Reliability of the Semmes Weinstein Monofilaments to measure coetaneous sensibility in the feet of healthy subjects.

PURPOSE To determine the intrarater-reliability, interrater-reliability and normal reference scores of the Semmes Weinstein Monofilament test (SWM) of the feet of healthy subjects. In addition, the stability of the SWM for prospective use was assessed by determining systematic changes in sensory thresholds. METHODS Interrater-reliability was assessed on five locations of the plantar side of both feet using monofilaments 1.65, 2.36, 2.44, 2.83, 3.22, 3.61, 3.84, 4.08, 4.31, 5.56, 6.65 in 60 healthy subjects by two or three investigators (test day 1). Intrarater-reliability and systematic changes in sensory thresholds were assessed 3 weeks later (test day 22) by one investigator. RESULTS Median interrater-reliability for the five test locations for both feet was poor to moderate. Median intrarater-reliability was good for the left foot and poor to moderate for the right foot. Significantly lower median sensory thresholds were found for the first SWM measurement at test day 22 compared to the first and second measurement of test day 1. Given the observed reliability of the SWM, a normal sensory score for the feet was situated between monofilament 3.22 and 4.08. CONCLUSIONS The SWM are reliable when measured by one researcher. Systematic changes in sensory thresholds were observed; therefore, the stability of the SWM for use in prospective studies could not be verified.