Plantar temperatures in stance position: A comparative study with healthy volunteers and diabetes patients diagnosed with sensoric neuropathy

Abstract

Background

Microcirculatory defects in diabetes are linked with neuropathy and the onset of diabetic foot syndrome. In this study we quantify pressure- and posture-dependent changes of plantar temperatures as a surrogate of tissue perfusion in healthy volunteers versus diabetes patients diagnosed with neuropathy in the absence of macroangiopathy.

Methods

Healthy volunteers (n = 31) as well as patients with diabetes diagnosed with severe polyneuropathy (n = 30) were enrolled in a clinical study to test for plantar temperature changes in the feet during extended episodes of standing. These lasted between 5 and 20 min each over 95 min, in between the participants were asked to take a seated position for 5 min and release the pressure from the feet. Major macroangiopathy was excluded before study enrolment. Custom-made insoles harbored temperature and pressure sensors positioned at eight preselected positions for recording.

Findings

In both subgroups a significant plantar temperature downshift occurred within 10 min of standing, which was especially detected during the initial 45 min of the study protocol. Comparisons between healthy volunteers and patients with diabetes revealed no differences in the magnitude of temperature downshifts during stance episodes. Pressure sensor recordings revealed that healthy volunteers intermittently released pressure during the longer stance episodes due to discomfort, whereas the patients with diabetes and polyneuropathy did not.

Interpretation

Our findings demonstrate a tight plantar temperature regulation following pressure exposure. In patients with diabetes and peripheral sensoric neuropathy the temperature drop is similar to healthy volunteers. Potentially, prolonged stance periods resulting in less perfused plantar tissue may remain unrecognized with polyneuropathy, whereas discomfort develops in healthy controls.

Important figure

Figure 3. Temperature changes with study protocol recorded by sensor-equipped insole. a. Sensor positioning in relation to foot placement (left). Pressure and temperature recordings corresponding to the different sensors are depicted as time curves generated from six sensors with a healthy volunteer (right). Note the indentations of temperature curve especially detected with sensors placed at MTHI (2) and MTHV (6). Ambient temperature recordings are indicated by a dashed line. b. The “normalization” of sensor temperatures was performed by subtracting the ambient in-shoe temperatures from the sensor values obtained at each insole position. In the depicted example obtained with a healthy volunteer the resultant \(T_{norm}\) values demonstrates marked downshifts at stance episodes 2 and 3 and to a lesser extent thereafter.

BibTeX citation

@article{Niemann:EBioMedicine2020,
  author    = {Uli Niemann and Myra Spiliopoulou and Jan Malanowski and Juliane
               Kellersmann and Thorsten Szczepanski and Silke Klose and Eirini
               Dedonaki and Isabell Walter and Antao Ming and Peter R. Mertens},
  journal   = {EBioMedicine},
  title     = {{Plantar temperatures in stance position: A comparative study
               with healthy volunteers and diabetes patients diagnosed with
               sensoric neuropathy}},
  year      = {2020},
  issn      = {2352-3964},
  number    = {102712},
  pages     = {1--11},
  volume    = {54},
  doi       = {10.1016/j.ebiom.2020.102712},
  url       = {https://www.sciencedirect.com/science/article/pii/S2352396420300876},
}