Tentorium cerebelli subdural haematoma complicating subarachnoid haemorrhage.

Acute subdural haematoma (SDH) as a result of aneurysmal rupture is a rare event. We report a tentorium cerebelli SDH, secondary to a ruptured aneurysm which we believe is unique in the literature. This report also gives further support to the theory that a sentinel bleed causes inflammation and adhesion between the aneurysm and arachnoid as the underlying pathology in these unusual subdural haematomas. Since the first report of acute SDH from a ruptured aneurysm by Hasse in 1855, only about 150 further cases have been reported in the literature. We describe a further case, but at an as yet unreported site with radiological evidence of a sentinel bleed.