Shingles and Chickenpox (Varicella-Zoster Virus)

Description

Alternative Names

Treatment for Postherpetic Neuralgia

Postherpetic neuralgia is difficult to treat. Once PHN develops, a multidisciplinary approach that involves a pain specialist, psychiatrist, primary care physician, and other health-care providers may provide the best means to relieve the pain and distress associated with this condition. At this time, some experts recommend the following treatment steps:

• First, topical preparations, usually the lidocaine skin patch (Lidoderm). Effective in many people without producing any known severe side effects.

If that fails:

• Low-dose tricyclic antidepressant, preferably nortriptyline (Pamelor, Aventyl).

If that fails:

• Gabapentin (an antiseizure agent). Starting with a low dose and increasing it until relief or severe side effects occur.

If that fails:

• Opioids or similar potent painkillers.

These treatments often fail to provide complete pain relief, although they can be very helpful for many patients. Even given the limitations of these proven treatments, one study reported that 70% of older patients with PHN received inappropriate pain medications.

Topical Substances for Postherpetic Neuralgia

Topical Pain Relievers. Creams, patches, or gels containing various substances can provide some pain relief.

• Lidocaine and Other Anesthetic Patches. A patch that contains the anesthetic lidocaine (Lidoderm) is approved specifically for postherpetic neuralgia (PHN). The patch appears to reduce pain and improve quality of life for many patients. One to four patches can be applied over the course of 24 hours. Another patch (EMLA) contains both lidocaine and prilocaine, a second anesthetic. These patches are expensive. The most common side effects are skin redness or rash.
• Capsaicin (Zostrix) is prepared from the active ingredient in hot chili peppers. An ointment form has been approved for postherpetic neuralgia. Its benefits are limited, however and it is uncertain whether they are meaningful for most patients. A new patch form that uses a higher than standard dose may be more effective than current options. In one study, it reduced pain by 33% in nearly half of patients. Capsaicin should not be used until the blisters have completely dried out and are falling off the skin. Capsaicin ointment should be handled using a glove, and applied to affected areas three or four times daily. The patient will usually experience a burning sensation when the drug is first applied, but this sensation diminishes with use. It may take up to six weeks for the patient to experience its full effect, however, and about a third cannot tolerate the burning sensation. Many find no benefit.
• Topical Aspirin. Topical aspirin, known chemically as triethanolamine salicylate (Aspercreme) may bring relief.
• Menthol-Containing Preparations. Topical agents containing menthol, such as high-strength Flexall 454, may be helpful.

Skin Coolants. Ethyl chloride (Chloroethane) and fluori-methane are chemicals that cool the blood vessels in the skin. Sprays that contain these chemicals are not anesthetics, but are used to inactivate the sensitive areas. To use the spray, the patient must be in a comfortable position. The spray bottle is held upside-down, about 12 to 18 inches from the targeted area, and the face must be covered if the spray is being used near the head.

Tricyclic Antidepressants

Tricyclic antidepressants relieve pain in up to two-thirds of patients. These agents not only relieve depression, which can be common in PHN sufferers, but certain tricyclics specifically block sodium channels, which play a role in causing pain in PHN. Nortriptyline (Pamelor, Aventyl), amitriptyline (Elavil, Endep), and desipramine (Norpramin) are standard agents.

According to one study, two thirds of patients obtain pain relief if they take tricyclics within three months to a year after a herpes zoster attack. The agents are less successful when taken after that. It may take several weeks for the drugs to become fully effective, however. They are much less successful in patients who experience burning pain or allodynia (pain that occurs with normally non-painful stimulus, such as a light touch or wind).

Unfortunately, tricyclics have side effects that are particularly severe in the elderly, who are also more likely to have PHN. Desipramine and nortriptyline have fewer side effects than amitriptyline and are preferred for older patients. Side effects include:

• Dry mouth.
• Blurred vision.
• Constipation.
• Dizziness.
• Difficulty in urinating.
• Disturbances in heart rhythm.
• An abrupt drop in blood pressure when standing up.

Anti-Seizure Drugs

Certain anti-seizure drugs have effects that block over-excitation of nerve cells and may be helpful for PHN patient.

Gabapentin. Gabapentin (Neurontin) is the most effective of these to date and is the first oral agent approved for PHN. Studies are reporting significant pain relief in patients with PHN and reduction in the use of opioids. Many patients also report improved quality of life, including better sleep. (It is also showing promise in combination with valacyclovir for reducing pain from an acute herpes zoster attack.)

Side effects include skin rashes, increased risk for infection, headache, dizziness, sleepiness, swelling, and upset stomach. Some people experience visual disturbances, ringing in the ears, agitation, or odd movements when drug levels are at their peak. These side effects may limit their value in older people who are at risk of falling. In general, however gabapentin is safer than the tricyclics for this group.

Other Anti-Seizures Agents. Other anti-seizure medications used for PHN include carbamazepine (Tegretol), valproic acid (Depakene, Depakote), and phenytoin (Dilantin), although they are not as beneficial as gabapentin. Newer anti-seizure agents, including lamotrigine, oxcarbazepine, topiramate, and zonisamide, are being investigated but no data supports their use for PHN as yet. Pregabalin is an investigative anti-seizure agent that has actions similar to gabapentin. A small 2003 study reported that some patients with PHN experienced over 60% reduction in pain and 50% improvement in sleep. Over 30% of those taking the drug withdrew because of side effects, however.

Opioids and Opioid-like Agents

Opioids. Powerful pain-killing opioid drugs may be needed in patients with severe pain that does not respond to tricyclic antidepressants. They may be delivered orally or using a patch. Oxycodone is the standard opioid for PHN. Methadone (Dolophine) may also be helpful. In one 2002 study of elderly patients, opioids were more effective than tricyclics and had fewer side effects. Although there is some concern that drug dependency may develop, studies indicate that if these narcotics are carefully monitored, they remain effective and the risk for addiction is very low. Side effects include nausea, sleepiness, and constipation.

Tramadol. Tramadol (Ultram) is a pain reliever that has been used as an alternative to opioids. It has opioid-like properties but is not as addictive. (Dependence and abuse have been reported, however.) It can cause nausea but does not cause severe gastrointestinal problems, as NSAIDs can. Studies suggest it might be very helpful for PHN patients, particularly those with heart problems or other conditions that preclude tricyclic antidepressants.

Investigative Agents

Cannabinoids. Cannabinoids are compounds in marijuana (cannabis), which may have properties that protect nerve cells. They are being studied for a number of nerve-disorders, including chronic nerve-related pain. In one study, it was effective in reducing pain and had no major side effects.

Mexiletine. Mexiletine (Mexitil) is an agent that dampens the peripheral nerves (those that connect the nerves in the skin, muscles, and organs to the central nervous system.) It is normally used for heart rhythm disorders, but is being used in some cases for PHN in patients who do not respond to standard agents. The agent can have adverse effects, including serious allergic reactions.

Psychologic Approaches

Stress Reduction Techniques. A panel of experts concluded that a number of relaxation and stress-reduction techniques were helpful in managing chronic pain. They include meditation, deep breathing exercises, biofeedback, and muscle relaxation. Such techniques may apply to those with severe pain from acute infection and from persistent long-term postherpetic neuralgia. [For more information, see Well-Connected Report #31, Stress.]

Behavioral Cognitive Therapy. Behavioral cognitive therapy is showing benefit in enhancing patients' beliefs in their own abilities for dealing with pain. Using specific tasks and self-observation, patients gradually shift their fixed ideas that they are helpless against the pain that dominates their lives to the perception that it is only one negative and, to a degree, a manageable experience among many positive ones. Cognitive therapy may be expensive and is often not covered by insurance. The skill of the therapist is also very important to its success.

Alternative Remedies

Many people with chronic pain, such as those with PHN, turn to alternative treatments for relief. It should be noted that few have been rigorously tested and some can be harmful. Among those tried for PHN include the following:

• Hypnosis. There are some reports that hypnosis may be useful for alleviating pain.
• Topical use of diluted apple cider vinegar. (No proof that this is effective at all.)
• Acupuncture. Although acupuncture is becoming increasingly popular for a number of painful conditions, one study reported that it offered no benefits for postherpetic neuralgia.
• Colostrum, a pre-milk fluid produced by mammals. This fluid contains transfer factor, a substance that carries immune factors and is being studied for viral disease.
• Pantothenic acid (Vitamin B5). (No proof of effectiveness.)

Procedures Used for PHN

Intrathecal Corticosteroid Injections. Intrathecal administration is injection of medication within the dura mater (the tough membrane surrounding the spinal cord). Some studies have reported that intrathecal injections of corticosteroids may relieve persistent PHN. According to a 2000 study, they are particularly beneficial in combination with the anesthetic lidocaine. In the study, more than 90% of PHN patients reported good to excellent pain relief for up to two years. Extreme sensitivity to touch (allodynia) was reduced by more than 70%. The procedure is invasive, however, and poses a risk for serious complications. Experts recommend this only as a last option.

Techniques to Block Pain. Certain surgical techniques in the brain or spinal cord have been used to block nerve centers associated with postherpetic neuralgia. These methods carry risk for permanent damage, however, and should be used only as a last resort when all other methods have failed and the pain is intolerable.