Deviation of the Subjective Vertical in Long-standing Unilateral Vestibular Loss

We evaluated changes in the subjectively perceived gravitational vertical as an index of imbalance in the function of the right and left otolith organs. In addition to normal subjects (n =25), we measured patients with a longstanding (mean 4.5 year ± 3.2 SD; range 0.5-11.5 years) unilateral vestibular loss after surgery for acoustic neuroma (n = 32), patients with partial unilateral vestibular loss (n = 7) and patients with bilateral vestibular hyporeflexia (n = 8). Normal subjects could accurately align a vertical luminous bar to the gravitational vertical in an otherwise completely dark room (mean setting –0.14° ± 1.11 SD). Patients with leftsided (complete; n = 13) or rightsided (complete; n = 19 and partial; n = 7) unilateral vestibular loss made mean angular settings at 2.55° ± 1.57 (SD) leftward and 2.22° (±1.96 SD) rightward, respectively. These means differed highly significantly from the normal mean (p < 0.00001). In the time interval investigated (0.5-11.5 years) the magnitude of the tilt angle ...