Researchers call for more evidence for TMS guidelines for pain

TMS, a non-invasive therapy, uses magnetic
fields to stimulate brain nerve cells.

by Anne Crawford

Monash researchers investigating Transcranial Magnetic Stimulation (TMS) therapy have responded to an international paper on proposed guidelines for pain treatment research using the technique by calling for more evidence.

The original paper was published in the journal Pain following a workshop sponsored by Harvard's Radcliffe Institute, which solicited advice from world experts in TMS, pain research and clinical trials. It recommended that researchers standardise and document parameters for research into TMS, a non-invasive technique that uses a magnetic field to electrically stimulate parts of the brain via a small coil placed on the patient’s scalp.


TMS devices were approved by the Food and Drug Administration in 2008 for depression, and are also used in the US for migraine and other conditions. However, while multiple studies report that high-frequency transcranial magnetic stimulation of the motor cortex reduces neuropathic pain, these have been insufficient to support FDA application for this use, the study notes. This prompted the workshop.

In Australia, TMS is used less widely than in the US, mostly for depression and some other psychiatric disorders.

Researchers including Dr Bernadette Fitzgibbon, Research Fellow at the Monash Alfred Psychiatry Research Centre, responded to the Klein et al. article agreeing with the need to standardise all assessment tools, instruments and metrics, and saying that the comprehensive guidelines would no doubt improve future research.

But they cautioned that it was too early to standardise TMS parameters and protocols or to limit treatment options to patient groups amenable to motor cortex stimulation, as proposed.

The researchers’ comment, published in May, points to the importance of investigating alternative brain sites to the motor cortex, and says the length of stimulation needed for best treatment outcomes had not yet been determined.

“It’s an excellent article and important because it sets the parameters and asks the major questions,” Dr Fitzgibbon said. “But I don’t feel the evidence is sufficient enough to answer the question of which groups of pain TMS works for or what the parameters are,” she said.

“TMS is not just used in one way, there are a lot of factors involved.

“My letter was a response to say that I don’t think we’ve answered all the questions – with other patient groups, with other brain sites, other types of pain, with the length and frequency of treatment – to definitely say that this is only relevant for neuropathic pain applied to the motor cortex,” she said.

“I felt the language was pushing the field in a direction where we also need to take a step back and say ‘yes, we do need to standardise our protocols, we do all need to be doing similar things but we also need to make sure we don’t miss out on something. We need to do the evidence first’.”

The paper itself noted that the best methods for using TMS in pain treatment were yet to be established and that more trials were needed to optimise design, she wrote.

Seeking participants

The Monash Alfred Psychiatry Research Centre is currently seeking volunteers for a clinical trial using repetitive Transcranial Magnetic Stimulation (rTMS) for fibromyalgia, conducting the study to see whether the symptoms associated with fibromyalgia can be reduced. For information:
https://ccs-clin-trials.med.monash.edu.au/trials/repetitive-transcranial-magnetic-stimulation-treatment-fibromyalgia

References

Fitzgibbon BM, Hoy KE, Guymer EK, Littlejohn GO, Fitzgerald PB. Repetitive transcranial magnetic stimulation for pain: is it too early to standardise repetitive transcranial magnetic stimulation protocols? Pain. 2016 May;157(5):1174-5.

Klein MM, Treister R, Raij T, Pascual-Leone A, Park L, Nurmikko T, Lenz F, Lefaucheur JP, Lang M, Hallett M, Fox M, Cudkowicz M, Costello A, Carr DB, Ayache SS, Oaklander AL.
Transcranial magnetic stimulation of the brain: guidelines for pain treatment research.
Pain. 2015 Sep;156(9):1601-14.