Herpes zoster is a reactivation of the varicella-zoster virus (VZV), more commonly known as shingles. It can occur with natural infection or after immunization to varicella, although immunization-mediated zoster is less frequent. The reactivation can occur in any age group or demographic.
The primary risk factors for herpes zoster are increasing age and immunosuppression.
The clinical manifestations are typically a painful, one-sided, and dermatomal rash that begins with erythema or erythematous papules, progresses to erythematous vesicles or bullae, and can then become pustular. Pain is often described as burning, throbbing, or stabbing and may be present before any skin manifestations.
The thoracic dermatome is the most common location for this rash to present. The approximate breakdown for commonly involved dermatomes: thoracic (53%), cervical (20%), and trigeminal (15%), including ophthalmic and lumbosacral (11%). While rarer, multiple, usually contiguous, dermatomes or sides can be affected.
Herpes zoster should be on your differential diagnosis for any one-sided and dermatomal rash, and even a consideration should be made if it crosses the midline or is in two contiguous dermatomes. If it is in your differential diagnosis, then because of the complications that can happen from shingles it needs to be ruled in or out and accounted for in your treatment. This can be done with a viral culture of the rash, treating with one of the approved treatments, or ideally doing both when possible. The goal is to prevent or lessen any complications.
It should be noted that herpes zoster, especially in early disease presentation, can mimic cellulitis. It is thus sometimes necessary to run a bacterial culture, viral culture, and treat for both a cellulitis and herpes zoster while cultures are pending and then narrowing coverage based on culture data. This is especially true in high-risk areas, such as the ear or face.
The complications of shingles depend partially on location but can be devastating. Post-herpetic neuralgia occurs in 10-20% of cases. Other complications include, but are not limited to, herpes zoster ophthalmicus, herpes zoster oticus (Ramsay Hunt syndrome), aseptic meningitis, encephalitis, and Guillain-Barre.
The above paragraph discussed the use of viral cultures for the rash in the evaluation of shingles. Additionally, if a rash is noted in the first or second branches of the trigeminal nerve, a fluorescein stain should be performed in the clinic to exclude dendritic involvement, and the patient should follow up with an ophthalmologist. Similarly, lesions of or near the ear require otoscopic evaluation and close ENT follow-up.
Treatment is one of three approved agents: valacyclovir, acyclovir, and famciclovir. Most providers prefer valacyclovir and famciclovir for fewer daily doses, but some patients find that acyclovir carries a lower financial burden. The goal of treatment is to lower the duration and severity of illness and the risk of complications. For uncomplicated zoster, the evidence does not currently support a role for any adjunctive therapy such as gabapentin, TCAs, or glucocorticoids. It is still utilized in complicated zoster cases such as Ramsay Hunt or herpes zoster ophthalmicus, although the evidence behind this and which dosing to use is contested.
The prevention of shingles is done via vaccination. The only vaccine currently on the market in the United States is Shingrix. The vaccine is indicated for all patients age 50 and older and can be given, even if the patient has had a herpes zoster outbreak before. The vaccine reduces the incidence of shingles and post-herpetic neuralgia. In the two largest trials, Shingrix reduced the risk of developing herpes zoster by 90-97% and post-herpetic neuralgia by 89-99%.
Daniel Ralston, MD
Regional Medical Director
Peachtree Immediate Care
E-mail: dralston@peachtreemed.com
