Revision Carpal Tunnel Release: Risk Factors and Rate of Secondary Surgery

Sir: With great interest we read the article entitled “Revision Carpal Tunnel Release: Risk Factors and Rate of Secondary Surgery,” by Westenberg et al.1 We would like to congratulate the authors on their important analysis. Carpal tunnel syndrome is one of the most abiding issues in hand surgery, resulting in approximately 600,000 carpal tunnel releases a year in the United States.2 In their study, Westenberg et al. retrospectively evaluated 7464 patients who underwent carpal tunnel release between 2002 and 2015. In 113 patients (1.5 percent), revision surgery was necessary due to recurrent carpal tunnel syndrome or persistent symptoms. Two patients had a second revision surgery for persistent carpal tunnel syndrome. The authors were able to show in a multivariable logistic regression analysis that age, male sex, bilateral carpal tunnel release, and endoscopic carpal tunnel release were associated with a higher revision rate. Further, they showed that rheumatoid arthritis and smoking are risk factors for revision surgery, whereas preoperative splint treatment reduces the risk of revision surgery. There are some points that we would like to comment on that may be worth further discussion. In the current literature, recurrence of symptoms may occur after either open or endoscopic carpal tunnel release and often correlates with incomplete release of the transverse carpal ligament.3 The authors noted in their study that 39 percent of patients who received revision surgery had recurrent carpal tunnel syndrome. Might this result from incomplete retinaculum release or from potential rejoining of the retinaculum from scarring? In our department, our experience has shown that rather than just splitting, a partial resection of the transverse carpal ligament prevents rejoining and leads to a reduced revision rate. With regard to higher rates of incomplete release by performing an endoscopic procedure, we would recommend this surgical modification.4 To evaluate the cause for revision surgery after carpal tunnel release, diagnosis is crucial. The roles of electromyography and nerve conduction velocity in diagnosis are clinical standards. The authors reported that 56 percent of their patients had prerevision electromyography and nerve conduction velocity results that were of similar severity to results before the initial carpal tunnel release. Sometimes after long-persisting symptoms, the median nerve is so compressed that recovery after release is unlikely, but release prevents further functional loss. Hence, constant data on prerevision electromyography and nerve conduction are expected. Consequently, further diagnostic imaging, such as ultrasonography or magnetic resonance imaging, is indicated.5 In case of incomplete release of the carpal ligament or recompression of the median nerve, the findings of these imaging tools could provide the cause and have important clinical implications. It would be interesting to know whether the authors considered further diagnostic imaging in patients who received revision surgery. Furthermore, based on our experience, severity and duration of symptoms are potential factors in revision surgery. Symptoms, especially pain, are subjectively perceived, thus initial assessment of patients varies greatly.6 As a result, potential nerve damage varies as well and may lead to different prognoses. In the present study, it is unclear how long symptoms were present before the initial operation was performed. Although carpal tunnel syndrome is a well-studied nerve entrapment syndrome, several important questions remain unanswered. We compliment the authors for their research outcome and would welcome a resulting discussion, which may lead to further insights in treating carpal tunnel syndrome. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. Maximilian Zaussinger, M.D.Christine Radtke, M.D., Ph.D.Division of Plastic and Reconstructive SurgeryDepartment of SurgeryMedical University of ViennaVienna, Austria