Aesthesiometry: quantification of cutaneous pressure sensation in diabetic peripheral neuropathy

The Semmes-Weinstein pressure aesthesiometer, which measures cutaneous pressure sensation, was used for quantifying sensory loss in diabetic peripheral neuropathy. Eighty subjects comprising four groups were tested: nondiabetic controls (Group C); non-neuropathic, diabetic controls (Group DC); diabetic subjects with neuropathy and without a history of pedal ulcerations (Group DN); and, diabetic subjects with a history of or active pedal ulceration (Group DU). Cutaneous pressure sensation of 10 dorsal and plantar sites on the foot were tested, using a method of interval comparison modeled after the two-alternative forced choice algorithm. The sensitivity threshold level was defined as the lightest probe in which the subject accurately chose the correct interval in at least 2 out of 3 trials. The mean sensitivity threshold level for Group DC was not significantly increased (p greater than .05) compared to Group C. In contrast, patients with neuropathy (Group DN or DU) showed a significantly higher mean sensitivity threshold (p less than .001) than either Group C or DC. In addition, this technique demonstrated that patients in Group DU had a mean sensitivity threshold that was statistically higher (p less than .001) than Group DN, although both groups of patients had symptomatic neuropathy. This study provides a direct demonstration that decreased sensation of pressure occurs in the feet of diabetic patients with a history of ulceration. The best discrimination between groups is obtained by requiring that three of the six plantar forefoot sites have a sensitivity threshold level of greater than 5.07 log (0.1 mg) force as the risk discriminator level. Semmes-Weinstein aesthesiometry should now be tested in a prospective study to demonstrate its effectiveness in determining those patients at great risk of developing foot ulcers.