Postherpetic Neuralgia (cont.)

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What causes postherpetic neuralgia?

Postherpetic neuralgia is thought to be caused by the damage or alteration of nerves that register pain, pressure, and other sensory nerves (for example, touch) that occur when the reactivated HZ viruses travel down nerves to the skin. This process first begins when the virus causes chickenpox in an individual; the viruses can infect various dorsal root ganglia (nerve cells) as the chickenpox subsides. These viruses then can be reactivated, usually decades later, and produce shingles lesions. The reactivation of HZ is thought to be due to a stress on the body from either another infection or a immunocompromised state (for example, some patients undergoing treatments for leukemia) that allows the HZ to escape the dorsal root cells. PHN does not occur in everyone who gets shingles; about 9%-14% have symptoms after one month post-shingles and about 5% have PHN three months post-shingles.

What are the risk factors for postherpetic neuralgia?

Age is a high risk factor for PHN; the older a person when he or she develops shingles, the more likely it is that the person will develop PHN. People over 60 years of age have about a 60% chance while people 70 or older have about a 75% chance of developing PHN after getting shingles. Another risk factor is family; those people who have close relatives who developed PHN are at a higher risk than people with no family history of PHN.

What are postherpetic neuralgia symptoms and signs?

The main symptom is pain. The pain can be severe (allodynia); patients describe the pain as burning, sharp, jabbing, deep, and aching. Often, the patient feels increased pain when any pressure, even clothing, touches the area. Some patients describe itchy skin and weakness or paralysis of the area.

Medically Reviewed by a Doctor on 4/15/2015

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