Spinal dural arteriovenous fistula with perimesencephalic subarchnoid haemorrhage

A case is reported of a 66 year old woman presenting with perimesencephalic subarachnoid haemorrhage (SAH) which was caused by a spinal dural arteriov enous fistula at the C1 level. The fistula drained into the venous system o f the posterior cranial fossa through a perimedullary vein. The bleeding wa s thought to result from venous hypertension induced by the fistula, This c ase may support the hypothesis that perimesencephalic nonaneurysmal SAH can be ascribed to venous bleeding and that venous hypertension is the key to its pathology. (C) 2000 Harcourt Publishers Ltd.