Hypoglossal dural arteriovenous fistula: a rare cause of unilateral hypoglossal nerve palsy

Ms Y, a 57-year-old female presented with a 1-week history of tongue deviation. The history of the presenting complaint also included minor dysarthria, dysphagia for solids and liquids as well as a 2- to 3-month history of pulsatile tinnitus affecting the right ear. Examination of the cranial and peripheral nerves revealed a right hypoglossal nerve lower motor neurone palsy. MRI demonstrated a dural arteriovenous fistula (DAVF) in the region of the right hypoglossal canal. She underwent a cerebral angiogram, which confirmed a hypoglossal DAVF with predominant supply from the neuromeningeal branches of the right ascending pharyngeal artery. She has been able to cope with her symptoms and remains on active surveillance. Hypoglossal nerve palsy is uncommon, causes may be classified according to location. DAVFs are a rare cause of hypoglossal nerve palsy. DAVFs can be graded according to their pattern of venous drainage. This case illustrates the complex venous anatomy of the craniocervical junction, which enables postural-dependent drainage through the internal jugular and vertebral venous systems. This network of veins is encountered during interventional radiology procedures and neurosurgical skull base approaches.