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Shingles
(Acute Herpes Zoster) and Postherpetic Neuralgia (PHN)
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What
is Shingles?
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.
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.
What
is Postherpetic Neuralgia?
If the pain from shingles does not go away, it is called
postherpetic neuralgia (PHN). Only a small number of people
with shingles develop PHN.
What Causes Shingles and Postherpetic
Neuralgia?
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.
Can You Prevent Postherpetic Neuralgia?
Scientists have not found a treatment that prevents all
patients with shingles from developing PHN. However, there
are several treatments that some think might reduce the chances
of developing PHN. These treatments are:
Antiviral
Medication
(such
as acyclovir, valacyclovir or famciclovir): These medications
kill the herpes virus during the shingles phase. Studies have
shown that they shorten the time and pain of shingles. Because
of this, antiviral medications probably reduce the chances
of developing PHN after shingles, but this has never been
totally proved.
Nerve
Blocks: Nerve
blocks are injections of numbing medications, called local
anesthetics, into different nerves. Some doctors believe that
doing several nerve blocks during the shingles phase will
stop patients from developing PHN. Unfortunately, no studies
have proven this. Nerve blocks may be a good treatment for
the pain of shingles but should not be given to patients as
a treatment to prevent PHN.
Tricyclic
Antidepressants:
One scientific study reported that giving the antidepressant
amitriptyline (Elavil) during the shingles phase reduced the
chance of developing PHN. Scientists need to do another study
like this, with the same results, before everyone with shingles
is given this type of medication. 
Herbs
and Other Medicinals:
Many patients visit their doctors and ask about cures or treatments
they have heard about in medical magazines, on the Internet,
or from friends or relatives. Doctors might discourage their
patients from using some of these treatments if there could
be any harmful effects. Patients should not expect that any
of these treatments will prevent them from getting PHN --
the sad fact remains that no treatment given during the
shingles has been shown in scientific studies to prevent PHN.
Who
Gets Shingles and Postherpetic Neuralgia?
Age is an important factor in determining who gets shingles
and PHN. The older you are, the greater chance you have of
developing shingles. And, the older you are when you get shingles,
the greater chance you have of developing PHN.
Recently,
a good scientific study showed that older people with a neuropathy
(nerves of the body that are not working correctly, usually
due to old age or diabetes) are more likely to develop PHN
after shingles. It is interesting that most people in this
study who had a neuropathy before they got shingles did not
know they had a neuropathy -- they did not have any symptoms.
Therefore, having a neuropathy, even if it is not causing
symptoms, may increase the chances of getting PHN.
Other
studies have suggested that the more severe and painful the
shingles rash is, the greater the chance of long-lasting PHN
pain. Also, some studies have concluded that people who do
not cope well with stress and pain may have worse PHN than
others who cope better.
Pain
from Shingles and Postherpetic Neuralgia
Patients often describe the pain from shingles as a horrible,
unbearable pain in the area of the rash. Each patient may
experience different types and degrees of pain. The words
used to describe the pain include sharp, electric-like jabs,
burning, throbbing, aching, and skin sensitivity.
Most
patients who develop the chronic pain of PHN say that the
pain is less severe than the shingles pain, but it may still
be intense. Like shingles pain, the pain of PHN can be described
as sharp, electric-like jabs, burning, throbbing, aching,
and skin sensitivity, and the pain is different from patient
to patient. Patients might also have intense itching in the
painful area. The pain of PHN may spread beyond the original
shingles rash, and often includes several inches above the
rash area. Some patients have severe skin sensitivity (called
"allodynia") that can be very disabling, especially if the
sensitive area is on the chest, trunk, or limbs, making the
touch of clothing unbearable.
Other
Symptoms and Problems Associated with Shingles and Postherpetic
Neuralgia
People suffering from shingles or PHN may develop depression,
anxiety, and sleeping difficulties because of the severe pain.
The patient should tell his or her doctor about these problems
so they may be treated.
Also,
some patients describe a "sagging of the muscles" in the area
of the shingles. When doctors examine the region, a loss of
muscle tone is seen. This might be caused by damage of some
nerves that control the muscle tone in the area of the shingles.
Diagnosing
Postherpetic Neuralgia
PHN is simple for a doctor to diagnose, without any laboratory
testing. Any patient who develops a chronic pain at the site
of the shingles rash has PHN. The area of pain of PHN may
be smaller than the shingles rash or may spread several inches
larger than the shingles rash.
.
Treatment
for Shingles
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.
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.
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.
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.
Tricyclic
Antidepressants
(such
as amitriptyline [Elavil]  and
nortriptyline [Pamelor]): One study has shown that giving
tricyclic antidepressants during the early shingles phase
can help reduce the pain and help reduce the chance of developing
chronic PHN pain. When used in this way, tricyclic antidepressants
are not given to treat any kind of depression -- they are
prescribed for pain relief and perhaps to reduce the chance
of getting PHN.
Recommended
Treatments For Postherpetic Neuralgia
There is good and bad news about treating PHN. The bad
news is that there are no treatments that reverse the nerve
damage caused by shingles, and there are no treatments that
can improve the healing of the nerves. The good news is that
there are many different treatments available for the pain
of PHN. Some treatments work better for some patients than
for others, and some cause bad side effects in some patients
but no side effects in others. So each patient with PHN should
be tried on a variety of medications until the drug or combination
of drugs is found that gives good pain relief with no or little
side effects.
It
is very important that doctors start all oral medications
(that is, medications taken by mouth in pill, tablet or syrup
form) at a low dose and then gradually increase the dose until
pain is relieved or side effects occur. This gradual increase
in dosage, called "titration," is important because every
patient with PHN is different and each may respond to a different
dose of each medication.
Topical
Lidocaine Patch:
This is a new medication that can be used to treat the pain
of PHN. 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 12 hours on the skin and
then removed from the skin for 12 hours. Lidocaine patches
are a unique treatment because they can reduce the pain and
skin sensitivity of PHN without causing any blood level of
lidocaine. The medication acts locally in the skin's damaged
nerves. Within 1-2 weeks, most patients begin to notice relief.
Anticonvulsants
(such as gabapentin [Neurontin] and carbamazepine [Tegretol]):
Drugs used to treat epilepsy and seizures have been used for
many years to help relieve the pain of PHN. In recent years,
the antiseizure drug gabapentin (Neurontin) has become available,
and it is widely prescribed for PHN by pain specialists today
(often as the first medication tried). It has been shown in
a large study to be effective and safe for many patients with
PHN, with few side effects. Also, gabapentin does not interact
with any other medication, making it a good choice for many
patients who are taking several different medications at once.
Carbamazepine
(Tegretol) is an older antiepilepsy drug that has been used
for PHN pain. This medication helps some patients, but many
others complain of side effects, such as mental changes and
dizziness. Patients taking this drug need regular blood tests.
Many
other anticonvulsant medications are available, and doctors
may try using others to treat PHN.
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.
Newer
antidepressant drugs, such as fluoxetine (Prozac), paroxetine
(Paxil), and sertraline (Zoloft), might be helpful for some
patients with PHN. These medications usually have less side
effects than the tricyclic antidepressants, but studies have
found that they are generally less effective for pain.
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.
The
use of opioid medications for chronic pain continues to be
controversial. Pain specialists now agree, however, that some
patients greatly benefit from taking opioids. When used properly,
the drugs can be taken long-term for pain management with
few side effects. It is very rare that patients become addicted
to opioid pain medication. Fear of addiction should not prevent
a doctor from prescribing opioids for pain in appropriate
cases. Patients can be safely taken off of opioid medications
without withdrawal symptoms.
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.
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