Chiari-I malformation associated with asymmetric sensorineural hearing loss.

Chiari-I malformation is a deformity of the structures of the posterior fossa in which there is inferior herniation of the cerebellar tonsils through the foramen magnum without significant caudal dislocation of the brainstem. Patients are usually asymptomatic until adulthood, when they commonly present with recurrent headaches, weakness, vertigo and/or imbalance, nystagmus and hearing loss. A review of 226 consecutive patients evaluated for asymmetric sensorineural hearing loss revealed 32 patients with retrocochlear pathology. Three of these patients were discovered to have a Chiari-I malformation by magnetic resonance imaging as their only pathology. We suggest a possible association between a Chiari-I malformation and isolated asymmetric sensorineural hearing loss secondary to long-standing traction on the eighth cranial nerve.