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UTRECHT, The Netherlands, Jan. 19 - An epidural injection of steroids with a local anesthetic did not provide the long-term pain relief doctors anticipated for patients suffering from post-herpetic neuralgia, researchers here said.

While the epidural modestly reduced pain for one month, the effect disappeared rapidly after that, said Albert J.M. van Wijck, M.D., of the University Medical Center Utrecht here. It was virtually absent at three months.

The results suggested that the single epidural injection approach -- currently used by many clinicians -- should be reserved for treating severe, acute shingles pain in patients not responding to standard analgesic therapy, Dr. van Wijck and colleagues said in the Jan. 21 issue of The Lancet.

The study involved nearly 600 patients 50 or older, with acute herpes zoster rash and significant pain. Half received standard therapy (oral antivirals and analgesics), and half received standard therapy plus an epidural injection of 80 mg of methylprednisolone acetate and 10 mg of bupivacaine.

At one month, significantly fewer patients in the epidural group reported zoster-associated pain (relative risk=0.83; 95% confidence interval=0.71-0.97; P=0.02).

By three months, however, there was not a clear significant difference between the groups (RR=0.89; 95% CI=0.65-1.21; P=0.47), and by six months, the end of the study period, the effect had disappeared altogether, the researchers said.

The study was not blinded, because that would have been too difficult to maintain, and the study was not placebo-controlled, because the potential risks of a sham epidural to a placebo group could not be justified, the authors said.

For the time being, the Dutch team recommended the more burdensome approach of hospitalizing patients with chronic severe shingles pain that is not responding to standard treatment. There, giving corticosteroids and anesthetics via an epidermal catheter for one to three weeks may be the best option, the authors suggested. Recent research has shown this approach to be effective, they added.

The lack of efficacy demonstrated by this study shows “that the invasive procedure of epidural injection with steroids and local anesthetics in herpes zoster—which is commonly used in many countries—can not be recommended,” said Ralf Baron, M.D., of the Schleswig-Holstein University in Kiel, Germany, and Gunnar Wasner, M.D., of the University of New South Wales in Sydney, Australia, in a an editorial.