Color Doppler ultrasound for evaluation of vasomotor activity in patients with carpal tunnel syndrome

Background: Patients with carpal tunnel syndrome (CTS) have a variety of vasomotor symptoms. Here, we aimed to study the vasomotor activity of the radialis indicis (RI) artery (median nerve territory) and the radial palmar digital (RPD) artery of the little finger (ulnar nerve territory) before and after sympathetic stimulation in CTS patients using color Doppler ultrasound.

Methods: We performed a cross-sectional study of 46 consecutive CTS patients plus 36 healthy controls. All patients underwent electromyography studies and were classified into mild and moderate/severe groups according to electrodiagnostic findings. Color Doppler examination of the RI artery and the RPD artery of the little finger were performed with the participants in a relaxed sitting position and after a deep breath followed by a cough (sympathetic stimulation). The pulsatility index (PI) was recorded at the point of maximal change in waveform, before and after this stimulus.

Results: The PI of RI artery was significantly lower (p < 0.01) in CTS patients than healthy controls, both before and after stimulation. The changes in PI of RI artery after stimulation were significantly lower in CTS patients than healthy controls (1.18 ± 0.37 vs. 5.41 ± 0.87; p < 0.001). The same pattern was seen for PI of RI artery when comparing patients with mild vs. moderate/severe CTS. No difference was found in PI of RPD artery of the 5th finger between patients vs. controls and between patients with mild vs. moderate/severe CTS, both before and after stimulation.

Conclusions: We showed that color Doppler ultrasound can readily determine impaired vasomotor activity in CTS patients.