Title

The reliability and validity of the vestibular autorotation test (VAT) in a clinical sample of subjects with complaints of dizziness

Date of Award

2003

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Physical Therapy

First Committee Member

Kathryn E. Roach - Committee Chair

Abstract

Purpose. To establish intra-rater and inter-rater reliability and diagnostic validity of the VAT in patients complaining of dizziness. Methods. Ninety-eight (N = 98) subjects participated from a patient testing pool within a tertiary care setting that specializes in assessment and management of dizziness. Reliability. A sub-sample of subjects (n = 69) performed 6 sequential horizontal VAT trials. In 49 of these subjects, an additional rater performed a second series of 6 trials. Diagnosis. Sensitivity and specificity of the VAT were calculated against diagnosis as determined by caloric testing (n = 92) and rotary chair testing (n = 47). In patients with unilateral caloric asymmetry (>25%) (n = 37), comparison was made to asymmetry as determined by the VAT (>5%). Results. Reliability. Intra-rater reliability for gain values ranged from 0.95(95%CI 0.93--0.97) to 0.82 (95%CI 0.75--0.88) when 6 trials were utilized to calculate these values. Phase and asymmetry reliability was found to be influenced by the number of practice trials a subject performed. The last three trials for the VAT variables phase and asymmetry revealed good reliability when subjects were given three trials to practice, ICC range: Phase 0.96(95% CI 0.92--0.98) to 0.88(95%CI 0.84--0.91); Asymmetry 0.88(95%CI 0.72 --0.91) to 0.73(95%CI 0.61--0.81)). Inter-rater reliability for gain ranged from 0.95 (95%CI 0.93--0.97) to 0.82 (95% CI 0.75--0.88). Inter-rater reliability for phase ranged from to 0.91(95%CI 0.87--0.94) to 0.50 (95%CI 0.06--0.66). Inter-rater reliability for asymmetry ranged from 0.91(95%CI 0.86--0.94) to 0.72(95%CI 0.59--0.81). Diagnosis. Maximum sensitivity was achieved when the VAT diagnostic criterion of two or more mean gain values +/-1 s d or phase were used to define abnormal VAT performance, sensitivity 0.81(95%CI 0.73--0.89); specificity was 0.28(95%CI 0.18--0.37)). Specificity was maximized using 2 or more mean gain & phase values in series, specificity 0.83(95%CI 0.76--0.90); sensitivity 0.33(95%CI 0.23--0.43). Conclusions. Improved reliability of the VAT can be achieved by allowing subjects a minimum of three practice trials; second, subjects must produce head movements of ≥3.9 Hz. It appears that the VAT in isolation cannot produce a definitive diagnosis of peripheral vestibulopathy.

Keywords

Health Sciences, Audiology; Health Sciences, Rehabilitation and Therapy

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3090846

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