Peripheral sensory function in non-freezing cold injury patients and matched controls

The aim of this study was to compare peripheral sensory neural function of individuals with non-freezing cold injury (NFCI) with matched controls (without NFCI) with either similar (COLD) or minimal previous cold exposure (CON). Thirteen individuals with chronic NFCI in their feet were matched with the control groups for sex, age, race, fitness, body mass index and foot volume. All undertook quantitative sensory testing (QST) on the foot. Intraepidermal nerve fibre density (IENFD) was assessed 10 cm above the lateral malleolus in 9 NFCI and 12 COLD participants. Warm detection threshold was higher at the Great toe in NFCI than COLD (NFCI 45.93 [4.71] ^oC vs. COLD 43.44 [2.72] ^oC, P = 0.046), but was non-significantly different to CON (CON 43.92 [5.01] ^oC, P = 0.295). Mechanical detection threshold on the dorsum of the foot was higher in NFCI (23.61 [33.59] mN) than in CON (3.83 [3.69] mN, P = 0.003), but was non-significantly different to COLD (10.49 [5.76] mN, P > 0.999). Remaining QST measures did not differ significantly between groups. IENFD was lower in NFCI than COLD (NFCI 8.47 [2.36] fibre.mm^-2 vs. COLD 11.93 [4.04] fibre.mm^-2, P = 0.020). Elevated warm and mechanical detection thresholds may indicate hyposensitivity to sensory stimuli in the injured foot for individuals with NFCI and may be due to reduced innervation given the reduction in IENFD. Longitudinal studies are required to identify the progression of sensory neuropathy from the formation of injury to its resolution, with appropriate control groups employed.