Light therapy to reduce chronic neuropathic pain

Promising work offers hope to people suffering from chronic neuropathic pain: the application of a combination treatment to the exposure of infrared radiation skin could relieve their pain and help them lead a normal life.

How to succeed in carrying out daily activities when the movement of a single hair on the arm can cause intense pain? This is the question that the 7 to 8% of people in Europe suffer from chronic neuropathic pain.

This chronic disease is linked to a dysfunction of the nervous system treating the neurological message of pain ("the circuit of pain") and proves to be a nightmare for those who suffer from it. Benefiting for the moment from any truly effective treatment, these neuropathic pain can be mild or intermittent.

However, for a tiny minority of patients, the pain felt is so intense that every day activity becomes a torment. The anomaly on the pain circuit can be either central (in the spinal cord or the brain) or peripheral. In this case, it is the contact of the skin with anything that causes the pain ("hyperpathy").

Cut the nerve endings of the skin

It is to these patients suffering from peripheral neuropathic pain that researchers attached to the European Molecular Biology Laboratory (EMBL) in Rome could help. Their work, published in the journal Nature Communications, focus on a series of cells called TrkB-positive and responsible for chronic pain. They also expose the treatment they have developed to relieve neuropathic pain in mice: a light-sensitive chemical that binds selectively to this type of nerve cell.

Researchers began by modifying TrkB-positive cells to make them sensitive to light. They then tested their treatment on mice, applying it on a parcel of skin sensitive to neuropathic pain. Exposed to infrared light, nerve cells retract from the surface of the skin, resulting in pain relief.

The use of light has the effect of cutting the nerve endings of the skin: the intense pain felt by neuropathic patients at the slightest skin contact disappears instantly. "It's like eating a strong curry, which burns the nerve endings in the mouth and desensitizes them for a while," says Dr. Paul Heppenstall, researcher at EMBL and lead author of the study. of our technique is that we can specifically target the small subgroup of neurons causing neuropathic pain. "

A test in vitro on human tissues

However, the treatment developed by Dr. Heppenstall's team is not permanent. Indeed, cut nerve endings grow back after a few weeks, again causing pain.

This does not prevent researchers from continuing their work, especially on human skin tissue in vitro. In studying it, they found that its overall composition and the specificity of its neurons appear to be similar to that of mice, indicating that the treatment could be effective in the management of neuropathic pain in humans.

"Of course, a lot of work needs to be done before we can do a similar study in people with neuropathic pain, which is why we are actively looking for partners and are open to new collaborations to develop this method, with the hope for one day to see her used clinically, "concludes Dr. Heppenstall.

Video: Laser Therapy for Chronic and Neuropathic Pain - Dr. Paul Bradley (December 2019).