Shingles and Post-herpetic Neuralgia

Shingles and Post-herpetic Neuralgia

By Lori Montgomery, MD, CCFP

Introduction

Shingles (say: SHING-uhlz) (or herpes zoster infection) is a painful condition that affects certain areas of the skin. It follows a chicken pox (or varicella zoster) infection — the kind that usually happens in childhood. After the chicken pox infection goes away, the virus still lives in certain nerve cells. As you age and your immune system becomes weaker, or if your immune system is weak for some other reason, the virus may reactivate (be active again) and cause pain and a rash. This most often lasts between one and three months.

Post-herpetic neuralgia is the name given to shingles pain that goes on beyond the time when the rash heals and the pain normally goes away. About 20% (20 out of 100) of people who get shingles will get post-herpetic neuralgia. It is not always in a severe form.

Signs and symptoms

  • blistering rash in a certain pattern that corresponds to a nerve root
  • pain in that same area (sometimes happens before the rash, or even without a rash at all)
  • pain may be described as burning, shooting, stabbing, or electric shock-like
  • itching, numbness, or pins and needles in the area of the rash or pain
  • very sensitive skin, as if you have a bad sunburn
  • at first, shingles may involve nausea, fever, chills, or diarrhea
  • shingles that affects the face can also involve the eyes, causing pain and redness

If this happens, you should see a doctor right away, because this can cause damage to the eye.

Causes

The rash and pain is caused by the herpes zoster virus, which lives in your nerve cells after you have a chicken pox (varicella) virus. If you have had the chicken pox vaccine, you are much less likely to get varicella. You are therefore much less likely to get shingles or post-herpetic neuralgia.

Diagnostic tests

Your doctor will diagnose shingles by looking at the rash and by talking to you about your symptoms. There is no diagnostic testing needed in most cases. If the rash is not usual, your doctor may take a scraping of the rash to be looked at in a lab.

Treatment approach

Medicines
In the early stages of a shingles episode, it is important to see a doctor as soon as you can. Antiviral medicines, steroids, and medicines to treat nerve pain may be prescribed. They are most effective when used early in the infection. Pain from shingles normally goes away within three months, even if you do not treat it. If it becomes post-herpetic neuralgia, the pain may last longer. Even then, most people are pain-free at the end of one year. A small number may go on to have chronic pain (beyond one year).

There are a number of medicines that are used to control nerve pain. Some patients may benefit from:

  • tricyclic antidepressants (such as amitriptyline or nortriptyline)
  • gabapentin or pregabalin
  • tramadol or other opioid-like medicines (such as morphine)
  • serotonin-norepinephrine reuptake inhibitors (such as venlafaxine or duloxetine)
  • over-the-counter creams containing capsaicin
  • gels or creams that include a local anaesthetic such as lidocaine

Acupuncture and TENS
Some patients find things like acupuncture or transcutaneous electrical nerve stimulation (TENS) helpful as well.

Non-drug therapies
Studies have shown that non-drug therapies can help to reduce pain levels and enhance pain coping. These include:

  • relaxation
  • meditation
  • activity pacing
  • cognitive behavioural therapy

These self-management strategies can help you to improve your function so you can do more and enjoy life more.


References

Herpes Zoster and Postherpetic Neuralgia: Prevention and Management, AL Mounsey, LG Matthew, and DC Slawson, American Family Physician September 15, 2005.

National Institute of Neurological Disorders and Stroke, National Institutes of Health. Shingles Information Page (www.ninds.nih.gov). Last updated November 19, 2008.