Acute Herpes Zoster of the Thoracic Dermatome

THE CLINICAL SYNDROME

Herpes zoster is an infectious disease that is caused by the varicella-zoster virus (VZV), which also is the causative agent of chickenpox (varicella). The thoracic nerve roots are the most common site for the development of acute herpes zoster. Primary infection in the nonimmune host manifests itself clinically as the childhood disease chickenpox. It is postulated that during the course of primary infection with VZV, the virus migrates to the dorsal root of the thoracic nerves. The virus then remains dormant in the ganglia, producing non clinically evident disease. In some individuals, the virus may reactivate and travel along the sensory pathways of the first division of the trigeminal nerve, producing the pain and skin lesions characteristic of shingles. The reason that reactivation occurs in only some individuals is not fully understood, but it is theorized that a decrease in cell-mediated immunity may play an important role in the evolution of this disease entity by allowing the virus to multiply in the ganglia and spread to the corresponding sensory nerves, producing clinical disease. Patients who are suffering from malignancies (particularly lymphoma), receiving immunosuppressive therapy (chemotherapy, steroids, radiation), or suffering from chronic diseases are generally debilitated and much more likely than the healthy population to develop acute herpes zoster. These patients all have in common a decreased cell-mediated immune response, which may be the reason for their propensity to develop shingles. This may also explain why the incidence of shingles increases dramatically in patients older than 60 years and is relatively uncommon in persons younger than 20 years.

SIGNS AND SYMPTOMS

As viral reactivation occurs, ganglionitis and peripheral neuritis cause pain, which is generally localized to the segmental distribution of the thoracic nerve roots. In most patients, the pain of acute herpes zoster precedes the eruption of rash by 3 to 7 days, often leading to erroneous diagnosis (see Differential Diagnosis). However, in most patients, the clinical diagnosis of shingles is readily made when the characteristic rash appears. Like chickenpox, the rash of herpes zoster appears in crops of macular lesions, which rapidly progress to papules and then to vesicles . As the disease progresses, the vehicles coalesce and crusting occurs. The area affected by the disease can be extremely painful, and the pain tends to be exacerbated by any movement or contact (e.g., with clothing or sheets). As healing takes place, the crusts fall away, leaving pink scars in the distribution of the rash that gradually become hypopigmented and atrophic.

Acute herpes zoster occurs most commonly in the thoracic dermatomes.

In most patients, the hyperesthesia and pain generally resolves as the skin lesions heal. In some, however, pain may persist beyond lesion healing. This most common and feared complication of acute herpes zoster is called postherpetic neuralgia, and the elderly are affected at a higher rate than the general population suffering from acute herpes zoster. The symptoms of postherpetic neuralgia can vary from a mild self-limited problem to a debilitating, constantly burning pain that is exacerbated by light touch, movement, anxiety, or temperature change or a combination. This unremitting pain may be so severe that it completely devastates the patient’s life, and ultimately it can lead to suicide. It is the desire to avoid this disastrous sequel to a usually benign self-limited disease that dictates the clinician use all possible therapeutic efforts for the patient suffering from acute herpes zoster in the thoracic nerve roots.

Age of patients suffering from acute herpes zoster.

Treatment

The therapeutic challenge of the patient presenting with acute herpes zoster involving the first division of the trigeminal nerve is twofold: (1) the immediate relief of acute pain and symptoms and (2) the prevention of complications, including postherpetic neuralgia. It is the consensus of most pain specialists that the earlier in the natural course of the disease that treatment is initiated, the less likely it is that postherpetic neuralgia will develop in the patient. Furthermore, because the older patient is at highest risk for developing postherpetic neuralgia, early and aggressive treatment of this group of patients is mandatory.

Nerve Blocks

Sympathetic neural blockade with local anesthetic and steroid via stellate ganglion block appears to be the treatment of choice to relieve the symptoms of acute herpes zoster involving the first division of the trigeminal nerve as well as to prevent the occurrence of postherpetic neuralgia. Sympathetic nerve block is thought to achieve these goals by blocking the profound sympathetic stimulation that is a result of the viral inflammation of the nerve and gasserian ganglion. If untreated, the sympathetic hyperactivity can cause ischemia secondary to decreased blood flow of the intraneural capillary bed. If this ischemia is allowed to persist, endoneural edema forms, increasing endoneural pressure and causing a further reduction in endoneural blood flow with irreversible nerve damage.

As vesicular crusting occurs, the addition of steroids to the local anesthetic may decrease neural scarring and further decrease the incidence of postherpetic neuralgia. These sympathetic blocks should be continued aggressively until the patient is pain free and should be reimplemented at the return of pain. Failure to use sympathetic neural blockade immediately aggressively, especially in the elderly, may sentence the patient to a lifetime of suffering from postherpetic neuralgia. Occasionally, some patients suffering from acute herpes zoster involving the first division of the trigeminal nerve may not experience pain relief from stellate ganglion block but will respond to blockade of the trigeminal nerve.

Opioid Analgesics

Opioid analgesics may be useful in relieving the aching pain that is often present during the acute stages of herpes zoster as sympathetic nerve blocks are being implemented. They are less effective in the relief of the neuritic pain that is often present. Careful administration of potent, long-acting narcotic analgesics (e.g., oral morphine elixir or methadone) on a time contingent rather than an as-needed basis may represent a beneficial adjunct to the pain relief provided by sympathetic neural blockade.

Adjuvant Analgesics

The anticonvulsant gabapentin represents a first line treatment in the palliation of neuritic pain of acute herpes zoster involving the thoracic nerve roots. Studies also suggest that gabapentin may help prevent the development of postherpetic neuralgia. Treatment with gabapentin should begin early in the course of the disease, and this drug may be used concurrently with neural blockade, opioid analgesics, and other adjuvant analgesics, including the antidepressants compounds if care is taken to avoid central nervous system side effects. Gabapentin is started at a dose of 300 mg at bedtime and is titrated upward in 300-mg increments to a maximum dosage of 3600 mg daily given in divided doses as side effects allow.

Antidepressant Compounds

Antidepressants may also be useful adjuncts in the initial treatment of the patient suffering from acute herpes zoster. On an acute basis, these drugs will help alleviate the significant sleep disturbance that is commonly seen in this setting. In addition, the antidepressants may be valuable in helping ameliorate the neuritic component of the pain, which is treated less effectively with narcotic analgesics.

Adjunctive Treatments

Topical application of aluminum sulfate as a tepid soak provides excellent drying of the crusting and weeping lesions of acute herpes zoster, and most patients find these soaks to be soothing. Zinc oxide ointment may also be used as a protective agent, especially during the healing phase, when temperature sensitivity is a problem. Disposable diapers can be used as an absorbent padding to protect healing lesions from contact with clothing and sheets.

Because the pain of herpes zoster usually precedes the eruption of skin lesions by 5 to 7 days, an erroneous diagnosis of other painful conditions (e.g., thoracic radiculopathy, cholecystitis) may be made. In this setting, the astute clinician will advise the patient to call immediately should rash appear as the diagnosis of acute herpes zoster is a possibility. Some pain specialist believe that in a small number of immuno-competent patients, when reactivation of virus occurs, a rapid immune response may attenuate the natural course of the disease and the characteristic rash of acute herpes zoster may not appear. This pain in the distribution of the thoracic nerve roots without associated rash s called zoster sine herpete and is by necessity a diagnosis of exclusion. Therefore, other causes of thoracic and subcostal pain must be ruled out before invoking this diagnosis.

Low intensity laser therapy as well as a coordinated wellness program is also effective in treating this disorder.

Low Intensity Laser Therapy (LILT)

The low intensity Laser (LILT) sends photons (light) into the injured tissues and can penetrate two to three inches to treat affected areas. It uses a natural enhancement of the cellular machinery that can and has been dynamically measured in published studies to promote healing without burning affected tissue. Once the photons find the injured tissues, they stimulate and energize the cells to repair and strengthen at a remarkable rate. The treatment does not hurt, takes about 30 minutes and is very cost advantageous.

Wellness Program

A wellness program whichindividualizes treatment for age, performance and function has been shown in pilot studies to improve the overall health and well being of the individuals evaluated. A well conceived dietary and supplementary regimen based on scientific age–related decline in certain necessary compounds can improve quality of life, correct the ravages of hormone imbalance, balance critical neurotransmitter function without resorting to powerful drugs for depression that often have unfavorable side-effect profiles and restore vitality and youth in daily exercise routines. Furthermore, when wellness products are utilized with success, individuals often seek less costly interventions including unnecessary surgeries and narcotic options to treat pain. For more information go to www.drpwellness.com.