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Pain 101

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 greatly.

Acute pain, 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. (Source: National Institutes of Health)

Chronic pain 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. A person may have two or more co-existing chronic pain conditions. Such conditions can include chronic fatigue syndrome, endometriosis, musculoskeletal pain, fibromyalgia, inflammatory bowel disease, myofascial pain, interstitial cystitis, surgical pain, temporomandibular joint dysfunction, and vulvodynia. It is not known whether these disorders share a common cause.(Source: National Institutes of Health)

Additionally, research has shown that in some cases, opioid medications themselves can contribute to and worsen chronic pain. Journal of Opioid Management. 2008 May-Jun; 4(3):123-30.

The A to Z of Pain

The spectrum of pain is immense. 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. Below is a sampling of common pain syndromes follows, listed alphabetically.


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.


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 is a serious condition, called radiculopathy, that can be extremely painful. Read more – National Institute of Neurological Disorders and Stroke – Back Pain Information Page

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.

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.


The three most common types of chronic headache are migraines, cluster headaches, and tension headaches.

Headaches affect 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. Migraines are 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. Cluster headaches are characterized by excruciating, piercing pain on one side of the head; they occur more frequently in men than women. Tension headaches are often described as a tight band around the head. Read more – Severe Headache and Migraine, Cervicogenic Migraines and Myofascial Trigger Points

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 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.

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 non-restorative sleep causing fatigue, stiffness, cognitive dysfunction, 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 syndrome

A disabling condition characterized by knotted up pieces of muscle fiber called trigger points that radiate pain and other symptoms in a predictable pattern. Trigger points can be easily felt by the patient and examiner unless they are beneath bone or in deep muscles, in which case their location is identified by the pain referral pattern. It often coexists with fibromyalgia, making diagnosis more difficult. Myofascial pain syndrome is best treated with specific myofascial therapies, including myofascial trigger point therapy and trigger point injections.

Neuropathic pain

A type of pain that can result from injury to nerves, either in the peripheral or central nervous system. 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, 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.

Reflex sympathetic dystrophy syndrome (RSDS)

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 called causalgia.

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 * tendonitis or tenosynovitis, affecting one or more tendons.


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.


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: * vasculitis, or inflammation of blood vessels; * other infections, including herpes simplex; * skin tumors and cysts, and * tumors associated with neurofibromatosis, a neurogenetic disorder.

Spinal senosis

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.

Sports Injuries

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.

Temporomandibular 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.

Vascular disease

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.

Source Credits:

Primary Source: National Institutes of Health; Muscle and Myofascial pain definitions adapted from Integrative Therapies for Fibromyalgia, Chronic Fatigue Syndrome, and Myofascial Pain: The Mind-Body Connection

Acute pain

Pain that comes on quickly, can be severe, but lasts a relatively short time.


A primary, chronic, neurobiologic disease whose development and manifestations are influenced by genetic, psychosocial, and environmental factors. It is characterized by behavior that includes one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving.


Pain due to a stimulus that does not normally provoke pain.

Allostatic load

The cumulative physiological cost to the body of chronic exposure to the stress response.


Absence of pain in response to a stimulus that would normally be painful.

Our beliefs influence how we interpret the cause or meaning of pain.


Assumptions about reality that shape the interpretation of events and, consequently, the appraisal of pain.

Biopsychosocial model

A framework that accounts for the biological, psychological, and social dimensions of illness and disease. The biopsychosocial model provides a basis for the understanding and treatment of disease, taking into account the patient, his/her social context, and the impact of illness on that individual from a societal perspective. The model states that ill health and disease are the result of interaction among biological, psychological, and social factors.

Muscle pain can range from an aching muscle, spasm, or strain, to the severe spasticity that accompanies paralysis.

Chronic pain

Ongoing or recurrent pain lasting beyond the usual course of acute illness or injury or, generally, more than 3 to 6 months and adversely affecting the individual’s well-being. A simpler definition for chronic or persistent pain is pain that continues when it should not.

Cognitive-behavioral therapy

An empirically supported treatment focusing on patterns of thinking that are maladaptive and the beliefs that underlie such thinking. Cognitive-behavioral therapy is based on the idea that our thoughts, not external factors, such as people, situations, and events, cause our feelings and behavior. As a result, we can change the way we think to improve the way we feel, even if the situation does not change.


Increased pain from a stimulus that normally provokes pain.


Refers to efforts in which professionals from several disciplines combine their professional expertise and understanding to solve a problem.

Neuromatrix theory

Proposes that pain is a multidimensional experience produced by characteristic “neurosignature” patterns of nerve impulses generated by a widely distributed neural network—the “body-self neuromatrix”—in the brain. These neurosignature patterns may be triggered by sensory inputs, but they may also be generated independently of them

Neuropathic pain

Pain caused by a lesion or disease of the somatosensory nervous system.


The neural processes of encoding and processing noxious stimuli.


Any compound that binds to an opioid receptor. Includes the opioid drugs (agonist analgesics and antagonists) and the endogenous opioid peptides.


An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage.

Pain Catastrophizing

An individual’s tendency to focus on and exaggerate the threat value of painful stimuli and negatively evaluate his/her ability to deal with pain.

Referred pain

Pain subjectively localized in one region although due to irritation in another.


Beliefs that individuals hold about their capability to carry out actions in a way that will influence the events that affect their lives.


An increased response of neurons to a variety of inputs following intense or noxius stimuli.

Source Credits:

Institute of Medicine, Relieving Pain in America, 2011