Association between vitamin D deficiency and residual dizziness in idiopathic BPPV: Focus on otolith dysfunction and...

Residual dizziness (RD) following successful canalith repositioning maneuvers (CRMs) in idiopathic benign paroxysmal positional vertigo (BPPV) is multifactorial, with vitamin D (VD) deficiency hypothesized to influence otolith-mediated vestibular pathways.

To determine the impact of VD deficiency severity on RD incidence and vestibular dysfunction, and to evaluate the effects of VD supplementation on vestibular dysfunction.

A cross-sectional study enrolled 138 idiopathic BPPV patients with different VD level. Participants were stratified by deficiency severity: normal (>20 ng/mL), insufficiency (10-20 ng/mL), and deficiency (<10 ng/mL). RD risk factors (gender, age, times of CRMs, involved semicircular canals) were recorded. Otolith function was assessed via cervical/ocular vestibular-evoked myogenic potentials (cVEMP/oVEMP), and vestibular function via bithermal caloric testing. RD severity was measured using the Dizziness Handicap Inventory (DHI) at 1 week post-CRM. A subgroup (n = 30) with deficiency/insufficiency received 12-week VD3 supplementation (0.25 μg of oral calcitriol twice daily). Binary regression analysis was used to analyze predictors of RD.

A moderate positive correlation emerged between serum VD and DHI scores (r = 0.365, P < 0.001). cVEMP abnormalities were the only otolith parameter associated with RD (χ² = 9.75, P = 0.002). The degree of VD deficiency, cVEMP, and age emerged as significant predictors of RD. There was a significant increase in VD levels before and after treatment (13.29 ± 2.99 vs. 23.24 ± 4.78, P = 0.00) in the treatment group. Both groups showed significant shortening of cVEMP N23 wave latency after three months (P = 0.01 and P = 0.02), but only the treatment group showed significant reduction in oVEMP N10 wave latency (P = 0.01), with DHI scores reduced by 48.2 % (P = 0.008).

We confirmed that VD enhances otolith function and neural integrity. CVEMP, age, and VD levels predict RD likelihood. This research is the first to show VD supplementation improves saccule function and transmission pathways.