TORSIONAL EYE-MOVEMENTS IN PATIENTS WITH SKEW DEVIATION AND SPASMODICTORTICOLLIS - RESPONSES TO STATIC AND DYNAMIC HEAD ROLL

We measured torsional eye movements induced by sinusoidal rotation or static tilt of the head in roll while viewing a far or near target in 4 patients with skew deviation due to brainstem lesions, 4 patients wi th spasmodic torticollis (ST), 2 patients with unilateral eighth nerve section (VIIIS), and 10 normal subjects. Torsional nystagmus was pres ent in all 4 patients with skew deviation. In subjects and patients, r esponses to both sinusoidal and static roll were larger while viewing the far target, consistent with factors dictated by geometry. Response gains to sinusoidal roll were abnormal in 3 patients with skew (incre ased in one, decreased in two), abnormal in 3 with ST (increased in 1, decreased in 2), and in abnormal both VIIIS patients (decreased). Gre ater abnormalities were evident in 3 skew patients while rolling away from the side of their brainstem lesions and in both VIIIS patients wh ile rolling toward their lesioned cars. There were similar but less pr onounced changes during static head roll, We conclude that patients wi th skew, ST, and VIIIS may all have abnormal ocular counter-rolling th at is more evident during dynamic testing while viewing a far target, Such abnormalities endure because of the limited influence exerted by vision on torsional eye movements.