Postherpetic neuralgia

DEFINITION

Postherpetic neuralgia (post-her-PET-ic noo-RAL-jah) is a complication of shingles, which is caused by the chickenpox (herpes zoster) virus. Most cases of shingles clear up within a few weeks. But if the pain lasts long after the shingles rash and blisters have disappeared, it’s called postherpetic neuralgia.

Postherpetic neuralgia affects your nerve fibers and skin, and the burning pain associated with postherpetic neuralgia can be severe enough to interfere with sleep and appetite. The risk of postherpetic neuralgia increases with age, primarily affecting people older than 60. The area affected also makes a difference. When shingles occurs on the face, for example, the likelihood of postherpetic neuralgia is significantly higher than for other parts of the body.

Currently, there’s no cure for postherpetic neuralgia, but there are treatment options to ease symptoms. For most people, postherpetic neuralgia improves over time.

CAUSES

Once you’ve had chickenpox, the virus that caused it remains in your body for the rest of your life. As you grow older, the virus can reactivate. Sometimes this occurs when your body is stressed — because of another infection or due to medications that suppress your immune system, for example. The result is shingles. Because you have some immunity against the virus, rather than getting a full body rash, the rash occurs in areas of skin supplied by the nerve where the virus is reactivated.

Postherpetic neuralgia occurs if your nerve fibers are damaged during an outbreak of shingles. Damaged fibers aren’t able to send messages from your skin to your brain as they normally do. Instead, the messages become confused and exaggerated, causing chronic, often excruciating pain that may persist for months — or even years.

SYMPTOMS

The signs and symptoms of postherpetic neuralgia are generally limited to the area of your skin where the shingles outbreak first occurred — most commonly in a band around your trunk, usually on just one side of your body.

Signs and symptoms may include:

• Pain. The pain associated with postherpetic neuralgia most commonly has been described as burning, sharp and jabbing, or deep and aching.
• Sensitivity to light touch. People who have postherpetic neuralgia often cannot bear even the touch of clothing on the affected skin, a condition called allodynia.
• Itching and numbness. Less commonly, postherpetic neuralgia can produce an itchy feeling or numbness.
• Weakness or paralysis. In rare cases, you might also experience muscle weakness or paralysis if the nerves involved also control muscle movement.

When to see a doctor

See a doctor at the first sign of shingles. Often the pain starts before you notice a rash. Your risk of developing postherpetic neuralgia is cut in half if you begin taking antiviral medications within 72 hours of developing the shingles rash. While steroids are sometimes prescribed for a more rapid resolution of the shingles rash and to provide short-term pain relief, their role in preventing postherpetic neuralgia has not been proved.