Carpal tunnel pressure is correlated with electrophysiological parameters but not the 3 month surgical outcome

Tunnel pressure (TP) has been linked to carpal tunnel syndrome (CTS), but the clinical significance of TP is still under investigation. The present study included 58 hands that were diagnosed with idiopathic CTS by nerve conduction velocity (NCV) and received divisions of the flexor retinaculum through a mini-open procedure. Preoperative and postoperative TP were measured segmentally, and surgical outcomes were assessed by the Boston Symptom Severity Score for CTS before surgery and 3 months after surgery. We detected significantly increased TP in patients with CTS at 1.5-2.5 cm distal to the distal wrist crest (DWC), and the highest value was observed at 2 cm. Interestingly, there were still seven hands with a TP of > 30 mmHg at 3 cm distal to the DWC. The highest mean TP decreased from 52.7 mmHg to 7.8 mmHg after the operation. No patient had a pressure of >15 mmHg proximal to the DWC. The mean Boston Symptom Severity Score decreased from 3.1 to 1.8 at the 3-month follow-up. Although the highest preoperative TP was slightly correlated with the compound muscle action potential and was moderately correlated with the distal motor latency, the latency of the sensory nerve action potential and the sensory conduction velocity, highest preoperative TP could not predict the 3-month outcome. The correlations between the electrophysiological parameters and the highest TP in our series were stronger than previous reports; however, NCV is still better than TP as a tool for predicting the 3-month surgical outcome.