Cryotherapy has been used to reduce chronic pain for many years due in part to its ease of use, affordability, and simplicity.
Twenty-five studies (22 randomized controlled trials, one prospective analysis, 1 one-group pretest/posttest study, and one case–control study) were included after the literature search. Cryotherapy applications show promise in reducing chronic pain associated with various chronic diseases including those of rheumatic and degenerative origin. Cryotherapy appears to be a safe therapy in carefully selected patients, with only minimal adverse effects reported in the literature (1)
Whole-body cryotherapy (WBC) involves a large chamber, creating cold by either combining cooled nitrogen with oxygen and injecting it into the chamber or by circulating nitrogen within the chamber walls (2).
Physicians and physical therapists today still commonly prescribe cryotherapy as a way to reduce chronic aches and pains, especially due to the ease of use, simplicity, and low cost of this kind of therapy (1)
Inflammation/Edema
Chronic inflammation can contribute to constant pain by chemical and mechanical stimulation of pain receptors and free nerve endings (3), which commonly occurs in autoimmune disease such as rheumatoid arthritis, ankylosing spondylitis, and multiple sclerosis, this is also witnessed in persons with musculoskeletal ailments such as lower back pain, shoulder pain and pain after surgery of hip, knee and shoulder replacement/s. Thus, there is a strong interest in using cryotherapy to reduce this inflammation in these chronic pain syndromes and to reduce the subsequent pain associated.
Edema and cytokines are key inflammatory markers used to assess the effects of treatments on inflammation. Edema is a cardinal sign of inflammation, caused by vascular changes and increased permeability that allows fluid to enter the extravascular space. The increased pressure in this space often leads to mechanical stimulation and pain production (3). Cryotherapy is thought to decrease swelling (4) by a combination of decreasing vascular permeability (5) and reducing both arterial and soft tissue blood flow to the affected areas (6).
Studies have suggested that cryotherapy decreases inflammation by decreasing pro-inflammatory cytokine TNF-α (7, 8, 9) increasing anti-inflammatory cytokine IL-10 and contrary to expectations, increasing pro-inflammatory cytokine IL-6. However, new evidence suggests that IL-6 may also possess anti-inflammatory properties (10, 11).
Nerve Transmission in Pain Fibers
Another proposed mechanism of cryotherapy is reducing nerve transmission velocity in pain fibers(12), which may be a way that cryotherapy induces an analgesic effect and pain relief. Previous literature concluded that cryotherapy significantly reduced both motor and sensory nerve conduction velocity (13) Algalfy and George found decreased nerve conduction velocity at the site of cryotherapy application, as well as increased pain threshold and tolerance. Of note, the effect on pain threshold and tolerance also extended distally to an area beyond the site of application, but supplied by the same nerve (14).
Conclusion
Chronic pain is a crucial aspect in the management of many chronic diseases as it can have a profound effect on the function of the associated body parts and may significantly hinder a patient’s daily life. Cryotherapy has been around and used for the management of chronic pain for decades, dating back to the time of Hippocrates and still being commonly prescribed by physicians and physical therapists today.
According to the research, the mechanism behind this pain reduction is thought to occur through the reduction of inflammation and edema, oxidative stress, and nerve conduction velocity in pain fibers. In regard to patients with rheumatic diseas
es such as, rheumatoid arthritis, and musculoskeletal ailments such as lower back pain, cryotherapy shows promising results. Whole-body cryotherapy demonstrated a reduction in both pain and disease activity, with temperatures of at least − 110 °C having the best results.
A point of conjecture though is everyone is different so the prescription of management of cryotherapy will be different for each particular person. Some may only need one or two sessions initially to reduce pain and inflammation with maintenance sessions periodically such as weekly or monthly.
1. Garcia, C., Karri, J., Zacharias, N.A. et al. Use of Cryotherapy for Managing Chronic Pain: An Evidence-Based Narrative. Pain Ther (2020). https://doi.org/10.1007/s40122-020-00225-w
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