Reliability of the tonic vibratory reflex

Reliability of the tonic vibratory reflex was examined in 30 able-bodied subjects over different time periods (5-minute, 24-hour, and 2-week intervals) and with different coupling pressures (20 mm Hg and 45 mm Hg). A high average correlation ( r = 0.85) was found for intraday test-retest situations. The average 24-hour and 2-week interval interday correlatins were r = 0.64 and r = 0.54, respectively. Various pressures of vibrator head attachments did not produce significantly different tonic vibratory reflex responses. All subjects showed a significant decrease in tonic vibratory reflex responses over the 2-week period (F = 9.71, DF 8,224). The conclusions were that a) intraday but not interday tonic vibratory reflex responses were adequate for diagnostic purposes, and b) that the reasons for the significant decrease of the tonic vibratory reflex response over time need further investigation.