Symptoms may return after carpal tunnel surgery. by Paul Cotton v265 JAMA, The Journal of the American Medical Association April 17 '91 p1922(2) TEXT COPYRIGHT American Medical Association 1991 THE INITIAL relief of carpal tunnel surgery may be shadowed by significant scar pain and weakness in almost a third of subjects after 2 years. The surgery, in which the carpal tunnel is decompressed by release of the transverse ligament and debridement, is the most common surgery in the worker's compensation population. Painful scars were most common in patients receiving such compensation, compared to patients covered by private insurance or other forms of payment, according to a retrospective review of 60 cases at the State University of New York, Buffalo, School of Medicine. "This high incidence of symptom recurrence has not been previously reported," says Michael P. Nancollas, MD, a fellow in hand surgery at the western New York school who presented the findings at the American Academy of Orthopaedic Surgeons meeting in Anaheim, Calif. Five-Year Follow-up The study found at an average of 5.5 years' follow-up that 30% of all patients rate the results as poor to fair. And 57% report return of some preoperative symptoms, most commonly pain, beginning an average of 2 years after surgery, although only one patient required further surgery. Intermittent pain was reported by 42%, digital numbness by 32%, and tingling by 35%. No correlation between postoperative results and preoperative symptoms, extent of surgical dissection, physical findings, or electrodiagnostic test results could be identified, Nancollas said. The 42% of patients covered by worker's compensation had slower initial improvement, and were off work longer-8.4 vs 1.7 months for non-compensation patients. Differences between worker's compensation and other patients before and after surgery were also noted in a review of 105 carpal tunnel surgeries in 82 patients at Rose Medical Center and University (of Colorado) Hospital in Denver. The 43 worker compensation patients were younger and predominantly male in contrast to non-compensation patient populations, says Bert F. Jones, MD, who also presented results at the orthopedic academy's meeting. Jones says the study was conducted because while compensation has been documented to be a significant outcome variable in other conditions like low back pain, a literature review turned up no references on compensation as a factor in carpal tunnel surgery outcome. As in the New York study, compensation patients lost more time from work than non-compensation patients. They were also less likely to return to original jobs or to resume working at all. "Occupational carpal tunnel syndrome is a different disease," says Nancollas. Since sear tenderness is the most significant postoperative complaint, attention should focus on retraining or on workplace modifications to prevent recurring pain after surgery, and on techniques such as endoscopic surgery that minimize the size of incisions, he concludes. Endoscopic Limitations The endoscopic approach to the carpal tunnel may still have important limitations, though, according to another report at the meeting. In trials on 13 fresh-frozen cadavers by surgeons who had "extensive" clinical endoscopic carpal tunnel surgery experience at three Boston, Mass, teaching hospitals, complete release of the transverse carpal ligament was achieved in only five. In four others, fine transverse fibers remained that may have been remnants of the ligament, and in the remaining four there clearly was incomplete release, says J. Theodore Schwartz, Jr, MD, previously a Harvard Medical School hand surgery fellow and now practicing in Livermore, Calif. Schwartz cautions that the endoscope blade comes within 2 mm of neurovascular structures that cannot be directly observed with the particular endoscope used, an Agee 3M (Minneapolis, Minn) Inside Job System. Incomplete release most commonly occurred distally, "where concern about the superficial palmar arterial arch may have caused hesitation. " The fat pad between the edges of the cut transverse ligament obscures the view and may also contribute to incomplete sections, he says. "The recurrence rate in patients undergoing endoscopic carpal tunnel release must be scrutinized long-term in light of the high incidence of incomplete sectioning and the very narrow margin of safety," concludes Schwartz. We've all heard of sporadic cases of digital nerve and arterial lacerations" with endoscopic release, comments Roy Meals, MD, chief of hand surgery at the University of California, Los Angeles (UCLA) Medical Center. The fact that the study was done by experienced endoscopists discounts the possibility that a steep learning curve is to blame, says Meals, adding that it might have been safer for the patients had the authors done the cadaver study first." Meals notes that neither of the clinical studies examined or controlled for conservative preoperative treatments, or for what guidelines were used to recommend surgery. "So at best we can draw only general conclusions, " he says. "Rather than perfect treatment, we should perfect prevention," he adds. Summing up, Meals predicts: We are not going to solve work-induced carpal tunnel syndrome with any kind of surgery." This is no more likely than expecting "to solve asbestos, highway carnage, or any other environmental hazard with surgery," concludes Meals.