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Definition/Background
Polymicrogyria is a cerebral cortical malformation characterized
by interruption of the normal cortical development during the late stages of
neuronal migration and cortical organization. This results in abnormal development
of the deeper layers of the cortex, with multiple small gyri and shallow
cortical sulci.
Characteristic
Clinical Features
Clinical features
include developmental delay, and seizures.
Associations:
Congenital cytomegalovirus infection, in utero ischemia, and chromosomal
mutations (mutations of Xq28, 16q12.2-21).
Syndromic
associations: Congenital bilateral perisylvian syndrome and Aicardi
syndrome.
Characteristic
Radiologic Findings
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MR imaging is the gold standard to evaluate for polymicrogyria.
3DFT spoiled gradient acquisition (T1W) analyzed
in at least two imaging planes is essential. The typical imaging appearance is
of small irregular cortical gyri with shallow or absent sulci. Occasionally, a
thick, bumpy cortex is seen. Perisylvian cortex is the most common location,
although any area of the cerebral cortex can be involved. Usually focal,
unilateral; multifo-cal; bilateral, asymmetrical; or bilateral, symmetrical forms
have been described. Bilateral involvement is often syndromic.
Primary Differential
Diagnosis
1-Pachygyria
Discussion of
Differential Diagnosis
Pachygyria: Characterized by a broad thick gyrus and does
not demonstrate the typical irregular, bumpy
cortical surface noted in polymicrogyria. However, sometimes it can be
difficult to distinguish the two entities.
The patient is a 14-year-old boy with developmental delay.
Coronal 3DFT SPGR sequence demonstrates shallow, absent cortical sulci in the left perisylvian region.
Axial 3DFT SPGR sequence demonstrates a bumpy left perisylvian cortex.
Sagittal 3DFT SPGR sequence demonstrates a thickened cortex with small irregular cortical gyri and absent sulci involving predominantly the frontal operculum in the left perisylvian region. Diagnosis: Polymicrogyria.
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Labels: Brain, Congenital Anomalies
