Isolated angiitis of the CNS presenting as subarachnoid haemorrhage.

Isolated angiitis of the CNS (IACNS) commonly presents with recurrent ischaemic or haemorrhagic infarcts, but subarachnoid haemorrhage is rare. Three patients with IACNS and subarachnoid haemorrhage are reported. Florid granulomatous angiitis with Langhans and foreign body type giant cells was found at necropsy in a child with sudden death. In two other patients the diagnosis was made angiographically. In one patient multifocal infarcts on MRI became evident one week after subarachnoid haemorrhage despite initial treatment with prednisone. Subarachnoid haemorrhage may be the first presentation of IACNS. Characteristic radiographic findings may allow early diagnosis.