Saccadic velocity measurements in internuclear ophthalmoplegia

Five patients with internuclear ophthalmoplegia had horizontal saccades measured by electro-oculography. In all patients, abduction saccadic velocities were normal while adduction saccades were slowed either binocularly or monocularly. In one patient, adduction saccades were reduced in velocity, even though full adduction was present. Saccadic velocity measurements may be helpful in diagnosing internuclear ophthalmoplegia, especially in the early or subclinical case. As bilateral internuclear ophthalmoplegia frequently suggests multiple sclerosis, prolonged examination with more sophisticated and difficult diagnostic tests is avoided.