Determination of reference intervals for vibratory perception thresholds of the lower extremities in normal subjects

The assessment of vibratory perception thresholds (VPTs) is important for evaluating human somatosensory functions and provides new aspects in clinical practice and research. However, there has been little information concerning determinants of the VPT in normal individuals, and there has been no investigation to determine the reference intervals for the lower extremities by vibrometers using appropriate statistical analysis. We determined reference intervals for the VPT in lower extremities of 377 healthy subjects (241 males, 136 females; ages 11-74 years) using Suzuki-Matsuoka vibrometer-5 according to the National Committee for Clinical Laboratory Standards guidelines. The VPT was measured at 12 points: ulnar styloids, patellae, medial and lateral malleoli and the tip of the great toes, dorsal aspect of the distal phalanx of the fifth toes. The effects of age, sex, height, weight, alcohol consumption, and smoking on the VPTs were also investigated. The VPTs of normal subjects increased significantly with age. The difference between the two sides was negligible for determining reference intervals of the VPT. The average VPT was higher in men than in women at the lateral malleolus, the great toe, the patella, and the ulnar styloid but not significantly different at the fifth toe or the medial malleolus. There were no significant differences in the VPTs among the four sites of the foot. The reference interval for the VPT of the lower extremity is less than 13 x 10(-2) G. The influence of body mass index, smoking, and alcohol consumption on the VPT was not significant. We provide the reference interval for the VPT of lower extremities in normal subjects. This information can serve as a basis for future clinical applications of VPT measurements.