Results of High-Frequency and High-Acceleration Rotary Chair Test in Patients with Acute Unilateral Vestibular Neuritis

Lee, Hwan Seo; Park, Jun Woo; Lee, Chang Wook; Song, Chan Il; Yoo, Myung Hoon; Park, Hong Ju

Abstract

BACKGROUND AND OBJECTIVES
The aim of this study was to evaluate the results of high-frequency and high-acceleration rotary chair test in patients with acute unilateral vestibular neuritis.
MATERIALS AND METHODS
Twenty-four patients who were diagnosed as acute vestibular neuritis and underwent rotational chair and caloric tests during March 2012 to March 2013 were included. Slow harmonic acceleration (SHA) test was performed at 0.01, 0.04, 0.16, 0.64, 1.28, and 2.00 Hz. Step velocity tests at the peak velocity of 100degrees/sec (low-acceleration) and 240degrees/sec (high-acceleration) were performed. Gains and phases in SHA test and gains and time constants (Tc) in step velocity test were analyzed.
RESULTS
In SHA test, decreased gain and phase lead was observed mostly in low frequencies. Gains (phases) at 0.01, 0.04, 0.16, 0.64, 1.28, and 2.00 Hz were 0.2+/-0.1 (62.2+/-15.4), 0.3+/-0.2 (24.5+/-13.0), 0.4+/-0.2 (7.2+/-18.8), 0.5+/-0.1 (7.2+/-11.3), 0.7+/-0.2 (11.0+/-7.5), and 0.8+/-0.3 (4.4+/-14.4), respectively. In step velocity (SV) test, gains stimulating the lesion side were significantly lower than those stimulating the intact side in both low- and high-acceleration SV test (p<0.05) and per-rotatory gain stimulating the lesion side in high-acceleration SV test was significantly lower than that in low-acceleration SV test. Tc stimulating the lesion side were significantly shorter than those stimulating the intact side in low- acceleration SV test (p<0.05) but not in high-acceleration SV test. Per- and post-rotatory Tc in high-acceleration SV test stimulating the intact side was significantly lower than those in low-acceleration SV test (p<0.05).
CONCLUSION
At high-frequency SHA test, gain was pretty normal and phase lead was observed in some patients. High-acceleration SV test showed shortened Tc regardless of the sides, suggesting that high-acceleration SV test can reveal the impaired velocity storage system in patients with vestibular neuritis more frequently than low-acceleration SV test.