Imaging the Effects of rTMS on Chronic Pain

Chronic pain is highly prevalent in patients with opioid use disorder on methadone maintenance therapy, and associated with problems related to psychosocial functioning, medical and psychiatric health, and substance craving and use. Neuroimaging has strongly correlated pain processing with the medial prefrontal and dorsal anterior cingulate cortices. This study will investigate the effects of repetitive transcranial magnetic stimulation (rTMS) using the H7 coil targeting these same brain areas for the treatment of chronic pain in patients on methadone maintenance therapy,and magnetic resonance imaging and spectroscopy (MRI/MRS) will be used to evaluate target engagement and mechanism.

The research aims of this study are to (1) investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) of the medial prefrontal cortex and dorsal anterior cingulate cortex for the treatment of chronic non-cancer pain in participants with opioid use disorder on methadone-maintenance therapy, and (2) investigate target engagement by measuring changes in gray matter volume and glutamate-glutamine in these brain regions by magnetic resonance imaging and spectroscopy. Given the high incidence of chronic pain in the OUD population and specifically the methadone-maintained population, there is great need for effective treatments. Untreated chronic pain contributes to medical and psychiatric problems, reduced quality of life, and increased risk of substance use and overdose. Non-invasive neuromodulation like rTMS, which is currently FDA-approved for treatment-resistant depression and OCD, holds promise as a safe and effective therapeutic. This project will investigate rTMS of brain regions known to process the affective and cognitive components of chronic pain, utilizing a treatment protocol modeled after the FDA-approved protocol for obsessive-compulsive disorder.

Volunteers will be randomized in a double-blind manner to 25 sessions (5 weeks) of either active high-frequency rTMS or sham stimulation. Participants will regularly complete measures to evaluate changes in pain severity and interference. The primary clinical outcome measures will be pain severity and interference scores on the Brief Pain Inventory (BPI). Additionally, participants will undergo MRI/MRS scans before and after the 5 weeks of rTMS to evaluate target engagement and help elucidate the potential mechanism of action of the intervention.

Eligibility Criteria:
Inclusion Criteria:

1. Chronic pain (back pain, osteoarthritis, complex regional pain syndrome, phantom limb pain, thalamic pain, pain related to injury of nerve plexus/plexi, or neuropathic facial pain).
2. Able to give informed consent, and comply with study procedures.
3. Opioid use disorder, moderate or severe.
4. Enrolled in methadone maintenance treatment program for at least 2 months and at least 1 month on a stable dose of methadone (up to 300mg/day).

Exclusion Criteria:

1. Medical conditions that preclude rTMS, including glaucoma, increased intracranial pressure, cardiac disease, migraine disorder, cerebral vascular events (CVA, TIA) any brain lesions (such multiple sclerosis),or seizure disorders.
2. Meet DSM-5 criteria for major psychiatric illness, such as bipolar disorder, major depression (severe), suicidal thoughts, mania, or psychosis, that would interfere with participation or pose a risk for rTMS.
3. Cognitive disorder.
4. Currently pregnant.
5. Metal implants or paramagnetic objects contained within the body which may interfere with the MRI scan, as determined in consultation with a neuroradiologist and according to the guidelines set forth in the following reference book commonly used by neuroradiologists: "Guide to MR procedures and metallic objects" Shellock, PhD, Lippincott-Raven press, NY 1998.14. This includes metal or shrapnel or bullet in the head or body, including metal shavings.
6. Subjects with positive responses to the Transcranial Magnetic stimulation Adult safety screen (TASS).
7. Currently taking a medication known to increase the risk of seizure.
8. Subjects with claustrophobia making them unable to tolerate MRI scanning.
9. Subjects involved in litigation regarding injury or worker's compensation benefits.
10. Subjects with a diagnosis of vasculitis, peripheral vascular disease, peripheral neuropathy, small-fiber neuropathy, or fibromyalgia.