Carpal tunnel syndrome is a very common pain disorder associated with compression of the median nerve at the carpal tunnel. Approximately 139 women and 67 males per 100,000 people will report this problem over the course of one year, although this depends on the definition used. The problem with CTS is not only that it is common, but also that it affects function – it is really difficult to carry out normal daily life with a numb or tingly hand, poor grip strength (particularly in the fingertips), and disruption to sleep from the ongoing deep achy sensation in the hand. Additionally, some studies show that people with CTS also experience widespread pressure pain hypersensitivity, and an increased response to heat, suggesting that the problem either triggers, or is part of a central sensitisation process.
Diagnosing CTS is conducted using two main approaches – firstly the clinical signs of pain, paraesthesia in the median nerve distribution, symptoms worse at night, and positive Tinel and Phalen signs; secondly, electrodiagnostic testing must show deficits of both sensory and motor median nerve conduction.
In this study, the authors were interested in establishing the relationship between clinical signs and symptoms, physical signs and symptoms (notably CROM and pinch grip force), as well as neurophysiological measures – and they also measured depression. I wish they’d included measures of pain anxiety, or catastrophising, but this was not included in this study.
224 women were included in the study, which carefully screened out individuals with potential confounding contributory causes such as whiplash, pregnancy or diabetes. The initial and expected findings were that women with higher reports of pain also demonstrated poorer CROM, pinch grip, lower heat pain hypersensitivity, and overall poorer functional hand use.
The first interesting finding was that women in this study reporting only moderate levels of pain also reported poor functioning. The authors suggest that, as a result of this finding “it may not be necessary to report higher levels of pain to find a repercussion in functional activities.” In other words, the impact of CTS on functional use of the hand appears ahead of the pain intensity, although the two are associated.
The study also found that heat pain hyperalgesia over the carpal tunnel as also associated with the intensity of hand pain – they suggest this may be due to peripheral sensitisation which is present from very early on in the presentation.
Looking at depression and the relationship with CTS, interestingly, the women did not demonstrate very high levels of depression, which surprised me a little given they had been selected for inclusion on the basis of having CTS symptoms for 12 months or more. The analysis found that depression was associated with poorer hand function and greater pain, even though the women did not report very high levels of depression. These authors suggest that “perhaps proper management of depressive symptoms in CTS may reduce, not only chronicity, but also induce an improvement in hand pain-related disability.”
Somewhat more controversially for some physiotherapists, these authors also argue that because depressive symptoms resolve during (as a result of perhaps?) physiotherapy treatment in 40% of people with work-related musculoskeletal pain injuries, perhaps those treatments should target mood management as well. So much for “but it’s not in my scope of practice”!
In fact, the authors are very clear that “proper management of individuals with CTS should include therapeutic interventions targeting physical impairments, that is, manual therapies; psychological disturbances (cognitive behaviour), and mechanical hypersensitivity (that is, neuromodulatory pain approaches).” If ever there was a time to get upskilled in a whole person approach to rehabilitation, this paper supports doing so now.
Fernández-Muñoz, J., Palacios-Ceña, M., Cigarán-Méndez, M., Ortega-Santiago, R., de-la-Llave-Rincón, A., Salom-Moreno, J., & Fernández-de-las-Peñas, C. (2016). Pain is Associated to Clinical, Psychological, Physical, and Neurophysiological Variables in Women With Carpal Tunnel Syndrome The Clinical Journal of Pain, 32 (2), 122-129 DOI: 10.1097/AJP.0000000000000241