The diagnostic value of measuring pressure pain perception in patients with diabetes mellitus

Repetitive skin trauma and reduced pressure pain sensation are necessary components of plantar ulcer risk in patients with diabetic neuropathy. The diagnostic value of measuring pressure nociception to detect ulcer risk is, however, unknown. Instead, measuring the vibration perception threshold (VPT) by 64 Hz graduated Rydel-Seiffer tuning fork has become standard clinical practice to screen for neuropathy and ulcer proneness. We therefore set up a diagnostic case-control study to compare the VPT, the cutaneous pressure pain perception threshold (CPPPT) and the deep pressure pain perception threshold (DPPPT) at the foot sole in diabetic patients with and without past or present painless plantar ulcer.A total of 68 patients were studied, 34 with active or previous plantar ulcer. VPT was measured by Rydel-Seiffer tuning fork at the 1st metatarsal head (≤4/8 grade indicating clinical neuropathy). CPPPT was measured at a toe skinfold by calibrated monofilaments. DPPPT was measured by Algometer II(®) over musculus hallucis longus and over a metatarsophalangeal joint.The sensitivity and specificity to identify patients with present or past foot ulcer were as follows: 0.82 and 0.88 (VPT cut-off 1/8); 0.97 and 0.62(VPT cut-off 4/8); 0.93 and 0.77 (CPPPT cut-off 513 mN); 0.76 and 0.58 (DPPPT muscle, cut-off 545 kPa); 0.82 and 0.79 (DPPPT joint, cut-off 760 kPa).Pressure algometry was not superior to measuring VPT for distinguishing between patients with and without painless plantar ulcers; VPT ≤1/8 was more efficient than ≤4/8 grade in identifying ulcer patients.