Abnormal sweating patterns associated with itching, burning and tingling of the skin indicate possible underlying small-fibre neuropathy

Background Itching, burning, numbness and tingling of the skin are frequent reasons for dermatology consultation. We hypothesized that these sensations may be attributable to a small-fibre neuropathy. Sweating, which is mediated by small nerve fibres, may be a surrogate marker of small-fibre neuropathy. Objectives To investigate the results of thermoregulatory sweat testing (TST), which depicts and estimates whole-body sweating, in patients with itching, burning, numbness and tingling sensations. Methods We retrospectively reviewed the medical records of 227 patients with itching, burning, numbness and tingling sensations involving the skin who were seen at our institution during 2008 and also underwent TST. Results The mean age of the cohort was 54 years (range 3-89), and 58% were female. In all, 149 patients (66%) had abnormal TST results; in 119 (80%) of these patients the areas of anhidrosis on TST corresponded to their symptomatic areas. For each symptom analysed separately, the area of anhidrosis correlated with the area of symptoms in most patients. Conclusions Patients with burning, itching, numbness and tingling have abnormal sweating patterns and often do not sweat in the symptomatic areas. These novel findings suggest that a small-fibre neuropathy may underlie many cutaneous symptoms and that the neuropathy can be estimated using TST. What's already known about this topic? Peripheral neuropathies can cause itch and strange sensations in the skin, although reports are limited. Abnormal sweating is a finding in and marker for neuropathies, especially small-fibre neuropathy. Thermoregulatory sweat testing (TST) is an excellent tool to measure whole-body sweating. It is not known whether otherwise unexplained itch and strange sensations in the skin can result from peripheral neuropathy and, if so, how they can be diagnosed. What does this study add? Results of TST were abnormal in the majority of patients with itching, burning, numbness and tingling sensations involving the skin, and the areas of anhidrosis on TST corresponded to their symptomatic areas. These results indicate that itching and strange sensations in the skin may be attributable to small-fibre neuropathy. Small-fibre neuropathy may underlie many cutaneous symptoms, and the neuropathy may be estimated using TST.