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12/6/2000

Methylprednisolone Relieves Shingles Pain

Kate Traynor

Intrathecal injections of methylprednisolone relieve the painful neuralgia that sometimes persists long after the rash from shingles, or herpes zoster, resolves, according to a study conducted in Japan.

Throughout the two-year study, over 90 percent of the 89 patients who completed a four-week series of intrathecal methylprednisolone and lidocaine injections had "good or excellent" pain relief. This same level of relief was reported by, at most, 4 percent of the 91 patients given no treatment and 15 percent of the 90 patients given intrathecal lidocaine alone.

According to the report, which was published in the Nov. 23 New England Journal of Medicine, both the size of the most painful areas and the intensity of pain lessened after patients received methylprednisolone. Each patient whose pain decreased after a methylprednisolone injection maintained the same level of pain relief throughout the entire two-year follow-up period.

Only patients who had had postherpetic neuralgia for at least one year were eligible for the study. Before acceptance into the study, patients must have tried specific conventional treatments—topical analgesics, physiotherapy, epidural local anesthetics, and antidepressants or anticonvulsive drugs—without obtaining adequate relief.

In all study groups, patients had had the neuralgia—which typically manifests as severe burning, pain similar to that from an electric shock, and extreme sensitivity of the skin to normally nonpainful contact—for at least three years on average.

Patients in the two injection groups received either 3 mL of 3 percent lidocaine alone or 3 mL of 3 percent lidocaine mixed with 60 mg of methylprednisolone.

The same physician injected the drugs into each patient’s lumbar spine, in the L2-L3 intervertebral space, once a week for four weeks. The physicians who administered the intrathecal injections were aware of the patients’ random treatment assignment. Patients in the no-treatment control group were not given sham lumbar punctures.

In addition to the 270 patients who completed the study, seven patients enrolled but later withdrew from the trial. The researchers did not disclose the treatment assignments of these patients, at what point during the study they withdrew, why the patients did not complete the study, or whether they had reacted adversely to treatment. Data from these seven patients were excluded from analysis.

Except for the 24 hours preceding scheduled pain assessments, all patients could take up to 200 mg a day of diclofenac, a nonsteroidal anti-inflammatory drug. Starting four weeks after the treatment period, patients could also use topical analgesics and physiotherapy agents other than diclofenac to treat "unbearable pain." Use of these agents was not allowed during the two weeks preceding pain assessments, which were done just before randomization and repeated at four weeks and one and two years.

The use of intrathecal, epidural, or neurolytic nerve blocks, oral narcotics, and nonnarcotic analgesics other than diclofenac was prohibited during the two-year follow-up.

According to the diaries kept by the patients, the use of diclofenac decreased by 70 percent during treatment with methylprednisolone and the four weeks afterward. Use of diclofenac by patients in the lidocaine-only group decreased by less than 20 percent during treatment, then rose to initial levels afterward. Patients in the no-treatment group used the same amount of diclofenac throughout the study.

The study authors stated that none of the patients in the methylprednisolone group had adverse reactions or recurrent pain during the follow-up period. However, the authors did not disclose whether any patient had complications from the injection procedure.

Pharmacia Corp., manufacturer of the Depo-Medrol brand of injectable methylprednisolone acetate, advises against intrathecal use of the drug because this administration method has been associated with "severe medical events." The study authors did not specify the source of the methylprednisolone acetate that they used.

Patients whose symptoms suggested involvement of the trigeminal nerve were excluded from the study. The researchers also excluded patients with immunodeficiency or neurologic diseases and patients whose postherpetic neuralgia had been treated with neurolytic nerve blocks.

Patients in the methylprednisolone group were 63 years old on average, while patients in the lidocaine-only and control groups were 65. Forty-two percent of methylprednisolone, 47 percent of lidocaine-only, and 43 percent of control group patients were women.