BPPV is the most common cause of vertigo. The pathophysiology of BPPV has not been cleared, several studies show that symptoms are caused by the displacement of otoconia from the macula of the utricle into the semicircular canals. These calcium carbonate particles then stimulate non-physiological movement of the endolymph leading to a false sensation of angular acceleration.

Biomarkers represent measurable products of biological processes, thus making an assessment of those processes more practical. Biomarkers in circulation are powerful indicators of normal and pathological biological processes, as well as, responses to pharmacological treatments. The inner ear-inclusive protein that has been published included Otolin-1, Otoconin-90/95, Prestin, Otoancorin, Otogelin, α-tectorin, β-tectorin and Cochlin.

The posterior canal BPPV is the most common BPPV variant, diagnosed with the Dix-Hallpike test. The lateral canal BPPV is diagnosed with a supine roll test. After treatment of the posterior canal BPPV with a single cycle of the CRP, the rate of negative DHT was 68-80% in the 1st week. Rate of an absence of vertigo and nystagmus on the supine roll test after-treatment of the lateral canal BPPV with the barbecue maneuver plus forced prolonged positioning was 81%.

Biomarkers are often measured in body fluids, they eliminate the need for costly modalities to diagnose and monitor progression. Otolin-1 is a secreted glycoprotein whose messenger RNA (mRNA) expression is restricted to the inner ear, specifically the support cells of the vestibular maculae, semicircular canal cristae, organ of Corti, and marginal cells of the stria vascularis. Otolin-1 blood levels are significantly higher in patients older than 65 years old and increased prevalence of BPPV with age. There were reports of a relationship between vitamin D and otolin-1. Significantly higher serum levels of the otolin-1 protein in patients with BPPV than in healthy controls has been reported. This also confirmed evidence of the otolin-1 as a potential biomarker for BPPV episodes and maybe clinically used to promote better management of BPPV. No data on inner ear biomarkers has been exited in Thailand.

Inclusion Criteria:

1. Age 18 - 80 years
2. History of brief episodes of positioning vertigo
3. Positive positioning test; either Dix-Hallpike test or supine roll test in one or both ears
4. First diagnosis of BPPV or recurrent BPPV

Exclusion Criteria:

1. Clinical symptoms or sign of other central or peripheral vestibular disorder
2. Previous history of balance disorders (for controlled group) or Previous history of balance disorders except BPPV (for BPPV group)
3. Active infection
4. Active cancer disease
5. Conditions that may affect the level of otolin-1 such as previous mastoidectomy
6. Conditions that may affect the level of vitamin D such as cardiovascular disease, diabetes mellitus type2, chronic liver disease, osteoporosis osteomalacia and active symptoms of migraine
7. Major health conditions; except common chronic conditions e.g. hypertension, hypothyroidism, hypercholesterolemia, and reflux
8. Major systemic illness, were undergoing active cancer treatment, took prednisone above 10 mg daily, took other immunosuppressive drugs, took any medications for rheumatoid arthritis other than NSAIDs, or had received antibiotics in the previous 6 months
9. Unable to complete Thai-Dizziness handicap inventory questionnaire
10. Unable to obtain the blood specimen

BPPV cases in outpatient Ear Nose and Throat (ENT) Clinic at CMU Hospital, Faculty of Medicine, Chiang Mai University during the study period.