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

Abstract

While high-frequency transcranial magnetic stimulation (HF-rTMS) is now included in the armamentarium to treat chronic neuropathic pain (NP), direct-current anodal stimulation (a-tDCS) to the same cortical targets may represent a valuable alternative in terms of feasibility and cost. Here we performed a head-to-head, randomized, single-blinded, cross-over comparison of HF-rTMS versus a-tDCS over the motor cortex in 56 patients with drug-resistant NP, who received 5 daily sessions of each procedure, with a washout of at least 4 weeks. Daily scores of pain, sleep, and fatigue were obtained during 5 consecutive weeks, and functional magnetic resonance imaging (fMRI) to a motor task was performed in a subgroup of 31 patients. The percentage of responders, defined by a reduction in pain scores of > 2 SDs from pre-stimulus levels, was similar to both techniques (42.0% vs. 42.3%), while the magnitude of "best pain relief" was significantly skewed towards rTMS. Mean pain ratings in responders decreased by 32.6% (rTMS) and 29.6% (tDCS), with half of them being sensitive to only one technique. Movement-related fMRI showed significant activations in motor and premotor areas, which did not change after 5 days of stimulation, and did not discriminate responders from non-responders. Both HF-rTMS and a-tDCS showed efficacy at 1 month in drug-resistant NP, with magnitude of relief slightly favoring rTMS. Since a significant proportion of patients responded to one procedure only, both modalities should be tested before declaring a patient as unresponsive.

Beyond trial‐and‐error: Individualizing therapeutic transcranial neuromodulation for chronic pain

“…In a first head‐to‐head trial, while 10 Hz rTMS to M1 relieved peripheral neuropathic pain due to radiculopathy, anodal tDCS proved not better than sham stimulation (Attal et al, 2016). Two larger and cross‐over head‐to‐head trials, however, showed that both tDCS and rTMS could relieve neuropathic pain to comparable levels, with only a slight superiority of rTMS in the reported amount of pain relief (André‐Obadia et al, 2023; Bonifácio de Assis et al, 2022). In these two studies, responders to one technique were not necessarily responders to the other, probably due to the different mechanisms driving pain relief in each of them; the corollary being that both modalities probably deserve to be tested before declaring a patient as unresponsive to cortical neuromodulation (e.g.…”

Noninvasive Brain Stimulation for Cancer Pain Management in Nonbrain Malignancy: A Meta-Analysis

“…Te results of this study are comparable to those of a previous network metaanalysis that showed that the pain score of the rTMS group was signifcantly lower than that of the control group (SMD: −0.92, 95% CI: −1.56 to −0.28; P � 0.01), while that of the tDCS group was not (SMD: −0.70, 95% CI: −1.45 to 0.04; P � 0.06). Moreover, a recent head-to-head randomized trial showed that rTMS was superior to tDCS in improving neuropathic pain [51,52]. Te advantage of rTMS compared to tDCS and CES results from a higher intensity with a more focused electrical feld [53].…”

Non-invasive cortical stimulation for drug-resistant pain

“…One study contrasting their effects in patients with lumbosacral radiculopathy reported rTMS superiority 127 . However, patients unresponsive to conventional rTMS can also be alleviated by subsequent tDCS 128 , and two recent cross-over head-to-head trials in different neuropathic pain conditions reported similar global efficacy but a different subset of responding patients to each technique 129▪,130▪▪ . The use of tDCS as an add-on therapy to invasive procedures was recently reported in a small ( n =16) randomised study, where combining tDCS with dorsal root ganglion (DRG) stimulation provided better results than DRG alone 131▪ .…”