Standardization of Rotatory Chair Velocity Step and Sinusoidal Harmonic Acceleration Tests in Adult Population

Objective: To standardize the rotatory chair sinusoidal harmonic acceleration and velocity step tests in adult population. Study Design: Prospective study. Setting: Clinical tertiary care vestibular function test center. Patients: One hundred normal participants (66 male and 34 females without suspected vestibular disorder) evaluated with bithermal binaural caloric and sinusoidal and step-velocity rotary chair (RC) tests. Intervention: Hearing, VNG and RC tests. Material and Methods: All participants were selected according to the following criteria: (1) No past history of dizziness; (2) Normal otological examination; (3) Normal hearing evaluation; (4) Normal VNG testing; (5) Rotational Chair Testing: The patient was positioned and secured to the rotational chair with the patient’s head restrained and adjusted so that both lateral semicircular canals were close to the plane of stimulus (30º forward tilt), The rotational chair testing paradigms used in this study were: (A) The Rotational Sinusoidal Harmonic Acceleration (SHA) Test and (B) The Rotational Velocity Step (RVS) Test. Results: The demographic criteria for the study group as following: the age range was 18-56 years with mean age of 36.47 years; the gender distribution was 66% for males and 34% for females. The mean, standard deviation, range and 95% confidence limits of the SHA and RVS test was calculated and compared with the manufacture normal values. It demonstrated that no significant statistical difference between our lab test results and the manufacture measured values of the rotational SHA test and the RVS; this could be attributed to the strict selection criteria of the study group. Conclusion: In summary, the information gleaned from rotational chair testing may provide valuable information in the diagnosis and subsequent management of patients with vestibular disorders. It completes the spectrum of tests necessary for diagnosing vestibular abnormalities, assists in identification of peripheral vestibular deficits not detectable with existing procedures. The major clinical advantage of computerized rotational testing is the ability to produce angular accelerations that can be precisely controlled and repeated. Multiple stimuli of varying intensities can be applied to the vestibular system within a relatively short time.