Association Between Benign Paroxysmal Positional Vertigo and Vitamin D Deficiency .

Introduction Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibular disorder, accounting for approximately 20-30% of vertigo cases in clinical practice. It is characterized by brief episodes of vertigo triggered by changes in head position, often due to dislodged otoconia in the semicircular canals. While canalith repositioning maneuvers like the Epley maneuver are highly effective for treatment, BPPV has a notable recurrence rate of 30-50% within the first year. The etiology remains largely idiopathic, but emerging evidence suggests a potential link to metabolic factors, particularly vitamin D deficiency.

Vitamin D plays a crucial role in calcium homeostasis and bone metabolism, which extends to the inner ear's otolithic apparatus, where calcium carbonate crystals (otoconia) are essential for vestibular function. Deficiency in vitamin D may impair otoconia maintenance, increasing susceptibility to dislodgement and thus BPPV onset or recurrence. Globally, vitamin D deficiency affects up to 1 billion people, with higher prevalence in regions like the Middle East due to limited sun exposure, dietary habits, and cultural factors such as veiling.54cc4a In Egypt, studies report deficiency rates exceeding 70% in the general population, exacerbated by urban lifestyles and pollution in areas like Sohag.

At Sohag University Hospital, a tertiary care center serving a large rural-urban population in Upper Egypt, BPPV constitutes a significant portion of otolaryngology consultations. Preliminary local data indicate a high BPPV incidence among young adults and the elderly, yet the role of vitamin D has not been systematically explored in this setting. This study addresses this gap by examining the association between serum vitamin D levels and BPPV, potentially informing preventive strategies like supplementation in high-risk groups.

Aim of the Work The primary aim is to investigate the association between serum 25-hydroxyvitamin D (25-OH D) levels and the presence of BPPV in patients attending the Otolaryngology Department and Audiovestibular unit at Sohag University Hospital. Secondary aims include identifying potential confounders (e.g., age, sex, comorbidities).

Patients and Methods Study Design: This is a hospital-based case-control study. Setting: Otolaryngology (ENT) Outpatient Clinic and Audiovestibular unit at Sohag University Hospital, Sohag, Egypt.

Study Duration: 5 months (recruitment period: April 2026 to September 2026) from approval of Medical Research Ethics Committee; till September 2026 data analysis: October 2026).

Sample Size: Eighty patients and 80 age- and sex-matched controls will be enrolled (total n=160).

Recruitment: Consecutive sampling. Cases will be identified from patients presenting with vertigo symptoms. Controls will be selected from non-vertigo ENT patients (e.g., those with sinusitis or hearing loss) during the same period to minimize selection bias.

Data Collection:

• Demographic data (age, sex, etc.) via structured questionnaire.
• Clinical history (vertigo duration, recurrence, comorbidities like osteoporosis or diabetes).
• Full ENT examination including Dix Hallpike test to confirm the diagnosis of BPPV and exclude other causes of vertigo.
• Serum 25-OH D levels measured by enzyme-linked immunosorbent assay (ELISA). Ethical Considerations: Approval from the Institutional Review Board (IRB) of Sohag Faculty of Medicine. Informed written consent obtained from all participants. Data confidentiality will be maintained.

Inclusion Criteria

• Cases: Adults with a confirmed diagnosis of idiopathic BPPV based on positive Dix-Hallpike maneuver (nystagmus and vertigo lasting <1 minute).
• Controls: Adults attending ENT clinic without history of vertigo or BPPV, confirmed by negative Dix-Hallpike test.

Exclusion Criteria

• Known causes of secondary vertigo (e.g., Meniere's disease, vestibular neuritis, central vertigo).
• Conditions affecting vitamin D metabolism (e.g., chronic kidney disease, malabsorption syndromes, hyperparathyroidism).
• Use of medications interfering with vitamin D levels (e.g., anticonvulsants, glucocorticoids) in the past 3 months.
• Pregnancy or lactation.
• Inability to provide consent. Methodology This case-control study will compare serum 25-OH D levels between BPPV cases and controls to assess the odds of vitamin D deficiency (<30 ng/mL) in cases.
• Step 1: Diagnosis Confirmation All participants undergo otoscopic examination and Dix-Hallpike testing.
• Step 2: Laboratory Assessment Venous blood sampling for serum 25-OH D and calcium levels. Vitamin D status categorized as: deficiency (<20 ng/mL), insufficiency (20-30 ng/mL), sufficient (>30 ng/mL).
• Step 3: Data Management Data entered into SPSS.
• Step 4: Statistical Analysis Descriptive statistics: Means ± SD for continuous variables (e.g., vitamin D levels); frequencies for categorical (e.g., deficiency prevalence).

Inferential: Independent t-test; chi-square/Fisher's exact for categorical associations. Logistic regression to compute odds ratios (OR) for vitamin D deficiency and BPPV.

• Expected Outcomes: Anticipated higher prevalence of vitamin D deficiency in cases (OR >2), supporting supplementation as a preventive measure.