Evaluation of Pressure Threshold Prior to Foot Ulceration

Abstract

A prospective study of 29 patients with diabetic neuropathy and 47 nondiabetic patients with tarsal tunnel syndrome were evaluated with computer-assisted neurosensory testing at three sites on the foot. The sensitivity and specificity of one-point static touch thresholds for identifying the presence of large fiber axonal loss was done using the calculated thresholds for monofilaments derived from their markings. The sensitivity for one-point static touch in identifying axonal loss was 33% for the 5.07, 38% for the 4.93, 50% for the 4.17, and 60% for the 4.08 monofilament-equivalent, with a specificity of 100% at each level. Therefore, one-point static touch testing, even using monofilaments thinner than 5.07, has a high percentage of false-negative results in identifying patients with axonal loss.

Estudo comparativo da sensibilidade nos pés de diabéticos com e sem úlceras utilizando o PSSD™

“…The average age was around 61 years old, with mean time of 12 years since disease diagnosis, which is in line with literature -a mean time of more than 10 years for appearance of complications and with the study of Barber et al 8 where the time of disease was 10.5 years for patients with no ulcers and 11.8 for those with ulcers. The patients were selected as a part of the population with sensation thresholds lower than 100 g/mm 2 , tested with monofilament 5.07.…”

“…This assesses the density of nerve fibers and of the sensitive skin receptors on a specific area. 8 The PSSD™ (Pressure-Specified Sensory Device), introduced in 1990, aims to determine thresholds of skin sensibility with more precision; patients report whether they felt the sensation after static pressure of the prong or after dynamic pressure of the tip. The result is recorded by a computer on a continuous scale.…”

Quantitative Sensory Testing

“…There is then the need to examine the patient's ability to distinguish that there are two points of touch at a certain distance apart while also measuring the amount of pressure needed to be applied before the discrimination at the specified distance can be made. The patient's ability to distinguish between one and two points of pressure is related to the number of axons innervating the cutaneous area [1]. Distinguishing two points of pressure then becomes important in evaluating the extent of axonal damage.…”

“…It can also measure the perception of static two-point discrimination and moving twopoint discrimination and the pressure needed to perceive the two-point discrimination. Two-point discrimination testing evaluates the slowly adapting fibers' receptor system [1]. This system is programmed by intensity or by increasing spatial recruitment of the neighboring fibers.…”

Diagnosis and management of diabetic neuropathy

“…Sensitivity and specificity are further augmented if the pretest probability of DSP is determined with simple clinical data [25••]. The validity of such simple screening maneuvers in determining a preliminary diagnosis is further supported by a methodology involving single stimuli [26]. These studies indicate that simple screening algorithms can be used to establish an accurate preliminary diagnosis of DSP in the primary care or diabetes clinic without full specialist neurologic examination unless alternative diagnoses are entertained or inconsistencies with the syndrome of diabetic polyneuropathy exist.…”