Myelopathy due to intracranial dural arteriovenous fistula with perimedullary venous drainage: clinical and medico-legal aspects in a case of diagnostic pitfall.

Abstract

BACKGROUND\nAn intracranial dural arteriovenous fistula (DAVF) consists of a meshwork of arteriovenous shunts. Drainage of the fistula may be into a dural sinus or directly into cortical veins. Rarely, DAVFs drain exclusively into perimedullary veins. Prompt diagnosis is important as the clinical course is potentially life-threatening.\n\n\nCASE DESCRIPTION\nA 67-year-old man presented with difficulties in walking and bladder retention. Magnetic resonance imaging (MRI) revealed central myelopathy, edema from C6 to T8, and dilated posterior medullary veins. Spinal angiography showed no abnormalities. The diagnostic impression was one of inflammatory demyelinating disease, and the patient was treated with corticosteroids. Three days later, the patient had become paraparetic. Brain MRI revealed abnormal vascular structures around the lower brain stem and cervical cord. Cerebral angiography showed a dural fistula at the skull base, supplied by the neuromeningeal branch of the ascending pharyngeal artery and draining into the posterior medullary veins. Following neurosurgical referral, the draining vein was clipped just beyond the arterial feeders. At that time, the patient was wheelchair-bound and needed assistance in daily activities.\n\n\nCONCLUSIONS\nThe early diagnosis of this rare vascular malformation is challenging; angiographic studies must include the cranial vasculature when spinal studies are normal or if the abnormality on MRI is maximal in the upper spinal cord.In the case described, as only medullary angiography was performed, the intracranial DAVF with perimedullary venous drainage was not diagnosed. Delayed diagnosis is likely to lead to severe neurological consequences.