Autonomic dysfunction on the affected side in Meniere's disease.

For ascertaining the existence of autonomic dysfunction on the affected side as being the cause of Meniere's disease, the mecholyl tests were conducted by means of conjunctival instillation in normal subjects as well as in patients with Meniere's disease, labyrinthitis and vestibular neuritis. The rate at which significant miosis (more than 10%) appeared in the mecholyl test was 3.1% among normal subjects, whereas the rate among Meniere's disease patients on the affected side was significantly higher during the attack, quasi-attack and interval stages. The appearance rate among Meniere's disease patients on the unaffected side was not different from that in normal subjects during any of the three stages. None of the patients with labyrinthitis or vestibular neuritis showed significant miosis on the affected side alone in the mecholyl test. This indicates that abnormality of vestibular-autonomic reflex in itself does not cause a positive reaction in the mecholyl test. Hence it can be concluded that the cause of Meniere's disease is related to the existence of autonomic dysfunction on the affected side.