When drug treatment does not work
Patients with chronic pain are usually treated with medication. The basic approach is to start with nonsteroidal anti-inflammatory drugs and switch to opioid drugs when pain is severe. Sometimes other techniques such as physical therapy or infiltration are also used, and even different interventions are combined. Unfortunately, these interventions are not correcting the central nervous system pain mechanisms that underlie the problem. So what can we do when the pain is so severe that it does not respond to any of these treatments? As a response, non-invasive brain stimulation therapies have been proposed over the past two decades to correct the underlying mechanisms of pain.
Non–invasive brain stimulation
Repetitive magnetic stimulation (rTMS) consists of the administration of a series of magnetic pulses using a coil on the scalp surface. It induces changes in cortical physiology in the sense of excitation or inhibition, depending on the stimulation parameters. rTMS has a promising field of application in neuropsychiatry, including the treatment of drug-resistant neuropathic pain.
Transcranial current stimulation (tCS) is based on the application of a weak electrical current (1 – 2 mA) to the brain by means of contact electrodes placed on the scalp. The tCS is easy to use, portable and safe. To date, although many studies show positive analgesic effects of tDCS, the evidence is not entirely consistent, mainly due to the heterogeneity of the research. For this reason, a panel of experts in this field has recently made modest recommendations on its effectiveness. Experts believe there is sufficient evidence to recommend tDCS as a level C (possible efficacy) intervention for neuropathic lower extremity pain and level B (probable efficacy) for fibromyalgia 1.
1 Lefaucheur, J. P., Antal, A., Ayache, S. S., Benninger, D. H., Brunelin, J., Cogiamanian, F & Marangolo, P. (2017). Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS).Clinical Neurophysiology,128(1), 56-92.