Can Hyperbaric Oxygen Therapy cure Fibromyalgia?

Fibromyalgia, a painful burden

According to Mayo Clinic, fibromyalgia syndrome (FMS, usually called only fibromyalgia) is a chronic condition characterized by pervasive musculoskeletal pain, concomitant with manifestations of fatigue, disturbances in sleep architecture, cognitive impairments, and fluctuations in mood. Current research theorizes that fibromyalgia intensifies by heightening the sensitivity of pain perception, impacting the processing of nociceptive and non-nociceptive signals within the central nervous system, particularly the brain and spinal cord (Clauw DJ, 2011). Fibromyalgia often starts off with a trigger which can be emotional or physical, such as Traumatic Brain Injury (TBI).

FMS is often associated with trigger or tender points, focal pain points on the body. Even though tender points are no longer part of the diagnostic criteria for FMS, they are still often described as one of the major symptoms of it. While NY Presbyterian Health Library cites 9 tender points, Mayo Clinic cites 18 and the American College of Rheumatology (ACR) clearly states the importance of these tender points, including ‘pain in 11 of 18 tender point sites on digital palpation’ as one of 2 criteria for diagnosis. The other criterion is ‘history of widespread pain.’

Recent advances in Fibromyalgia treatment

Recently, (Cracchiolo, 2023)presented a case study of a 54-year-old woman suffering from FMS, who was treated with HBOT, in addition to a variety of multidisciplinary therapies. Their reasoning for HBOT treatment was based on a hypothesis that came to light in the 1970’s, basically linking reduction in the availability of oxygen as a causal effect of FSM. In this case, HBOT would be an attractive therapy, as it is non-invasive and involves the patient intermittently breathing pure oxygen.

Increased Oxygen in the blood

Researchers theorize that based on Henry’s Law (as the pressure of a gas above a liquid increases, the concentration of that gas dissolved in the liquid also increases proportionately, assuming constant temperature), HBOT increases the amount of oxygen in the body’s plasma, resulting in more available oxygen. Based on Henry's Law, more oxygen is transported into the blood plasma, leading to ‘significant improvement of all metabolic parameters’ effectively improving neurological functions. Of late, HBOT has been expanded for the treatment of serious infections, air in blood vessels and chronic wounds.

The prevailing approach for FMS management involves multidisciplinary interventions, with pharmacological agents playing a relatively modest role. Unfortunately, even the existing interventions are both largely inaccessible and success rates are modest. The treatment of FMS with HBOT is a relatively new phenomenon. In their prospective randomized, single blind, controlled trial, (Ablin, 2023), et al. assessed the therapeutic impact of HBOT on FMS patients with a well-defined clinical history of TBI for a period of 3 months. FMS patients in the second arm of the trial received either Duloxetine or Pregabalin. Thus, this evaluation included a comprehensive comparison with the established standard pharmacological treatment currently in use. For our purposes, we will concentrate on Albin, et al. Quantitative Sensory Testing (QST) assessment which consisted of pressure pain thresholds and conditioned pain modulation (CPM).

Quantitative sensory testing in Fibromyalgia

Pressure pain threshold (PPT) was assessed using a handheld computerized pressure algometer with a circular 1 cm2 probe (AlgoMed, Medoc LTD, Israel). PPTs were tested using the Method of Limits with incrementally increasing pressure at a rate of 30 kPa per second (max 1000 kPa), measured on the upper trapezius muscle, 3 times. The participants were given instructions ‘to report when the sensation changed from pressure to pain, at which point the probe was removed.’ (Ablin, 2023)

CPM was evaluated by repeating the PPT test while immersing the non-dominant hand in cold water (10˚C). Subsequent analyses involved the utilization of the mean derived from the second and third measurements (2nd and 3rd PPT trials average subtracted from the 2nd and 3rd trials average while hand was immersed). Hence, higher (positive) values serve as indicators of effective pain inhibitory mechanisms. (Albin) CPM is a well-known tool for evaluating endogenous pain modulation, drawing parallels with the concept of "Diffuse Noxious Inhibitory Control" (DNIC) observed in animal models. In FMS, a syndrome which falls under the current classification of nociplastic pain, and is associated with a reduced efficacy in CPM in this patient group. This deficiency in inhibitory pain control is regarded as a crucial aspect in the pathophysiology of FMS. (Ablin, 2023)

Patients in both arms of this study were also evaluated using other measurements as well: 4 separate FMS symptoms questionnaires; Widespead Pain Index (WPI), Fibromyalgia symptoms severity scale (SSS), Fibromyalgia Impact Questionnaire (FIQ), and the Global Pain Scale (GPS). Fibromyalgia diagnosis was based on a combination of WPI and SSS scores: as: WPI ≥ 7/19 and SSS ≥ 5/12, or WPI = 3-6/19, and SSS ≥ 9/12.

For quality of life the RAND Health Status Survey, Short Form-36 (Quality of Life questionnaire) was used and the Medical Outcome Sleep Scale (MOS) measured sleep quality. Two separate psychological questionnaires were used; the Brief Symptoms Inventory-18 (BSI-18) and the Beck Depression Inventory (BDI-II). In addition, all of the participants underwent brain single photon emission computed tomography (SPECT) with contrast. (Ablin, 2023)

How did HBOT affect pain?

The primary results demonstrated a noteworthy interaction between arms and time, which was observed in the assessment of pain intensity using the Visual Analog Scale (VAS) score after HBOT when compared to the medication arm. The effect size of this interaction was substantial suggesting a notable and impactful difference between the two arms over time in terms of pain intensity (d = -0.95, p = 0.001). (Ablin, 2023)

Did HBOT affect Fibromyalgia?

In terms of the questionnaires, at the start of the trial, all of the participants were diagnosed with FMS based on their combined score of WPI and SSS. Amazingly enough, following HBOT, 11 participants, constituting 37.9% of the cohort, no longer met the diagnostic criteria for FMS, using WPI and SSS scores, as opposed to 0% of the medication cohort. (Ablin, 2023)

According to Albin, the use of PPT has been common for diagnosing FMS and assessing treatment response.

The link between QST and other measures in improvement

The secondary results demonstrated parallels between QST and other measures. For the HBOT cohort, results on each of the 4 FMS questionnaires demonstrated a highly significant improvement with notable improvement in symptoms related to FMS and pain. CPM improved in both patient groups, and notably, the improvement in CPM efficacy was significantly correlated to improvement in Fibromyalgia index. (Ablin, 2023)

According to 3 additional sources (Chen, 2023)(Cao, 2023) (Atzeni, 2019) HBOT is a promising therapy for patients suffering from FMS. As Albin, et al. used QST to assist with the comparison of the patient’s pain thresholds before and after HBOT, QST can be an aid to be a measure of treatment success, when decreased pain sensitivity can be objectively measured and quantified.