Diagnostic Value of Velocity Step Rotational Test on Unilateral Peripheral Vestibulopathy

Park, Hyun Min; Kim, Young Hoon; Rhee, Chung Ku

Abstract

BACKGROUND AND OBJECTIVES: Rotational chair tests are divided into two categories according to the types of stimuli, namely, the velocity step test and the sinusoidal harmonic acceleration (SHA) test. In particular, the velocity step test evaluates the pattern of nystagmic responses to the step rotational stimuli. However, its diagnostic value has not been well documented. This study attempts to answer the following three questions: 1) what is the most useful parameter of the velocity step rotational test in the diagnosis of the unilateral peripheral vestibulopathy, 2) what is the normal range of parameters in the velocity step test, 3) what is the clinical usefulness of the velocity step rotational test in the diagnosis of compensation status and the localization of the peripheral vestibulopathy.
MATERIALS AND METHODS
Velocity step rotational tests were performed in twenty patients diagnosed with unilateral peripheral vestibulopathy at Dankook University Hospital. The five parameters of the test, namely, gain, initial velocity, duration, slow cumulative eye position (SCEP) and a time constant, were compared with those of the controls (n=32). We divided the patients into the compensated and the uncompensated groups, and evaluated the differences among the patient groups and the control group.
RESULTS
SCEP was apparently the most useful parameter, as shown by the Receiver Operating Characteristics (ROC) analysis. SCEP (m+/-sd) of the compensated and the uncompensated groups were 341.1+/-92.9degrees, 170.9+/-134.0degrees, respectively. These values were significantly different from those of the control group (537.7+/-157.5degrees). The values between the uncompensated group and the compensated group were also significantly different.
CONCLUSION
Directional preponderance as well as the raw value of the parameters proved to be useful in confirming the degree of compensation in unilateral peripheral vestibulopathy.