Severe intracranial atherosclerotic disease presenting as symptomatic isolated convexity subarachnoid haemorrhage.

Isolated convexity cortical subarachnoid haemorrhage (cSAH) is a rare form of non-traumatic subarachnoid haemorrhage localised to one or few cortical sulci of the brain without involving the adjacent brain parenchyma or spreading to sylvian fissure, interhemispheric fissure, basal cisterns and ventricles. cSAH has multiple aetiologies described in medical literature. Intracranial high-grade stenosis is rarely presented as cSAH, especially in young adult patients. Patients presenting with cSAH warrant appropriate diagnostic work up to identify and treat the underlying aetiology.