This is a pain syndrome developing after an attack of shingles. The term PHN is used if the pain of shingles, or the pain caused by shingles, persists after the shingles rash and lesions are resolved.
What is Shingles?
It is a term to describe a particular rash due to activation of varicella-zoster virus (VZV). This is the same virus causing chickenpox in young age. Studies have shown that almost all Americans were exposed to this virus in young age, which remains dormant in the body until decades later when it reactivates itself and causing shingles. When activated, it travels in a nerve, from its root forward. This is the reason that the shingles rash is always in the distribution of a nerve. The rash can cause pinkish discoloration and blisters, which dry up in a few days and can disappear in a few weeks. In most patients, no complication occurs. But in about 15-20% of patients, it can lead to severe burning and stinging pain, which is called post-herpetic neuralgia (PHN).
How is PHN diagnosed?
It is diagnosed by its typical rash and associated symptoms. In most cases, no test is required.
What are the symptoms of PHN?
Its main symptom is burning, stinging, or electric jabs type of pain, which can be severe and disabling. Pain may be triggered by different sensory stimuli, like touch or cold, a classical feature of all neuralgias. Depending upon its location and the nerve involved, it may also cause other symptoms such as hearing loss, visual loss, or weakness.
How is PHN treated?
As soon as shingles is suspected, patient is started on an antiviral drug, like acyclovir, valacyclovir, or famciclovir. Taking one of these medicines can help to shorten the disease course and minimize complications. For pain, medicines that can help to treat neuropathic pain are used. In this category are tricyclics (amitriptyline or nortriptyline), gabapentin, pregabalin, carbamazepine, duloxetine, and a few others. Local application of Lidocaine patch may also help, but it is not a long-term solution. Botox may also help but is rarely used or approved. Patients also require treatment for associated depression and anxiety (due to pain). Sometimes, this pain is very difficult to control, and the patient requires combination of medicines.
Is PHN a communicable disease?
Not really. It is not transmitted in the air, but if the oozing fluid from the blisters of shingles touches an area of open skin of a different individual, viruses can be transmitted. In that case though, the person may get chickenpox, not shingles. This way of transmission stops after the rash dries up. Shingles is caused by reactivation of virus in one’s own body, not from another person.
Who usually gets shingles?
Young people usually do not have shingles, unless they are immune compromised. Shingles is a disease of middle-age and older population. For some reason, the virus wakes up and start causing trouble, or the defense mechanism against it weakens after a certain age.
How is PHN prevented?
The best strategy is to get shingles vaccine. It is recommended for people 60 and above. Even people 50 and above should consider it. Vaccination prevents having shingles and its complications like PHN. Two shingles vaccines are available: Zostavax, weakened but live virus vaccine; and Shingrix, a recombinant non-live vaccine. Both are reasonably safe, but Shingrix is preferred as it is more effective and safer. Zostavax may not be available in the USA anymore. Protection from vaccine may last for 5 years. Zostavax should be avoided in patients with weakened immune system. Shingrix is safe to take with weakened immune system. It is also recommended in younger population (18 and up) with immune weakness, who are at higher risk of having shingles. Shingrix vaccination is more than 97% effective in preventing shingles. It is an intramuscular shot requiring two injections, the second given 2-6 months after the first one.
Where can I get more information about the post-herpetic neuralgia?
Center for Disease Control and Prevention
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