Isolated hypoglossal nerve palsy due to a vascular anomaly.

The case of a patient with an unusual cause of an isolated hypoglossal nerve palsy is presented. Magnetic resonance (MR) imaging demonstrated marked dilatation and ectasia of the right vertebral artery and basilar artery, thereby causing compression of the brainstem. It is therefore proposed that a dilated vascular loop compression of the nerve rootlets, as they exit the medulla, has caused the hypoglossal nerve palsy. This case demonstrates that excellent images can be obtained from MR imaging, and also emphasises that other pathologies must be considered in the differential diagnosis of hypoglossal nerve palsy.