Shingles, also called herpes zoster, is a viral infection caused by the varicella virus. Data show that 95% of Americans contract chickenpox (varicella) by age 18 and that nearly 30% are affected by shingles before age 85.^1,2

Etiology

Shingles infection is more common in people older than 60, but anyone who has previously been infected with varicella in the form of chickenpox can develop shingles. The theory is that the varicella virus remains dormant in the cells of the peripheral nerves and is triggered by something that awakens or reactivates the virus, causing it to re-emerge in the form of herpes zoster years later.³What prompts the virus to awaken and cause problems in otherwise healthy people is not known. The term "zoster" refers to the dermal and neurologic components of the infection.

The majority of people who develop shingles are usually otherwise healthy. Regardless of this tendency, always evaluate patients with shingles for the possible presence of an underlying disease state that may influence its development. This includes conditions that alter the immune system, such as AIDS or cancer. Patients who have received chemotherapy or radiation treatments may also be at higher risk for developing shingles.

Family history appears to play a role in herpes zoster. A recent study of 504 patients treated for shingles found that the patients were 4.35 times more likely than control patients to have a first-degree relative with a history of the infection.⁴

Symptoms

The symptoms of shingles vary and are often vague. Patients typically feel them before they become apparent to visual observation. Symptoms first appear as flu-like symptoms - typically headache, nausea, sensitivity to light and, less commonly, fever. A generalized skin sensitivity develops and is present for a few days, followed by a readily identifiable rash. Pain along the course of a dermatome surfaces soon after the rash appears. Typically, only one side of the body is affected (reflecting the affected nerve root). But more than one dermatome on the same side may be involved.

Because the early symptoms of shingles mimic other conditions, the disease often is not diagnosed until it progresses and vesicles appear. For example, patients whose thoracic nerves are affected may suspect they are having cardiac or respiratory problems. Dermatome L3 runs across the lower back to the top of the hip, and symptoms in this area can be mistaken for appendicitis or a severe lumbar strain.

The first sign of a shingles attack can be isolated pain or numbness along a nerve or under the skin, or a shooting pain around the trunk, up over the face, or down the arm or leg. Allodynia - the severe discomfort that arises with such normal occurrences as clothes rubbing against the body or water striking the affected skin - is another common manifestation.

The shingles rash usually erupts 48 to 72 hours after the onset of nerve pain. The lesions of shingles appear along the dermatomes in the thorax or lumbar area, and they typically appear as a band or strip on one side of the body or as clusters extending on one side of the face and scalp in an area where the patient previously experienced pain. Less commonly, shingles rash can occur in the ophthalmic branch of the trigeminal nerve.

The typical shingles rash begins as a single blister, and it progresses in a linear fashion. The lesions first appear as an erythematous, macular-papular rash that rapidly develops into vesicles that coalesce and fill with fluid. The lesions continue to form for the next 3 to 5 days. The fluid associated with the blisters changes from clear to cloudy as the white blood cells absorb the varicella virus. Eventually the blisters heal and scab over. Scarring does not typically occur unless the lesions become infected.

Although shingles lesions are unsightly and may itch, a more bothersome problem is the accompanying nerve pain. Patients often describe the initial dermatome pain as stabbing or prickling, with some numbness and burning. (See the sidebar for my experience as a patient affected by shingles.)

The blister phase usually subsides after a few weeks, but the next phase can feature the infection's most dreaded consequence: postherpetic neuralgia (PHN). This is the persistence of pain beyond integument healing, or symptoms lasting more than 1 to 3 months after disease onset.

PHN pain, which patients often describe as burning and tearing, is chronic and persistent. Fifty percent of shingles patients older than 50 experience debilitating PHN pain for more than 1 month.⁵Sometimes, this pain lasts for years.⁵

Treatment

There is no cure for shingles, but prompt therapy may shorten the duration of external manifestations and, more importantly, limit neuralgia. Antiviral therapy is effective and should be initiated within 48 to 72 hours of symptom onset or as soon as possible after the rash appears.¹ dministering therapy within the effective time frame is often difficult because the disease usually is not diagnosed until the rash appears.

Three oral antiviral agents are available to treat herpes zoster (see table). The two newer agents are famciclovir (Famvir) and valacyclovir (Valtrex). Acyclovir (Zovirax), the oldest agent, differs from the other drugs in that it must be taken five times a day rather than three. Each of the drugs must be taken for 7 consecutive days. No evidence suggests that initiating therapy after the first 48 to 72 hours of symptoms is beneficial.⁶ owever, in an effort to shorten the disease course and prevent PHN, most providers prescribe antivirals as soon as the diagnosis is made, even outside the 72-hour window. More research is needed.

Pain relievers are a vital part of the plan of care for shingles. OTC analgesics and NSAIDs can be effective, but stronger prescription pain medications may sometimes be necessary. Other medications, such as pregabalin (Lyrica) and gabapentin (Neurontin), are approved for the treatment of nerve pain associated with PHN and can be quite effective at managing associated discomfort.⁷

Thankfully, shingles usually occurs only once in a lifetime. In rare instances, a second round may occur years later. This second bout usually involves a different dermatome.⁷