Background: Diabetic sensorimotor polyneuropathy is one of the greatest risk factors for foot ulceration. The current study investigated the measurement properties of the Pressure-Specified Sensory Device in comparison with traditional threshold screening instruments, in several categories of sensory loss. Knowledge of these values may help to identify diabetics at risk for ulceration more reliably.
Methods: A partially cross-sectional cohort study was carried out in patients with diabetes. Traditional instruments classified each patient into groups representing severity of diabetic sensorimotor polyneuropathy. Demographic characteristics, laboratory measures, and Pressure-Specified Sensory Device measurements were compared between groups. The Bland-Altman method was used to characterize reliability of the Pressure-Specified Sensory Device, and construct validity was determined by comparison with Semmes-Weinstein monofilaments.
Results: One hundred fifty-five diabetic patients were measured. Fifteen patients had a diabetic ulcer in their medical history, seven patients were insensate to the 10-g monofilament and had diminished vibration sense (group 1), 34 patients had diminished vibration sense but no elevated cutaneous threshold (group 2), and 99 patients acted as controls (no elevated cutaneous threshold or diminished vibration sense, group 3). The Pressure-Specified Sensory Device distinguished these groups with one-point static cutaneous thresholds alone. Semmes-Weinstein monofilament and Pressure-Specified Sensory Device measurements were not interchangeable. Spatial discrimination (two-point static and two-point moving discrimination) by the Pressure-Specified Sensory Device was more reliable compared with one-point static discrimination. Semmes-Weinstein monofilament (force in grams and pressure in grams per square millimeter) correlations with Pressure-Specified Sensory Device measurements differed between groups.
Conclusions: The Pressure-Specified Sensory Device is able to distinguish between categories of sensory loss. The Pressure-Specified Sensory Device is valid in measuring cutaneous thresholds and can reliably measure spatial discrimination at the feet.
Clinical question/level of evidence: Diagnostic, II.