Teaching NeuroImages: A rare cause of trigeminal neuralgia: dysplastic venous aneurysm of dural arteriovenous fistula.

A 56-year-old man presented with episodic intense facial pain. Trigeminal neuralgia was the presumed diagnosis. MRI revealed vascular compression of the root entry zone (REZ) of the trigeminal nerve (TN) (figure 1, A and B). A dural arteriovenous fistula was detected at the left side of the cerebellar tentorium on digital subtraction angiography (figure 2). A dysplastic venous aneurysm of the draining vein was determined to be the compressive vascular lesion seen on MRI. Trigeminal neuralgia is a common neuropathic disorder characterized by episodes of intense facial pain, most often because of a vascular compression of the REZ of the TN.