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

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 cm(2)) 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 cm(2) of pressure yielded equal vibration thresholds. Vibration threshold was higher when tested under 100 g/1.22 cm(2) 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 cm(2).

Quantitative sensory testing: effect of site and skin temperature on thermal thresholds.

OBJECTIVE: To determine the effect of different sites and local skin temperature on thermal thresholds. METHODS: Cool and warm detection and cold and heat pain thresholds were compared in 46 normal volunteers at the thenar eminence (TE), dorsum of the hand (DH), volar surface of the wrist (VW) and dorsum of the foot (DF). RESULTS: The hand is more sensitive than the foot for cool and warm. TE is more sensitive for warm than DH and VW but the difference is clinically negligible. DH and VW are equally sensitive to warm. TE, DH, and VW are equally sensitive to cool. Inter-individual variance is smallest at TE. Warm and cool thresholds are independent of local skin temperature (range of 27-37 degrees C). TE is less sensitive for cold pain but otherwise the hand and the foot are equally sensitive to thermal pain. CONCLUSION: Testing of thermal thresholds in normal subjects can be adequately conducted at several sites at the hand, however, TE is preferred given the small inter-individual variability. TE may be preferred for evaluating hyperalgesia to cold given its higher threshold. Warming or cooling of the skin is unnecessary within the range normally encountered in routine clinical evaluation.