This article published in the Journal of ECT in 2011 outlines a preliminary study conducted into the use of low-frequency TMS to treat neuropathic pain. Neuropathic pain can be highly debilitating, and pharmaceuticals are not always able to provide adequate relief.
In the article, the authors include a diagram that provides an overview of the pain sensation pathways and pain modulation system. These diagrams show areas of the brain that are also involved in mood regulation. The authors explain that this may account for the strong link between experiencing neuropathic pain and depression, and the benefit of antidepressant treatment for chronic pain.
Prior studies have shown benefits from using rTMS treatment for neuropathic pain, particularly when targeting the motor cortex. Due to the link in pain and mood systems, the authors were interested in the possible benefits of rTMS treatment protocols primarily used for depression on the treatment of pain-related symptoms. Previous studies have shown improvements in pain when using high-frequency (10 Hz) stimulation on the left dorsolateral prefrontal cortex (the most common protocol for depression). In this article, the authors conducted a study to instead examine the effect of using low-frequency stimulation on the right dorsolateral prefrontal cortex (another commonly used protocol for depression).
Nine participants with long-term refractory neuropathic pain received fifteen sessions of low-frequency (1 Hz) rTMS treatment. Four out of nine subjects experienced a significant improvement in their pain levels. Three of these subjects experienced benefits within the first week of treatment, and two subjects continued to experience benefits at their 2-3 month follow up. These preliminary findings provided promising evidence for the use of this protocol in treating pain, and provided a basis for future studies to continue investigating the optimisation of protocols.
