Oral manifestations and differential diagnosis of isolated hypoglossal nerve palsy: report of two cases.

Isolated hypoglossal nerve palsy is rare, but occasionally it appears as the initial or solitary sign of an intracranial or extracranial space-occupying lesion, a head and neck injury, or a vascular abnormality of the internal carotid artery. Therefore it should be considered in differential diagnosis. We report two cases of isolated unilateral hypoglossal nerve palsy. In Case 1 the cause of the palsy appeared to be hypoglossal nerve neurilemmoma within the hypoglossal canal, whereas in Case 2 the cause could not be identified. Neither patient complained of any disability other than slight dysarthria. The tongue deviated toward the healthy side at rest and toward the affected side on protrusion. Hemiatrophy of the tongue with fatty displacement was demonstrated by means of T1-weighted magnetic resonance imaging. Dentists who might at times see patients with isolated hypoglossal nerve palsy should be aware of the significance of its oral manifestation, and they should be able to perform differential diagnosis of patients with the condition who appear for treatment.