> Postherpetic Neuralgia
Postherpetic Neuraglia - PHN
To understand Postherpetic Neuralgia (PHN), we need to look at the
subsequent viral disease called herpes zoster, or shingles. Shingles
is a viral disease characterized by a painful rash of blisters that
usually arises on one side of the body in a strip or ‘belt’
shape (zoster actually means ‘belt’ in Greek). Shingles
is the result of the varicella zoster virus (VZV) which initially
causes chicken pox. Although you cannot ‘get’ chicken
pox more than once, the virus associated with it never leaves the
body. As such, subsequent physical manifestations of the virus (shingles)
are common, especially with older people.
The varicella zoster virus resides in the nerve cells, even in it’s
dormant state, much the same way the herpes simplex virus (HSV) does.
Periodic outbreaks of shingles are the result of the virus manifesting
on the skin for the purpose of spreading (shedding). Because the virus
lives in the nerve cells, there is a chance that the manifestation
of an outbreak can actually damage the nerve cells hosting the virus.
When this happens, the nerve-brain communication becomes confused
and can result in great pain, and can last months or even years. This
condition is called Postherpetic Neuralgia.
Herpes Zoster, or shingles, affects people above the age 50 much more
frequently than younger adults or teens. Proportionally, PHN is also
much more predominant in elderly people. It is estimated that over
1 million people contract herpes zoster each year, and of them almost
20% will experience postherpetic neuralgia. Of those 20% (or approx.
200,000), more than 90% are over the age of 50.
Postherpetic Neuralgia Causes
As mentioned the damage of nerve cells is what causes postherpetic
neuralgia. The herpes zoster virus itself needs to travel through
the nerve fibres to get to the skin’s surface. Once it reaches
the skin, it manifests as a long strip of blisters and rashes called
shingles, usually on one side of the body. Although painful and irritating,
shingles usually disappears within a month. However, when topical
blistering and subsequent skin damage takes place, the underlying
nerve cells and nerve fibres can also be damaged. This is why postherpetic
neuralgia and its symptoms persist months or years after the initial
herpes outbreak. Damaged nerve cells can be repaired by the body under
Below is a chronological list of the causes of postherpetic neuralgia:
• Contraction of the varicella zoster virus (VZV) causing chiken
pox, usually during childhood
• Re-emergence of the dormant virus, manifesting on the skin
as herpes zoster (shingles)
• Damage to the nerve cells from the zoster virus using nerve
fibres to reach the skin’s surface, resulting in pain, numbness
or in extreme cases, paralysis (postherpetic neuralgia)
Although related to herpes zoster, the symptoms of postherpetic neuralgia
are very different. Where herpes zoster bears symptoms of pain and
itchiness while a visible symptoms exist (rash, blisters), the symptoms
of PHN occur after the visible symptoms have subsided. In many cases,
people who suffer from a shingles outbreak will still experience some
itchiness after the visible symptoms are gon – however, if pain
and itchiness is still experienced weeks after the shingles have disappeared,
you are probably suffering from PHN due to nerve damage. Here are
some common symptoms of PHN:
• Pain or burning sensation at the area of the skin where a
shingles outbreak had previously occurred
• Moderate to severe pain in the area over 3 months after the
shingles outbreak has disappeared
• Numbness at the area of a previous shingles outbreak
• Hypersensitivity at the area of a previous shingles outbreak
• Scarring of the skin where there was a previous shingles outbreak
• In rare cases, muscle fatigue or restriction of muscle control
at the affected area due to nerve/muscle damage
Although PHN is defined as having moderate to severe pain for over
3 months after the visible symptoms of shingles have disappeared,
if you are in extreme pain only weeks after, it is probably best to
see your physician who can monitor the situation and test for any
severe nerve damage. In many cases, simply wearing a loose shirt or
pants is almost unbearable. Living your life day to day may be hampered
by bouts of extreme in which case a physician will want to make a
proper diagnosis earlier. Below are some treatment options that may
be recommended by your doctor.
There are many treatment options for PHN. In particular, many focus
on the pain associated with PHN. It is important to mention that even
some of the more extreme pain relieving treatments do not always eradicate
all of the pain associated with PHN; in many cases, it simply lessens
the pain to different degrees. Some of the more extreme treatment
methods may help lessen the pain more effectively, but in most cases
the preferred pain relief depends on the individual. Here are some
common pain relieving treatment options.
• Plant Extracts: It has been shown that some anthraquinones
found in plant extracts can work as an antiviral agent. Natural products,
sold over the counter, consist of various plant extracts which can
inhibit shingles eruptions and therefore reduce the chance of getting
PHN. These natural products can be found as topical creams, tablets
and even oils which are rubbed on the skin (not necessarily the affected
area) and enter the blood stream.
• Lidocaine: comes in topical patches (like medicated band-aids)
and is used for temporary pain relief. The patches can be quite large
and cut to fit. Lidocaine is only available through prescription.
Although lidocaine is not as effective as other treatments, it is
sometimes preferred over ingesting prescriptions drugs or using topical
• Corticosteroids: In some cases, doctors may recommend corticosteroid
injections at the site of the pain. Corticosteroids can help reduce
the pain, but constant injections are needed. Steroids do have adverse
side effects; make sure you ask your doctor about them before agreeing
to use this treatment method.
• Painkillers: there are painkillers that are sometimes prescribed
for the pain of PHN. Examples include Percocet, Oxycontin and Ultram.
These painkillers can be extremely addictive, and therefore should
only be taken for shot periods.
• Antidepressants: Used for various afflictions and symptoms,
antidepressants have been used as a painkiller for many years. The
active ingredients affect norepinephrine and serotonin levels in the
brain. Antidepressants do not necessarily eradicate pain but they
do make the pain more tolerable. Examples include Pamelor, Cymbalta
• Anticonvulsants: These are used to dull the electrical activity
in the nervous system. When nerves are damage, the electrical activity
can increase or decrease – antivonvulsants are used in the case
of increased electrical activity (which causes muscle spasms). Separate
anticonvulsants are prescribed depending on the type of pain experienced
– burning or stabbing pain for example.
• Antiviral Agents: Famciclovir, sold as Famvir, has been shown
to reduce the frequency of shingles outbreaks, reduce the duration
of shingles outbreaks and reduce the occurrence of complications (like
PHN for example). It is believed that the active ingredient inhibits
replication from the DNA level.
• TENS – TENS stands for transcutaneous electrical nerve
stimulation and is used to reduce the pain of nerve damage for shingles,
burns, accidents etc. With tiny electrodes attached to the affected
area, turning the TENS unit on when experiencing pain gives the area
a very small electrical impulse, affecting nerves and induces the
production of endorphins which relieve pain.
• Spinal Cord Stimulation: SCS works with the same principals
of TENS. The difference being that the electrodes are surgically implanted.
The unit can still be manipulated (on/off) so that it is only used
when there is pain present. This treatment does not work for everyone
and in many cases ‘trial runs’ will be used to test its
efficacy on a particular patient.
Preventing Postherpetic Neuralgia
Although there are no preventative measures proven to work specifically
for PHN, there are certain vaccines that may lessen the frequency
of shingles outbreaks and PHN symptoms. The vaccine Varivax, used
as a chicken pox vaccine, has been shown to significantly reduce the
occurrence of shingles (by about 50% in some studies). The newer vaccine
Zostavax (for shingles) has also been shown to reduce the frequency
of shingles outbreaks. Reducing the frequency of shingles outbreaks
will lessen the chances of getting PHN, as PHN is the result of shingles
manifestations and its damage to the nerve cells. The vaccine has
been approved for people over 60, the age which PHN predominantly
Preventative measures can also be taken during a shingles outbreak.
People who have had shingles outbreaks can usually detect early symptoms.
If an antiviral medication such as acyclovir is used on the rash early
enough, studies have shown (inconclusively thus far) that this may
reduce the chances of the shingles outbreak leading to PHN.
AAFP (American Academy of Family Physicians: