Nov. 22, 2000 -- Once the unsightly, red blisters of shingles go away, the agony of the herpes zoster infection has only just begun for those patients who develop the excruciating complication called postherpetic neuralgia. Because the burning, stabbing pain lasts for months or even years, and can be triggered by even the lightest breeze or even the touch of clothing on the affected area, many patients are afraid to leave the house, and may even contemplate suicide.
Although there are currently no good treatments for postherpetic neuralgia, a new study reported in the Nov. 23, 2000 issue of The New England Journal of Medicine showed that injecting steroids into the spinal canal offered "impressive pain relief." The steroid methylprednisolone relieves pain by decreasing inflammation around the source of the nerves, suggest authors Naoki Kotani, MD, and colleagues from the anesthesiology department at the University of Hirosaki School of Medicine in Japan.
"You have to try the usual treatments first," C. Peter N. Watson, MD, tells WebMD. These include anesthetic skin patches, capsaicin cream, antidepressant and antiseizure medications, anti-inflammatory drugs that don't contain steroids, and even narcotics.
"This was a single study following a limited number of people for a limited amount of time," says Watson, an assistant professor of medicine at the University of Toronto in Canada, and author of an accompanying editorial. Although the treatment appeared to be safe and effective for up to 2 years, potential complications could include nerve damage from scar tissue around the nerve roots, which could become evident later.
The researchers followed nearly 300 patients who had postherpetic neuralgia for at least one year, and divided them into three groups. Patients with postherpetic neuralgia involving the face were excluded from the study. One group had a steroid and an anesthetic injected into the spinal fluid through a needle inserted in the lower spinal canal; one group was injected with only anesthetic; and the third group received no treatment. Injections were given once weekly for up to 4 weeks.
In the group receiving injections of the steroid and anesthestic, the intensity and area of pain decreased by almost three-quarters, as did the need for anti-inflammatory drugs taken by mouth. Approximately 90% had good or excellent pain relief lasting up to 2 years, compared with fewer than 5% in those receiving no treatment. There were no complications related to the treatment, and MRI scans of the spinal cord showed no abnormalities.
The researchers measured concentrations of a chemical associated with inflammation in the spinal fluid. In patients treated with steroid injections, concentrations of this chemical decreased by about half. As those patients with the largest decrease in concentration had the most pain relief, it appeared that steroid injections relieve pain by decreasing inflammation.
Herpes zoster, caused by reactivation of the virus causing chicken pox, is the most common neurologic illness in the U.S., affecting up to 850,000 people each year. Approximately 10% of all patients, and up to three-quarters of those over age 70, develop postherpetic neuralgia. It is still too early to tell if vaccination against herpes zoster could prevent this dreaded complication.
Watson applauds the authors for a well-done and well-designed study, but recommends repeating it with larger numbers of patients followed for longer periods.