What three main types are recognised? Which type is this?
Isolated (affects only one cerebral hemisphere without out associated syndromes); Syndromic (hemimegalencephaly is part of an associated syndrome); Total (the cerebral hemisphere and cerebellum and brainstem are affected). This case demonstrates enlargement of the cerebellum, consistent with total hemimegalencephaly.
What other conditions are associated with the syndromic form?
Epidermal nevus synbdrome; Klippel-Trenaunay Syndrome; McCune-Albright syndrome; Proteus syndrome; Unilateral hypomelanosis of Ito.
MRI of the brain demonstrates the right cerebral hemisphere to be markedly enlarged. The grey matter is disorganized and thickened, consistent with migration arrest. The right lateral ventricle demonstrates an abnormal morphology and is also markedly enlarged. There is diffuse T2 hyperintensity throughout the white matter of the right hemisphere. The right cranial vault is also expanded.
Additionally the right cerebellar hemisphere is also enlarged with abnormal cortical formation.
The left hemisphere is essentially normal in appearance.