Mariano E. Menendez, research fellow and David Ring, professor of orthopaedic surgery
Middleton and Anakwe (1) reviewed the epidemiology, diagnosis, and treatment of carpal tunnel syndrome. We would like to offer several points for consideration.
First, it is worth restating that best evidence supports the concept that idiopathic median neuropathy at the carpal tunnel is due to a genetically narrow tunnel, with environmental factors such as hand use exerting a minor, less consistent, and more debatable epigenetic role.(2-11) Given the psychological power and negative implications of speculative causal associations and the large medical and non-medical readership of this journal, this paper represents a missed opportunity to put an end to the strong cultural conception (likely a full fledged myth) that repetitive hand use (e.g. typing) causes carpal tunnel syndrome. Carpal tunnel syndrome is not pain with typing. The primary symptom of a genetically narrow carpal tunnel is intermittent numbness. Numbness that can, at times, be so intense that it is unsettling or painful.
Second, an important point of debate is whether carpal tunnel syndrome is a progressive disease or not. The authors claim that “good evidence suggests that carpal tunnel syndrome is not necessarily progressive and that the simple method of splinting is all that is sometimes required to control symptoms”, but provide no references for this statement. In our impression, the collective evidence to date makes the case that a genetically narrow tunnel occurs bilaterally and progresses to permanent numbness, weakness, and atrophy if left untreated. Problems arise when we confuse symptom relief with modification of pathophysiology.
Third, patients with advanced disease evidenced by thenar atrophy, weakness of palmar abduction, and constant numbness should expect that some or all of these problems will persist after surgery.(12-16)
Fourth, it should be emphasized that surgery to increase the size of the carpal tunnel is the only known disease-modifying treatment.(17-24) None of the commonly used non-operative strategies (e.g. corticosteroid injections, wrist splinting, activity modification or rest) are proved to be disease modifying. Patients and healthcare providers may be safest considering these treatments as palliative at best until proved otherwise. Specifically, if we emphasize relief of symptoms, there is a risk that patients with decreased symptoms will present years later with permanent nerve damage. We don’t treat the symptoms of hypertension or diabetes—we treat the disease in order to limit pathophysiology. Idiopathic median neuropathy at the carpal tunnel syndrome may merit a similar approach.
Fifth, the authors recommend the use of electrophysiological testing in patients who experience no improvement in symptoms after surgery. Yet, it is well established that electrophysiological tests do not always return to normal after surgery, particularly for more advanced pathology.(25-29) Their utility among patients with electrophysiologically severe disease following carpal tunnel release may be limited. It is an error to measure electrophysiology after carpal tunnel release and interpret measurable median nerve pathology as an indication of incomplete release or other pathophysiology. Patients who have carpal tunnel release for advanced median neuropathy with permanent nerve damage may not experience relief of constant numbness, atrophy, or weakness of palmar abduction no matter how many surgeries they have. Patients who have surgery for pain rather than numbness are often unsatisfied with the result of surgery, but this is more likely because the diagnosis was incorrect than that the surgery could have been done better.
A review article in a prominent medical journal is an opportunity to correct common misconceptions that are prevalent among health professionals and laypersons alike. We contend that the most constructive, practical, optimistic, and accurate way to conceive of carpal tunnel syndrome based on current best evidence is that it is idiopathic median neuropathy at the carpal tunnel, due to a genetically narrow tunnel, unrelated to activity, causing intermittent numbness progressing to permanent numbness, which can only be prevented by surgery to increase the size of the carpal tunnel. All things considered, it seems better to treat carpal tunnel syndrome according to these principles until future research refutes them. In our opinion, treating carpal tunnel syndrome as an activity related injury causing wrist pain and modifiable by nonoperative treatments exposes patients to the harm of unnecessary disability, unnecessary surgery, and permanent nerve damage due to under treatment.
1. Middleton SD, Anakwe RE. Carpal tunnel syndrome. BMJ 2014; 349:g6437.
2. Bland JD, Rudolfer SM. Clinical surveillance of carpal tunnel syndrome in two areas of the United Kingdom, 1991-2001. J Neurol Neurosurg Psychiatry 2003; 74(12):1674-9.
3. Boz C, Ozmenoglu M, Altunayoglu V, et al. Individual risk factors for carpal tunnel syndrome: an evaluation of body mass index, wrist index and hand anthropometric measurements. Clin Neurol Neurosurg 2004; 106(4):294-9.
4. de Krom MC, Kester AD, Knipschild PG, et al. Risk factors for carpal tunnel syndrome. Am J Epidemiol 1990; 132(6):1102-10.
5. Hakim AJ, Cherkas L, El Zayat S, et al. The genetic contribution to carpal tunnel syndrome in women: a twin study. Arthritis Rheum 2002; 47(3):275-9.
6. Kamolz LP, Beck H, Haslik W, et al. Carpal tunnel syndrome: a question of hand and wrist configurations? J Hand Surg Br 2004; 29(4):321-4.
7. Lozano-Calderon S, Anthony S, Ring D. The quality and strength of evidence for etiology: example of carpal tunnel syndrome. J Hand Surg Am 2008; 33(4):525-38.
8. Nathan PA, Meadows KD, Doyle LS. Occupation as a risk factor for impaired sensory conduction of the median nerve at the carpal tunnel. J Hand Surg Br 1988; 13(2):167-70.
9. Nathan PA, Takigawa K, Keniston RC, et al. Slowing of sensory conduction of the median nerve and carpal tunnel syndrome in Japanese and American industrial workers. J Hand Surg Br 1994; 19(1):30-4.
10. Schottland JR, Kirschberg GJ, Fillingim R, et al. Median nerve latencies in poultry processing workers: an approach to resolving the role of industrial "cumulative trauma" in the development of carpal tunnel syndrome. J Occup Med 1991; 33(5):627-31.
11. Stevens JC, Witt JC, Smith BE, et al. The frequency of carpal tunnel syndrome in computer users at a medical facility. Neurology 2001; 56(11):1568-70.
12. Hobby JL, Venkatesh R, Motkur P. The effect of age and gender upon symptoms and surgical outcomes in carpal tunnel syndrome. J Hand Surg Br 2005; 30(6):599-604.
13. Iida J, Hirabayashi H, Nakase H, et al. Carpal tunnel syndrome: electrophysiological grading and surgical results by minimum incision open carpal tunnel release. Neurol Med Chir (Tokyo) 2008; 48(12):554-9.
14. Leit ME, Weiser RW, Tomaino MM. Patient-reported outcome after carpal tunnel release for advanced disease: a prospective and longitudinal assessment in patients older than age 70. J Hand Surg Am 2004; 29(3):379-83.
15. Nolan WB, 3rd, Alkaitis D, Glickel SZ, et al. Results of treatment of severe carpal tunnel syndrome. J Hand Surg Am 1992; 17(6):1020-3.
16. Tomaino MM, Weiser RW. Carpal tunnel release for advanced disease in patients 70 years and older: does outcome from the patient's perspective justify surgery? J Hand Surg Br 2001; 26(5):481-3.
17. Andreu JL, Ly-Pen D, Millan I, et al. Local injection versus surgery in carpal tunnel syndrome: neurophysiologic outcomes of a randomized clinical trial. Clin Neurophysiol 2014; 125(7):1479-84.
18. Korthals-de Bos IB, Gerritsen AA, van Tulder MW, et al. Surgery is more cost-effective than splinting for carpal tunnel syndrome in the Netherlands: results of an economic evaluation alongside a randomized controlled trial. BMC Musculoskelet Disord 2006; 7:86.
19. Page MJ, Massy-Westropp N, O'Connor D, et al. Splinting for carpal tunnel syndrome. Cochrane Database Syst Rev 2012; 7:CD010003.
20. Page MJ, O'Connor D, Pitt V, et al. Exercise and mobilisation interventions for carpal tunnel syndrome. Cochrane Database Syst Rev 2012; 6:CD009899.
21. Page MJ, O'Connor D, Pitt V, et al. Therapeutic ultrasound for carpal tunnel syndrome. Cochrane Database Syst Rev 2013; 3:CD009601.
22. Scholten RJ, Mink van der Molen A, Uitdehaag BM, et al. Surgical treatment options for carpal tunnel syndrome. Cochrane Database Syst Rev 2007(4):CD003905.
23. Shi Q, MacDermid JC. Is surgical intervention more effective than non-surgical treatment for carpal tunnel syndrome? A systematic review. J Orthop Surg Res 2011; 6:17.
24. Verdugo RJ, Salinas RA, Castillo JL, et al. Surgical versus non-surgical treatment for carpal tunnel syndrome. Cochrane Database Syst Rev 2008(4):CD001552.
25. Aulisa L, Tamburrelli F, Padua R, et al. Carpal tunnel syndrome: indication for surgical treatment based on electrophysiologic study. J Hand Surg Am 1998; 23(4):687-91.
26. Kanatani T, Fujioka H, Kurosaka M, et al. Delayed electrophysiological recovery after carpal tunnel release for advanced carpal tunnel syndrome: a two-year follow-up study. J Clin Neurophysiol 2013; 30(1):95-7.
27. Mondelli M, Reale F, Sicurelli F, et al. Relationship between the self-administered Boston questionnaire and electrophysiological findings in follow-up of surgically-treated carpal tunnel syndrome. J Hand Surg Br 2000; 25(2):128-34.
28. Padua L, LoMonaco M, Aulisa L, et al. Surgical prognosis in carpal tunnel syndrome: usefulness of a preoperative neurophysiological assessment. Acta Neurol Scand 1996; 94(5):343-6.
29. Rotman MB, Enkvetchakul BV, Megerian JT, et al. Time course and predictors of median nerve conduction after carpal tunnel release. J Hand Surg Am 2004; 29(3):367-72.
Competing interests: No competing interests