INCREASING recognition of the fact, as Wagman1 stated, that "vertical deviations are frequently the true underlying imbalance [in horizontal deviations], the horizontal deviation actually being a secondary phenomenon" has led to a keen interest in vertical motor anomalies in recent years.
Unfortunately, the elucidation of the accurate diagnosis and differential diagnosis of vertical motor imbalance is not complete. Smith2 called attention to the confusion in differentiating between paresis of the superior rectus and that of the contralateral superior oblique muscle and suggested that definite diagnostic criteria be set up for this differentiation. Bielschowsky3 stated that the most frequent and important type of a single vertical motor paralysis is palsy of the trochlear nerve, and with this view have concurred Chavasse4 and Davis.5 White and Brown,6 however, expressed the belief that paresis of the superior rectus muscle is by far the most common vertical motor
EPSTEIN GJ. CONGENITAL VERTICAL MOTOR PARESES. Arch Ophthalmol. 1947;37(3):369-374. doi:10.1001/archopht.1947.00890220379011