Theta-Burst Stimulation of Forearm Muscles in Patients With Complex Regional Pain Syndrome: Influence on Brain and Clinical Outcomes

Abstract

Objective: Complex regional pain syndrome (CRPS) is a common pain condition characterized by the changes in the brain that are not yet addressed by conventional treatment regimens. Repetitive peripheral magnetic stimulation (rPMS) of muscles is painless and non-invasive and can influence these changes (the induction of brain plasticity) to reduce pain and improve motricity. In patients with CRPS, this open-label pilot study tested rPMS after-effects on the pain intensity and sensorimotor control of the upper limb along with the excitability changes of the primary motor cortex (M1).Methods: Eight patients with CRPS were enrolled in a single-session program. Patients were tested at pre- and post-rPMS over the flexor digitorum superficialis (FDS) muscle. The clinical outcomes were pain intensity, proprioception, active range of motion (ROM), and grip strength. M1 excitability was tested using the single- and paired-pulse transcranial magnetic stimulation (TMS) of M1.Results: In our small sample study, rPMS reduced instant and week pain, improved proprioception and ROM, and reduced the hemispheric imbalance of several TMS outcomes. The more M1 contralateral to the CRPS side was hyperactivated at baseline, the more pain was reduced.Discussion: This open-label pilot study provided promising findings for the use of rPMS in CRPS with a focus on M1 plastic changes. Future randomized, placebo-controlled clinical trials should confirm the existence of a causal relationship between the TMS outcomes and post-rPMS decrease of pain. This will favor the development of personalized treatments of peripheral non-invasive neurostimulation in CRPS.

Peripheral magnetic stimulation for chronic peripheral neuropathic pain: A systematic review and meta‐analysis

“…After reviewing and resolving any conflicts in screening, a total of 23 studies fulfilled the eligibility criteria and were included in the review. Of the included studies, 15 were randomized controlled trials, 14,21–34 5 were case series, 35–37 2 were case reports, 38,39 and 1 was a non‐randomized trial 40 …”

“…Studies were published across several countries (according to location of primary author) including Azerbaijan (n = 1), 37 Canada (n = 2), 35,38 Egypt (n = 4), 21,29,31,32 Germany (n = 1), 22 India (n = 1), 30 Italy (n = 2), 39,41 Japan (n = 1), 42 Poland (n = 2), 26,27 Romania (n = 1), 23 Russia (n = 1), 40 Thailand (n = 1), 33 Turkey (n = 1), 28 and United States (n = 5). 14,24,25,34,36 The total number of patients across all studies was 1123.…”

“…The type of neuropathic condition, study design, treatment groups, trial size, intervention characteristics, and duration of interventions are reported in Table 1. PMS was evaluated across several neuropathic pain disorders: carpal tunnel syndrome (n = 3), 24,27,33 chemotherapy-induced polyneuropathy (n = 1), 22 complex regional pain syndrome (n = 3), 28,35,39 diabetic peripheral neuropathy (n = 5), 25,26,30,34,37 glossopharyngeal neuralgia (n = 1), 38 lumbar radiculopathy (n = 2), 23,32 orofacial pain (n = 1), 41 phantom limb pain (n = 1), 14 post-herpetic neuralgia (n = 1), 29 post-traumatic neuroma/nerve entrapment (n = 1), 36 pudendal neuralgia (n = 1), 42 traumatic brachial plexopathy (n = 1), 31 and trigeminal neuropathy (n = 2). 21,40 Nine studies compared PMS to a sham device, while the other studies compared a number of different controls (physiotherapy, 23 physiotherapy and vitamins, 33 transcutaneous electrical nerve stimulation, 29 laser therapy 21,27 ), or no additional treatment above the standard of care.…”

“…21,40 Nine studies compared PMS to a sham device, while the other studies compared a number of different controls (physiotherapy, 23 physiotherapy and vitamins, 33 transcutaneous electrical nerve stimulation, 29 laser therapy 21,27 ), or no additional treatment above the standard of care. 30,40 Included studies used varying types of PMS devices including round coils, 21,28,42 figure-of-eight coils, 31,35,36,38 racetrack coils, 23,33 diamagnetic pumps, 39 wearable devices, 24,41 and magnetic mattresses. 26,27 The range of magnetic field intensities ranged from 0.1 to 1500 mT, with variable frequencies ranging from 1 Hz to 1 MHz (median 20 Hz [IQR 70 Hz]).…”

Checklist on the Quality of the Repetitive Peripheral Magnetic Stimulation (rPMS) Methods in Research: An International Delphi Study

“…It is non-invasive and painless with negligible side effects. Over the two last decades, this technique has gained popularity to reduce chronic pain or improve sensorimotor function in physiopathology and its clinical potential is currently being tested in several population ( 1 , 5 – 24 ).…”