Postherpetic Neuralgia: Causes and Treatment
Author: Thomas C. Weiss : Contact: Disabled World
Published: 2015-01-15 : (Rev. 2018-03-16)
Synopsis and Key Points:
Postherpetic neuralgia (PHN) is a neuropathic pain syndrome that happens after an outbreak of varicella-zoster virus (VSV) or shingles.
Postherpetic neuralgia (PHN) is the same virus that causes chickenpox. During the initial infection of chickenpox, the virus remains in the person's body, lying dormant inside nerve cells. Years later, illness, age, stress, medications, or decreased immune system function may reactivate the virus and cause a shingles outbreak. At times, there is no apparent reason for the outbreak.
After it has been reactivated, the virus travels along a person's nerve fibers, causing them pain. When the virus reaches a person's skin, it produces a rash and blisters. A shingles outbreak usually resolves within a month or so, yet some people continue to experience pain a long time after the rash and blisters heal. The pain is known as, 'postherpetic neuralgia.'
Some people who have experienced a reactivation of the virus develop postherpetic neuralgia. But postherpetic neuralgia is a common complication of shingles in seniors and older adults. The greater a person's age when the virus reactivates, the greater their chance for developing postherpetic neuralgia. In the majority of people, the pain of postherpetic neuralgia decreases over time. In the meantime, particularly if a person's symptoms are addressed early, treatments for postherpetic neuralgia may ease nerve-related pain. Neuralgia are generally limited to the area of a person's skin where the shingles outbreak first occurred, with symptoms and signs that include:
- Itching and numbness
- Sharp and jabbing, burning, or deep and aching pain
- Extreme sensitivity to touch and change of temperature
Causes of Postherpetic Neuralgia
Postherpetic neuralgia results when a person's nerve fibers are damaged during an outbreak of shingles. Damaged nerve fibers are not able to send messages from a person's skin to their brain as they usually do. Instead, the messages become confused and exaggerated and cause chronic, many times excruciating pain that persists for months or even years in the area where shingles first happened. The complication of shingles occurs far more often in older adults. Less than 10% of people under the age of 60 develop postherpetic neuralgia after experiencing shingles. Around 40% of people older than 60 experience the complication.
It is important to visit a doctor at the first sign of shingles. Treating shingles early, within 3 days of developing the rash, with oral antiviral medications might actually prevent postherpetic neuralgia. If you do develop the complication, visit a doctor at once. Finding an effective treatment to relieve the pain can at times be frustrating. You might have to work with a doctor and at times other specialists to try a variety of treatments before you find something that works for you.
Treating Postherpetic Neuralgia
Once postherpetic neuralgia has happened, a comprehensive and multidisciplinary pain management-oriented approach is helpful. Potential treatment options for the condition include the following:
Corticosteroid medications injected into the area around the person's spinal cord may help to relieve persistent pain related to postherpetic neuralgia.
Some people may need opiate medication such as tramadol or oxycontin to control their pain. These medications; however, may be less effective than either the antidepressants or anticonvulsants and may be habit-forming.
Lidocaine Skin Patches:
The patches are small and bandage-like and contain the topical, pain-relieving medication lidocaine. The patches may be cut to fit only the areas of a person's body that are affected. A person applies the patches directly to painful skin to provide pain relief.
The cream, made from the seeds of hot chili peppers, may relieve pain from postherpetic neuralgia. Capsaicin may cause a burning sensation and irritate a person's skin, yet these side-effects usually disappear over time. Capsaicin cream can be very irritating if rubbed on areas of a person's body that are not affected, such as their eyes.
Medications for treatment of seizures may also lessen the pain associated with postherpetic neuralgia. The medications stabilize abnormal electrical activity in a person's nervous system caused by injured nerves. Doctors might prescribe pregabalin, gabapentin, or any other anticonvulsant to help control pain and burning sensations.
A doctor might prescribe antidepressants for postherpetic neuralgia, even if a person is not depressed, because these medications affect key brain chemicals to include norepinephrine and serotonin, which have roles in both depression and how a person's body interprets pain. Doctors typically prescribe antidepressants for postherpetic neuralgia in smaller dosages than they would for depression.
Transcutaneous Electrical Nerve Stimulation (TENS):
The treatment involves the placement of electrodes over the painful areas of a person's body. The electrodes deliver tiny and painless electrical impulses to nearby nerve pathways. A person turns their TENS unit on and off as needed to control pain. Exactly how the impulses relieve pain remains uncertain at this time. One theory is that the impulses stimulate production of endorphins, the body's natural painkillers. The treatment does not work for everyone.
Spinal Cord or Peripheral Nerve Stimulation:
The devices are similar to TENS, but are implanted underneath a person's skin. As with TENS units, a person may turn these units on and off as needed. Before the device is surgically implanted, doctors do a trial first using a thin wire electrode. The trial is done to ensure that the stimulator will provide effective relief from pain for the person. The electrode is inserted through the person's skin and into the epidural space over their spinal cord for a spinal cord stimulator, or under their skin above a peripheral nerve in the case of a peripheral nerve stimulator.
In some instances, treatment of postherpetic neuralgia brings complete pain relief. Yet most people still experience some level of pain and a few do not receive any pain relief. While some people have to live with postherpetic neuralgia for the remainder of their lives, most can expect the condition to gradually disappear during the first three months.
Preventing Postherpetic Neuralgia
Even though a vaccine to prevent chickenpox is available, its effect on postherpetic neuralgia is not known. The vaccine, made from a weakened form of the varicella-zoster virus, might keep chickenpox from occurring in non-immune children and adults, or at least decrease the risk of the chickenpox virus lying dormant in a person's body and reactivating at a later time as shingles. If shingles could be prevented, postherpetic neuralgia could be avoided entirely.If you have already had chickenpox, the vaccine cannot prevent shingles because the varicella-zoster virus is already in your body.
Researchers; however, from the year 2005 reported the results of a ten year trial of a more potent version of the chickenpox vaccine. In what was called the, 'Shingles Prevention Study,' researchers reported that the vaccine reduced the incidence of shingles by approximately half when compared to a placebo. In people who developed shingles, the vaccine notably reduced the severity of the disease and lessened the risk of complications like postherpetic neuralgia. The vaccine is awaiting approval from the Food and Drug Administration.
- 1: High-frequency Electrical Stimulation to Spinal Cord Eases Chronic Pain : Case Western Reserve University (2015/12/04)
- 2: Dry Eye and Chronic Pain Syndrome : University of Miami Miller School of Medicine (2016/01/08)
- 3: Adenosine: A Switch to Turn Off Pain : Saint Louis University (2014/11/29)
- 4: Spinal Cord Stimulation Reduces Chronic Pain Emotional Aspect : Ohio State University Wexner Medical Center (2016/03/22)
- 5: Caffeine Can Help Reduce Joint and Other Pain : Disabled World (2014/06/17)
- 6: Complex Regional Pain Syndrome (CRPS) Study Insights : University of Bath (2017/07/10)
- 7: Pain: A Multi-layered Gradual Event : Max-Planck-Gesellschaft (2016/03/25)
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