Anterior semicircular canal benign paroxysmal positional vertigo: a series of 20 patients.

OBJECTIVES: The purpose of this study is to define the diagnostic criteria for anterior semicircular canal benign paroxysmal positional vertigo (BPPV) based on clinical data and the available anatomical and pathophysiological data.

MATERIAL AND METHOD: Between July 2006 and June 2007, 4320 patients consulting for otoneurological disease were investigated by otological examination, videonystagmography and neurological examination.

RESULTS: BPPV was diagnosed in 1430 patients, involving the posterior semicircular canal in 1325 patients, the horizontal semicircular canal in 85 patients, the posterior semicircular canal and ipsilateral anterior (superior) semicircular canal in 19 patients and the anterior semicircular canal only in one patient. In the 20 patients with anterior semicircular canal BPPV, the Dix-Hallpike (DH) test induced ageotropic horizontal torsional nystagmus beating towards the uppermost ear in the lateral supine position with reversal on standing. The modified Epley manoeuvre was effective in 94.1% of cases on the 8th day and in 97.5% of cases at 1 month.

DISCUSSION/CONCLUSION: Nystagmus beating towards the uppermost ear on the DH test is consistent with BPPV involving the anterior semicircular canal of the uppermost ear. The torsional component of nystagmus and not just the vertical component must be taken into account to facilitate the diagnosis with videonystagmoscopy glasses and identify the affected side. The anterior semicircular canal is rarely affected due to its anatomical position. Settling of otoconia in this canal requires hyperextension of the head. Treatment is simple, consisting of the modified Epley particle repositioning manoeuvre.