Aetna considers vestibular autorotation test (VAT) experimental and investigational for the diagnosis of individuals with vestibular disorders or any other indications because its sensitivity, specificity, reproducibility, and clinical utility have not been demonstrated.

See also CPB 0238 - Chronic Vertigo.

Impairment of the vestibular-ocular reflex (VOR) may result in chronic dizziness and imbalance.  The vestibular autorotation test (VAT) is a high-frequency, active head rotation (AHR) test to subjectively evaluate the VOR and its function.  Patients wear a light-weight head-strap with a velocity sensor on the back.  They follow instructions to shake their head, first side-to-side, and then up-and-down.  Conventional electro-olfactogram electrodes placed around the eyes measure patients' eye movements.

Although some published studies have suggested that the VAT may be useful in evaluating patients with vestibular disorders/diseases, there are few studies that examined the sensitivity and specificity of the VAT in evaluating patients with suspected vestibular abnormalities.  Furthermore, there is a lack of data supporting the value of the VAT in the management of patients with vestibular disorders/diseases.

Additional drawbacks of the VAT include (i) slippage of the head velocity sensor at high frequencies and accelerations during testing, (ii) contribution of the cervico-ocular reflex to the compensatory eye movement response, and this contribution may be increased significantly in the presence of bilateral, peripheral vestibular pathology, (iii) results of different head autorotation tests may not be directly comparable, and (iv) poor test-retest reliability.

In an assessment on vestibular testing techniques in adults and children, the American Academy of Neurology (Fife et al, 2000) stated that AHR testing is not an established technique.  This type of testing does not appear useful in detecting unilateral vestibular loss (e.g., as a consequence of unilateral acoustic neuroma, Meniere's disease or vestibular neuritis).  Furthermore, a recent study (Tirelli et al, 2004) reported that the test-retest of the Vorteq system, a head-autorotation test is not sufficiently reliable and hence can not be used in clinical practice.

Ozgirgin and Tarhan (2008) noted that the head autorotation tests can be affected with the dynamic changes within the semicircular canals caused by benign paroxysmal positional vertigo (BPPV).  The VAT is a method of examining the VOR (especially the VOR that develops at higher frequencies like those that occur in the everyday environment).  In this study, 20 patients who had been diagnosed as having posterior semicircular canal BPPV were evaluated with head autorotation tests before and after Epley maneuver.  The head autorotation tests were performed just before the use of the Epley maneuver and after the resolution of symptoms and the typical nystagmus pattern.  The mean gain values for horizontal rotation tests during the pre-treatment period were 0.823, 0.844, and 0.840 for the frequencies 1, 2, and 3 Hz, respectively.  The mean gain values increased by 0.095 (95 % confidence interval) with Epley maneuver.  But this difference between the pre-treatment and post-treatment values was not statistically significant.  All patients were also evaluated with vertical active tests.  The differences between the pre-treatment and post-treatment values were not statistically significant in the vertical autorotation group.  The phase values were within normal range in the horizontal and vertical rotation tests and remained so after the Epley maneuver.  The stimulation of the VOR caused by BPPV did not affect gain and phase values to a statistically significant degree, and the values noted after the resolution of the patient's symptoms improved slightly but without statistical significance.

Blatt and colleagues (2008) established intra-rater and inter-rater reliability of the VAT in a clinical sample of individuals reporting dizziness.  A total of 98 patients with reports of dizziness referred for vestibular function testing performed repeated trials of horizontal VAT.  A sub-sample of 49 individuals repeated the test for a second rater.  About 66 % of subjects were unable to meet the performance criterion of 6 consecutive trials where data was displayed at frequencies greater than or equal to 3.9 Hz with coherence values held constant trial to trial. There was a good level of intra-rater reliability for gain independent of the effects of practice (intraclass correlation coefficient [ICC] = 0.78 [95 % confidence interval [CI]: 0.69 to 0.87] to 0.95 [(95 % CI: 0.93 to 0.97]).  A significant difference in intra-rater reliability was found when the first 3 trials were compared to the last 3 trials for phase (ICC ranged from 0.04 [95 % CI: 0.00 to 0.31] to 0.96 [95 % CI: 0.93 to 0.97]) and asymmetry (ICC ranged from 0.39 [95 % CI: 0.17 to 0.56] to 0.73 [95 % CI: 0.32 to 0.81]) particularly at frequencies greater than or equal to 4.3 Hz.  Inter-rater reliability was good to excellent across all variables at frequencies less than or equal to 3.9 Hz.  The authors concluded that many patients had difficulty performing the VAT.  The reliability estimates for phase and asymmetry, but not gain, were significantly affected by practice.  They stated that careful attention to patient preparation, instruction, and test monitoring including sufficient patient practice before data collection are likely to be critical factors to ensure quality data.

Gao et al (2010) evaluated the utility of VAT in the diagnosis of BPPV.  Caloric test and VAT were performed on 41 patients with BPPV; VAT results were analyzed according to the affected semicircular canal.  Results of VAT were abnormal in 34 (82.93%) patients with BPPV.  Fourteen cases were found with abnormal vertical phase, 1 case with abnormal vertical gain in a total of 21 vertical semicircular canal BPPV patients.  Six cases with abnormal horizontal phase lead, 5 cases with abnormal horizontal gain, 2 cases with asymmetry were found in 12 patients with horizontal semicircular canal BPPV.  Phase lead was abnormal in all frequencies in 4 patients, and in 2 to 3 Hz in 21 patients; 24 (58.5 %) patients showed abnormal canal paresis and direction preference in caloric test.  The authors concluded that VAT can indicate information of vestibular function in both vertical as well as horizontal semicircular canal; and phase of VAT is constantly enhanced in BPPV, especially in 2 to 3 Hz.  They noted that as the supplement of caloric test, VAT may prove helpful in the  assessment of semicircular canal function.