Unilateral centrifugation: Utricular assessment and protocol comparison

Objective: The purpose of this study was to examine how 2 different methods of lateral translation affect subjective visual vertical (SVV), ocular torsion position, and symptoms of nausea in a healthy population. Study Design: Prospective study. Setting: Tertiary referral center. Patients: Eleven healthy control subjects ranging between 26 and 48 years of age with normal hearing sensitivity and no history of balance disorders, dizziness, or neurologic involvement. Intervention(s): Subjects underwent 2 types of lateral translation: 1) lateral translation followed by rotation, and 2) lateral translation during rotation. The order of lateral translation type and order of translation were randomized to avoid an order effect. Main Outcome Measure(s): Ocular torsion and SVV deviation were measured during each lateral translation trial. A visual analog scale was used to assess each participant's level of nausea before and directly after each lateral translation trial. Results: There was no significant difference in ocular torsion, SVV deviation, or level of nausea between the 2 methods. Both ocular torsion and SVV deviation were symmetrical to the right and left within both methods, and both demonstrated a linear relationship with the gravito-inertial acceleration vector. Conclusion: Both ocular torsion and SVV have been shown to offset systematically in response to unilateral utricular stimulation regardless of the lateral translation method used, with no significant difference in subjective sensations of nausea.