Abstract
Studies of the cervico-ocular reflex and the vestibulo-ocular reflex were carried out separately and in combination on a patient with gait ataxia due to a cerebellar tumor. With the head fixed in space, body rotation to the right (left neck torsion) induced marked nystagmus to the left in darkness. Vestibulo-ocular responses to sinusoidal rotation were symmetrical while the neck was immobilized and asymmetric when it moved freely. The cervical nystagmus was apparently the result of removal of cerebellar inhibition upon the cervico-ocular reflex and abnormal interaction of cervical and vestibular inputs could have played a role in the patient''s unsteadiness.