DIAGNOSIS OF SPONTANEOUS POSTERIOR FOSSA HAEMORRHAGE BY AETIOLOGY: A RETROSPECTIVE COHORT OF 312 PATIENTS

Purpose: to determine the aetiology-specific clinical and imaging features of spontaneous PF haemorrhage and formulate a contemporary diagnostic sequence. Materials and methods. We retrospectively analysed 312 consecutive patients aged 15 years or older who were treated for non-traumatic haemorrhage involving the cerebellum, brainstem, or PF subarachnoid spaces during 1991-2009. All underwent urgent non-contrast computed tomography; magnetic resonance imaging and angiography were used selectively, and 122 patients underwent digital subtraction angiography. Aetiology was assigned from clinical, imaging, operative, and histological data. Results. Hypertensive small-vessel disease accounted for 170 cases (54.5%), ruptured saccular aneurysm for 98 (31.4%), arteriovenous malformation for 24 (7.7%), and cavernous malformation for 20 (6.4%). Among hypertensive haemorrhages, 101 involved the brainstem, 62 the cerebellum, and 7 both sites. Aneurysmal haemorrhage was predominantly subarachnoid; arteriovenous malformations were usually cerebellar or vermian; and circumscribed subependymal brainstem haematomas were characteristic of cavernous or occult vascular malformations. Hydrocephalus developed in 35 patients, including 22 with a progressive course requiring surgery. Conclusions. Non-contrast computed tomography is the immediate first examination. Early vascular imaging is required when a macrovascular cause is plausible; blood-sensitive magnetic resonance imaging is preferred for cavernous malformations and thrombosed lesions; and digital subtraction angiography remains decisive when non-invasive studies are negative or inconclusive despite persistent suspicion of a macrovascular cause.