■ OBJECTIVES: Surgical drilling of the skull or head trauma is a well known precipitating factor of benign paroxysmal positional vertigo (BPPV). Since the characteristics of postmastoidectomy BPPV have not been well described in the literature, authors analyzed the clinical characteristics of BPPV developed after mastoid surgery.

■ METHODS:From May 2003 through April 2007, 891 patients got surgical drilling of the mastoid in Seoul National University Bundang Hospital and BPPV was detected in 8 patients (0.9%) after surgery. Localization and lateralization of BPPV were done by positional testusing video eye movement recording system and videonystagmography.

■ RESULTS: Onset of positional vertigo was mostly within 3 days except one case (6th postoperative day). The involved side was contralateral in 6 patients, bilateral in 1 patient and ipsilateral in one patient. Including one bilateral case, BPPV after mastoid drilling was predominantly on the contralateral ear (7/8, 88%). And contralateral horizontal canal was primarily affected in 6 patients. In 2 of them, posterior canal was also involved and, in 1 of them, bilateral posterior canal was involved. One case developed in contralateral anterior canal only and the other one case was developed in ipsilateral horizontalcanal and posterior canal. Positional vertigo was resolved after repositioning maneuver in every case, though several sessions of maneuver were necessary to resolve BPPV. None of them showed aggravation of bone conducting threshold.

■ CONCLUSIONS: The incidence of BPPV after mastoid surgery was around 1% and the lateral canal of the contralateral side waspredominantly involved. Surgical position and compressive mastoid bandage after surgery seem to be responsible for  such predominance. Appropriate differential diagnosis and management plans should be prompted in the evaluation of dizziness after mastoid surgery.