Carpal Tunnel Syndrome and Wound Healing

The defining characteristic of any repetitive stress injury (RSI) is that it's a cumulative trauma. Not all carpal tunnel syndromes are cumulative, however. You can fall on your wrist and suffer a blunt trauma also diagnosed as carpal tunnel syndrome. Healing that type of injury would, however, be much different than with an RSI. With repetitive motion, the process of wound healing, where tissues try to return to normal in terms of both architecture and function after an injury, the process gets interrupted and the whole thing can go haywire. A complete description of the latest understanding of this process and how it gets high jacked with RSIs can be found in the chapter Repetitive Stress Pathology: Soft Tissue by Nancy N. Byl, Mary F. Barbe, and Jane Fedorzyck of the book Pathology and Intervention in Musculoskeletal Rehabilitation, 2nd Edition.

There are four phases of this wound healing: (1) clotting (2) inflammation (3) the creation of fibers to fill in the damaged tissues and (4) remodeling where the body tries to reform the structures damaged. What happens in a cumulative trauma, where what's injuring the tissues in the first place repeats over and over again, is that the tissues never get a chance to heal. The wound healing process gets disrupted and a number of maladaptive processes infiltrate the wound site. If stuck in the first phase, the coagulation process, which breaks down the injured cells for removal, can proliferate into nearby healthy tissues. Protective muscle spasms can’t resolve and stiffness sets in. Continual cramping can also lead to abnormal movement patterns, which can further erode into the involuntary movements seen in focal dystonia. 

If stuck in the second phase, you get chronic inflammation that becomes systemic. Scarring takes place in phase three through fibroblasts, the building blocks of muscle and soft tissue. If there are too many of them, the area becomes a tangle of lesions instead and movement becomes difficult if not impossible. Soft tissues get sticky and every gesture tears into the already damaged tissues. The repair phase isn’t supposed to begin until all debris has been cleared from the site of injury. If it begins before, then debris can get coagulated, inflamed and trapped by fibroblasts in the original injury.

In the final stage of remodeling, the fibroblasts create a new architecture. But if the previous phases have not gone on as designed, the new architecture is compromised and you have permanent scarring of one type or another, even in tissues that were not originally damaged. If you’re talking about wound healing of say a puncture injury (you stepped on a nail), the tissue architecture affected has little consequences beyond the puncture wound. But when you’re talking about the entire shoulder girdle, as in thoracic outlet syndrome, you can see how the architecture becomes crucial to moving the entire body.

Its important to know that the phases of this wound healing process can overlap each other, but one is supposed to flow into another, then the next, until the process completes itself. When one phase is prolonged or interrupted or diverted, the next phase then can’t do it's job either and the entire progression breaks down. Wonky wound healing then also creates changes in what the tissue can tolerate. The authors have speculated, “The mechanisms leading to tissue repair are prevented by the continued cycle of tissue trauma in repetitive motion injury”.  Furthermore, the authors think it's the overexertion events that are the hallmark of RSIs, which initiate a persistent inflammatory response that leads to systemic infiltration of the disorder.  This can mean tissues can’t be repaired; they can also die or completely fail biomechanically for the surrounding area. Functional performance gets further reduced, not just in the original injury site, but in surrounding tissues and mechanisms as well.

The authors recommend a holistic approach to treatment including inflammation reducing nutrition, hydration and physical exercise to promote oxygen delivery, massage techniques that release scar tissue, postural alignment and strengthening exercises, and finally sensory motor retraining if need be. My own experience validates this approach, though honestly, I’m only now working on the nutritional aspects. If your practitioner will not apply these modalities, you might want to refer him or her to the book Pathology and Intervention in Musculoskeletal Rehabilitation, 2nd Edition.

@JillGambaro is the author of The Truth About Carpal Tunnel Syndrome . She has lived with multiple repetitive strain injuries known as a “double crush” for over 15 years. A former board member of the Los Angeles Repetitive Strain Injury Support Group and the Cumulative Trauma Disorders Resource Network, Jill advocates for prevention, patient engagement and healthy playing for musicians through her Blog, Facebook and Twitter @IckyFingersMovi. Look for her upcoming documentary Icky Fingers.