The opercular syndrome--diagnostic trap in facial paralysis.

We describe a patient with a left facial paralysis and hemotympanum following left parieto-occipital skull trauma. The initial admission diagnosis of intratemporal facial nerve injury secondary to temporal bone fracture was incorrect. Normal facial movements during involuntary activity (yawning, laughing at a joke) and focal seizure activity on the paralyzed side of the face, seen subsequently, indicated the site of lesion as supranuclear. The diagnosis of opercular syndrome was made. This syndrome can result when the contralateral frontal lobe is injured. Supranuclear weakness of muscles supplied by the hypoglossal or spinal accessory nerves is also present. Unlike other central paralyses, the facial paralysis in operculum syndrome may not demonstrate "forehead sparing" and consequently it may be mistaken for a peripheral paralysis. The neuroanatomic basis for the syndrome is discussed. Signs and symptoms are outlined to help the otolaryngologist avoid this diagnostic pitfall.