Eye movements in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is characterized by degeneration of the upper motor neurons in the frontal cortex and the motor neurons of the brain stem and spinal cord. Cranial nerve nuclei III, IV, VI are usually normal histopathologically, as are the eye movements clinically. Using electro-oculography, we found decreased saccadic or smooth pursuit velocities in four of ten patients unidirectional saccadic pursuit in one of these four, and progressively decreasing saccadic velocities in another. We believe the defect is supranuclear and that the ocular motor system is more often abnormal in patients with ALS than previously recognized.