Exploratory study of optimal parameters of repetitive transcranial magnetic stimulation for neuropathic pain in the lower extremities

Abstract

Supplemental Digital Content is Available in the Text. Repetitive transcranial magnetic stimulation to the foot or hand's primary motor cortex at intensities below the resting motor threshold may be optimal for leg pain.

Non-invasive cortical stimulation for drug-resistant pain

“…It underscored their multiple biases due to low patient samples, absent blinding, lack of follow-up, no report on withdrawals, etc., but also recognised ‘low-quality evidence’ of positive rTMS effects on chronic pain and quality of life up to 6 weeks post-intervention. Between 2018 and 2023, at least seven new controlled studies (single/double-blinded, with at least 20 patients in the active group) have been reported on motor cortex rTMS in chronic neuropathic pain, with positive results in all but one of them 36–39▪,40▪▪ – 42▪ . A recent report of the US Department of Veterans Affairs using a ‘best-evidence approach’ concluded that rTMS, which has fewer side effects compared to most approved pharmaceuticals for neuropathic pain, ‘could be a treatment option for patients who have exhausted other available options for treatment of chronic pain’ 43▪▪ .…”

“…Stimulus intensity is universally set at 80–90% of the motor threshold; conversely, the optimal number of pulses per session has been variously considered as being 1000 51 , 1200 2 or even 3000 pulses 1 . One recent comparative study reported significant analgesia in neuropathic pain when using 2000 pulses, but not 500 42▪ . An excessive number of stimuli, however, can reverse the effects of rTMS in humans 52 , and trigger allodynia in rodents 53 , hence more than 3000 stimuli per session are not advised.…”

“…While a somatotopic match between the cortical stimulus and the painful region may be critical for neurosurgically implanted motor cortex stimulation 54,55 , it appears much less relevant for rTMS, whose pain-relieving effects seem independent of any strict relation between pain location and rTMS placement over the motor homunculus 56,57 , and in patients with facial or leg neuropathic pain, the stimulation of the hand area proved as efficacious, or better, than that of the somatotopically corresponding area 4,42▪,58,59 .…”

Cerebellar TMS Induces Motor Responses Mediating Modulation of Spinal Excitability: A Literature Review

“…Transcranial Magnetic Stimulation (TMS) is a widely used technique for assessing neural circuit function within the brain [ 9 , 10 ]. It is used to investigate motor control in the primary motor cortex [ 11 , 12 ], test neuromodulation treatments [ 13 , 14 ], and probe cerebellar function for motor control by applying TMS over the posterior fossa [ 8 , 15 ]. Figure 2 presents a simulation of the cerebellar electrical field generated by the default settings of the SimNIBS software (ver.…”

Better Fields or Currents? A Head-to-Head Comparison of Transcranial Magnetic (rTMS) Versus Direct Current Stimulation (tDCS) for Neuropathic Pain

“…Although methodological drawbacks limited the quality of evidence of early studies due to low patients' samples, absent blinding, lack of randomization and follow-up, etc. [3,4], a number of well-conducted studies using single or double-blinded methodology, randomization, and inclusion of more than 20 patients in active groups have been recently reported in chronic NP of various origins, with positive results when using stimulus frequencies of at least 10 Hz [5][6][7][8][9][10][11]. Accordingly, recent reviews concluded to a significant superiority over placebo of high-frequency (HF) motor cortex rTMS in chronic neuropathic pain [12][13][14][15], and clinical recommendations have now included HF-rTMS of the motor cortex as a "third line" therapeutic option, at the same level as spinal cord stimulation [16].…”