Bilateral Posterior Canal Benign Paroxysmal Positional Vertigo Tends to Reoccur.

Objective: We analyzed the clinical characteristics of quite a large cohort of patients with bilateral posterior canal benign paroxysmal positional vertigo (bil-BPPV) with respect to the rate and types of recurrence.
Study Design: Retrospective case review.
Setting: Outpatient dizziness clinic.
Patients: About 2,050 patients diagnosed with BPPV during the years 2003 to 2018 were reviewed.
Results: Sixty (2.9%) were diagnosed with bil-BPPV. Fifty three (88%) were idiopathic and seven (12%) posttraumatic. Multiple BPPV episodes were encountered in 28 (47%) patients. Patients with bil-BPPV and multiple BPPV episodes were comparable with patients with a single attack of bil-BPPV except for older age and longer follow up. The most frequent type of recurrence following a bil-BPPV episode was posterior canal canalolithiasis (37.5%) and bil-BPPV (31.3%). Combined (posterior and horizontal) BPPV was encountered in 12.5% while horizontal canal involvement was found in only 7% of recurrences.
Conclusions: The prevalence of bil-BPPV amongst all BPPV patients was lower than previously reported possibly due to stricter selection criteria. Older age and longer follow up of patients with multiple BPPV episodes than those with a single episode of bil-BPPV is in accordance with the theory of degenerative otoconia loosening. In contrast to the general consensus regarding random recurrences of BPPV side and subtypes, bil-BPPV recurred more frequently than expected. This might be the consequence of individual vulnerability to head movements, increased bone metabolism or an underlying vestibular pathology.