Unilateral mimicking bilateral BPPV- a forgotten entity? Characteristics of a large cohort of patients, comparison with posterior canal BPPV and clinical implications.

Abstract: Objective Unilateral mimicking bilateral benign paroxysmal positional vertigo (umb-BPPV) was attributed to inappropriate head positioning during testing of the posterior canal. Despite its inclusion in the Diagnostic criteria for the classification of vestibular disorders of the Barany Society, the clinical characteristics and treatment responsiveness of this BPPV subtype have not been intensively studied. Methods Records of patients with BPPV seen at a single outpatient dizziness clinic during the years 2000-2020 were reviewed. Eighty seven patients with umb-BPPV and 86 random patients with posterior canal BPPV (p-BPPV) were retrieved. Their demographics and BPPV characteristics were analyzed. Results Patients' and BPPV characteristics were similar in umb- and p-BPPV except for the prevalence of males in the umb-BPPV group. No differences were found between treatment responsiveness and recurrences in both groups. The recurrence rate of umb-BPPV was not influenced by age, gender, BPPV side, duration of symptoms or treatment responsiveness during the first attack. Conclusions In accordance with our hypothesis about mixed canalo- and cupulolithiasis as the underlying mechanism of umb-BPPV, patients did not differ in characteristics and treatment responsiveness from p-BPPV patients. Recognition of umb-BPPV is important since inappropriate treatment can cause an unnecessary delay in therapy success.