Intracranial dural arterio-venous fistula.

Intracranial dural arteriovenous fistulae are rare, acquired lesions that may present with intracranial haemorrhage or progressive neurological deficits. Their cause is uncertain, although they are often associated with intracranial venous thrombosis. Their importance lies in the fact that they are potentially curable by endovascular or neurosurgical procedures, but easily missed on routine brain imaging. In addition, clinical presentation is variable, with no easily recognisable "syndrome". A high index of suspicion is therefore required, as well as familiarity with the characteristic radiological abnormalities seen on appropriate imaging.