The effect of hyperventilation on downbeat nystagmus in cerebellar disorders

Hyperventilation can affect nystagmus in patients with vestibular disorders . However, the effects on nystagmus in patients with cerebellar disease hav e not been systematically studied. Using the magnetic field search coil tec hnique, we studied the effects of hyperventilation on nystagmus in a series of cerebellar patients. In four of eight patients, hyperventilation produc ed an increase in the slow-phase velocity of downbeat nystagmus. We specula te that this effect may be mediated through metabolic effects on cerebellar calcium channels.