Doctors Soothe Nerve Pain With Tiny Ice Crystals

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Nerve pain may feel like fire, and doctors might be able to end it with ice.

Millions of people worldwide suffer from neuralgia, or nerve pain, which can be caused by damage from a range of conditions: diabetes, injuries or surgery. Cryoneurolysis, also known as cryoanalgesia or cryoneuroablation, is a way for doctors to freeze nerve pain right at the source.

As anyone who has stubbed a toe, burned a finger or wrenched a knee knows, an ice pack is a great way to relieve pain. Likewise, applying cold directly to a nerve is thought to mute the pain signal to the brain.

A more modern and precise use of cold in pain management for nerve pain began in 1961, when a group of scientists developed a special hollow tube with an insulated tip, containing liquid nitrogen that could reach temperatures of -190 degrees Celsius (-310 Fahrenheit). The term “cryoanalgesia” was coined in 1976 by a trio of doctors from Abindgon Hospital in the U.K., who reported in the Lancet on their success in treating 64 patients with “intractable pain,” some of whom found relief for more than seven months.

Dutch scientists have had some success with using cryoanalgesia to treat phantom limb pain in amputees. In one study of five patients published in the journal Pain Practice last December, freezing problem nerves in the stump of the amputated limb was highly effective in three of the subjects, with a 90 to 100 percent decrease in pain complaints after 2.5 years or more.

In a more recent study presented on Sunday at the annual meeting of the Society of Interventional Radiology, Stony Brook University School of Medicine researchers examined the effectiveness of cryoneurolysis in 20 patients with a range of pain conditions. The treatment begins with a small nick in the skin near the source of the pain. A radiologist inserts a probe, about the size of a needle used for a blood draw, that is carefully advanced toward the target nerves. The probe is cooled by pressurized gas, and creates ice crystals on the edge of the nerve.

“The effect is equivalent to removing the insulation from a wire, decreasing the rate of conductivity of the nerve. Fewer pain signals means less pain, and the nerve remains intact,” study leader William Moore said in a statement Sunday.

On average the patient’s pain scores dropped from 8 out of 10 on a visual scale to 2.4 out of 10 one week after treatment was applied. But the pain returned after about six months, increasing to an average of about 4 out of 10 for the patients. Repeat treatments may be needed as the patient’s nerves regenerate, according to Moore.

Nevertheless, “cryoneurolysis offers these patients an innovative treatment option that provides significant lasting pain relief and allows them to take a lower dose of pain medication -- or even skip drugs altogether,” Moore said.

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