Postherpetic Neuralgia

What is postherpetic neuralgia?

Postherpetic neuralgia is the most common complication of shingles. Shingles, also known as herpes zoster, or zoster, is caused by infection with the varicella zoster virus (VZV), the same virus that causes chickenpox. After the chicken pox heals, the varicella zoster virus moves from the skin along the nerves and into an area called the dorsal root ganglia, a part of the nerves which lie next to the spinal cord. The virus stays there for many years in an inactive state.

The virus is usually inactive for several years. It can "wake up," become active again and multiply when a person's immune system becomes weakened. The most common reason for lowered immunity in shingles patients is being elderly and experiencing a stressful event, such as an illness in the family or emotional distress.

After the shingles rash resolves, pain may persist in the area where the rash was present. This is known as postherpetic neuralgia (PHN), and it occurs in 8% to 70% of shingles cases. The pain of PHN can last for weeks or months but occasionally persists for many years. The frequency, duration, and severity of PHN increases with increasing age: It occurs rarely among persons under 40 years of age but occurs in up to 50% (and possibly more) of persons 60 years of age and older.

Can You Prevent Postherpetic Neuralgia?

Scientists have not found a treatment that prevents all patients with shingles from developing PHN. However, there are several treatments that some think might reduce the chances of developing PHN. These treatments are:
- Antiviral Medication
- Nerve Blocks
- Tricyclic Antidepressants

Pain from Shingles and Postherpetic Neuralgia

Patients often describe the pain from shingles as a horrible, unbearable pain in the area of the rash. Each patient may experience different types and degrees of pain. The words used to describe the pain include sharp, electric-like jabs, burning, throbbing, aching, and skin sensitivity.

Most patients who develop the chronic pain of PHN say that the pain is less severe than the shingles pain, but it may still be intense. Like shingles pain, the pain of PHN can be described as sharp, electric-like jabs, burning, throbbing, aching, and skin sensitivity, and the pain is different from patient to patient. Patients might also have intense itching in the painful area. The pain of PHN may spread beyond the original shingles rash, and often includes several inches above the rash area. Some patients have severe skin sensitivity (called allodynia) that can be very disabling, especially if the sensitive area is on the chest, trunk, or limbs, making the touch of clothing unbearable.

Other Symptoms and Problems Associated with Shingles and Postherpetic Neuralgia

People suffering from shingles or PHN may develop depression, anxiety, and sleeping difficulties because of the severe pain.

Also, some patients describe a "sagging of the muscles" in the area of the shingles. When doctors examine the region, a loss of muscle tone is seen. This might be caused by damage of some nerves that control the muscle tone in the area of the shingles.

Diagnosing Postherpetic Neuralgia

PHN is simple for a doctor to diagnose, without any laboratory testing. Any patient who develops a chronic pain at the site of the shingles rash has PHN. The area of pain of PHN may be smaller than the shingles rash or may spread several inches larger than the shingles rash.

Recommended Treatments For Postherpetic Neuralgia

There are many different treatments available for the pain of PHN. Some treatments work
better for some patients than for others. So each patient with PHN should be tried on a variety of medications until the drug or combination of drugs is found that gives good pain relief with no or
little side effects.

- Topical Lidocaine Patch
- Anticonvulsants: Drugs used to treat epilepsy and seizures have been used for many years to 
  help relieve the pain of PHN.
- Tricyclic Antidepressants
- Opioids
- Nondrug Therapies:
* Rehabilitation therapies as TENS (Trancutaneous Electrical Nerve Stimulation)
* Psychological therapies (such as relaxation therapy and biofeedback)

References:
Pain Medicine and Palliative Care, BethIsrael University Hospital; https://www.stoppain.org/
pain_medicinechronicpain
Centers for Disease Control and Prevention, USA, https://www.cdc.gov/vaccines/vpd-vac/shingles
The Medical City, Pain Management Center

Note: This information is not intended to be used as a substitute for professional medical advise, diagnosis or treatment. If you or someone you know have any of the symptoms mentioned above, it is advisable to seek professional help.

The Medical City offers a roster of competent Pain specialist who may assess and treat people with pain. For any inquiries, please call:

PAIN MANAGEMENT CLINIC
Tel. no. (632) 988-1000 / (632) 988-7000 ext 6453

CENTER FOR PATIENT PARTNERSHIP
Tel. no. (632) 988-1000 / (632) 988-7000 ext 6444