Treatment for Postherpetic Neuralgia:

Postherpetic neuralgia (PHN) is difficult to treat. Once PHN develops, a patient may need a multidisciplinary approach that involves a pain specialist, psychiatrist, primary care physician, and other health care providers.

The American Academy of Neurology (AAN) treatment guidelines for postherpetic neuralgia recommend:

• Tricyclic antidepressants (amitriptyline, nortriptyline, desipramine, maprotiline)
• Anticonvulsants (gabapentin and pregabalin)
• Lidocaine skin patches
• Opioids (oxycodone, methadone, morphine)

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). One to four patches can be applied over the course of 24 hours. Another patch (EMLA) contains both lidocaine and prilocaine, a second anesthetic. 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. A patch form that uses a higher than standard dose may work better. Patients should not use capsaicin until the blisters have completely dried out and are falling off the skin. They should handle capsaicin ointment using a glove, and apply it to affected areas three or four times daily. The patient will usually feel a burning sensation when the drug is first applied, but this sensation diminishes with use. It may take up to 6 weeks for the patient to feel the ointment's full effect, and about a third of patients cannot tolerate the burning sensation.
• Topical Aspirin. Topical aspirin, known chemically as triethanolamine salicylate (Aspercreme), may bring relief.
• Menthol-Containing Preparations. Topical drugs 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 they 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 - 18 inches from the targeted area. 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 drugs 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 drugs.

They may be more effective when started during the first year after symptoms begin. It may take several weeks for the drugs to become fully effective. They do not work as well in patients who have 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 urinating, disturbances in heart rhythms, and an abrupt drop in blood pressure when standing up.

Anticonvulsant (Anti-Seizure) Drugs

Certain anticonvulsant drugs have effects that block over-excitation of nerve cells and may be helpful for PHN patient. (Anticonvulsant drugs are also known as anti-seizure drugs.)

Gabapentin. Gabapentin (Neurontin) was the first anticonvulsant drug approved for PHN. Studies suggest 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. Gabapentin is also showing promise in combination with valacyclovir for reducing pain from an acute herpes zoster attack.

Side effects include skin rashes, mood swings or thoughts of suicide, headache, dizziness, sleepiness, swelling, and upset stomach. Some people have 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 tricyclic antidepressants for elderly patients.

Pregabalin. Pregabalin (Lyrica) is similar to gabapentin. Like gabapentin, side effects can include sleepiness and dizziness

Other Anticonvulsant Drugs. The AAN guidelines found insufficient evidence to recommend carbamazepine (Tegretol).

Opioids and Opioid-like Drugs

Opioids. Patients with severe pain that does not respond to tricyclic antidepressants may need powerful painkilling opioid drugs. They may be taken by mouth or delivered through a skin patch. Oxycodone is the standard opioid for PHN. Morphine is also used. Methadone (Dolophine) may also be helpful. Constipation, drowsiness, and dry mouth are common side effects of opioids.

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 not 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 restrict tricyclic antidepressants.

Other Medical Treatments

Antiviral Drugs. Researchers are investigating whether treatment with antiviral drugs may help reduce the pain associated with postherpetic neuralgia.

Surgery. Certain surgical techniques in the brain or spinal cord attempt 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. Most studies indicate that surgery does not relieve PHN pain.

Psychologic Approaches

Stress Reduction Techniques. A number of relaxation and stress-reduction techniques may be helpful for managing chronic pain. They include meditation, deep breathing exercises, biofeedback, and muscle relaxation. These techniques may apply to patients with severe pain from acute infection or persistent long-term postherpetic neuralgia. [For more information, see In-Depth 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 a manageable experience. The skill of the therapist is very important to its success.

Alternative Remedies

Many people with chronic pain such as PHN turn to alternative treatments for relief. Aside from hypnosis, little evidence indicates that these treatments work for PHN. Acupuncture is one such unproven remedy.