Residual dizziness (RD) following the resolution of a benign paroxysmal positional vertigo (BBPV) episode is frequently reported by patients. Possible causes are still under debate in the literature. This study discusses the possible role of otolithic function and of elapsed time from onset of symptoms to diagnosis in the genesis of RD. In total, 116 patients younger than 65 years with their first episode of BPPV and without any other comorbidities were enrolled in the study. Before a bedside examination, subjective visual vertical (SVV) was determined in the case of a history suggestive of BPPV. SVV was tested 1 week later in those patients with BPPV of the posterior semicircular canal, and in whom positioning maneuvers showed resolution of BPPV. At 1 week control, reported RD and Dizziness Handicap Inventory (DHI) were recorded. Diagnosis and treatment of BPPV occurred within 4 days in 43 patients (group A), between 5 and 8 days in 38 patients (group B) and in more than 9 days in 35 patients (group C). Higher values of reported RD and DHI were recorded in group C, while higher values of SVV deviation were recorded in group A with an inverse relationship between SVV and DHI. Initial peripheral vestibular function asymmetry due to BPPV can induce a new central adaptation. This adaptation becomes better established the longer otoconia remain floating in the endolymph. Because of these changes, the brain is unable to quickly readapt to the old pattern after resolution resulting in more persistent RD.
Keywords: BPPV; DHI; Otolithic function; Residual dizziness; SVV.