Pain — Hope
Table of Contents
Introduction: The Universal
You know it at once. It may
be the fiery sensation of a burn moments after your finger touches the
stove. Or it's a dull ache above your brow after a day of stress and
tension. Or you may recognize it as a sharp pierce in your back after
you lift something heavy.
It is pain. In its most
benign form, it warns us that something isn't quite right, that we
should take medicine or see a doctor. At its worst, however, pain robs
us of our productivity, our well-being, and, for many of us suffering
from extended illness, our very lives. Pain is a complex perception that
differs enormously among individual patients, even those who appear to
have identical injuries or illnesses.
In 1931, the French medical
missionary Dr. Albert Schweitzer wrote, "Pain is a more terrible lord of
mankind than even death itself." Today, pain has become the universal
disorder, a serious and costly public health issue, and a challenge for
family, friends, and health care providers who must give support to the
individual suffering from the physical as well as the emotional
consequences of pain.
A Brief History of Pain
recorded on stone tablets accounts of pain and the treatments used:
pressure, heat, water, and sun. Early humans related pain to evil,
magic, and demons. Relief of pain was the responsibility of sorcerers,
shamans, priests, and priestesses, who used herbs, rites, and ceremonies
as their treatments.
The Greeks and Romans were
the first to advance a theory of sensation, the idea that the brain and
nervous system have a role in producing the perception of pain. But it
was not until the Middle Ages and well into the Renaissance-the 1400s
and 1500s-that evidence began to accumulate in support of these
theories. Leonardo da Vinci and his contemporaries came to believe that
the brain was the central organ responsible for sensation. Da Vinci also
developed the idea that the spinal cord transmits sensations to the
In the 17th and 18th
centuries, the study of the body-and the senses-continued to be a source
of wonder for the world's philosophers. In 1664, the French philosopher
René Descartes described what to this day is still called a "pain
pathway." Descartes illustrated how particles of fire, in contact with
the foot, travel to the brain and he compared pain sensation to the
ringing of a bell.
In the 19th century, pain
came to dwell under a new domain-science-paving the way for advances in
pain therapy. Physician-scientists discovered that opium, morphine,
codeine, and cocaine could be used to treat pain. These drugs led to the
development of aspirin, to this day the most commonly used pain
reliever. Before long, anesthesia-both general and regional-was refined
and applied during surgery.
"It has no future but
itself," wrote the 19th century American poet Emily Dickinson, speaking
about pain. As the 21st century unfolds, however, advances in pain
research are creating a less grim future than that portrayed in
Dickinson’s verse, a future that includes a better understanding of
pain, along with greatly improved treatments to keep it in check.
The Two Faces of Pain:
Acute and Chronic
What is pain? The
International Association for the Study of Pain defines it as: An
unpleasant sensory and emotional experience associated with actual or
potential tissue damage or described in terms of such damage.
It is useful to distinguish
between two basic types of pain, acute and chronic, and they differ
for the most part, results from disease, inflammation, or injury to
tissues. This type of pain generally comes on suddenly, for example,
after trauma or surgery, and may be accompanied by anxiety or
emotional distress. The cause of acute pain can usually be diagnosed
and treated, and the pain is self-limiting, that is, it is confined
to a given period of time and severity. In some rare instances, it
can become chronic.
is widely believed to represent disease itself. It can be made much
worse by environmental and psychological factors. Chronic pain
persists over a longer period of time than acute pain and is
resistant to most medical treatments. It can—and often does—cause
severe problems for patients.
The A to Z of Pain
Hundreds of pain syndromes
or disorders make up the spectrum of pain. There are the most benign,
fleeting sensations of pain, such as a pin prick. There is the pain of
childbirth, the pain of a heart attack, and the pain that sometimes
follows amputation of a limb. There is also pain accompanying cancer and
the pain that follows severe trauma, such as that associated with head
and spinal cord injuries. A sampling of common pain syndromes follows,
Arachnoiditis is a
condition in which one of the three membranes covering the brain and
spinal cord, called the arachnoid membrane, becomes inflamed. A number
of causes, including infection or trauma, can result in inflammation of
this membrane. Arachnoiditis can produce disabling, progressive, and
even permanent pain.
Arthritis. Millions of
Americans suffer from arthritic conditions such as osteoarthritis,
rheumatoid arthritis, ankylosing spondylitis, and gout. These disorders
are characterized by joint pain in the extremities. Many other
inflammatory diseases affect the body's soft tissues, including
tendonitis and bursitis.
Back pain has become
the high price paid by our modern lifestyle and is a startlingly common
cause of disability for many Americans, including both active and
inactive people. Back pain that spreads to the leg is called sciatica
and is a very common condition (see below). Another common type of back
pain is associated with the discs of the spine, the soft, spongy padding
between the vertebrae (bones) that form the spine. Discs protect the
spine by absorbing shock, but they tend to degenerate over time and may
sometimes rupture. Spondylolisthesis is a back condition that
occurs when one vertebra extends over another, causing pressure on
nerves and therefore pain. Also, damage to nerve roots (see
Spine Basics in the Appendix) is a serious
condition, called radiculopathy, that can be extremely painful.
Treatment for a damaged disc includes drugs such as painkillers, muscle
relaxants, and steroids; exercise or rest, depending on the patient's
condition; adequate support, such as a brace or better mattress and
physical therapy. In some cases, surgery may be required to remove the
damaged portion of the disc and return it to its previous condition,
especially when it is pressing a nerve root. Surgical procedures include
discectomy, laminectomy, or spinal fusion (see section on surgery in
How is Pain Treated? for more information on
Burn pain can be
profound and poses an extreme challenge to the medical community.
First-degree burns are the least severe; with third-degree burns, the
skin is lost. Depending on the injury, pain accompanying burns can be
excruciating, and even after the wound has healed patients may have
chronic pain at the burn site.
Central pain syndrome-see
Cancer pain can
accompany the growth of a tumor, the treatment of cancer, or chronic
problems related to cancer's permanent effects on the body. Fortunately,
most cancer pain can be treated to help minimize discomfort and stress
to the patient.
millions of Americans. The three most common types of chronic headache
are migraines, cluster headaches, and tension headaches. Each comes with
its own telltale brand of pain.
characterized by throbbing pain and sometimes by other symptoms,
such as nausea and visual disturbances. Migraines are more frequent
in women than men. Stress can trigger a migraine headache, and
migraines can also put the sufferer at risk for stroke.
are characterized by excruciating, piercing pain on one side of the
head; they occur more frequently in men than women.
are often described as a tight band around the head.
Head and facial pain
can be agonizing, whether it results from dental problems or from
disorders such as cranial neuralgia, in which one of the nerves in the
face, head, or neck is inflamed. Another condition, trigeminal
neuralgia (also called tic douloureux), affects the largest of the
cranial nerves (see The Nervous Systems in the
Appendix) and is characterized by a stabbing, shooting pain.
Muscle pain can range
from an aching muscle, spasm, or strain, to the severe spasticity that
accompanies paralysis. Another disabling syndrome is fibromyalgia,
a disorder characterized by fatigue, stiffness, joint tenderness, and
widespread muscle pain. Polymyositis, dermatomyositis, and
inclusion body myositis are painful disorders characterized by
muscle inflammation. They may be caused by infection or autoimmune
dysfunction and are sometimes associated with connective tissue
disorders, such as lupus and rheumatoid arthritis.
Myofascial pain syndromes
affect sensitive areas known as trigger points, located within the
body's muscles. Myofascial pain syndromes are sometimes misdiagnosed and
can be debilitating. Fibromyalgia is a type of myofascial pain
Neuropathic pain is a
type of pain that can result from injury to nerves, either in the
peripheral or central nervous system (see The Nervous
Systems in the Appendix). Neuropathic pain can occur in any part of
the body and is frequently described as a hot, burning sensation, which
can be devastating to the affected individual. It can result from
diseases that affect nerves (such as diabetes) or from trauma, or,
because chemotherapy drugs can affect nerves, it can be a consequence of
cancer treatment. Among the many neuropathic pain conditions are
diabetic neuropathy (which results from nerve damage secondary to
vascular problems that occur with diabetes); reflex sympathetic
dystrophy syndrome (see below), which can follow injury; phantom
limb and post-amputation pain (see Phantom
Pain in the Appendix), which can result from the surgical removal of
a limb; postherpetic neuralgia, which can occur after an outbreak
of shingles; and central pain syndrome, which can result from
trauma to the brain or spinal cord.
dystrophy syndrome, or RSDS, is accompanied by burning pain and
hypersensitivity to temperature. Often triggered by trauma or nerve
damage, RSDS causes the skin of the affected area to become
characteristically shiny. In recent years, RSDS has come to be called
complex regional pain syndrome (CRPS); in the past it was often
Repetitive stress injuries
are muscular conditions that result from repeated motions performed in
the course of normal work or other daily activities. They include:
writer's cramp, which
affects musicians and writers and others,
compression or entrapment
neuropathies, including carpal tunnel syndrome, caused by chronic
overextension of the wrist and
tenosynovitis, affecting one or more tendons.
Sciatica is a painful
condition caused by pressure on the sciatic nerve, the main nerve that
branches off the spinal cord and continues down into the thighs, legs,
ankles, and feet. Sciatica is characterized by pain in the buttocks and
can be caused by a number of factors. Exertion, obesity, and poor
posture can all cause pressure on the sciatic nerve. One common cause of
sciatica is a herniated disc (see Spine Basics in
Shingles and other painful
disorders affect the skin. Pain is a common symptom of many skin
disorders, even the most common rashes. One of the most vexing
neurological disorders is shingles or herpes zoster, an infection that
often causes agonizing pain resistant to treatment. Prompt treatment
with antiviral agents is important to arrest the infection, which if
prolonged can result in an associated condition known as postherpetic
neuralgia. Other painful disorders affecting the skin include:
inflammation of blood vessels;
including herpes simplex;
skin tumors and
tumors associated with
neurofibromatosis, a neurogenetic disorder.
Sports injuries are
common. Sprains, strains, bruises, dislocations, and fractures are all
well-known words in the language of sports. Pain is another. In extreme
cases, sports injuries can take the form of costly and painful spinal
cord and head injuries, which cause severe suffering and disability.
Spinal stenosis refers
to a narrowing of the canal surrounding the spinal cord. The condition
occurs naturally with aging. Spinal stenosis causes weakness in the legs
and leg pain usually felt while the person is standing up and often
relieved by sitting down.
Surgical pain may
require regional or general anesthesia during the procedure and
medications to control discomfort following the operation. Control of
pain associated with surgery includes presurgical preparation and
careful monitoring of the patient during and after the procedure.
disorders are conditions in which the temporomandibular joint (the
jaw) is damaged and/or the muscles used for chewing and talking become
stressed, causing pain. The condition may be the result of a number of
factors, such as an injury to the jaw or joint misalignment, and may
give rise to a variety of symptoms, most commonly pain in the jaw, face,
and/or neck muscles. Physicians reach a diagnosis by listening to the
patient's description of the symptoms and by performing a simple
examination of the facial muscles and the temporomandibular joint.
Trauma can occur after
injuries in the home, at the workplace, during sports activities, or on
the road. Any of these injuries can result in severe disability and
pain. Some patients who have had an injury to the spinal cord experience
intense pain ranging from tingling to burning and, commonly, both. Such
patients are sensitive to hot and cold temperatures and touch. For these
individuals, a touch can be perceived as intense burning, indicating
abnormal signals relayed to and from the brain. This condition is called
central pain syndrome or, if the damage is in the thalamus (the
brain's center for processing bodily sensations), thalamic pain
syndrome. It affects as many as 100,000 Americans with multiple
sclerosis, Parkinson's disease, amputated limbs, spinal cord injuries,
and stroke. Their pain is severe and is extremely difficult to treat
effectively. A variety of medications, including analgesics,
antidepressants, anticonvulsants, and electrical stimulation, are
options available to central pain patients.
Vascular disease or injury-such
as vasculitis or inflammation of blood vessels, coronary artery disease,
and circulatory problems-all have the potential to cause pain. Vascular
pain affects millions of Americans and occurs when communication between
blood vessels and nerves is interrupted. Ruptures, spasms, constriction,
or obstruction of blood vessels, as well as a condition called ischemia
in which blood supply to organs, tissues, or limbs is cut off, can also
result in pain.
There is no way to tell how
much pain a person has. No test can measure the intensity of pain, no
imaging device can show pain, and no instrument can locate pain
precisely. Sometimes, as in the case of headaches, physicians find that
the best aid to diagnosis is the patient's own description of the type,
duration, and location of pain. Defining pain as sharp or dull, constant
or intermittent, burning or aching may give the best clues to the cause
of pain. These descriptions are part of what is called the pain history,
taken by the physician during the preliminary examination of a patient
Physicians, however, do have
a number of technologies they use to find the cause of pain. Primarily
procedures include electromyography (EMG), nerve
conduction studies, and evoked potential (EP) studies.
Information from EMG can help physicians tell precisely which
muscles or nerves are affected by weakness or pain. Thin needles are
inserted in muscles and a physician can see or listen to electrical
signals displayed on an EMG machine. With nerve conduction
studies the doctor uses two sets of electrodes (similar to those
used during an electrocardiogram) that are placed on the skin over
the muscles. The first set gives the patient a mild shock that
stimulates the nerve that runs to that muscle. The second set of
electrodes is used to make a recording of the nerve's electrical
signals, and from this information the doctor can determine if there
is nerve damage. EP tests also involve two sets of
electrodes-one set for stimulating a nerve (these electrodes are
attached to a limb) and another set on the scalp for recording the
speed of nerve signal transmission to the brain.
magnetic resonance imaging or MRI, provides physicians with pictures
of the body's structures and tissues. MRI uses magnetic fields and
radio waves to differentiate between healthy and diseased tissue.
examination in which the physician tests movement, reflexes,
sensation, balance, and coordination.
pictures of the body's structures, such as bones and joints.
How is Pain Treated?
The goal of pain management
is to improve function, enabling individuals to work, attend school, or
participate in other day-to-day activities. Patients and their
physicians have a number of options for the treatment of pain; some are
more effective than others. Sometimes, relaxation and the use of imagery
as a distraction provide relief. These methods can be powerful and
effective, according to those who advocate their use. Whatever the
treatment regime, it is important to remember that pain is treatable.
The following treatments are among the most common.
Acetaminophen is the
basic ingredient found in Tylenol® and its many generic equivalents. It
is sold over the counter, in a prescription-strength preparation, and in
combination with codeine (also by prescription).
Acupuncture dates back
2,500 years and involves the application of needles to precise points on
the body. It is part of a general category of healing called traditional
Chinese or Oriental medicine. Acupuncture remains controversial but is
quite popular and may one day prove to be useful for a variety of
conditions as it continues to be explored by practitioners, patients,
Analgesic refers to
the class of drugs that includes most painkillers, such as aspirin,
acetaminophen, and ibuprofen. The word analgesic is derived from ancient
Greek and means to reduce or stop pain. Nonprescription or
over-the-counter pain relievers are generally used for mild to moderate
pain. Prescription pain relievers, sold through a pharmacy under the
direction of a physician, are used for more moderate to severe pain.
used for the treatment of seizure disorders but are also sometimes
prescribed for the treatment of pain. Carbamazepine in particular is
used to treat a number of painful conditions, including trigeminal
neuralgia. Another antiepileptic drug, gabapentin, is being studied for
its pain-relieving properties, especially as a treatment for neuropathic
sometimes used for the treatment of pain and, along with neuroleptics
and lithium, belong to a category of drugs called psychotropic drugs. In
addition, anti-anxiety drugs called benzodiazepines also act as muscle
relaxants and are sometimes used as pain relievers. Physicians usually
try to treat the condition with analgesics before prescribing these
include the triptans- sumatriptan (Imitrex®), naratriptan (Amerge®), and
zolmitriptan (Zomig®)-and are used specifically for migraine headaches.
They can have serious side effects in some people and therefore, as with
all prescription medicines, should be used only under a doctor's care.
Aspirin may be the
most widely used pain-relief agent and has been sold over the counter
since 1905 as a treatment for fever, headache, and muscle soreness.
Biofeedback is used
for the treatment of many common pain problems, most notably headache
and back pain. Using a special electronic machine, the patient is
trained to become aware of, to follow, and to gain control over certain
bodily functions, including muscle tension, heart rate, and skin
temperature. The individual can then learn to effect a change in his or
her responses to pain, for example, by using relaxation techniques.
Biofeedback is often used in combination with other treatment methods,
generally without side effects. Similarly, the use of relaxation
techniques in the treatment of pain can increase the patient's feeling
Capsaicin is a
chemical found in chili peppers that is also a primary ingredient in
pain-relieving creams (see Chili Peppers, Capsaicin,
and Pain in the Appendix).
Chemonucleolysis is a
treatment in which an enzyme, chymopapain, is injected directly into a
herniated lumbar disc (see Spine Basics in the
Appendix) in an effort to dissolve material around the disc, thus
reducing pressure and pain. The procedure's use is extremely limited, in
part because some patients may have a life-threatening allergic reaction
Chiropractic refers to
hand manipulation of the spine, usually for relief of back pain, and is
a treatment option that continues to grow in popularity among many
people who simply seek relief from back disorders. It has never been
without controversy, however. Chiropractic's usefulness as a treatment
for back pain is, for the most part, restricted to a select group of
individuals with uncomplicated acute low back pain who may derive relief
from the massage component of the therapy.
therapy involves a wide variety of coping skills and relaxation
methods to help prepare for and cope with pain. It is used for
postoperative pain, cancer pain, and the pain of childbirth.
Counseling can give a
patient suffering from pain much needed support, whether it is derived
from family, group, or individual counseling. Support groups can provide
an important adjunct to drug or surgical treatment. Psychological
treatment can also help patients learn about the physiological changes
produced by pain.
("superaspirins") may be particularly effective for individuals with
arthritis. For many years scientists have wanted to develop the ultimate
drug-a drug that works as well as morphine but without its negative side
effects. Nonsteroidal anti-inflammatory drugs (NSAIDs) work by blocking
two enzymes, cyclooxygenase-1 and cyclooxygenase-2, both of which
promote production of hormones called prostaglandins, which in
turn cause inflammation, fever, and pain. Newer drugs, called COX-2
inhibitors, primarily block cyclooxygenase-2 and are less likely to have
the gastrointestinal side effects sometimes produced by NSAIDs. On 1999,
the Food and Drug Administration approved two COX-2 inhibitors-rofecoxib
(Vioxx®) and celecoxib (Celebrex®). Although the long-term effects of
COX-2 inhibitors are still being evaluated, they appear to be safe. In
addition, patients may be able to take COX-2 inhibitors in larger doses
than aspirin and other drugs that have irritating side effects, earning
them the nickname "superaspirins."
including transcutaneous electrical stimulation (TENS), implanted
electric nerve stimulation, and deep brain or spinal cord stimulation,
is the modern-day extension of age-old practices in which the nerves of
muscles are subjected to a variety of stimuli, including heat or
massage. Electrical stimulation, no matter what form, involves a major
surgical procedure and is not for everyone, nor is it 100 percent
effective. The following techniques each require specialized equipment
and personnel trained in the specific procedure being used:
TENS uses tiny
electrical pulses, delivered through the skin to nerve fibers, to
cause changes in muscles, such as numbness or contractions. This in
turn produces temporary pain relief. There is also evidence that
TENS can activate subsets of peripheral nerve fibers that can block
pain transmission at the spinal cord level, in much the same way
that shaking your hand can reduce pain.
stimulation uses electrodes placed surgically on a carefully
selected area of the body. The patient is then able to deliver an
electrical current as needed to the affected area, using an antenna
stimulation uses electrodes surgically inserted within the
epidural space of the spinal cord. The patient is able to deliver a
pulse of electricity to the spinal cord using a small box-like
receiver and an antenna taped to the skin.
Deep brain or
intracerebral stimulation is considered an extreme treatment and
involves surgical stimulation of the brain, usually the thalamus. It
is used for a limited number of conditions, including severe pain,
central pain syndrome, cancer pain, phantom limb pain, and other
Exercise has come to
be a prescribed part of some doctors' treatment regimes for patients
with pain. Because there is a known link between many types of chronic
pain and tense, weak muscles, exercise-even light to moderate exercise
such as walking or swimming-can contribute to an overall sense of
well-being by improving blood and oxygen flow to muscles. Just as we
know that stress contributes to pain, we also know that exercise, sleep,
and relaxation can all help reduce stress, thereby helping to alleviate
pain. Exercise has been proven to help many people with low back pain.
It is important, however, that patients carefully follow the routine
laid out by their physicians.
approved for medical use by the American Medical Association in 1958,
continues to grow in popularity, especially as an adjunct to pain
medication. In general, hypnosis is used to control physical function or
response, that is, the amount of pain an individual can withstand. How
hypnosis works is not fully understood. Some believe that hypnosis
delivers the patient into a trance-like state, while others feel that
the individual is simply better able to concentrate and relax or is more
responsive to suggestion. Hypnosis may result in relief of pain by
acting on chemicals in the nervous system, slowing impulses. Whether and
how hypnosis works involves greater insight-and research-into the
mechanisms underlying human consciousness.
Ibuprofen is a member
of the aspirin family of analgesics, the so-called nonsteroidal
anti-inflammatory drugs (see below). It is sold over the counter and
also comes in prescription-strength preparations.
Low-power lasers have
been used occasionally by some physical therapists as a treatment for
pain, but like many other treatments, this method is not without
increasingly popular with athletes who swear by their effectiveness for
the control of sports-related pain and other painful conditions. Usually
worn as a collar or wristwatch, the use of magnets as a treatment dates
back to the ancient Egyptians and Greeks. While it is often dismissed as
quackery and pseudoscience by skeptics, proponents offer the theory that
magnets may effect changes in cells or body chemistry, thus producing
Nerve blocks employ
the use of drugs, chemical agents, or surgical techniques to interrupt
the relay of pain messages between specific areas of the body and the
brain. There are many different names for the procedure, depending on
the technique or agent used. Types of surgical nerve blocks include
neurectomy; spinal dorsal, cranial, and trigeminal rhizotomy; and
sympathectomy, also called sympathetic blockade (see
Nerve Blocks in the Appendix).
anti-inflammatory drugs (NSAIDs) (including aspirin and ibuprofen)
are widely prescribed and sometimes called non-narcotic or non-opioid
analgesics. They work by reducing inflammatory responses in tissues.
Many of these drugs irritate the stomach and for that reason are usually
taken with food. Although acetaminophen may have some anti-inflammatory
effects, it is generally distinguished from the traditional NSAIDs.
Opioids are derived
from the poppy plant and are among the oldest drugs known to humankind.
They include codeine and perhaps the most well-known narcotic of all,
morphine. Morphine can be administered in a variety of forms,
including a pump for patient self-administration. Opioids have a
narcotic effect, that is, they induce sedation as well as pain relief,
and some patients may become physically dependent upon them. For these
reasons, patients given opioids should be monitored carefully; in some
cases stimulants may be prescribed to counteract the sedative side
effects. In addition to drowsiness, other common side effects include
constipation, nausea, and vomiting.
Physical therapy and
rehabilitation date back to the ancient practice of using physical
techniques and methods, such as heat, cold, exercise, massage, and
manipulation, in the treatment of certain conditions. These may be
applied to increase function, control pain, and speed the patient toward
Placebos offer some
individuals pain relief although whether and how they have an effect is
mysterious and somewhat controversial. Placebos are inactive substances,
such as sugar pills, or harmless procedures, such as saline injections
or sham surgeries, generally used in clinical studies as control factors
to help determine the efficacy of active treatments. Although placebos
have no direct effect on the underlying causes of pain, evidence from
clinical studies suggests that many pain conditions such as migraine
headache, back pain, post-surgical pain, rheumatoid arthritis, angina,
and depression sometimes respond well to them. This positive response is
known as the placebo effect, which is defined as the observable or
measurable change that can occur in patients after administration of a
placebo. Some experts believe the effect is psychological and that
placebos work because the patients believe or expect them to work.
Others say placebos relieve pain by stimulating the brain's own
analgesics and setting the body's self-healing forces in motion. A third
theory suggests that the act of taking placebos relieves stress and
anxiety-which are known to aggravate some painful conditions-and, thus,
cause the patients to feel better. Still, placebos are considered
controversial because by definition they are inactive and have no actual
Ice, Compression, and Elevation-are four components
prescribed by many orthopedists, coaches, trainers, nurses, and other
professionals for temporary muscle or joint conditions, such as sprains
or strains. While many common orthopedic problems can be controlled with
these four simple steps, especially when combined with over-the-counter
pain relievers, more serious conditions may require surgery or physical
therapy, including exercise, joint movement or manipulation, and
stimulation of muscles.
Surgery, although not
always an option, may be required to relieve pain, especially pain
caused by back problems or serious musculoskeletal injuries. Surgery may
take the form of a nerve block (see Nerve Blocks
in the Appendix) or it may involve an operation to relieve pain from a
ruptured disc. Surgical procedures for back problems include
discectomy or, when microsurgical techniques are used,
microdiscectomy, in which the entire disc is removed; laminectomy,
a procedure in which a surgeon removes only a disc fragment, gaining
access by entering through the arched portion of a vertebra; and spinal
fusion, a procedure where the entire disc is removed and replaced with a
bone graft. In a spinal fusion, the two vertebrae are then fused
together. Although the operation can cause the spine to stiffen,
resulting in lost flexibility, the procedure serves one critical
purpose: protection of the spinal cord. Other operations for pain
include rhizotomy, in which a nerve close to the spinal cord is
cut, and cordotomy, where bundles of nerves within the spinal
cord are severed. Cordotomy is generally used only for the pain of
terminal cancer that does not respond to other therapies. Another
operation for pain is the dorsal root entry zone operation, or
DREZ, in which spinal neurons corresponding to the patient's pain are
destroyed surgically. Because surgery can result in scar tissue
formation that may cause additional problems, patients are well advised
to seek a second opinion before proceeding. Occasionally, surgery is
carried out with electrodes that selectively damage neurons in a
targeted area of the brain. These procedures rarely result in long-term
pain relief, but both physician and patient may decide that the surgical
procedure will be effective enough that it justifies the expense and
risk. In some cases, the results of an operation are remarkable. For
example, many individuals suffering from trigeminal neuralgia who are
not responsive to drug treatment have had great success with a procedure
called microvascular decompression, in which tiny blood vessels are
surgically separated from surrounding nerves.
What is the Role of Age
and Gender in Pain?
It is now widely believed
that pain affects men and women differently. While the sex hormones
estrogen and testosterone certainly play a role in this phenomenon,
psychology and culture, too, may account at least in part for
differences in how men and women receive pain signals. For example,
young children may learn to respond to pain based on how they are
treated when they experience pain. Some children may be cuddled and
comforted, while others may be encouraged to tough it out and to dismiss
Many investigators are
turning their attention to the study of gender differences and pain.
Women, many experts now agree, recover more quickly from pain, seek help
more quickly for their pain, and are less likely to allow pain to
control their lives. They also are more likely to marshal a variety of
resources-coping skills, support, and distraction-with which to deal
with their pain.
Research in this area is
yielding fascinating results. For example, male experimental animals
injected with estrogen, a female sex hormone, appear to have a lower
tolerance for pain-that is, the addition of estrogen appears to lower
the pain threshold. Similarly, the presence of testosterone, a male
hormone, appears to elevate tolerance for pain in female mice: the
animals are simply able to withstand pain better. Female mice deprived
of estrogen during experiments react to stress similarly to male
animals. Estrogen, therefore, may act as a sort of pain switch, turning
on the ability to recognize pain.
Investigators know that males
and females both have strong natural pain-killing systems, but these
systems operate differently. For example, a class of painkillers called
kappa-opioids is named after one of several opioid receptors to which
they bind, the kappa-opioid receptor, and they include the compounds
nalbuphine (Nubain®) and butorphanol (Stadol®). Research
suggests that kappa-opioids provide better pain relief in women.
Though not prescribed widely,
kappa-opioids are currently used for relief of labor pain and in general
work best for short-term pain. Investigators are not certain why
kappa-opioids work better in women than men. Is it because a woman's
estrogen makes them work, or because a man's testosterone prevents them
from working? Or is there another explanation, such as differences
between men and women in their perception of pain? Continued research
may result in a better understanding of how pain affects women
differently from men, enabling new and better pain medications to be
designed with gender in mind.
Pain is the number one
complaint of older Americans, and one in five older Americans takes a
painkiller regularly. In 1998, the American Geriatrics Society (AGS)
issued guidelines* for the management of pain in older people. The AGS
panel addressed the incorporation of several non-drug approaches in
patients' treatment plans, including exercise. AGS panel members
recommend that, whenever possible, patients use alternatives to aspirin,
ibuprofen, and other NSAIDs because of the drugs' side effects,
including stomach irritation and gastrointestinal bleeding. For older
adults, acetaminophen is the first-line treatment for mild-to-moderate
pain, according to the guidelines. More serious chronic pain conditions
may require opioid drugs (narcotics), including codeine or morphine, for
relief of pain.
Pain in younger patients also
requires special attention, particularly because young children are not
always able to describe the degree of pain they are experiencing.
Although treating pain in pediatric patients poses a special challenge
to physicians and parents alike, pediatric patients should never be
undertreated. Recently, special tools for measuring pain in children
have been developed that, when combined with cues used by parents, help
physicians select the most effective treatments.
Nonsteroidal agents, and
especially acetaminophen, are most often prescribed for control of pain
in children. In the case of severe pain or pain following surgery,
acetaminophen may be combined with codeine.
* Journal of the American
Geriatrics Society (1998; 46:635-651).
A Pain Primer: What Do We
Know About Pain?
We may experience pain as a
prick, tingle, sting, burn, or ache. Receptors on the skin trigger a
series of events, beginning with an electrical impulse that travels from
the skin to the spinal cord. The spinal cord acts as a sort of relay
center where the pain signal can be blocked, enhanced, or otherwise
modified before it is relayed to the brain. One area of the spinal cord
in particular, called the dorsal horn (see section on
Spine Basics in the Appendix), is important in the
reception of pain signals.
The most common destination
in the brain for pain signals is the thalamus and from there to the
cortex, the headquarters for complex thoughts. The thalamus also serves
as the brain's storage area for images of the body and plays a key role
in relaying messages between the brain and various parts of the body. In
people who undergo an amputation, the representation of the amputated
limb is stored in the thalamus. (For a discussion of the thalamus and
its role in this phenomenon, called phantom pain, see section on
Phantom Pain in the Appendix.)
Pain is a complicated process
that involves an intricate interplay between a number of important
chemicals found naturally in the brain and spinal cord. In general,
these chemicals, called neurotransmitters, transmit nerve
impulses from one cell to another.
There are many different
neurotransmitters in the human body; some play a role in human disease
and, in the case of pain, act in various combinations to produce painful
sensations in the body. Some chemicals govern mild pain sensations;
others control intense or severe pain.
The body's chemicals act in
the transmission of pain messages by stimulating neurotransmitter
receptors found on the surface of cells; each receptor has a
corresponding neurotransmitter. Receptors function much like gates or
ports and enable pain messages to pass through and on to neighboring
cells. One brain chemical of special interest to neuroscientists is
glutamate. During experiments, mice with blocked glutamate receptors
show a reduction in their responses to pain. Other important receptors
in pain transmission are opiate-like receptors. Morphine and other
opioid drugs work by locking on to these opioid receptors, switching on
pain-inhibiting pathways or circuits, and thereby blocking pain.
Another type of receptor that
responds to painful stimuli is called a nociceptor. Nociceptors
are thin nerve fibers in the skin, muscle, and other body tissues, that,
when stimulated, carry pain signals to the spinal cord and brain.
Normally, nociceptors only respond to strong stimuli such as a pinch.
However, when tissues become injured or inflamed, as with a sunburn or
infection, they release chemicals that make nociceptors much more
sensitive and cause them to transmit pain signals in response to even
gentle stimuli such as breeze or a caress. This condition is called
allodynia -a state in which pain is produced by innocuous stimuli.
The body's natural
painkillers may yet prove to be the most promising pain relievers,
pointing to one of the most important new avenues in drug development.
The brain may signal the release of painkillers found in the spinal
cord, including serotonin, norepinephrine, and opioid-like chemicals.
Many pharmaceutical companies are working to synthesize these substances
in laboratories as future medications.
enkephalins are other natural painkillers. Endorphins may be
responsible for the "feel good" effects experienced by many people after
rigorous exercise; they are also implicated in the pleasurable effects
compounds that make up proteins in the body, play a role in pain
responses. Mice bred experimentally to lack a gene for two peptides
called tachykinins-neurokinin A and substance P-have a reduced
response to severe pain. When exposed to mild pain, these mice react in
the same way as mice that carry the missing gene. But when exposed to
more severe pain, the mice exhibit a reduced pain response. This
suggests that the two peptides are involved in the production of pain
sensations, especially moderate-to-severe pain. Continued research on
tachykinins, conducted with support from the NINDS, may pave the way for
drugs tailored to treat different severities of pain.
Scientists are working to
develop potent pain-killing drugs that act on receptors for the chemical
acetylcholine. For example, a type of frog native to Ecuador has
been found to have a chemical in its skin called epibatidine, derived
from the frog's scientific name, Epipedobates tricolor. Although
highly toxic, epibatidine is a potent analgesic and, surprisingly,
resembles the chemical nicotine found in cigarettes. Also under
development are other less toxic compounds that act on acetylcholine
receptors and may prove to be more potent than morphine but without its
The idea of using receptors
as gateways for pain drugs is a novel idea, supported by experiments
involving substance P. Investigators have been able to isolate a tiny
population of neurons, located in the spinal cord, that together form a
major portion of the pathway responsible for carrying persistent pain
signals to the brain. When animals were given injections of a lethal
cocktail containing substance P linked to the chemical saporin, this
group of cells, whose sole function is to communicate pain, were killed.
Receptors for substance P served as a portal or point of entry for the
compound. Within days of the injections, the targeted neurons, located
in the outer layer of the spinal cord along its entire length, absorbed
the compound and were neutralized. The animals' behavior was completely
normal; they no longer exhibited signs of pain following injury or had
an exaggerated pain response. Importantly, the animals still responded
to acute, that is, normal, pain. This is a critical finding as it is
important to retain the body's ability to detect potentially injurious
stimuli. The protective, early warning signal that pain provides is
essential for normal functioning. If this work can be translated
clinically, humans might be able to benefit from similar compounds
introduced, for example, through lumbar (spinal) puncture.
Another promising area of
research using the body's natural pain-killing abilities is the
transplantation of chromaffin cells into the spinal cords of animals
bred experimentally to develop arthritis. Chromaffin cells produce
several of the body's pain-killing substances and are part of the
adrenal medulla, which sits on top of the kidney. Within a week or so,
rats receiving these transplants cease to exhibit telltale signs of
pain. Scientists, working with support from the NINDS, believe the
transplants help the animals recover from pain-related cellular damage.
Extensive animal studies will be required to learn if this technique
might be of value to humans with severe pain.
One way to control pain
outside of the brain, that is, peripherally, is by inhibiting hormones
called prostaglandins. Prostaglandins stimulate nerves at the
site of injury and cause inflammation and fever. Certain drugs,
including NSAIDs, act against such hormones by blocking the enzyme that
is required for their synthesis.
Blood vessel walls stretch or
dilate during a migraine attack and it is thought that serotonin plays a
complicated role in this process. For example, before a migraine
headache, serotonin levels fall. Drugs for migraine include the triptans:
sumatriptan (Imitrix®), naratriptan (Amerge®), and zolmitriptan (Zomig®).
They are called serotonin agonists because they mimic the action
of endogenous (natural) serotonin and bind to specific subtypes of
Ongoing pain research, much
of it supported by the NINDS, continues to reveal at an unprecedented
pace fascinating insights into how genetics, the immune system, and the
skin contribute to pain responses.
The explosion of knowledge
about human genetics is helping scientists who work in the field of drug
development. We know, for example, that the pain-killing properties of
codeine rely heavily on a liver enzyme, CYP2D6, which helps convert
codeine into morphine. A small number of people genetically lack the
enzyme CYP2D6; when given codeine, these individuals do not get pain
relief. CYP2D6 also helps break down certain other drugs. People who
genetically lack CYP2D6 may not be able to cleanse their systems of
these drugs and may be vulnerable to drug toxicity. CYP2D6 is currently
under investigation for its role in pain.
In his research, the late
John C. Liebeskind, a renowned pain expert and a professor of psychology
at UCLA, found that pain can kill by delaying healing and causing cancer
to spread. In his pioneering research on the immune system and pain, Dr.
Liebeskind studied the effects of stress-such as surgery-on the immune
system and in particular on cells called natural killer or NK
cells. These cells are thought to help protect the body against
tumors. In one study conducted with rats, Dr. Liebeskind found that,
following experimental surgery, NK cell activity was suppressed, causing
the cancer to spread more rapidly. When the animals were treated with
morphine, however, they were able to avoid this reaction to stress.
The link between the nervous
and immune systems is an important one. Cytokines, a type of protein
found in the nervous system, are also part of the body's immune system,
the body's shield for fighting off disease. Cytokines can trigger pain
by promoting inflammation, even in the absence of injury or damage.
Certain types of cytokines have been linked to nervous system injury.
After trauma, cytokine levels rise in the brain and spinal cord and at
the site in the peripheral nervous system where the injury occurred.
Improvements in our understanding of the precise role of cytokines in
producing pain, especially pain resulting from injury, may lead to new
classes of drugs that can block the action of these substances.
In the forefront of pain
research are scientists supported by the National Institutes of Health (NIH),
including the NINDS. Other institutes at NIH that support pain research
include the National Institute of Dental and Craniofacial Research, the
National Cancer Institute, the National Institute of Nursing Research,
the National Institute on Drug Abuse, and the National Institute of
Mental Health. Developing better pain treatments is the primary goal of
all pain research being conducted by these institutes.
Some pain medications dull
the patient's perception of pain. Morphine is one such drug. It works
through the body's natural pain-killing machinery, preventing pain
messages from reaching the brain. Scientists are working toward the
development of a morphine-like drug that will have the pain-deadening
qualities of morphine but without the drug's negative side effects, such
as sedation and the potential for addiction. Patients receiving morphine
also face the problem of morphine tolerance, meaning that over time they
require higher doses of the drug to achieve the same pain relief.
Studies have identified factors that contribute to the development of
tolerance; continued progress in this line of research should eventually
allow patients to take lower doses of morphine.
One objective of
investigators working to develop the future generation of pain
medications is to take full advantage of the body's pain "switching
center" by formulating compounds that will prevent pain signals from
being amplified or stop them altogether. Blocking or interrupting pain
signals, especially when there is no injury or trauma to tissue, is an
important goal in the development of pain medications. An increased
understanding of the basic mechanisms of pain will have profound
implications for the development of future medicines. The following
areas of research are bringing us closer to an ideal pain drug.
Systems and Imaging:
The idea of mapping cognitive functions to precise areas of the brain
dates back to phrenology, the now archaic practice of studying bumps on
the head. Positron emission tomography (PET), functional magnetic
resonance imaging (fMRI), and other imaging technologies offer a vivid
picture of what is happening in the brain as it processes pain. Using
imaging, investigators can now see that pain activates at least three or
four key areas of the brain's cortex-the layer of tissue that covers the
brain. Interestingly, when patients undergo hypnosis so that the
unpleasantness of a painful stimulus is not experienced, activity in
some, but not all, brain areas is reduced. This emphasizes that the
experience of pain involves a strong emotional component as well as the
sensory experience, namely the intensity of the stimulus.
Channels: The frontier
in the search for new drug targets is represented by channels. Channels
are gate-like passages found along the membranes of cells that allow
electrically charged chemical particles called ions to pass into the
cells. Ion channels are important for transmitting signals through the
nerve's membrane. The possibility now exists for developing new classes
of drugs, including pain cocktails that would act at the site of channel
Trophic Factors: A
class of "rescuer" or "restorer" drugs may emerge from our growing
knowledge of trophic factors, natural chemical substances found in the
human body that affect the survival and function of cells. Trophic
factors also promote cell death, but little is known about how something
beneficial can become harmful. Investigators have observed that an
over-accumulation of certain trophic factors in the nerve cells of
animals results in heightened pain sensitivity, and that some receptors
found on cells respond to trophic factors and interact with each other.
These receptors may provide targets for new pain therapies.
Certain genetic mutations can change pain sensitivity and behavioral
responses to pain. People born genetically insensate to pain-that is,
individuals who cannot feel pain-have a mutation in part of a gene that
plays a role in cell survival. Using "knockout" animal models-animals
genetically engineered to lack a certain gene-scientists are able to
visualize how mutations in genes cause animals to become anxious, make
noise, rear, freeze, or become hypervigilant. These genetic mutations
cause a disruption or alteration in the processing of pain information
as it leaves the spinal cord and travels to the brain. Knockout animals
can be used to complement efforts aimed at developing new drugs.
injury, the nervous system undergoes a tremendous reorganization. This
phenomenon is known as plasticity. For example, the spinal cord is
"rewired" following trauma as nerve cell axons make new contacts, a
phenomenon known as "sprouting." This in turn disrupts the cells' supply
of trophic factors. Scientists can now identify and study the changes
that occur during the processing of pain. For example, using a technique
called polymerase chain reaction, abbreviated PCR, scientists can study
the genes that are induced by injury and persistent pain. There is
evidence that the proteins that are ultimately synthesized by these
genes may be targets for new therapies. The dramatic changes that occur
with injury and persistent pain underscore that chronic pain should be
considered a disease of the nervous system, not just prolonged acute
pain or a symptom of an injury. Thus, scientists hope that therapies
directed at preventing the long-term changes that occur in the nervous
system will prevent the development of chronic pain conditions.
Just as mutations in genes may affect behavior, they may also affect a
number of neurotransmitters involved in the control of pain. Using
sophisticated imaging technologies, investigators can now visualize what
is happening chemically in the spinal cord. From this work, new
therapies may emerge, therapies that can help reduce or obliterate
severe or chronic pain.
Thousands of years ago,
ancient peoples attributed pain to spirits and treated it with mysticism
and incantations. Over the centuries, science has provided us with a
remarkable ability to understand and control pain with medications,
surgery, and other treatments. Today, scientists understand a great deal
about the causes and mechanisms of pain, and research has produced
dramatic improvements in the diagnosis and treatment of a number of
painful disorders. For people who fight every day against the
limitations imposed by pain, the work of NINDS-supported scientists
holds the promise of an even greater understanding of pain in the coming
years. Their research offers a powerful weapon in the battle to prolong
and improve the lives of people with pain: hope.
Spine Basics: The Vertebrae,
Discs, and Spinal Cord
Stacked on top of one another
in the spine are more than 30 bones, the vertebrae, which together form
the spine. They are divided into four regions:
the seven cervical or
neck vertebrae (labeled C1-C7),
the 12 thoracic or upper
back vertebrae (labeled T1-T12),
the five lumbar vertebrae
(labeled L1-L5), which we know as the lower back, and
the sacrum and coccyx, a
group of bones fused together at the base of the spine.
The vertebrae are linked by
ligaments, tendons, and muscles. Back pain can occur when, for example,
someone lifts something too heavy, causing a sprain, pull, strain, or
spasm in one of these muscles or ligaments in the back.
Between the vertebrae are
round, spongy pads of cartilage called discs that act much like
shock absorbers. In many cases, degeneration or pressure from
overexertion can cause a disc to shift or protrude and bulge, causing
pressure on a nerve and resultant pain. When this happens, the condition
is called a slipped, bulging, herniated, or ruptured disc, and it
sometimes results in permanent nerve damage.
The column-like spinal cord
is divided into segments similar to the corresponding vertebrae:
cervical, thoracic, lumbar, sacral, and coccygeal. The cord also has
nerve roots and rootlets which form branch-like appendages leading from
its ventral side (that is, the front of the body) and from its dorsal
side (that is, the back of the body). Along the dorsal root are the
cells of the dorsal root ganglia, which are critical in the transmission
of "pain" messages from the cord to the brain. It is here where injury,
damage, and trauma become pain.
The Nervous Systems
The central nervous system
(CNS) refers to the brain and spinal cord together. The peripheral
nervous system refers to the cervical, thoracic, lumbar, and sacral
nerve trunks leading away from the spine to the limbs. Messages related
to function (such as movement) or dysfunction (such as pain) travel from
the brain to the spinal cord and from there to other regions in the body
and back to the brain again. The autonomic nervous system controls
involuntary functions in the body, like perspiration, blood pressure,
heart rate, or heart beat. It is divided into the sympathetic and
parasympathetic nervous systems. The sympathetic and parasympathetic
nervous systems have links to important organs and systems in the body;
for example, the sympathetic nervous system controls the heart, blood
vessels, and respiratory system, while the parasympathetic nervous
system controls our ability to sleep, eat, and digest food.
The peripheral nervous system
also includes 12 pairs of cranial nerves located on the underside of the
brain. Most relay messages of a sensory nature. They include the
olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal
(V), abducens (VI), facial (VII), vestibulocochlear (VIII),
glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal (XII)
nerves. Neuralgia, as in trigeminal neuralgia, is a term that refers to
pain that arises from abnormal activity of a nerve trunk or its
branches. The type and severity of pain associated with neuralgia vary
Phantom Pain: How Does
the Brain Feel?
Sometimes, when a limb is
removed during an amputation, an individual will continue to have an
internal sense of the lost limb. This phenomenon is known as phantom
limb and accounts describing it date back to the 1800s. Similarly, many
amputees are frequently aware of severe pain in the absent limb. Their
pain is real and is often accompanied by other health problems, such as
What causes this phenomenon?
Scientists believe that following amputation, nerve cells "rewire"
themselves and continue to receive messages, resulting in a remapping of
the brain's circuitry. The brain's ability to restructure itself, to
change and adapt following injury, is called plasticity (see section on
Our understanding of phantom
pain has improved tremendously in recent years. Investigators previously
believed that brain cells affected by amputation simply died off. They
attributed sensations of pain at the site of the amputation to
irritation of nerves located near the limb stump. Now, using imaging
techniques such as positron emission tomography (PET) and magnetic
resonance imaging (MRI), scientists can actually visualize increased
activity in the brain's cortex when an individual feels phantom pain.
When study participants move the stump of an amputated limb, neurons in
the brain remain dynamic and excitable. Surprisingly, the brain's cells
can be stimulated by other body parts, often those located closest to
the missing limb.
Treatments for phantom pain
may include analgesics, anticonvulsants, and other types of drugs; nerve
blocks; electrical stimulation; psychological counseling, biofeedback,
hypnosis, and acupuncture; and, in rare instances, surgery.
Chili Peppers, Capsaicin,
The hot feeling, red face,
and watery eyes you experience when you bite into a red chili pepper may
make you reach for a cold drink, but that reaction has also given
scientists important information about pain. The chemical found in chili
peppers that causes those feelings is capsaicin (pronounced
cap-SAY-sin), and it works its unique magic by grabbing onto receptors
scattered along the surface of sensitive nerve cells in the mouth.
In 1997, scientists at the
University of California at San Francisco discovered a gene for a
capsaicin receptor, called the vanilloid receptor. Once in contact with
capsaicin, vanilloid receptors open and pain signals are sent from the
peripheral nociceptor and through central nervous system circuits to the
brain. Investigators have also learned that this receptor plays a role
in the burning type of pain commonly associated with heat, such as the
kind you experience when you touch your finger to a hot stove. The
vanilloid receptor functions as a sort of "ouch gateway," enabling us to
detect burning hot pain, whether it originates from a 3-alarm habanera
chili or from a stove burner.
Capsaicin is currently
available as a prescription or over-the-counter cream for the treatment
of a number of pain conditions, such as shingles. It works by reducing
the amount of substance P found in nerve endings and interferes with the
transmission of pain signals to the brain. Individuals can become
desensitized to the compound, however, perhaps because of long-term
damage to nerve tissue. Some individuals find the burning sensation they
experience when using capsaicin cream to be intolerable, especially when
they are already suffering from a painful condition, such as
postherpetic neuralgia. Soon, however, better treatments that relieve
pain by blocking vanilloid receptors may arrive in drugstores.
As a painkiller, marijuana
or, by its Latin name, cannabis, continues to remain highly
controversial. In the eyes of many individuals campaigning on its
behalf, marijuana rightfully belongs with other pain remedies. In fact,
for many years, it was sold under highly controlled conditions in
cigarette form by the Federal government for just that purpose.
In 1997, the National
Institutes of Health held a workshop to discuss research on the possible
therapeutic uses for smoked marijuana. Panel members from a number of
fields reviewed published research and heard presentations from pain
experts. The panel members concluded that, because there are too few
scientific studies to prove marijuana's therapeutic utility for certain
conditions, additional research is needed. There is evidence, however,
that receptors to which marijuana binds are found in many brain regions
that process information that can produce pain.
Nerve blocks may involve
local anesthesia, regional anesthesia or analgesia, or surgery; dentists
routinely use them for traditional dental procedures. Nerve blocks can
also be used to prevent or even diagnose pain.
In the case of a local nerve
block, any one of a number of local anesthetics may be used; the names
of these compounds, such as lidocaine or novocaine, usually have an
aine ending. Regional blocks affect a larger area of the body. Nerve
blocks may also take the form of what is commonly called an epidural, in
which a drug is administered into the space between the spine's
protective covering (the dura) and the spinal column. This procedure is
most well known for its use during childbirth. Morphine and methadone
are opioid narcotics (such drugs end in ine or one) that are sometimes
used for regional analgesia and are administered as an injection.
Neurolytic blocks employ
injection of chemical agents such as alcohol, phenol, or glycerol to
block pain messages and are most often used to treat cancer pain or to
block pain in the cranial nerves (see The Nervous
Systems). In some cases, a drug called guanethidine is administered
intravenously in order to accomplish the block.
Surgical blocks are performed
on cranial, peripheral, or sympathetic nerves. They are most often done
to relieve the pain of cancer and extreme facial pain, such as that
experienced with trigeminal neuralgia. There are several different types
of surgical nerve blocks and they are not without problems and
complications. Nerve blocks can cause muscle paralysis and, in many
cases, result in at least partial numbness. For that reason, the
procedure should be reserved for a select group of patients and should
only be performed by skilled surgeons. Types of surgical nerve blocks
(including peripheral neurectomy) in which a damaged peripheral
nerve is destroyed.
rhizotomy in which the surgeon cuts the root or rootlets of one
or more of the nerves radiating from the spine. Other rhizotomy
procedures include cranial rhizotomy and trigeminal
rhizotomy, performed as a treatment for extreme facial pain or
for the pain of cancer.
also called sympathetic blockade, in which a drug or an agent
such as guanethidine is used to eliminate pain in a specific area (a
limb, for example). The procedure is also done for cardiac pain,
vascular disease pain, the pain of reflex sympathetic dystrophy
syndrome, and other conditions. The term takes its name from the
sympathetic nervous system (see The Nervous
Systems) and may involve, for example, cutting a nerve that
controls contraction of one or more arteries.
Written by Stephanie E.
Clipper, Office of Communications and Public Liaison, NINDS
The National Institute of
Neurological Disorders and Stroke, a component of the National
Institutes of Health, is the leading federal supporter of research on
brain and nervous system disorders. The Institute also sponsors an
active public information program that offers information about
diagnosis, treatment, and research on painful neurological disorders.
For information on other
neurological disorders or research programs funded by the National
Institute of Neurological Disorders and Stroke, contact the Institute's
Brain Resources and Information Network (BRAIN) at:
P.O. Box 5801
Bethesda, MD 20824
Additional information about
pain research supported by the NIH may be obtained from:
Public Information and
National Institute of Dental and Craniofacial Research
National Institutes of Health
Building 45, Room 4AS19
Bethesda, MD 20892-6400
A number of private
organizations offer a variety of services and information that can help
those affected by pain. They include:
American Chronic Pain
P.O. Box 850
Rocklin, CA 95677-0850
Tel: 916-632-0922 800-533-3231
Provides self-help coping skills and peer support to people with chronic
pain. Sponsors local support groups throughout the U.S. and provides
assistance in starting and maintaining support groups.
American Pain Foundation
201 North Charles Street
Baltimore, MD 21201
Tel: 888-615-PAIN (7246) 410-783-7292
Independent non-profit information, education, and advocacy organization
serving people with pain. Works to improve the quality of life for
people with pain by raising public awareness, providing practical
information, promoting research, and advocating the removal of barriers
and increased access to effective pain management.
1330 West Peachtree Street
Atlanta, GA 30309
Tel: 800-283-7800 404-965-7100
Volunteer-driven organization that works to improve lives through
leadership in the prevention, control, and cure of arthritis and related
diseases. Offers free brochures on various types of arthritis, treatment
options, and management of daily activities when affected.
National Chronic Pain
Outreach Association (NCPOA)
P.O. Box 274
Millboro, VA 24460
National clearinghouse of information on chronic pain. Educates pain
patients, medical professionals, and the public about effective
management of intractable chronic pain.
National Foundation for
the Treatment of Pain
1330 Skyline Drive
Monterey, CA 93940
Not-for-profit organization dedicated to providing support for patients
who are suffering from intractable pain, their families, friends and the
physicians who treat them. Offers a patient forum, advocacy programs,
information, support resources, and direct medical intervention.
Mayday Fund [For Pain
136 West 21st Street, 6th Floor
New York, NY 10011
A private foundation dedicated to the alleviation of the incidence,
degree, and consequences of human physical pain. Works to increase
awareness and provide objective information concerning the treatment of
"Pain: Hope Through
Research," 2001, NINDS
This pamphlet was written and
published by the National Institute of Neurological Disorders and Stroke
(NINDS), the United States' leading supporter of research on disorders
of the brain and nerves and the pain that is often associated with these
disorders. NINDS, one of the U.S. Government's National Institutes of
Health in Bethesda, Maryland, is part of the Public Health Service
within the U.S. Department of Health and Human Services.
NIH Publication No. 01-2406
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
NINDS health-related material
is provided for information purposes only and does not necessarily
represent endorsement by or an official position of the National
Institute of Neurological Disorders and Stroke or any other Federal
agency. Advice on the treatment or care of an individual patient should
be obtained through consultation with a physician who has examined that
patient or is familiar with that patient's medical history.
information is in the public domain and may be freely copied. Credit to
the NINDS or the NIH is appreciated.
Reviewed November 7, 2001