Complications of the canalith repositioning procedure.

OBJECTIVE: To describe the conversion of benign paroxysmal positional vertigo involving the posterior canal into benign paroxysmal positional vertigo involving the anterior or horizontal canals after treatment using the canalith repositioning maneuver.
DESIGN: Retrospective study of outcome.
SETTING: Outpatient clinic. PATIENTS: Consecutive sample of 85 patients diagnosed as having benign paroxysmal positional vertigo affecting the posterior canal. Identification of posterior canal involvement was based on the observation of the direction of the vertical component of nystagmus after the Hallpike-Dix maneuver. INTERVENTION: Canalith repositioning maneuver. MAIN OUTCOME MEASURE: Eye movements were observed about 1 week after the treatment. The direction of nystagmus elicited after movement of the patient into the Hallpike-Dix position indicated which canal was involved in the patients who had not responded to treatment.
RESULTS: Of the 85 patients studied who originally had posterior canal benign paroxysmal positional vertigo, five (6%) had anterior canal (n=2) or horizontal canal (n=3) positional vertigo after undergoing this maneuver.
CONCLUSION: Careful observation of the direction of the nystagmus is necessary for correct identification of which canal is involved in patients who do not respond to the initial treatment using the canalith repositioning maneuver.