For someone with peripheral neuropathy, even the slightest touch can cause burning, stinging or shooting pain, usually in the hands or feet.
The pain is caused when the peripheral nervous system is damaged by diabetes, shingles, chemotherapy or some other medical condition. About 8% of adults worldwide suffer from some form of neuropathy. Medications prescribed to dull the pain – such as opioids, anti-depressants or gabapentin (Neurontin) — often prove to be ineffective, don’t last long or have unwanted side effects.
Scientists in Italy have now discovered an experimental way to treat neuropathy that provides pain relief for weeks at a time without the use of medication. In experiments on laboratory mice, researchers at the European Molecular Biology Laboratory (EMBL) in Rome identified a specific set of nerve cells in mouse skin that play a significant role in neuropathic pain.
When injected with a light-sensitive chemical and exposed to infrared light, these peripheral nerve cells pull away from the skin’s surface and stop sending pain signals. The pain-relieving effects of the light therapy appear to last for weeks.
The image shows the skin of a mouse, with the nerve cells that are responsible for sensitivity to touch highlighted in green. These neurons are primarily located around hair follicles.
The EMBL’s research, first reported in the journal Nature Communications, is still in its early stages. But scientists say human skin tissue is similar to that of mice, indicating that light therapy might be effective in managing neuropathic pain in humans.
“In the end, our aim is to solve the problem of pain in both humans and animals,” says Paul Heppenstall, PhD, EMBL group leader. “Of course, a lot of work needs to be done before we can do a similar study in people with neuropathic pain. That’s why we’re now actively looking for partners and are open for new collaborations to develop this method further, with the hope of one day using it in the clinic.”
Heppenstall says light therapy works on the treated nerve cells the same way spicy food or capsaicin patches can cause nerve fibers to retract.
“It’s like eating a strong curry, which burns the nerve endings in your mouth and desensitizes them for some time,” says Heppenstall. “The nice thing about our technique is that we can specifically target the small subgroup of neurons causing neuropathic pain.”
There are many different types of nerve cells in skin, which respond to different sensations like vibration, cold, heat or normal pain. Researchers say those cells are not affected by the light treatment. The skin is only desensitized to a gentle touch, breeze, or tickling.
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