Idiopathic bilateral vestibulopathy: an autoimmune disease?

Bilateral vestibulopathy (BV) is the loss of function of both peripheral labyrinths or of the eighth nerves. Its etiology remains obscure in approximately 20% to 50% of cases (so-called idiopathic bilateral vestibulopathy, IBV). Alternatively, the cause could be viral or vascular; to date, causative gene mutations have not been identified. Other potential disease mechanisms include autoimmune disorders. Antibodies have been detected against inner ear tissue (primarily against vestibular membranous labyrinth). The data suggest that the bulk of anti-labyrinthine autoantibodies may be an epiphenomenon, but a small subgroup of organ-specific autoantibodies may synergize with a cellular response to develop vestibular lesions. The two key symptoms of BV are the following: 1. unsteadiness of gait, particularly in the dark or on uneven ground, and 2. oscillopsia associated with head movements. Episodes of vertigo are reported by patients with IBV, particularly early in the development of vestibular loss. Associated hearing loss seldom occurs in the idiopathic type of this condition. Post-mortem examinations revealed a remarkably selective loss of vestibular hair cells in the vestibular end organs but normal hair cells in the cochlea. The diagnosis is made with a simple bedside test for defective vestibular function. The diagnosis can be confirmed by bithermal caloric testing and pendular body rotation. The therapy is based on steroid treatment, and the early initiation of immunosuppression appears to be essential for therapeutic success.