Two-point discrimination assessment in the upper limb in young adult men and women

Two-point discrimination sensitivity in the upper limb was evaluated in a sample of healthy, young adult men and women. A commercially available compass-type instrument was used to determine limits of two-point discrimination sensitivity in 11 skin areas on the subject's dominant side. For dermatomal regions of the arm and forearm, mean values ranged from 30.7 mm to 45.4 mm. In the hand, the skin overlying the first dorsal interosseous muscle demonstrated discrimination values of 21.0 mm while that covering the volar surface of the tips of the thumb and long and little fingers showed values of 2.6 mm. Mean discrimination values for men and women in the test sample were not significantly different for any of the areas tested except the medial surface of the forearm where women showed a greater degree of sensitivity than men. The most striking observation was the large interindividual variation in two-point discrimination sensitivity. The existence of large interindividual variation within the normal population suggested that caution should be used when one is interpreting the results of two-point discrimination testing in select patient populations.