Electrooculography and discriminant analysis in Duane's syndrome and sixth-cranial-nerve palsy.

Eye-movement recordings may be helpful in the differentiation of Duane's syndrome from sixth-cranial-nerve palsy. Voluntary horizontal saccades were recorded and quantitated by electrooculography in 18 patients with unilateral type I Duane's syndrome and in 25 patients with sixth-nerve palsy. When ranges of abduction were matched, the peak velocities of abducting saccades in affected eyes were decreased equally in both groups. However, the peak velocities of adducting saccades in sound eyes were slowed in patients with Duane's syndrome. Because the standard deviations in saccadic velocities are large, computer-based, stepwise discriminant analyses were performed to identify the variables that proved to be useful in differentiating the two disorders. By entering these variables into the discriminant functions that were created, we could distinguish Duane's syndrome from sixth-nerve palsy in a statistically significant manner.