Analysis

An estimated 1 million cases of HZ, or shingles, are diagnosed in the United States annually.1 The incidence is estimated to be 4/1,000 in the general population. Both severity of symptoms and incidence rise sharply with age, doubling in each decade past the age of 50 as natural immunity decreases. Almost half of all individuals older than 85 years have experienced an outbreak.

Immunocompromised persons are at high risk. Keep in mind the prodromal symptoms of HZ when evaluating an atypical presentation of severe pain in this population and add it to the list of differential diagnoses. The prodromal pain can be severe and is often misdiagnosed.


Continue Reading

HZ manifests when the varicella-zoster virus reactivates within the dorsal root of spinal nerves or cranial sensory ganglia after remaining latent for decades. Replication of the virus within the infected neurons results in an inflammatory reaction causing sensory nerve damage and pain.2

Prodromal symptoms typically include a tingling, itching, burning sensation that lasts one to four days; occasionally headache, photophobia, pain, and malaise are also present.3 The acute stage presents as a painful maculopapular rash that usually follows a unilateral dermatomal distribution. The most commonly involved dermatomes are in the thoracolumbar area and the face.

Pain is described as sharp, stabbing, or burning and can range from mild to severe. The rash evolves into clusters of vesicles with an erythematous base. Vesicles turn into pustules that ulcerate and crust over in 7-10 days. Two to three weeks after the crusting stage, the rash usually resolves without further incident, occasionally leaving scarring and pigment changes.

Precautions

If ocular involvement is suspected, refer to an ophthalmologist for management.4 An adult or child who has not had varicella or received the varicella vaccine and is exposed to the HZ virus may develop a severe case of chickenpox.5 Approximately 20% of HZ patients develop postherpetic neuralgia (PHN), which can be debilitating and may last for several months.6

Treatment

Therapy has three objectives: Treat the acute viral infection, manage the acute pain, and prevent PHN. The best method to avoid pain is to prevent the outbreak by vaccinating against the virus. Zostavax is a live, attenuated HZ vaccine recommended for individuals older than 60 years.7 The vaccine is well tolerated and decreases the likelihood of the acute eruption phase and potential subsequent PHN phase but is not used for treatment once an outbreak has occurred. If HZ does occur, prompt treatment with an antiviral agent has been shown to increase the rate of healing, decrease the severity of the pain, and decrease the incidence and duration of PHN.8

Treatment with an antiviral agent is well tolerated and should be initiated within 72 hours of acute-phase onset. Three options are available: Acyclovir (Zovirax) 800 mg orally five times daily for seven days, famciclovir (Famvir) 500 mg orally three times daily for seven days, or valacyclovir (Valtrex) 1,000 mg orally three times daily for seven days. A topical lidocaine patch (Lidoderm) can be applied every 4-12 hours as needed, or capsaicin cream (Zostrix) applied three to five times daily for temporary pain relief. Opioids may be given for relief of moderately severe to severe pain.

Acetaminophen/oxycodone 5/325 mg (Percocet) or hydrocodone/ acetaminophen 5/500 mg (Vicodin) one to two tablets can be taken orally every four to six hours as needed.4 If PHN occurs, a regular dosing schedule of analgesics results in better pain control than dosing “as needed.”6 Tricyclic antidepressants induce pain relief independent of their effect on mood. The dosage of amitriptyline is started at 12.5-25 mg daily and may be increased to a maximum of 150 mg daily. Desipramine (Norpramin) is started at 12.5-25 mg daily and may be increased by 12.5-25 mg every three to five days to a maximum of 250 mg daily.

Anticonvulsants are helpful if the pain is shooting or stabbing in nature. Gabapentin (Neurontin) is started at 100-300 mg at bedtime and may be increased to 300-900 mg three times daily. Carbamazepine (Tegretol) 100 mg started orally at bedtime may be increased by 100 mg every three days until dosage is 200 mg three times daily. Any of the above mentioned medications may be combined with topical analgesics.Ms. Torgerson is a recent graduate of the family nurse practitioner program at Pacific Lutheran University in Tacoma, Wash.

References

1. Tyring SK, Diaz-Mitoma F, Padget LG, et al. Safety and tolerability of a high-potency zoster vaccine in adults over 50 years of age. Vaccine. 2007;25:1877-1883.

2. Decroix J, Partsch H, Gonzalez R, et al. Factors influencing pain outcome in herpes zoster: an observational study with valaciclovir. J Eur Acad Dermatol Venereol. 2000;14:23-33.

3. Volpi A, Gross G, Hercogova J, Johnson RW. Current management of herpes zoster: the European view. Am J Clin Dermatol. 2005;6:317-325.

4. Emedicine. Herpes zoster oticus.

5. MedlinePlus. Herpes zoster

6. Stankus SJ, Dlugopolski M, Packer D. Management of herpes zoster (shingles) and postherpetic neuralgia. Am Fam Physician. 2000;61:2437-2444.

7. CDC Media Relations Press Release. CDC’s Advisory Committee Recommends “Shingles” Vaccination.

8. Mounsey A, Matthew LG, Slawson DC. Herpes zoster and postherpetic neuralgia: prevention and management. Am Fam Physician. 2005;72:1075-1080.