SYSTEMIC CONDITIONS
Herpes Zoster (Shingles)
Reactivation of the varicella-zoster virus causes infections in these patients.

Nearly 500,000 people a year are diagnosed with Herpes zoster, or shingles.¹ It's estimated that nearly 95% of adults in the United States have antibodies to the varicella-zoster virus.¹ The overall incidence is estimated to be around 15 to 20%.¹ The incidence of herpes zoster increases with age and is relatively rare in young patients. It tends to occur most frequently in the immunocompromised and elderly populations

Infection

The same virus responsible for chicken pox causes this condition. In this primary infection, the most contagious period begins on the day before onset of rash and five days after it appears. A single attack of chickenpox usually confers a lifetime of immunity. Reactivation of the virus typically occurs following a decrease in virus-specific cell-mediated immunity.

Although the exact mechanism as to why viral reactivation occurs is uncertain, it most commonly starts in the epithelial cells of the mucosa in the upper respiratory tract. The disease can be triggered by many factors, such as aging, stress, suppression of the immune system and certain medications. It can be isolated from the papule and clear vesicles for up to one week after the rash appears. Humans are the only natural host for this virus.

Although this virus is very contagious, fairly close contact must occur in order to transmit the active virus. If transmission does occur, the incubation period is 14 to 17 days.

Clinical presentation

Clinical manifestations of herpes zoster may be categorized into prodroman, acute and post-herpetic phases. Although there are a wide variety of presentations, one of the more common scenarios with herpes zoster is as follows: The patient presents with a prodrome consisting of hyperesthesia, paresthesias, burning dysesthesias or pruritus along the affected dermatome. This prodrome generally lasts between four and 24 hours but may precede the appearance of skin lesions by days, or in some cases, two to three weeks.

In most patients, the prodromal phase is followed by development of the characteristic skin lesions of herpes zoster. In the vast majority of patients, these lesions are unilateral and follow a "belt-like" pattern. The maculopapular rash evolves into vesicles with an erythematous base, which are typically very painful.

These painful eruptions are the most common complaint for which patients with herpes zoster seek medical care. This acute inflammation generally lasts anywhere from eight to 14 days. As the crusts fall off, patients are generally left with scarring and skin pigmentary changes.

The ophthalmic division of the trigeminal nerve is the most frequently involved cranial nerve dermatome. If this branch of the nerve is involved, the likelihood of ocular involvement is ex-tremely high.

Complications

The most common chronic complication of herpes zoster is postherpetic neuralgia. This is a situation in which the pain or neuralgia persists long after the outbreak itself has resolved. Affected patients usually report constant burning, lancinating pain that is often radicular in nature.

Diagnosis

In the majority of patients, diagnosis of herpes zoster is based primarily on clinical findings. However, in some patients, the presentation of herpes zoster can be atypical and may necessitate confirmatory testing, particularly in immunocompromised patients. One rapid and accurate method of confirming the diagnosis is through fluorescence microscopy in the first three or four days after the onset of lesions. You can obtain a Tzanck smear from the vesicular lesions. Serologic confirmation of diagnosis can also be made through the enzyme-linked immunosorbent assay (ELISA).

Treatment

As with any systemic condition, treatment begins with patient education. In the specific case of herpes zoster, coordinate care with the primary care physician to determine the status of a patient's immunity.

Encourage patients to trim and file fingernails to reduce the damage from scratching. In addition, bathing daily with antibacterial soap can prevent bacterial superinfection. A variety of medications including antiviral agents, oral corticosteroids and analgesics are available.

• Antiviral agents. These have a proven history of decreasing the duration of herpes zoster rash and helping with the pain associated with the rash. Examples include acyclovir (Zovirax, Glaxo Smith Kline), valacyclovir (Valtrex, Glaxo Smith Kline) and famciclovir (Famvir, Novartis).

• Corticosteroids. Oral prednisone used in combination with acyclovir has been shown to reduce the pain associated with herpes zoster.²

• Analgesics. The pain associated with herpes zoster varies, with some patients demonstrating mild, manageable pain to excruciating pain in others that requires narcotics.³

• Dermatologic agents. You can prescribe pramoxine/camphor/calamine cream to treat open lesions. Once the lesions have crusted over, capsaicin cream (Zostrix, AFT Pharmaceuticals) or topically administered lidocaine (Xylocaine, AstraZeneca) may provide relief.

Ocular involvement

Ocular complications occur in almost half of all patients with involvement of the ophthalmic division of the trigeminal nerve. The most common sequela from this is herpes zoster ophthalmicus, in which patients typically complain of nonspecific facial pain followed by a skin rash over one eye, respecting the vertical midline. This condition is almost always unilateral. Other ocular manifestations include follicular conjunctivitis, interstitial keratitis, uveitis, episcleritis or scleritis and chorioretinitis. If the anterior segment involvement is not brought under control, the virus continues to spread and may involve cranial nerves and result in optic neuropathy or isolated cranial nerve palsies (affecting cranial nerves 3, 4, or 6).

In general, there is no separate treatment for ocular herpes zos-ter. It is the same as treatment of systemic manifestations. Al-though most patients with ocular herpes zoster improve without lasting sequelae, some may develop severe complications, including loss of vision. The one notable exception is if the patient has uveitis or keratitis due to herpes zoster. In this case, many O.D.s will utilize a topical ste-roid and topical cycloplegic agent to help manage the uveitis and possibly a broad spectrum antibiotic for the keratitis.

1. Donahue JG, Choo PW, Manson JE, Platt R. The incidence of herpes zoster. Arch Intern Med 1995 Aug 7-21;155(15):1605-9.

2. Eaglstein WH, Katz R, Brown JA. The effects of early corticosteroid therapy on the skin eruption and pain of herpes zoster. JAMA Mar 9;211(10):1681-3.

3. Schmader K. Management of herpes zoster in elderly patients. Infect Dis 1999 Apr;28(4):736-9.

Dr. Gupta practices full scope optometry in Stamford, Conn. He's also clinical director of The Center for Keratoconus at Stamford Ophthalmology. Send an e-mail to Deegup4919@hotmail.com.