Quantitative sensory testing: effect of site and pressure on vibration thresholds

Abstract

Objective: To determine the effect of different sites and locally applied pressure on vibration thresholds.Methods: Vibration thresholds were compared in 47 normal volunteers at 3 sites of the index finger (pulp, dorsum of the middle phalanx and nail) and at two sites of the great toe (dorsum of the proximal phalanx and nail). The effect of local pressure (30, 50 and 100 g/1.22 cm2) were compared in 41 subjects at the dorsum of the middle phalanx of the index finger and the proximal phalanx of the great toe.Results: The hand was more sensitive than the foot for vibration. There were no significant differences in vibration thresholds at different sites of the index finger and different sites of the great toe. The pulp of the index finger yielded the least inter-individual variation. Testing under 30 and 50 g/1.22 cm2 of pressure yielded equal vibration thresholds. Vibration threshold was higher when tested under 100 g/1.22 cm2 at the index finger but not the great toe. This difference was small and clinically negligible.Conclusion: Testing of vibration thresholds in normal subjects can be adequately conducted at several sites of the index finger and the great toe. The test can be adequately done under low pressure of 30–50 g/1.22 cm2.