Static Otolith-ocular Reflex Reflects Superior Oblique Muscle Disorder

Purpose: To elucidate the action of static otolith-ocular reflex (sOOR) in patients with superior oblique palsy (SOP). Design: Observational case series study. Methods: Compensatory ocular countertorsion produced by sOOR was analyzed in 12 patients with unilateral SOP and 11 normal subjects using a head-mounted measuring system. Results: When the head was tilted laterally to the ipsilateral side, the mean ratio (%) of compensatory countertorsion of the paretic eye in SOP patients to the head-tilt angle was significantly decreased compared with that in normal subjects (7 ± 6% for patients and 17 ± 4% for normal subjects, P < .05). Mean ratio of compensatory countertorsion of the paretic eye in nine patients with superior oblique (SO) muscle atrophy was significantly lower than that in three patients with nonatrophy on tilting to the ipsilateral shoulder (6 ± 3% for patients with atrophy and 14 ± 6% for patients with nonatrophy, P < .05). Conclusions: sOOR reflects the anatomic disorder of the superior oblique muscle in SOP.