Polymicrogyria comes from the greek words poly ( many), micro ( small) and gyri (folds) on the surface of the brain.
It means there are many small gyri packed together. Sometimes they are so tightly packed together they are mistaken for pachygyri or thick and fewer gyri.
When they are bilateral and especially involve the fronto parietal region they may have a genetic basis ( gene identified - GPR56) and have an autosomal recessive inheritance. Perisylvian polymicrogyria may have AD, AR or XLR inheritence.
Degree of involvement of the brain decides the severity of MR, seizures, developmental delay.
On histopath the cortex may have 1 or 4 layers unlike the ususal 6 layers.
Causes include environmental insults during intrauterine life ( eg CMV or other TORCH infections), genetic disorders ( GRP56 deletion), metabolic disorders ( non ketotic hyperglycenemia, PDH def, glutaric aciduria II def, neonatal adrenoleukodystrophy)
( Ref: Polymicrogyria Overview -
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