Hypoglossal Nerve Palsy due to Compression by a Persistent Primitive Hypoglossal Artery: Case Report

A 51-year-old Japanese woman was admitted to our hospital because of speech difficulty following severe headache. Neurological examination showed dysarthria and tongue weakness on the right side, indicating right hypoglossal nerve palsy. Needle electromyography of the right side of the tongue showed fibrillation potentials. Magnetic resonance angiography and computed tomography angiography revealed a right, persistent, primitive hypoglossal artery (PPHA) that met Lie's diagnostic criteria. Digital subtraction angiography showed an extended PPHA with irregular caliber in the portion running through the right hypoglossal canal. We diagnosed compression neuropathy of the hypoglossal nerve due to PPHA enlargement based on the findings of ipsilateral hypoglossal nerve palsy, fibrillation that indicated peripheral nerve palsy, and the enlarged diameter of the portion of the PPHA running through the right hypoglossal canal. We prescribed antihypertensive therapy. At 1 year after onset, her tongue weakness was alleviated. Clinicians should consider compression neuropathy due to a PPHA as one of the possibilities in the differential diagnosis of hypoglossal nerve palsy.