Introduction: Although tunnel pressure (TP) has been linked to carpal tunnel syndrome (CTS), the clinical significance of tunnel pressure is still under investigation.

Methods: The present study included 58 hands that were diagnosed as idiopathic CTS by nerve conduction velocity (NCV) and received divisions of the flexor retinaculum through a mini-open procedure. The preoperative and postoperative TP was measured segmentally, and surgical outcome was assessed by the Boston symptom severity score for CTS before the operation and three months after the operation.

Results: We detected significantly increased TP in CTS patients at 1.5 to 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 more than 30 mmHg at 3 cm distal to the DWC. The highest mean TP decreased from 52.7 to 7.8 mmHg after the operation. None of the patients had a pressure of more than 15 mmHg proximal to the DWC. The mean Boston symptom severity score decreased from 3.1 to 1.8 at the three-month follow-up. Although the highest preoperative TP was slightly correlated with the compound muscle action potential and moderately correlated with the distal motor latency, the latency of the sensory nerve action potential, and the sensory conduction velocity, it could not predict the three-month outcome.

Conclusions: The correlations between the electrophysiological parameters and the highest TP in our series were stronger than previous reports; however, NCV is still a better tool to predict the three-month surgical outcome than TP.

Patient Care: Because the highest TP correlated with the NCV parameters, the NCV parameters appear to represent disease severity; however, they do not reflect the three-month outcome. None of the patients had abnormal pressure proximal to the DWC, and only a few cases had abnormal pressure 3 cm distal to the DWC. According to the present study, we suggest that pressure measurements are beneficial in guiding the extent of ligament division.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the clinical significance of carpal tunnel pressure. 2) Discuss, in small groups,about the relationship between tunnel pressure disease severity, and prognosis 3) Identify an effective surgical method to guide CTS surgery

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