Acute herpetic and post herpetic neuralgia

Introduction:

The medical term for shingles is acute herpes zoster. Shingles is a skin rash that develops on half of the body, in a belt-like pattern. The rash is usually on either the right or left side of the chest, starting in the middle of the back and wrapping around to the breast -- but it can occur on any part of the body, such as the forehead and abdomen.
Most of the time, shingles is very painful. Sometimes the pain from shingles starts several days before the rash appears. When the pain starts before the skin rash, it can be very hard for doctors to make the correct diagnosis. Many patients have been told they have heart attacks, appendicitis, and migraine headaches before getting the correct diagnosis of shingles.
Postherpetic neuralgia (PHN) is the most common complication of herpes zoster or shingles. It is defined broadly as any pain that remains after healing of herpes zoster lesions or rash, usually after a three month period.
This acute phase lasts until the lesions are healed, usually several weeks after the onset of the rash. Postherpetic neuralgia (PHN) refers to pain that persists after the acute phase of the illness passes. The exact point at which acute herpes becomes PHN is arbitrary.
Fortunately, in most cases the pain of shingles gradually disappears over several weeks or months. Most people with shingles will have no pain or just a little pain one year after the rash.

Causes:

Many people get chicken pox when they are children or even when they get older. Chicken pox is caused by the varicella zoster virus, a herpes type of virus. 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 decades. It can "wake up," become active again and multiply when a person's immune system becomes weakened. For most people who get shingles, the weakening of the immune system is not the result of a serious problem. It is true that shingles may be brought on by cancer, AIDS, or drugs that lower the immune system, but this happens in a very small group of patients. 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.
The reactivated virus begins to multiply within the dorsal root ganglia, which causes damage and swelling to this area of the nerve. This damage to the nerve causes the first pains of shingles. The virus then moves along the nerve to the skin, damaging the nerve and causing swelling as it goes. When the virus finally reaches the skin, it causes the shingles rash.

Treatment:

Antiviral Medication (such as acyclovir, valacyclovir, and famciclovir): For most patients with shingles, oral antiviral medication should be prescribed for 7 days. The earlier this medication is taken, the better the chance of stopping the virus from causing more damage to the nerves. Early treatment with antiviral medication can lessen the intensity and duration of shingles pain (but, as mentioned above, there is no definite proof that these medications will stop the patient from getting PHN). Once the rash has healed, the patient should stop taking antiviral medication.
Opioid Medication (narcotics): Opioid medications, such as morphine, oxycodone, codeine, hydromorphone, and methadone, can provide good pain relief without side effects for many patients. In most cases, there should be no concern about developing "addiction" when these drugs are used to treat the severe pain of shingles. Patients can be safely taken off of the narcotic medication if it is no longer needed.
Nerve Blocks: Pain specialists can inject numbing medications (called local anesthetics) directly into certain nerves to help with shingles pain. As mentioned above, these nerve blocks have not been proven to reduce the chances of developing PHN, but nerve blocks may provide good temporary pain relief for the shingles.
Steroids(such as prednisone): Some studies have shown that early treatment with a short course (usually 1-2 weeks) of steroids can decrease the intensity and duration of pain associated with acute shingles.
for Postherpetic Neuralgia
Nondrug Therapies: Like other kinds of patients with chronic pain, patients with PHN may benefit from many non drug treatments. These include rehabilitation therapies and psychological therapies (such as relaxation therapy and biofeedback). Also, patients may get pain relief from therapies that stimulate the nerves, such as TENS (Trancutaneous Electrical Nerve Stimulation). TENS units are small devices that send very small amounts of electrical current to the skin through electrodes that are stuck to the skin
Opioids (such as oxycodone, morphine, methadone): For some patients, opioid medications greatly relieve the pain of PHN without serious side effects. When using these drugs as the main pain medication, it is important that the doses be given "around-the-clock" to keep a certain amount of the drug in the bloodstream.
Tricyclic Antidepressants (such as amitryptiline [Elavil], nortriptyline [Pamelor], desipramine, doxepin): Up until the past year or so, tricyclic antidepressants (TCAs) were probably the most widely used medicines to treat the pain of PHN. Many studies have shown that some patients with PHN have good pain relief from these drugs. However, many patients also complain of side effects, such as severe dry mouth, constipation, sedation, trouble thinking, and dizziness.
Topical Lidocaine Patch: This is a new medication that can be used to treat the pain of PHN and other conditions. As many as 3 patches (each about the size of an adult hand) can be placed directly over the painful area of the skin. The patches are applied for at least 12 hours on the skin. They may be removed from the skin for 12 hours per day. The medication is believed to act locally. Within 1-2 weeks, most patients begin to notice relief.
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