Patients who suffer from shingles may also experience pain that lasts beyond 6 months after their rash has healed. This condition is called postherpetic neuralgia, or PHN. Postherpetic neuralgia is most commonly characterized by a burning, stinging and/or itching pain in the area where the rash first occurred. And, in some cases, the area of pain can grow wider than the original site of the rash.
What causes PHN?
PHN is a common complication of shingles, or acute herpes zoster. Shingles is an infection caused by the herpes zoster virus, which is the same virus that causes chicken pox (varicella zoster). When a person recovers from chicken pox, some of the virus can remain dormant (asleep) in the body, more specifically, in the nerve cells that are close to the spinal cord. Later on, the virus can become reactivated. This reactivation of the virus can happen due to such things as getting older, stress or decreased immunity, and can result in shingles.
The virus causes a painful rash and blisters that occur in a discrete pattern on the body or the face, almost always on one side. Due to damage to the infected nerves, the pain from shingles can carry on after the rash has healed; pain that lasts more that three months is often diagnosed as PHN. PHN occurs in about 20% of the reported cases of shingles.
What are the symptoms of PHN?
The symptoms of PHN can vary for each person; however, common symptoms include:
- Paresthesia (burning, tingling and itching sensations)
- Complete or partial loss of sensitivity to touch and temperature
- Allodynia (i.e. pain caused by light touch or other stimuli)
- Other feelings of pain such as cramping, aching or throbbing
- Muscle weakness (in rare cases)
How is PHN treated?
Currently available treatments for PHN are aimed at controlling pain until the condition resolves. Treatments currently used for the symptoms include antidepressants, topical creams, anticonvulsants and opioids. Gabapentin (Neurotin), Pregabalin, (Lyrica) and lidocaine patches (Lidoderm) have been approved for the treatment of PHN. Unfortunately these therapies have fallen short in their ability to treat the pain of PHN for many patients who suffer from it.
What are we doing about it?
The Translational Pain Research group is researching new and effective therapies for the pain associated with PHN. In doing so, we hope to provide a better quality of life for those who are affected by this painful condition.
If you are interested in learning more about our postherpetic neuralgia research study, please call us at 617-525-PAIN or email us at paintrials@partners.org.
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