Postherpetic neuralgia (PHN) facts
- PHN is a painful complication that
occurs after a shingles infection.
- PHN is caused by viral damage to nerve cells.
- PHN is diagnosed by the patient's history and physical exam.
- Treatment often
requires more than one agent to reduce pain.
- PHN may last one to two months, but some
patients have PHN for longer than a year.
- Older people and people with
relatives who get shingles are at a higher risk for PHN.
- Complications of PHN
may include severe pain, pain-medicine addiction, diminished lifestyle, and in a
few patients, paralysis of the affected area.
- The prognosis of PHN ranges from
good to poor, depending on the length of time the disease lingers and on the
development of complications.
- PHN can be prevented in many people by a vaccine
designed to prevent shingles (Zostavax).
What is postherpetic neuralgia (PHN)?
Postherpetic neuralgia (also termed PHN) is a condition of recurring or persistent pain in an area of the body that has undergone an outbreak of herpes zoster virus (HZ), also known as the varicella zoster virus, commonly termed shingles. It usually begins after shingles lesions (blisters) begin to crust over and heal but may occur in some patients who do not produce lesions. Some investigators suggest the pain has to be present for three months to be termed PHN.
What causes postherpetic neuralgia?
Postherpetic neuralgia is thought to be
caused by the damage or alteration of nerves that register pain, pressure, and
other sensory nerves (for example, touch) that occur when the reactivated HZ
viruses travel down nerves to the skin. This process first begins when the virus
causes chickenpox in an individual; the viruses can infect various dorsal root
ganglia (nerve cells) as the chickenpox subsides. These viruses then can be
reactivated, usually decades later, and produce shingles lesions. The
reactivation of HZ is thought to be due to a stress on the body from either another
infection or a immunocompromised state (for example, some patients undergoing
treatments for leukemia) that allows the HZ to escape the dorsal root cells. PHN
does not occur in everyone who gets shingles; about 9%-14% have symptoms after
month post-shingles and about 5% have PHN three months post-shingles.
What are postherpetic neuralgia symptoms and signs?
The main symptom is pain. The pain can be severe (allodynia - pain due to a stimulus that does not usually provoke pain); patients describe the pain as burning, sharp, jabbing, deep, and aching. Often, the patient feels increased pain when any pressure, even clothing, touches the area. Some patients describe itchy skin and weakness or paralysis of the area.
What are the risk factors for postherpetic neuralgia?
Age is a high risk factor for PHN; the older a person when he or she develops
shingles, the more likely it is that the person will develop PHN. People over 60
years of age have about a 60%
chance while people 70 or older have about a 75% chance of developing PHN after
getting shingles. Another risk factor is family; those people who have close
relatives who developed PHN are at a higher risk than people with no family
history of PHN.
How is postherpetic neuralgia diagnosed?
The majority of patients who are diagnosed with PHN are done by follow-up of
a shingles infection or by the patient's history of a recent shingles infection.
The pain is located in the same nerve distribution (dermatome) area, usually
on only one side of the person's body where the shingles lesions occurred.
See pictures of shingles and other viral skin conditions
Home Treatments for Shingles
What are medications for shingles?
Antiviral medications like acyclovir (Zovirax), valacyclovir (Valtrex), or
famciclovir (Famvir) can reduce the severity and duration of the rash if started
within 72 hours of the development of the skin rash, and pain medications like
acetaminophen (Tylenol), ibuprofen (Advil), and naproxen (Aleve), and even
narcotic pain-control medications may be useful in symptom control. In addition
to medications, many people find that home care remedies can also provide relief
for the pain of shingles.
Keeping the inflamed skin clean is essential, so wash the affected area with
cool water and mild soap. Taking a bath or shower is fine. The blisters of
shingles will crust over and fall off on their own, and it's important to avoid
picking at the blisters to prevent the development of a secondary skin infection
at the inflamed site. Cool compresses applied to the painful area after washing
may be helpful. In the first few days of an attack, you can apply ice packs for
10 minutes at a time several times throughout the day.
What is the treatment for postherpetic neuralgia?
Treatment is individualized for each patient; there is no treatment that is effective for all PHN patients, so clinicians often use two or more of the drug categories with examples listed below:
Because some drugs (opioids) can be addictive and because some patients may need long-term treatments (over one year), consultation with a pain-management specialist may be advised. Some individuals claim tamanu oil rubbed into the affected may reduce the symptoms of PHN. One small study and a few case reports indicate that acupuncture can be helpful in relieving the pain of PHN. Infrequently, other methods are used. TENS (transcutaneous electrical nerve stimulation) devices are designed to interrupt the body's pain sensations while nerve blocks (short-term chemical nerve sensation blockade) and nerve ablation (surgically cutting a nerve) are also used. Results vary but the methods often do not give lasting pain relief.
How long does postherpetic neuralgia last?
Only approximately 9%-15% of patients who get shingles develop PHN. For those few patients who develop PHN, the length of time that PHN lasts is variable; the majority of PHN patients have discomfort lasting one to two months. About one-third of PHN patients have symptoms that last about three months, and about one-fifth last a year or longer.
What are the complications of postherpetic neuralgia?
PHN itself is a complication of shingles. A serious complication of PHN is addiction to pain medications. Some patients may have an inability to live a normal lifestyle (unable to exercise) because of constant pain, while others have sleep and activities limited or even prohibited by touching the affected area, including just having contact with their own clothing. Patients taking opioids may become very constipated. In a few cases of PHN, muscle weakness can be an additional complication.
What is the prognosis for postherpetic neuralgia?
For the majority of patients who develop PHN, the prognosis is good although they may have to take pain medications for about one to three months. For others, the prognosis is fair to poor if the pain is severe, lasts longer than three months, or markedly reduces their quality of life. PHN occasionally results in permanent nerve damage; however, the disease is not fatal.
Is it possible to prevent postherpetic neuralgia?
If shingles can be prevented, then PHN can be prevented. Fortunately, the vaccine Zostavax is about 70% effective in preventing shingles. The CDC recommends that everyone older than 60 years of age get the vaccine; in 2011, the FDA approved the vaccine for people aged 50 and above. The CDC states, "Zostavax should not be given to pregnant women, persons with a primary or acquired immunodeficiency, or to persons with a history of anaphylactic reaction to gelatin, neomycin, or any other component of the vaccine. Herpes zoster vaccine can be administered simultaneously with other indicated vaccines."
Shingles is a painful rash caused by the same virus that causes chickenpox.
Medically Reviewed on 2/8/2018
DerSarkissian, Carol. "How to Treat Nerve Pain After Shingles." WebMD.com. Sept. 13, 2016. <https://www.webmd.com/skin-problems-and-treatments/shingles/understanding-postherpetic-neuralgia-treatment>.
McElveen, W. Alvin. "Postherpetic Neuralgia." Medscape.com. Dec. 1, 2017. <http://emedicine.medscape.com/article/1143066-overview>.
Stone, Jennifer A.M., Gettelfinger, Gary L., and Johnstone, Peter A.S. "Treatment of 13 Patients With Post-Herpetic Neuralgia Using Acupuncture." Journal of the Society for Integrative Oncology 8.4 Fall 2010: 125-130.
United States. Centers for Disease Control and Prevention. "Update on Herpes Zoster Vaccine: Licensure for Persons Aged 50 Through 59 Years." MMWR 60.44 Nov. 11, 2011: 1528. <http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6044a5.htm>.