The clinical approach to the treatment and prevention of herpes zoster has been changing significantly, according to a presentation at the scientific sessions of the American Academy of Dermatology in Orlando, Fla.
“[Herpes zoster] is one of the hot topics recently, because if this talk was given a decade ago it would not have included key elements in timely and evidence-based management of this condition,” Dr. Lorraine L. Rosamilia told AAD attendees.
"Our issue locally, as a specialty referral clinic, is that we often see patients in a late fashion in the spectrum of zoster symptoms. Perhaps they have gone to urgent care, then to a primary care doctor, and then they come to us, sometimes with varying acute treatment regimens,” she said.
The dermatologist, who practises in State College, Pa., reviewed the types of treatments available today for acute therapy of herpes zoster and subsequent post herpetic neuralgia.
Standard initial antiviral therapy (like oral acyclovir) is recommended and should be initiated within 72 hours of a rash emerging, or if new skin lesions continue to appear and/or systemic complications develop. Treatment with the antiviral typically lasts for one week and will reduce the time for zoster lesions to resolve and decrease viral shedding and pain.
Signs that acute treatment is required
“I think that we find, though, that there is an art to medicine that we need to preserve,” Dr. Rosamilia said of acute therapy for any patient older than 50 years with the herpes virus. “Some people may not meet the criteria of 72 hours, but my gut feeling is that they still need therapy. We also need to determine if that patient is sick, take thorough histories and gauge the patient’s acuity. For instance, we decide if other specialists need to be involved in that patient’s care or if the patient needs to be hospitalized. Indications for this and likely the IV route of antiviral therapy includes the immunocompromised or patients with severe eye, neurologic or other systemic complications. Then we focus on evidence-based therapies for pain and perhaps post-herpetic neuralgia.”
"Topical antivirals do not work for zoster,” Dr. Rosamilia said “And there is conflicting evidence for reducing acute pain with TCAs, gabapentin and pregabalin.”
Prednisone, however, can reduce pain and improve the patient’s daily functioning, but its use will not lower the incidence of post-herpetic neuralgia.
Post - herpetic neuralgia (PHN) ensues when the virus is replicated in the basal ganglia, disrupting the sensory nerve and causing pain in the specific dermatome affected by zoster, Dr. Rosamilia explained.
"The pain will persist well after a rash is arrested,” she advised, “and we’re not talking about a week or two. We’re talking ‘down the road’, technically a month after the acute zoster eruption.”
Pain risk heightened
Patients with zoster face a 10 to 50% risk for PHN pain, especially in women, older patients, those with severe pain and broad distribution from the initial eruption. The pain may be expressed as allodynia, hyperpathia, or dysesthesia, and may last as long as 16 months, sometimes longer.
"At the one-month mark, if the patient is finding the symptom is persisting then you put them in the category of post-herpetic neuralgia,” said Dr. Rosamilia. “Two per cent of zoster patients can have PHN that lasts longer than five years.”
Several randomized trials have reported PHN pain may be reduced with the use of gabapentin/pregabalin, opioids (oxycodone, morphine, methadone, tramadol) and tricyclic antidepressants (TCA) (nortriptyline, desipprimamine, amitryptiline). A combination of gabapentin and TCA or gabapentin and opiate is more effective, but will manifest more side effects, particularly in an older population. Additionally, topical lidocaine and capsaicin are not first line options, she said, but there is anecdotal evidence of localized pain relief.
"If you have a patient who has more severe pain when they do present, obviously antivirals would be appropriate,” Dr. Rosamilia told the AAD audience. “You would consider prednisone, and often at that point I will start them on gabapentin as well to pre-empt post-herpetic neuralgia pain, and it’s important to see that patient [again] in about one month to assess rash and pain improvement.
"As for the prevention of post-herpetic neuralgia from the start, the only evidence-based modality for this is zoster vaccination, which is a field burgeoning with novel formulations and approaches,” Dr. Rosamilia added.
Originally publishedin The Chronicle of Skin & Allergy (Sept. 2017; 23(6):page 1,14,)