Treatment Options for Carpal Tunnel Syndrome

Carpal tunnel syndrome is a symptom complex consisting of numbness in the median nerve distribution, typically involving the thumb, index finger, and middle finger. Symptoms frequently occur when performing certain tasks requiring wrist extension, while driving, and at night. Symptoms may progress to constant numbness in the affected nerve distribution and eventually can result in a total lack of sensation in the thumb, index finger, middle finger, and radial side of the ring finger, as well as loss of muscle function in abduction and opposition of the thumb. Carpal tunnel syndrome has the potential to substantially limit performance of activities of daily living for some individuals.

Rossignol et al¹ found that workers employed in occupations such as cleaning or data processing are most at risk for developing carpal tunnel syndrome. Some reports indicate that the incidence of carpal tunnel syndrome is increasing. Stevens et al² reported an incidence of carpal tunnel syndrome of 88 cases/100 000 population per year in Rochester, Minn, from 1961 to 1965. In a follow-up study from 1976 to 1980, the rate increased to 125 cases/100 000 population per year.² In a 1998 study, Nordstrom et al³ estimated the prevalence of carpal tunnel syndrome to be 346 cases/100 000 population per year. de Krom et al⁴ reported that the incidence of carpal tunnel syndrome in the Netherlands was 0.6% in men and 9.2% in women in the general adult population—rates the investigators considered to be minimal estimates of actual prevalence.

Carpal tunnel surgery is associated with substantial direct medical costs and with economic costs in terms of missed work and possible continuing disability. Carpal tunnel surgery is performed frequently in the United States and is the fifth most common procedure performed in the Medicare population.⁵ However, despite the critical need for and importance of research in carpal tunnel syndrome, no rigorous randomized controlled studies of treatment options had been reported previously.

The study by Gerritsen et al⁶ in this issue of THE JOURNAL provides a careful randomized controlled trial comparing 2 treatments (splinting vs surgery) for carpal tunnel syndrome. Gerritsen et al identified patients with carpal tunnel syndrome using clinical symptoms (ie, pain and paresthesias in the median nerve distribution) along with electrophysiological confirmation of the diagnosis. The investigators excluded patients with a history of wrist trauma; associated medical conditions such as diabetes, pregnancy, thyroid disease, or cervical radiculopathy; and severe thenar muscle atrophy—thereby probably excluding the least and most severe cases. The patients were randomly assigned to receive either splint treatment or surgery. Outcome measures were assessed at 3, 6, and 12 months after randomization and were scored by the patients as completely recovered, improved, or much worse. The investigators also used validated outcome measure scales,⁷ and the assessors were blinded to the patient's treatment group.

The overall results indicated that at 18 months, surgery was more effective than splinting. In the short term, the outcome measures favored splinting; however, investigators suggest this finding may partly reflect the immediate initiation of splinting at the time of randomization and the median 35-day delay from randomization to surgery. In the intent-to-treat analysis, the surgery group demonstrated more improvement than the splint group, with an overall success rate of 90% at 18 months and with significantly higher rates of patient satisfaction than with splinting. Moreover, at 18 months, the overall success rate for the splint group was 37% compared with 94% for patients in the splint group who also received surgery after splinting.

These results compare favorably with other reports indicating that carpal tunnel decompression is an effective treatment for carpal tunnel syndrome. Katz et al⁸ used the symptom severity score to evaluate patients 30 months after an intervention (operative or nonoperative). The authors confirmed that the group treated surgically improved significantly and the benefits persisted, whereas the group treated nonoperatively showed little benefit. DeStefano et al⁹ reported that patients with carpal tunnel syndrome treated surgically were 6 times more likely than those treated nonoperatively to have resolution of symptoms. Burke et al¹⁰ found that of 168 patients with carpal tunnel decompression performed in 1989, 68% considered themselves to be completely cured, whereas 24% noted mild residual or recurrent symptoms not requiring further treatment. Four cases (8%) were considered to be recurrent and benefited from repeat surgery.

Even though surgery for carpal tunnel syndrome is generally considered safe and effective, the possible risk associated with surgery and the potential for complications may contribute to the preference of some patients for nonsurgical treatment. In a study by Kaplan et al,¹¹ failure of conservative management of carpal tunnel syndrome was significantly associated with a patient age of 50 years or older, duration of symptoms in excess of 10 months, constant paresthesias, triggering of flexor tendons, and a positive Phalen test in 30 seconds or less. If none of these factors was present, two thirds of patients were successfully treated by splinting and anti-inflammatory medications without surgery. However, nonoperative treatment failed in 60% of cases when 1 of these factors was present, in 83% when 2 factors were present, in 93% when 3 factors were present, and in all patients when 4 or 5 of these factors were present. The findings among patients in the splinting group in the study by Gerritsen et al⁶ are consistent with these results, although the investigators did not differentiate clinical response by age, duration of symptoms, or severity of the problem. Moreover, while other conservative treatment options, such as vitamin B₆, diuretics, other anti-inflammatory drugs, and acupuncture, have been proposed for treatment of carpal tunnel syndrome, there are no solid studies to support these interventions. These and other nonoperative treatment options need to be studied in a controlled fashion and compared with surgical outcomes before these therapies are used for patients with carpal tunnel syndrome.

The overriding question facing the clinician treating a patient with carpal tunnel symptoms is when to consider surgery as a treatment option. The study by Gerritsen et al strongly reinforces findings that indicate splinting is an excellent adjunctive treatment in early cases, but is ineffective on a long-term basis for treating this condition. The findings of Gerritsen et al also suggest that there is no need for patients with carpal tunnel syndrome to continue to have pain, functional limitations, or sleep loss when surgery produces such a favorable outcome.