Assessment of the caloric-induced tilt in the perceived visual vertical: preliminary report.

OBJECTIVE: The perceived visual vertical (PVV) has been shown to be abnormal in patients with acute vestibular lesions but reverts to normal in compensated patients. The objectives of this study are to ascertain whether the PVV can be modulated by caloric stimulation and whether this modulation diminishes in compensated patients with unilateral vestibular lesions. DESIGN: Prospective. SETTING: Tertiary care facility. METHOD: Sixty-eight patients referred for vestibular testing had an electronystagmography and a PVV. MAIN OUTCOME MEASURES: Tilt in PVV, in degrees after caloric stimulation. RESULTS: Cold caloric stimulation resulted in a mean tilt in the PVV toward the irrigated ear and warm irrigation had the reverse effect. The mean modulation (amplitude of the angular distance in degrees between cold and warm tilts) was 4.3 degrees. In a subgroup of patients with severe unilateral vestibular dysfunction, this modulation of the PVV with caloric stimulation was diminished on the side of the lesion (p = .0001). CONCLUSION: Further study is required to assess the potential of the caloric PVV as a test of otolith function.