LAUSR

A porencephalic cyst is an aberrant accumulation of cerebrospinal fluid (CSF) within the brain parenchyma. Its occurrence is rare, with an incidence of 3.5 per 100,000 live births. Aetiology is considered the result of perinatal cerebral ischemia or haemorrhage, leading to parenchymal loss. Porencephalic cyst is diagnosed radiologically, and management depends on the clinical manifestation. Our case depicts a porencephalic cyst presenting with non-dominant parietal lobe symptoms in adulthood. We hypothesise that a membrane between the cyst and ventricle allowed formation of a one-way valve that led to slowly progressive cyst enlargement, eventually causing mass effect and non-dominant parietal lobe symptoms. Endoscopic fenestration of the cyst membrane into the lateral ventricle was successful in reducing cyst volume and improving mass effect.