POSTHERPETIC NEURALGIA
Related Disorders

Disclaimer.

Shingles is a painful disease caused by the herpes zoster virus which also causes chicken pox. It can affect the torso or the limbs (spinal ganglia shingles) or the face (trigeminal ganglia shingles). For most, shingles is an acute condition with the pain typically lasting one month.

However, in older patients, or those whose immune systems have been compromised, Postherpetic Neuralgia, a very painful chronic condition can develop. The incidence of postherpetic neuralgia is almost negligible before age 50, but at least 50% of patients older than 60 years and almost 75% beyond age 70 become affected following an attack of shingles. Luckily, there is also a marked natural tendency for postherpetic neuralgia to improve over time without treatment. Some estimates suggest that only 2%-3% of patients have pain that lasts for more than 1 year.

 There has been speculation and anecdotal evidence that some cases of trigeminal neuralgia could be caused by active herpes simplex lesions along the trigeminal nerve. If this is true, then acyclovir would be a possible treatment at the first tingling sensation that some sufferers have learned indicates the beginning of a period of TN pain. In addition, L-Lysine supplements and a high-protein diet could discourage further growth of the virus.

Here a few places to look for information on shingles and postherpetic neuralgia:

Managing the pain of shingles.

The Shingles Center
Massachusetts General Neurology has in depth information about shingles and postherpetic neuralgia  treatments, diagnosis and  research including a test for calculating your risk for developing PNH and tips for dealing with pain. Excellent.

  New Approaches to the Treatment of Herpes Zoster And Postherpetic Neuralgia.

The University of California, San Francisco Pain Clinical Research Center
UCSF is conducting two studies on postherpetic neuralgia.

Treatments for Postherpetic Neuralgia

Treating postherpetic neuralgia can be very challenging. Usually one of the the tricyclic anti-depressants, most often amitriptyline is the first line of treatment. There is strong evidence that the sooner these are given, the more likely they are to reduce pain. Since conventional analgesics, regional nerve blocks, and anticonvulsants have little beneficial effect in most cases when used alone, some physicians favor the use of another tricyclic anti-depressant as the second option if the first drug is unsuccessful.

Tricyclic Anti-depressants

  Amitriptyline

  Nortriptyline

  Desipramine

  Maprotiline

Anticonvulsants

Occasionally, carbamazepine has been found to provide some added benefit in conjunction with a tricyclic anti-depressant, especially for the stabbing type of pain similar to that of trigeminal neuralgia.

Tegretol

Chronic Opioid Therapy

When the pain from postherpetic neuralgia is resistant to the above treatments, sometimes opioid therapy is used, including controlled-release oral morphine. The issues of dependency and tolerance are minimized if the patient's care is carefully managed.

Oxycodone

Local Treatments for Postherpetic Pain.

The following treatments are applied locally to the affected area. While rarely effective on their own, they can be of help when used in conjunction with other treatments. Their use may be somewhat difficult in the case of postherpetic trigeminal neuralgia as the substances can irritate the eye and skin around the eye.

Capsaicin cream. (Zostrix)

Lidocaine cream. (Emla).

Treatments for Shingles

For shingles, antiviral therapies in combination with analgesics are recommended. Studies of the effect of anti-viral agents such as acyclovir on shingles show improved rates of healing and decreased severity of acute pain. Empiric observations suggest that nerve blocks during shingles infection reduce pain, shorten the acute episode, and prevent the emergence of postherpetic neuralgia.  

Acyclovir. (Zovirax).

Valacyclovir

Famciclovir

Lysine diet.