[ RadSafe ] Low-Dose Radiation Numbs Lengthy Post-Shingles Pain

[Susan Gawarecki]

Low-Dose Radiation Numbs Lengthy Post-Shingles Pain
   
By Ed Susman , MedPage Today Staff Writer

DENVER, Oct. 20 - Low-dose radiation could help relieve long-lasting 
post-herpetic neuralgia that often trails a painful herpes zoster 
outbreak, Swiss researchers reported.

"We think that radiation is at least as good as antiviral drugs in 
preventing post-herpetic neuralgia," said Mohammed Suleiman, M.D., a 
radiation oncologist at Hospital of Sion in Switzerland. "This 
treatment," he said, "could be an alternative for people who can't take 
antiviral medications," such as Zovirax (acyclovir) and Valtrex 
(valacyclovir).

Post-herpetic neuralgia endures in about 12% to 15% of people after 
shingles and can last for months or years, he noted at a poster 
presentation during the American Society for Therapeutic Radiology and 
Oncology meeting here.

Since 1975, Dr. Suleiman and colleagues have investigated using low-dose 
radiation directly to the rash to relieve acute pain and post-herpetic 
neuralgia. In the U.S. more than 800,000 people a year suffer attacks of 
shingles, triggered by the varicella zoster virus that caused chickenpox 
when they were youngsters.

In a retrospective study, 108 patients were studied in three treatment 
periods. From 1975 to 1983, patients received a total radiation dose of 
1,250 centigray; from 1983 to 2000, the dose was 1,500 centigray. From 
2000 to the present, the dose drifted between 225 and 640 centigray.

Despite the lower dose in the last group, 89% of the patients irradiated 
within the first week of the acute attack were pain relief at three 
months. By one year, 93% were pain free, Dr. Suleiman said. If the 
patients came for treatment between a week and one month, about 88% were 
pain free at one year, he said.

Patients were treated three times a week for two weeks. At each visit, 
radiation was directed 5 cm to 7 cm into the ganglia with a fraction of 
the total radiation dose.

Before radiation, 53 people complained of severe pain, 53 of moderate 
pain, and the others of mild or noticeable pain. By six months, all but 
11% of patients were pain free. Other reports, Dr. Suleiman said, 
indicate that lingering pain remains in about 20% of patients taking 
oral medication.

Although the radiation dose is only about one-tenth of that used to 
treat cancer, there is a risk of radiation-induced cancer developing 
years down the road, Dr. Suleiman noted. "But we have not seen any 
secondary cancers, even in patients treated 28 years ago," he said.

Phillip M. Devlin, M.D., director of brachytherapy at Brigham and 
Women's Hospital in Boston, a Harvard teaching hospital, said the 
researchers "raise a fascinating phenomenon" that should undergo further 
testing.

However, Dr. Devlin urged caution in using radiation to treat conditions 
other than cancer because ionizing radiation itself carries a finite 
risk of radiation-induced cancer.

Dr. Suleiman suggested that the radiation may work because it has 
anti-inflammatory, antiviral, and antipain effects. He noted that 
patients successfully treated with radiation and who achieved pain-free 
status did not have a recurrence of pain. He said he would welcome a 
controlled clinical trial.

Primary source: American Society for Therapeutic Radiology and Oncology 
47th annual meeting
Source reference:
Suleiman, M. Abstract 2333, Radiotherapy for Herpes Zoster in the Acute 
Phae: A Retrospective Study with A Long Follow-Up