Elucidating the Central Mechanisms of Action for Green Light Therapy in Managing Chronic Pain

Official title

Elucidating the Central Mechanism(s) of Action for Green Light Therapy in Managing Chronic Pain

Overview

Investigators have previously shown that specific colors of light can alter nociception. Green light emitting diode exposure (GLED) provides long-lasting antinociception in rodents, through the visual system. No adverse effects were noted, and motor performance was not impaired. Investigator clinical trials have shown GLED is also effective in decreasing pain intensity of fibromyalgia patients and decreasing the number of headache-days per month in migraine patients. However, investigators do not yet understand the mechanisms by which GLED reduces pain. Understanding the mechanisms of action of GLED will provide additional support for using light therapy as both a treatment and as a possible diagnostic tool. While investigators do not fully understand the mechanisms of action of GLED, investigators do know that it is centrally mediated. To better elucidate the mechanism of action for GLED, investigators propose a single-blinded randomized placebo-controlled clinical trial to elucidate the central mechanism(s) of action that GLED therapy has in improving fibromyalgia pain, conducted by a team with a successful record of collaboration. Investigator's hypothesis is that GLED decreases neuroinflammation leading to modulation of the signaling in the ascending and descending pain pathways.

Detailed description

After a patient is consented, investigators will collect the baseline Fibromyalgia Impact Questionnaire survey (FIQ), thermal and mechanical pain detection and tolerance threshold, conditioned pain modulation (CPM), collect cerebrospinal fluid (CSF), and obtain positron emission tomography scan (PET scan) for microglia baseline activity. It is expected that the PET scan will take place on different day given the time needed and preparation for the completion of a PET scan. Investigators expect the baseline value collections to take 1-2 days to complete. Once all baseline values are obtained, the light therapy exposure will begin. The start of light exposure will be considered the start of Week 1. Investigators will follow up with the patient over the phone every 2 weeks +/- 1 week to ensure safety and compliance and to answer any questions the patient may have. Recruited patients will also have investigator's contact information to contact investigators with any urgent questions. At the end of Week 10, investigators will obtain the final values for the FIQ survey, thermal and mechanical pain detection and tolerance threshold, CPM, collect CSF, and obtain PET scan.

Interventions

• Device Green Light
  This is a low-energy device. It produces almost no heat because it uses an LED source for light. The device does not store energy or electrical power that can be discharged later.

Primary outcome measures

• Decreased activation of glial cells. [Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]]

Secondary outcome measures (4)

• Decreasing Central Nervous System inflammation (CNS), Increasing Endorphins. [Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]]
• Decreasing the activity of ascending pain pathway, and increasing the activity the descending pain pathway [Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]]
• Improvement in Fibromyalgia Impact Questionnaire score [Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]]
• Decreased objective and subjective pain scores to mechanical and thermal stimulation [Time frame: [Time Frame: 10 - 22 weeks, depending on study arm]]

Eligibility criteria

Inclusion criteria

• 18 years or older who can speak and understand English
• Meets the diagnostic criteria for fibromyalgia accroding to the 2016 revisions to the 2010/2011 fibromyalgia diagnostic criteria.
• Average numeric pain score of 5 out of 10 or greater over the 10 weeks prior to enrolling in the study, and failure of medical therapy to control their pain.

Exclusion criteria

• Serious mental illness defined as distortions of perception, delusions, hallucinations, and unusual behaviors resulting in loss of contact with reality. This will be assessed during the screening interview. Patients with psychiatric disorders will have their medical record reviewed prior to enrollment
• History of color blindness or uncorrected cataracts
• Subjects receiving remuneration for their medical condition.
• Genotype of low affinity binders for translocator protein, (TSPO), as patients with low affinity binding TSPO may not have adequate uptake for the radioactive tracer used for the PET scan.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

United States · 1 center

• Banner University Medical Center Multispecialty Services Clinic — Tucson

Publications

• Burckhardt CS, Clark SR, Bennett RM. The fibromyalgia impact questionnaire: development and validation. J Rheumatol. 1991 May;18(5):728-33. PMID 1865419
• Potvin S, Marchand S. Pain facilitation and pain inhibition during conditioned pain modulation in fibromyalgia and in healthy controls. Pain. 2016 Aug;157(8):1704-1710. doi: 10.1097/j.pain.0000000000000573. PMID 27045524
• Overstreet DS, Michl AN, Penn TM, Rumble DD, Aroke EN, Sims AM, King AL, Hasan FN, Quinn TL, Long DL, Sorge RE, Goodin BR. Temporal summation of mechanical pain prospectively predicts movement-evoked pain severity in adults with chronic low back pain. BMC Musculoskelet Disord. 2021 May 10;22(1):429. doi: 10.1186/s12891-021-04306-5. PMID 33971876
• Mackey IG, Dixon EA, Johnson K, Kong JT. Dynamic Quantitative Sensory Testing to Characterize Central Pain Processing. J Vis Exp. 2017 Feb 16;(120):54452. doi: 10.3791/54452. PMID 28287532
• Yarnitsky D, Bouhassira D, Drewes AM, Fillingim RB, Granot M, Hansson P, Landau R, Marchand S, Matre D, Nilsen KB, Stubhaug A, Treede RD, Wilder-Smith OH. Recommendations on practice of conditioned pain modulation (CPM) testing. Eur J Pain. 2015 Jul;19(6):805-6. doi: 10.1002/ejp.605. Epub 2014 Oct 20. PMID 25330039
• Yarnitsky D, Granot M, Nahman-Averbuch H, Khamaisi M, Granovsky Y. Conditioned pain modulation predicts duloxetine efficacy in painful diabetic neuropathy. Pain. 2012 Jun;153(6):1193-1198. doi: 10.1016/j.pain.2012.02.021. Epub 2012 Apr 3. PMID 22480803

Identifiers

NCT: NCT05569486 · 00000333

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗