Electrical Implants Help Alleviate Arthritis Pain

Rheumatoid arthritis (RA) sufferers may soon benefit from embedded electrical implants that stimulate the vagus nerve to significantly reduce joint pain.

Developed by researchers at the Academic Medical Center (AMC; Amsterdam, The Netherlands) and GlaxoSmithKline (Brentford, United Kingdom), the implant is a small neurostimulation device implanted under the skin that sends electrical signals to electrodes surgically inserted into the neck adjacent to the vagus nerve. According to the researchers, the stimulation results in activation of acetylcholine receptor type 7 (α7nAChR) in the spleen, a receptor intimately involved in the cholinergic anti-inflammatory pathway (CAP).

The researchers studied the effects of α7nAChR activation in an animal model of RA, and showed that the stimulation of the CAP by vagus nerve stimulation improved experimental RA. Conversely, they also found an aggravation of arthritis activity after unilateral cervical vagotomy, as well as in mice with α7nAChR-knockout, in which they observed an increased production of mediators of inflammation and degradation. The study was published on November 20, 2014, in Best Practice and Research in Clinical Rheumatology.

“Even in patients who have failed everything, including the most modern pharmaceuticals, we have seen a clear trend of improvement,” said lead author Prof. Paul-Peter Tak, MD, PhD, in an interview with Sky News. “We may be able to achieve remission in 20%–30% of patients, which would be a huge step forward in the treatment of rheumatoid arthritis. It is very appealing to patients because they do not want to take medicines for 30 to 40 years. It’s also restoring the natural balance in the body.”

Because the vagus nerve is associated with many different functions and brain regions, research is being done to determine its usefulness in treating other illnesses as well, including various anxiety disorders, Alzheimer's disease, migraines, fibromyalgia, obesity, and tinnitus. For the study, the researchers used the Cyberonics (Houston, TX, USA) VNS system, originally developed for the treatment of epilepsy, which consists of a titanium-encased generator with a lithium battery to fuel the generator, a lead wire system with electrodes, and an anchor tether to secure the leads to the vagus nerve.

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Academic Medical Center
GlaxoSmithKline
Cyberonics