Postherpetic neuralgia (PHN) can be an unfortunate result of herpes zoster infection (shingles). It is defined broadly as any pain that remains after healing of herpes zoster lesions or rash, usually after a three month period.
Shingles (also known as herpes zoster) is a skin rash that can be very painful. It is a viral infection of the nerves, and the nerves affected by shingles can occasionally continue to cause severe pain after the shingles have cleared. Shingles appear as a rash, patch, or a line of painful blisters which arise on the skin over a nerve in the shape of a band. This band follows the distribution of a specific nerve where the virus has been living before its spread to the skin. Shingles affects both men and women equally. This disease is caused by the same virus that causes chicken pox (varicella zoster). Chicken pox usually affects young children, and its symptoms involve itchy blisters all over the body. Once these symptoms go away, the varicella zoster virus stays in the nerves near the spine. It is almost as if the virus “goes to sleep”. It will “wake up”, however, when the body’s immune system is
If the pain caused by shingles continues after the shingles is over – within two to four weeks – it is known as post-herpetic neuralgia. It is estimated that about one-in-five patients with shingles will go on to have post-herpetic neuralgia. Post-herpetic neuralgia (PHN) is more common as people get older – it is uncommon in children weakened. The virus then grows in the nerves, causing pain. When the virus reaches the skin, it causes the shingles rash.
Each year approximately 1,000,000 people in the U.S. develop shingles or herpes zoster. Of these, it is estimated approximately 10-20% (about 200,000) will go on to develop PHN.
The risk of developing PHN increases with age and can affect at least 40% of all herpes zoster patients over age 50 and 75% of herpes zoster patients over age 75. PHN is the single most common neurologic condition in elderly patients
Causes
The nerve damage caused by shingles disrupts the proper functioning of the nerve. The faulty nerve becomes confused and sends random, chaotic (uncontrolled) pain signals to the brain, which the patient feels as a throbbing, burning pain along the nerve.
Experts believe that shingles results in scar tissue forming next to nerves and pressing on them, causing them to send inaccurate signals, many of which are pain signals to the brain. However, nobody is really sure why some shingles patients go on to develop postherpetic neuralgia.
Symptoms
Symptoms are usually limited to the area of skin where the shingles outbreak first occurred. Symptoms may include:
- Occasional sharp burning, shooting, jabbing pain
- Constant burning, throbbing, or aching pain
- Extreme sensitivity to touch
- Extreme sensitivity to temperature change
- Itching
- Numbness
- Headaches
In rare cases, if the nerve also controls muscle movement, the patient may experience muscle weakness or paralysis.
Some patients may find the symptoms interfere with their ability to carry out some daily activities, such as bathing or dressing. Postherpetic neuralgia may also cause fatigue and sleeping difficulties.
Treatment
Treatment will depend on the type of pain, as well as some aspects of the patient’s physical, neurological and mental health.
Antidepressants – These help patients with postherpetic neuralgia not because the patient is depressed, but because they affect key brain chemicals, such as serotonin and norepinephrine, which influence not only depression, but also how the body interprets pain. Dosages for postherpetic neuralgia will tend to be lower than for depression, unless the patient has both depression and postherpetic neuralgia. Examples of drugs that inhibit the reuptake of serotonin or norepinephrine are tricyclic antidepressants, such as amitriptyline, desipramine (Norpramin), nortriptyline (Pamelor) and duloxetine (Cymbalta). They will not get rid of the pain, but are said to make it more bearable.
Anticonvulsants – As with trigeminal neuralgia pain, postherpetic pain can be lessened with anticonvulsants, because they are effective calming down nerve impulses and stabilize abnormal electrical activity in the nervous system caused by injured nerves. Gabapentin (Neurontin), pregabalin (Lyrica) are examples of commonly prescribed anticonvulsants for this type of pain.
Steroids – A corticosteroid medication is injected into the area around the spinal cord. Injected steroids are effective for postherpetic neuralgia patients with chronic pain (persistent long-term pain). The patient should not receive this medication until the shingles pustular skin rash has completely disappeared.
Painkillers – This may include tramadol (Ultram) or oxycodone (OxyContin). There is a small risk of dependency.
TENS (transcutaneous electrical nerve stimulation) – Electrodes are placed over the areas where pain occurs. Small electrical impulses are emitted. The patient turns the TENS device on and off as required. Some patients obtain significant pain relief from TENS, while others don’t. Experts are not sure why the electrical impulses relieve pain. Some say that TENS stimulates endorphin release – endorphins are the body’s natural painkillers; some people call them natural “feel good” chemicals.
Spinal cord or peripheral nerve stimulation – Similar to TENS, but here the devices are implanted under the skin, along the course of peripheral nerves. These devices are a safe, efficient, and effective way to relieve many types of neuropathic pain conditions, including trigeminal neuralgia.
Alternative Treatment
Proteolytic Enzymes – Proteolytic enzymes are enzymes that are produced naturally by the pancreas to help digest protein we eat. They help in pain relief and skin improvement.
Capsaicin Cream – Although people may not have heard of capsaicin before, if you’ve ever eaten a chili pepper and felt the mouth burn. Capsaicin is the active ingredient in chili peppers and is sometimes used for postherpetic neuralgia.
Colloidal silver is an extremely effective pathogen destroyer which can be taken internally as well as applied topically. Colloidal silver attaches itself to viruses and prevents them from replicating and there are specific silver receptors on human nerve tissue – the location where the shingles virus “hides out”.
Reference –
http://www.centerforhomeopathy.com/shingles-post-herpetic-neuralgia/
http://emedicine.medscape.com/article/1143066-treatment
http://www.nhs.uk/Conditions/postherpetic-neuralgia/Pages/Treatment.aspx
http://www.healingchronicpain.org/neuralgia/frequency
http://www.med.or.jp/english/pdf/2004_11/529_536.pdf
http://patient.info/health/postherpetic-neuralgia-leaflet
http://www.medicalnewstoday.com/articles/160253.php
http://www.nhs.uk/conditions/postherpetic-neuralgia/Pages/Introduction.aspx
http://emedicine.medscape.com/article/1143066-overview