortex or white matter.

The sections of hippocampus show moderate loss of neurons from the CA1, CA3 and CA4 sectors with relative preservation of neurons in CA2. There is also dispersion of neurons in the dentate fasciculus. Moderate astrocytic gliosis is noted throughout the hippocampal cortex and end-folium.  The features are of hippocampal sclerosis - ILAE Type 1a (classical hippocampal sclerosis).

Serial sections of the amygdala show a haphazard arrangement of enlarged dysmorphic neurons, similar in appearance to those in the areas of cortical dysplasia in temporal neocortex in specimens. No balloon cells are identified. There are no features of tumor. The features are of amydgala dysplasia equivalent to ILAE Type IIa cortical dysplasia.


  • Right lateral temporal lobe: Cortical dysplasia - ILAE Type IIa
  • Vascular changes consistent with Moya Moya disease/phenomenon collaterals in sub-arachnoid and Virchow-Robbin spaces; no ischemic parenchymal changes seen.
  • Hippocampus: Hippocampal sclerosis - ILAE Type Ia (classical hippocampal sclerosis) 
  • Amygdala:  Amygdala sclerosis equivalent to ILAE Type IIa cortical dysplasia.
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Case information

rID: 28185
Published: 7th May 2015
Last edited: 12th Jan 2016
Inclusion in quiz mode: Included

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