Assessment of causality and impairment following unilateral hypoglossal nerve paralysis: A case report.

Isolated hypoglossal nerve injury is an infrequent occurrence in clinical and forensic traumatology practice. Its etiology includes trauma, malignancy, vascular events, autoimmune diseases, and complications of surgical procedures. Clinical manifestations resulting from nerve damage may present early or be delayed. We present the case of a 44-year-old woman who sustained a fracture of the third cervical vertebra following a traffic accident. An anterior approach was employed for instrumentation using an anterior plate spanning two cervical segments. The patient developed dysphagia and swallowing difficulties and subsequently underwent evaluation for disability status. Physical examination revealed significant atrophy and asymmetry of the right half of the tongue body, slight rightward deviation of the tongue apex at rest, and fasciculations. Electromyography performed 22 months after the injury demonstrated chronic axonal injury of the right hypoglossal nerve. Causality assessment favored the traffic accident as the initiating event, with postoperative edema and retraction likely contributing to progression. The condition was classified as permanent, and a 25% functional loss was assigned for tongue paralysis according to national disability criteria. This report highlights the diagnostic, prognostic, and legal complexities of delayed hypoglossal nerve palsy following cervical trauma and underscores the importance of a multidisciplinary approach in determining the etiology and prognosis of isolated hypoglossal nerve paralysis, as well as in establishing medical causality.