Right perisylvian syndrome

Clinical History

The patient had a history of complex partial seizure for 15 years and was mentally retarded.

Imaging Findings

MRI brain revealed a small and bumpy polymicrogyric cortex in the right perisylvian region with blurring of gray white matter. Widening of right sylvian fissure was noted.

Discussion

Congenital bilateral perisylvian syndrome is synonymous with perisylvian syndrome, perisylvian polymicrogyria, Worster Drought syndrome and bilateral opercular syndrome. Perisylvian syndrome refers to a neurological disorder in which a particular area of the brain (called the perisylvian region) develops abnormally and the underlying developmental abnormality is polymicrogyria. [1]
Polymicrogyria refers to abnormal appearance of the cortex with multiple abnormally small convolutions and too few sulci. It is basically an organization anomaly in which the neurons reach their final destination in the cortex but are distributed abnormally. Gross assessment of the thickness of the cortical surface is due to fusion of the adjacent miniature gyri piled upon one another. Multiple syndromes of region specific bilateral symmetrical polymicrogyria have been reported. [1, 2]
This syndrome has been associated with congenital cytomegalovirus infection, Aicardi syndrome or can be sporadic. The anomaly usually occurs as a result of post-migration insult during fifth or sixth month of pregnancy. A new syndrome of familial perisylvian polymicrogyria has been described. However, no definite inheritance pattern could be attributed to the syndrome and it was regarded as genetically heterogeneous. Reports from different families with multiple affected family members suggest different modes of inheritance including X linked, autosomal dominant and autosomal recessive. [1]
The unilateral perisylvian dysplasia described here could correspond to the unilateral counterpart of the "bilateral perisylvian syndrome".' In this disorder the radiological features are very similar but the bilateral lesions lead to a special clinical picture dominated by suprabulbar signs and more severe mental retardation and epilepsy. [3]
MRI is the modality of choice for assessing polymicrogyria. Both morphology and signal intensity may be abnormal. Best diagnostic clue is focal cortical thickening. [2]
Polymicrogyric cortex usually has signal characteristics similar to normal grey matter. The subjacent white matter is not infrequently hyperintense on T2 weighted images (20-27%) which may relate to dilated perivascular spaces. Occasionally (<5%), and perhaps more so in patients with congenital infection, the abnormal cortex demonstrates regions of calcification. [2]
The numerous small gyri that lend their name to the condition are very small and only seen on thin section high resolution MRI, and even then may be difficult to distinguish from pachygyria, as both as associated with broad enlarged and often thickened gyri. The grey-white junction is often the best location to identify the 'bumpy' contour which on thicker slices may manifest as blurring. [2]
Treatment and prognosis: No specific treatment is available. Treatment is symptomatic and particularly aimed at controlling epilepsy, which is commonly present. [2]

Differential Diagnosis List

Final Diagnosis

Right perisylvian syndrome

URL:	https://www.eurorad.org/case/12216
DOI:	10.1594/EURORAD/CASE.12216
ISSN:	1563-4086