Patients with herpes zoster can become pain free despite persistent nerve damage
San Francisco, CA, September 26, 2013 – Persistent pain affects 100 million Americans—more than diabetes, heart disease, and cancer combined. Scientists at California Pacific Medical Center Research Institute (CPMCRI) are advancing what we know about the mechanisms and treatment of chronic pain.
With new findings recently published in the journal Pain and bevy of high-impact studies in pain research, Drs. Michael Rowbotham, Karin Petersen and their teams are incorporating human experimental pain models into the testing of new analgesic drugs for chronic neuropathic pain, including pain following herpes zoster (shingles), pain resulting from chemotherapy for cancer, post-stroke pain, and the pain experienced by melanoma patients after surgery. They are at the forefront of understanding the transition from acute to chronic pain, and developing novel protocols for treatment.
Drs. Rowbotham and Petersen’s latest study sheds new light on patients’ recovery from herpes zoster, a viral disease commonly accompanied by severe pain called post-herpetic neuralgia (PHN).
“This is the most comprehensive study re-examining patients years after their herpes zoster outbreak, to assess their experience with pain. And even though nerve damage persisted, patients still recovered in terms of becoming and remaining pain free,” said Karin Petersen (MD), a scientist at CPMCRI and first author of the study.
In collaboration with researchers in Albany, Drs. Petersen and Rowbotham assessed the pain of patients who had completed an observational six-month study of the natural history of herpes zoster. Forty-three of the original 94 patients in the observational study were tested for pain and sensory symptoms, and skin biopsies were obtained, after a median of 3.9 and 7.7 years following their first onset of herpes zoster.
After 3.9 years, none of the 29 patients who were pain free at six months experienced a return of pain. One patient with PHN at six months was symptom-free at 3.9 years but had mild pain at 7.7 years. Sensory nerve function was shown to partially recover but was still abnormal in many patients, and even at 7.7 years there were no signs of nerve regrowth in skin affected by herpes zoster.
"Although the incidence of clinically meaningful post-herpetic neuralgia may be small, its severity and impact is large,” said Michael Rowbotham (MD), a co-author of the study and Scientific Director of the Research Institute at CPMC. “These findings should reassure patients with acute herpes zoster that their pain will lessen over time."
Approximately one million people in the U.S. develop herpes zoster annually, and one third will still experience pain after three months of contracting the illness.