Shingles and Chickenpox (Varicella-Zoster Virus) - Complications

(Page 4)

Such experiences may also be more intense than even normal responses, defined in the following ways:

• Allodynia is pain caused by factors, such as a light touch of clothing or a cold wind, which occurs from very little stimulation.
• Hyperalgesia is a more intense painful response to a normally painful experience.

The pain tends to be more severe at night. Temperature changes can also affect pain. The pain may extend beyond the areas of the initial zoster attack. In most cases, it does not affect daily life. Rarely, however, the pain of herpes zoster affects sleep, mood, work, and overall quality of life. This can lead to fatigue, loss of appetite, depression, social withdrawal, and impaired daily functioning.

Itching. Many patients report itching (postherpetic itch) as the primary symptom, rather than pain. In rare cases, it can be disabling.

Postherpetic Neuralgia (PHN). Postherpetic neuralgia (PHN) is pain that persists for longer than a month after the onset of herpes. It is the most common severe complication of shingles. It is not clear why PHN occurs. Some theories for its development are:

• The herpes zoster virus appears to produce persistent inflammation in the spinal cord that causes long-term damage, including nerve scarring.
• Nerves that are injured in the initial attack may regrow abnormally and provoke an exaggerated response in the brain that signals intense sensitivity or pain.

In people with herpes zoster, the risk of developing PHN ranges from 10 - 70%. In general, however, the risk is likely to be in the lower range. People with impaired immune systems do not seem to be at any higher risk for persistent PHN than those with normal immune systems.

The following are risk factors for PHN:

• Age. PHN affects about 25% of herpes zoster patients over 60 years old. The older a person is, the longer PHN is likely to last. It rarely occurs in people under age 50.
• Gender. Some studies suggest that women may be at slightly higher risk for PHN than men.
• Severe or Complicated Shingles. People who had prodromal symptoms or a severe attack (numerous blisters and severe pain) during the initial shingles episode are also at high risk for PHN. The rate is also higher in people whose eyes have been affected by zoster.