Sunday 21 August 2011

Polymicrogyria MRI

MRI Axial T1w and sagittal rightward T1w images. 

Right Peri sylvian region show excessive small convolutions with multiple small gyri suggestive of polymicrogyria. An associated asymmetrically deep right central sulcus and right hemi atrophy.


A malformation due to abnormality in late neuronal migration and cortical organization.
Neurons reach the cortex but distribute abnormally forming multiple small undulating gyri.

MRI is the investigation of choice.
Imaging wise excessively small and prominent convolutions.
Predilection for perisylvian regions.
Often Unilateral. When bilateral often syndromic.
Periventricular Ca++ if secondary to CMV best seen on CT.

Intrauterine infection, ischemia, toxins or gene mutations are known etiology.
Associated with deletions of: 22q 11.2 (DiGeorge critical region), Xq28 and 16qI2.2-21

Associated anomalies are Congenital bilateral perisylvian syndrome (Foix-Chavany-Marie), Aicardi, Zellweger, and Peliziaeus-Merzbacher Disease.

Microscopic features
Range of histology reflecting derangement of the six layered lamination of the cortex.
Cortical layers 4 and 5 most involved.
Leptomeningeal embryonic vasculature overlies malformation.
Myelination within the subcortical or intracortical fibers changes the cortical appearance on T2 weighted images.

Clinical Presentation
Faciopharyngoglossomasticatory diplegia, developmental delay, seizure, hemiparesis. Onset and severity of seizures relates to extent of malformation. Variable life span based on severity of genetic mutation, resultant malformation and associated anomalies.

Medical management of seizures and supportive care.

Reference: Diagnostic Imaging Osborn.

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