Background & Objectives Sensory and motor manifestations in carpal tunnel syndrome (CTS) are well documented, whereas the associated autonomic dysfunction is often overlooked. The aim of this study is to demonstrate that autonomic dysfunction of the CTS hands can be quantified by measuring skin capacitance.
Methods Patients with clinical and electrophysiological signs of idiopathic carpal tunnel syndrome meeting the inclusion criteria were recruited. The patients were also scored based on the Brigham carpal tunnel severity score. Skin capacitance was measured using Corneometer CM825 (C&K Electronic, GmbH). The measurements were taken from the palmar aspect of distal phalanx of the index and little finger of the affected hand. Normal healthy patients with no signs and symptoms of carpal tunnel syndrome were recruited as controls and skin capacitance was measured in a similar fashion as the CTS group.
Results The CTS group consisted of 25 patients (18 female & 7 male) and 35 hands with an average age of 59.2 years (33-83 years). The mean symptom severity score was 2.80 (1.27-4.18; SD 0.82) and functional status score was 2.53 (1-4.26; SD 1.08). The mean ratio of skin hydration between the index and little finger was 0.85 (0.6-1.25; SD 0.155). Using the paired t-test to determine paired differences between index and little finger measurements, the mean difference was 12.6 (p<0.001).
The control group consisted of 15 people (9 female and 6 male) and 30 hands. The average age was 47.3 years. The mean ratio of skin hydration between the index and little finger was 0.97 (0.77-1.42 SD 0.105). Using the paired t-test to determine paired differences between index and little finger measurements, the mean difference was 1.31 (p=0.317). The difference in skin hydration between the index and little finger was directly compared between the controls and CTS group, this difference was statistically significant, p=0.002.
Conclusion A simple method to determine dysautonomia, using Corneometer CM825, by the clinician has been demonstrated. Measurement of skin capacitance will reduce the dependence on electrophysiological studies, thus reducing the time for arriving at a diagnosis, improved patient satisfaction and cost-effectiveness.