Long-term postural abnormalities in benign paroxysmal positional vertigo.

Benign paroxysmal positional vertigo (BPPV) is a disorder in which patients suffer from acute rotatory vertigo due to the presence of free otoconial debris migrating into one or more semicircular canals during head movements and resulting in abnormal stimulation of the ampullary crest. A prolonged loss of equilibrium of unclear origin is also present. Static posturography is a useful tool for the study of postural control systems and their role in these abnormalities. The aim of the present study was to evaluate the frequency of body sway and long-term instability of BPPV patients by posturography frequency analysis. Twenty patients with canalithiasis of the posterior semicircular canal and 20 normal controls were subjected to static posturography. Informed consent was obtained from all subjects. Patients were tested 1 h after diagnosis, and 3 days and 12 weeks after the characteristic Epley repositioning maneuver. Patients with BPPV showed significantly increased body sway both on lateral (X) and anteroposterior (Y) planes compared to normal subjects. Corporal oscillation with a broad-frequency spectrum was observed in both closed and open eye tests. The repositioning maneuver decreased the X plane body sway, while the anteroposterior sway was unchanged. Twelve weeks after treatment, a normalization of the anteroposterior sway was observed. Results of this study suggest that the long-term postural disturbance associated with BPPV differs from the acute disequilibrium that subsides after canalith repositioning: the former is a sagittal plane/broad spectrum body sway, while the latter is primarily a frontal plane/low frequency sway. The Epley maneuver was shown to reduce frontal sway, a postural abnormality that might therefore be linked to posterior semicircular canal function. Conversely, the observed sagittal body sway was only partially relieved by the restoration of canal function, and therefore, may be more related to the chronic dizziness observed in these patients.