November 22, 2019
Management of pain, especially when it becomes chronic, is a challenging task requiring a multidisciplinary approach. Currently, most pharmacological, nonpharmacological and interventional modalities achieve only temporary or modest improvements in pain symptoms and often produce intolerable adverse effects which interfere with quality of life and lead to nonadherence.
There is a need for new and effective chronic pain treatments that patients can tolerate without significant adverse effects. One such novel treatment is hyperbaric oxygen therapy (HBOT). It provides patients with 100% oxygen at pressures greater than atmospheric pressure. HBOT increases partial pressure of oxygen in the alveoli and results in a corresponding increase in the amount of dissolved oxygen carried by the blood which allows oxygenation of ischemic tissue with compromised circulation. HBOT leads to a net gain in oxygen concentration in tissues and subsequently induces neovascularization and angiogenesis, restores tissue homeostasis, and enhances leukocyte function.
Recently, published animal and human studies as outlined below have indicated that HBOT induces an analgesic effect in nociceptive, inflammatory, and neuropathic pain models and may be useful for the treatment of various chronic pain syndromes, although the mechanism is not well understood. There is a growing body of evidence to suggest that HBOT is a noninvasive modality with lasting efficacy and minimal side effects that can be used to treat chronic pain conditions. Hyperbaric oxygen therapy (HBOT) was initially developed to treat decompression sickness, a side effect of deep-sea diving.
In the narrative review “Hyperbaric Oxygen Therapy: A New Treatment for Chronic Pain?”, authors discuss the current understanding of pathophysiology of nociceptive, inflammatory and neuropathic pain, and the body of animal studies addressing mechanisms by which HBOT may ameliorate these different types of pain. The authors reviewed clinical studies suggesting that HBOT may be useful in treating chronic pain syndromes, including chronic headache, fibromyalgia, complex regional pain syndrome, and trigeminal neuralgia.
Twenty-five studies examining the role of HBOT in animal models of pain and human clinical trials were found and reviewed for this narrative review.
Several studies have examined the efficacy of HBOT in the treatment and prevention of migraine and cluster headaches. Five randomized control trials (RCTs) examined the use of HBOT for treatment and prevention of migraine. Bennett et al. summarized the findings from these trials in a 2008 systematic review. All the trials were found to be of moderate to low methodological quality, and although they were RCTs, they were underpowered and enrolled only a total of 103 patients (between 8 and 40 per study).
Two of the studies used a crossover design. Four of the trials treated patients with a single HBOT treatment of 60 minutes, while one trial treated patients with 30 minutes of HBOT on 3 consecutive days. Together, they provide some evidence that HBOT is efficacious in relieving an acute migraine attack.
In 2004, an RCT testing this hypothesis in 50 patients who met the 1990 diagnostic criteria of the American College of Rheumatology (ACR) for fibromyalgia demonstrated a decrease in pain scores and tender points. In this study, 26 patients received fifteen 90- minute HBOT sessions over 3 weeks, while 24 control patients breathed air at 1 ATA (sham treatment) for 90 minutes for fifteen sessions. The number of tender points, pain threshold as measured by algometer and VAS pain score was recorded for each patient before the first HBOT or sham session, and after the fifteenth. There was a significant decrease in the number of tender points and pain threshold in the HBOT group compared to the sham treatment group as early as after the first HBOT session that persisted after the 15th session.
HBOT has been shown to have antinociceptive and analgesic effects in animal models of nociception, as well as modulatory effects in animal models of inflammatory and neuropathic pain. Early clinical research demonstrates promise for the use of HBOT in the treatment of several human pain syndromes.
Sutherland AM, Clarke HA, Katz J, Katznelson R. Hyperbaric Oxygen Therapy: A New Treatment for Chronic Pain?. Pain Pract. 2016 Jun;16(5):620-8.