As with most medical disciplines, the field of pain management has its own specialized vocabulary. The terms and their definitions arranged alphabetically below provide brief descriptions of commonly used, and sometimes misunderstood, expressions. The list was derived or adapted from the published literature on pain management – see reference sources at the end – and will be periodically updated and expanded.

Please address any questions or comments regarding this glossary to:

[email protected].





A-δ nociceptors – Nociceptors (sensory receptors) associated with relatively rapidly conducting A-delta fibers.

Abstinence syndrome – A syndrome that may occur with abrupt cessation or diminution of chronic drug administration; the nature and time of onset of this syndrome vary with drug actions and half-life.

Activation – Excitation of a neuron sufficient to generate a nerve impulse (action potential).

Acupuncture – A traditional Chinese medical practice of insertion and manipulation of fine needles into specific exterior body locations (acupuncture points) to relieve pain, to induce surgical anesthesia, and for therapeutic purposes. This process is believed to adjust and alter the body’s energy flow into healthier patterns, and is used to treat a wide variety of illnesses and health conditions This alternative is often included in pain management programs (NIPC 2005).

Acute pain – Warning pain, the discomfort or signal that alerts of something physically wrong in the body. Pain may result from any condition that stimulates the body’s sensors, such as inflammation, infections, injuries, hemorrhages, tumors, and metabolic or endocrine problems. Acute pain usually abates as the underlying problem is treated. Early management of acute pain may hasten the recovery of the causative problem and reduce the length of treatment.

Addiction – A primary, chronic, neurobiological disease, with genetic, psychosocial, and environmental factors influencing its development and manifestations. It is characterized by behaviors that include one or more of the following: impaired control over drug use, compulsive use, continued use despite harm, and craving. Sometimes called “dependence,” addiction should not be confused with physiologic dependence — eg, tolerance, withdrawal — that may naturally occur with opioid analgesics.

Adjuvant analgesic – A medication that is not primarily and analgesic but that has independent or additive pain relieving effects.

Agonists – Agents that exert pharmacologic effects by binding to and activating specific receptors.

Algogenic – Pain-inducing. (Not to be confused with Allogenic, meaning from individuals of the same species. Tissue transplanted from one person to another is said to be allogenic.)

Allodynia – Pain caused by a stimulus that normally does not provoke pain, such as the light touch of a finger or feather..

Analgesia – Absence of pain in response to a normally painful stimulus, typically without loss of consciousness (NPEC 2006).

Analgesic ceiling – A dose of an analgesic beyond which no additional analgesia is obtained.

Anesthesia – Generally, a loss of sensation resulting from pharmacologic depression of nerve function or from neurological dysfunction (Stedman’s 2000).

Ankylosing spondylitis – Ankylosing (fusing together) spondylitis (spinal inflammation) is a type of arthritis that affects the spine.

Antagonists – Agents that competitively bind with the binding sites of agonists and thereby inhibit the agonist actions.

Antidepressant – An agent that stimulates the mood, generally relieving symptoms of depressive disorders (unipolar or bipolar) by increasing levels of excitatory neurotransmitters. The main types of antidepressant drugs in use are: tricyclic, selective serotonin reuptake inhibitors (SSRIs), and monoamine oxidase inhibitors (MAOIs). Antidepressant agents typically have a slow onset of action taking 3 to 5 weeks. Although adverse effects may be seen as early as the first dose, significant therapeutic improvement is delayed. Similarly, the effects of antidepressants will continue for a similar length of time after the drugs have been discontinued (NIPC 2006, Uretsky 2002).

Antiemetics – Agents that prevent or alleviate nausea and vomiting. They are typically used to treat motion sickness and the side effects of opioid analgesics and chemotherapy (NIPC 2006).

Antiepileptic Drug (AED) – An agent that combats epilepsy and also may be used in the treatment of chronic pain. AEDs may alter pain transmission by interacting with specific neurotransmitters and ion channels. The agents differ in neuropathic and non-neuropathic pain, and agents within each medication class have varying degrees of efficacy (NIPC 2006, Maizels and McCarberg 2005).

Arachnoiditis – Painful inflammation and thickening of the arachnoid membrane (one of three membranes covering the central nervous system) around nerve roots.

Arthritis – A general term for a group of more than 100 diseases, typically involving inflammation and swelling of a joint, or a state characterized by joint inflammation. There are many forms of arthritis, each of which has a different cause: rheumatoid arthritis and psoriatic arthritis are autoimmune diseases in which the body is attacking itself; septic arthritis is caused by joint infection; gouty arthritis is caused by deposition of uric acid crystals in the joint and subsequent inflammation; and the most common form of arthritis, osteoarthritis is also known as degenerative joint disease and occurs following trauma to the joint, following an infection of the joint, or simply as a result of aging (NIPC 2006, Cleveland Clinic 2005).

Autonomic responses – See sympathetic (nervous system) hyperactivity.

Back to Top >


Behavioral therapy or behavioral modification  Therapy that is concerned with the treatment or modification of observable behaviors rather than underlying psychological processes. Behavioral therapy applies learning principles to substitute desirable responses and behavior patterns for undesirable ones (for example, phobias or obsessions) (NIPC 2006).

Beta-blockers – A class of drugs that combine with and block the activity of the beta-receptor to decrease the heart rate and force of contractions and lower blood pressure. Beta-blockers are used to treat hypertension, angina pectoris, and ventricular and supraventricular arrhythmias by controlling certain hormones (catecholamines) released by the body as part of its response to heart failure. Beta-blockers are also used to prevent migraines, treat tremors, and control anxiety (NIPC 2006).

Bioavailability – The rate and extent to which an active drug or metabolite enters the general circulation, thereby permitting access to the site of action.

Biofeedback – The process of training a person (or animal) to regulate physiologic responses by providing feedback (typically sounds or light patterns) about those responses. Clinically, patients are typically taught to control finger temperature, perspiration, muscle tension, and other responses.

Biopsychosocial – Relating to the biological, psychological, and social aspects in contrast to the strictly biomedical aspects of disease or chronic pain. This is a way of looking at the mind and body of a patient as two important, interlinked systems (the mind-body connection) (NIPC 2006, Krames 2001).

Botulinum toxin type A (Botox) – A purified botulinum toxic, used by injection to relax muscles. It is often used to treat certain eye conditions, severe sweating of the armpits, in cosmetic dermatology and plastic surgery to minimize wrinkles, and in pain management to treat migraines (NIPC 2006, MedlinePlus 2006).

Buprenorphine – A semi-synthetic opioid agonist-antagonist used as an analgesic for moderate to severe pain and as an anesthesia adjunct. It can be administered sublingually or by intramuscular or intravenous injection, and is increasingly used (sublingually) rather than oral methadone for treating opioid abuse (NIPC 2006, WebMD 2006).

Breakthrough pain – Pain that overwhelms or “breaks through” any pain relief afforded by ongoing analgesics.

Back to Top >


C-nociceptors – Nociceptors associated with slowly conducting unmyelinated C-fibers.

CAM — Complementary and Alternative Medicine — a group of diverse medical and healthcare systems, practices, and products that are not presently considered to be part of conventional medicine as practiced in the United States. Conventional medicine is practiced by holders of MD (medical doctor) or DO (doctor of osteopathy) degrees and their allied health professionals, such as physical therapists, psychologists, and registered nurses. Some healthcare providers practice both conventional medicine and CAM, including a variety of techniques (eg, massage, acupuncture), agents (eg, nutritional supplements), or other therapies (eg, aromatherapy).

Capsaicin – A component of certain plants (cayenne, red pepper), used topically to relieve minor arthritis and neuralgia pain. Capsaicin, when applied to the skin, causes a burning sensation; it is believed that this burning depletes the nerve cells of a chemical (substance P), which has a role in transmitting pain messages (NIPC 2006; MedlinePlus 2006).

Cauda equina syndrome — Impairment of the nerves in the cauda equina, the bundle of spinal nerve roots that arise from the lower end of the spinal cord. The syndrome is characterized by dull pain in the lower back and upper buttocks and lack of feeling (anesthesia) in the buttocks, genitalia, and thigh, together with disturbances of bowel and bladder function.

Causalgia – A burning pain and sensitivity to vibration or touch, usually in the hand or foot, at a site removed from an injury of a peripheral nerve that has healed (NIPC 2006; NPEC 2006; Mersky and Bogduk 1994).

Celiac plexus – A network of nerve fibers in the abdomen that conducts pain sensation from the abdominal organs, including the liver, spleen, stomach, and pancreas ( 2005).

Central nervous system (CNS) – Consists of the brain and spinal cord.

Central pain – Pain associated, initiated, or caused by a lesion in the central nervous system (NPEC 2006; Mersky and Bogduk 1994).

Central sensitization – Enhanced excitability and responsiveness of spinal neurons producing long-lasting changes.

Cerebral cortex – Gray cellular “mantle” of the brain, which includes the sensory cortex, motor cortex, and association cortex.

Chronic noncancer pain (CNCP) – Persistent pain that is not associated with cancer.

Chronic nonmalignant pain (CNMP) – Persistent pain that is not attributable to a life-threatening condition; some prefer to use alternate terms, such as: chronic noncancer pain, chronic non-cancer–related pain.

Chronic pain – A long-term pain state that is persistent (usually defined as 3 months or longer) and in which identifying, treating, and/or removing the underlying cause poses a clinical challenge. Chronic pain sometimes may be associated with a long-term incurable or intractable medical condition or disease.

Chronic pain syndrome (CPS) – Psychosocial disorder that occurs in some patients with chronic noncancer pain in which symptoms of the pain consume the attention of the patients and becomes incapacitating.

Continuous dysesthesia – A continuous type of neuropathic pain that manifests as burning, electrical, or other abnormal sensations.

Corticosteroid – Anti-inflammatory drug created from, or based on, a naturally occurring hormone produced by the cortex of the adrenal glands (cortisone) ( 2005).

COX-2 inhibitor – A nonsteroidal anti-inflammatory drug (NSAID) that specifically inhibits the enzyme cyclooxygenase-2 (COX-2), which contributes to inflammation. COX-2 inhibitors are used to treat pain and are less likely to cause gastrointestinal bleeding than other NSAIDs. Recent studies began to uncover evidence that COX-2 inhibitors and other non-selective NSAIDs may increase the risk of heart attack and stroke. Prompted by these findings and other safety concerns, 2 of the 3 FDA-approved COX-2 inhibitors, brand names Vioxx® and Bextra®, were withdrawn from the market (MayoClinic 2005, MedlinePlus 2006).

CRPS – Complex regional pain syndrome, also known as reflex sympathetic dystrophy (RSD) and causalgia, has been recognized for the past 2,500 years and believed in for the past 150, but it has yet to be understood. These syndromes can be characterized by discrete sensory, motor, and autonomic findings, but many patients with CRPS continue to suffer for years without a diagnosis. The role of the sympathetic nervous system in maintaining these syndromes and its appropriateness as a target for treatment continue to be subjects of controversy (Bennett and Brookoff 2006).

Cyclooxygenase (COX) – Enzyme involved in prostaglandin synthesis; there are two isoforms: COX-1 and COX-2.

Back to Top >


Deafferentation  Temporary or permanent loss of primary afferent fibers due to injury or disease.

Deep somatic pain – A type of somatic pain associated with ongoing activation of nociceptors in muscles, tendons, joint capsules, fasciae, or bones.

Deep tissues – Tissues including bone, muscle, tendons, joint capsules, and fasciae.

Dermatomes – Cutaneous sensory pathways that are defined by sensation; each dermatome corresponds to the area of skin that is supplied by the dorsal roots of a particular sensory nerve.

Dorsal horn (DH) – The posterior gray matter of the spinal cord, which contains cell bodies (neurons). The spinal cord consists of 10 laminae (segments) and laminae I-VI comprise the dorsal horn.

Dorsal horn neurons – Neurons in the dorsal horn of the spinal cord, including interneurons and second order (projection) neurons.

Dysesthesia – An unpleasant abnormal sensation, which may be spontaneous or evoked, experienced by patients with neuropathic pain; distinct from pain in the classical sense.

Back to Top >


Endogenous opioids – Natural opioid compounds produced by the body; also referred to as enkephalins and endorphins.

Enkephalins – Naturally occurring molecules in the brain that attach to certain receptors in the brain and spinal cord to stop pain messages. These receptors respond to morphine and other opioid analgesics ( 2005, MedlinePlus 2006).

Epidural – Situated on the outside of the dura mater (a tough lining that surrounds the spinal cord; see Figure below).

Equianalgesic – Having an equivalent analgesic effect.

Equianalgesic dose chart – A chart that is used to convert from one analgesic or route of administration to another. Such charts typically describe the dose of an opioid required to produce the same degree of pain relief provided by a standard oral or parenteral dose of morphine.

Ergotamine – An alkaloid derived from ergot (fungus in the genus Claviceps), which narrows blood vessels (vasoconstriction). They sometimes relieve pain by reducing pressure on pain-sensitive structures that may be associated with cluster and/or migraine headaches. It may also affect certain brain chemicals that affect how a person feels pain (NIPC 2006, WebMD 2006).

Excitatory amino acids (EAAs) – These include the neurotransmitters glutamate and aspartate, which mediate most excitatory transmission in the central nervous system.

Back to Top >


Facet joints – Joints found between two adjacent vertebrae at every spinal level, which are connected by an intervertebral disk in the front and two facet joints in the back. Facet joints provide about 20% of torsional stability in the neck and lower back ( 2005).

Field block injection – A procedure used to relax a tender muscle, or to reduce muscle pain and inflammation. The targeted muscle is injected with a local anesthetic (for example, Lidocaine) and corticosteroid. Also called trigger point injection ( 2005).

Fibromyalgia – A syndrome described as inflammation of the fibrous or connective tissue of the body. Symptoms include diffuse musculoskeletal aching, chronic pain, stiffness, and tenderness of muscles, tendons, and joints. Diagnosis is difficult and frequently missed because symptoms of fibromyalgia are vague and generalized. It does not cause body damage or deformity; however, undue fatigue (and depression) plagues the large majority of patients, and sleep disorders are common (NPEC 2006, NIPC 2006).

Back to Top >


Glutamate – An excitatory amino acid neurotransmitter responsible for much of excitatory transmission in the central nervous system.

Back to Top >


Headache – A pain in the head above the eyes or ears, behind the head (occipital), or on the back of the upper neck. All headaches are grouped into primary headaches and secondary headaches. Primary headaches are not associated with other diseases and include migraine, tension, and cluster headaches. Secondary headaches are caused by other diseases, which may be major or minor (NIPC 2006).

Headache, cluster – A headache syndrome also called migrainous neuralgia. There are two main types of cluster headache: episodic and chronic. Episodic is the most common pattern, characterized by 1 to 3 short attacks of pain around the eyes per day. The attacks are clustered over a stretch of 1 to 2 months followed by an approximate remission of a year. Chronic cluster headache is characterized by the absence of sustained periods of remission and may start with no past history of cluster headaches or it may emerge several years after an episodic pattern of cluster headaches (NIPC 2006).

Headache, medication overuse – Daily use of simple analgesics, opioids, ergotamine, or barbiturate compounds can cause worsening of headaches once the medication is discontinued (NIPC 2006).

Headache, rebound – This type of headache is experienced by those who have taken analgesics or ergotamines for migraines or other health issues, and who have built up a tolerance. The headache frequently occurs immediately after the medication wears off. Using the medication less frequently or switching to a different medication may treat the headache. Some patients find relief from acute ergotamine rebound with injected phenothiazine or long-acting steroid medication (NIPC 2006).

Headache, sinus – Caused by pressure within the sinus cavities of the head, usually in connection with infection of the sinuses. Symptoms include pain and tenderness in the sinus area, discharge from the nose, and sometimes facial swelling (NIPC 2006).

Headache, tension – This headache type manifests with mild or moderate pain of variable duration. It affects both sides of the head and typically is accompanied by contraction of neck and scalp muscles (NIPC 2006).

Herpes zoster virus (related to shingles) – An acute viral inflammation of the sensory ganglia of spinal and cranial nerves. Caused by reactivation of the virus causing chicken pox, herpes zoster, resulting in vesicular eruption and neuralgic pain, usually on one side of the body (NIPC 2006, MedlinePlus 2006).

Hyperalgesia – An abnormally painful response to a normally painful stimulus.

Hyperesthesia – Increased sensitivity to stimulation.

Hyperpathia – A syndrome characterized by an abnormally painful and exaggerated reaction to a stimulus, especially a repetitive stimulus.

Hypersensitivity Pain Disorder (HPD) – A suggested category (possibly transient) denoting chronic pain with signs/symptoms typical of neuropathic pain mechanisms; however, due to limitations of currently available diagnostic tools, it does not achieve the level of a clinical definition of neuropathic pain.

Hypoalgesia – Diminished pain in response to a normally painful stimulus.

Hypoesthesia – Decreased sensitivity to stimulation.

Back to Top >


Iatrogenic – A response, usually unfavorable, to a medical or surgical treatment induced by the treatment itself.

Inflammation – A pathologic process involving complex chemical and cellular reactions that occurs in tissues in response to injury or abnormal stimulation. Its cardinal signs— rubor (redness), calor (heat or warmth), tumor (swelling), and dolor (pain)—reflect processes directed at destroying/removing injurious material and at promoting repair and healing.

Inflammatory mediators – These may include prostaglandins, bradykinin, serotonin, histamine, and other agents.

Imagery – A method for relieving pain by using mental images from memory or imagination (NPEC 2006).

Intermittent claudication – This condition, generally found in older people, is marked by cramping and pain in a muscular area. This pain, typically in the legs, is produced by exercise and relieved by rest (NPEC 2006).

Interventional pain management – Blocking of the body’s production and/or transmission of pain signals to the brain by use of a neurological procedure, nerve block, spinal cord stimulation, implantation of a drug delivery system, or injection of an anesthetic (NPEC 2006).

Intractable pain – Intense, usually chronic and unremitting, pain for which no accepted medical intervention has provided relief (NPEC 2006).

Intrathecal – Within either the subarachnoid or subdural space (see Figure).

IPN – Inflammatory pain, resulting from tissue response to disease or injury (pathological process involved in tissue destruction).

Ischemia – A reduction in local blood flow due to obstruction of the blood supply.

Back to Top >


Joint – In anatomy, the place of contact, generally moveable, between two or more bones. There are three structural types of joints: fibrous (connective tissue); cartilaginous (cartilage); and synovial (cavity) (Stedman’s 2000).

Ketamine – A parenterally administered anesthetic that produces catatonia, profound analgesia, increased sympathetic activity, and little relaxation of skeletal muscles. Can be used for minor surgical procedures in which muscle relaxation is not required. It is chemically related to phencyclidine (PCP) and can produce hallucinations; therefore, its use is not as prevalent as it was when originally used during the Vietnam War (Stedman’s 2000).

Lancinating pain – A type of neuropathic pain that manifests as an episodic shooting, stabbing, or knifelike pain.

Lidocaine – An anesthetic that produces pain relief by blocking signals at nerve endings in the skin. Lidocaine can be administered topically, as a patch or oral gel, or injected as a local anesthetic. It is used for pain and discomfort of, for example, infections of the skin. It also is used in the management of certain cardiac arrhythmias (NIPC 2006, Stedman’s 2000).

Local anesthetic – An anesthetic that reversibly blocks pain and/or movement nerve signals in a specific part of the body (see Lidocaine) ( 2005).

Limbic system – The limbic system includes structures such as the amygdala, hippocampus, septal nuclei, hypothalamus, and transitional cortical regions (e.g., cingulate gyrus). This part of the brain is involved with emotional responses.

Lumbar spondylosis – Degeneration and/or deformity of the lumbar spine (pertaining to the abdominal segment of the torso, between the diaphragm and the sacrum (pelvis), or degenerative disc disease. This may lead to spinal stenosis (narrowing of the spinal canal), vertebral instability, and/or malalignment, which may be associated with back pain and/or leg symptoms (Stedman’s 2000, NIPC 2006).

Back to Top >


Migraine – A vascular symptom complex of periodic headache, usually temporal and unilateral in onset. It is typically associated with irritability, nausea, vomiting, constipation, or diarrhea. Migraine headaches may occur with or without aura (prodrome of neurologic symptoms, often visual in nature) (NPEC 2006, NIPC 2006).

Migraine, menstrual – Refers specifically to migraines that occur within the first two days of the onset of menstruation (NIPC 2006).

Morphine – The principle and most active alkaloid of opium. Morphine acts directly on synapses of the arcuate nucleus and the CNS. The soluble salts are used in medicine as an analgesic, anesthetic, or sedative. It is available in oral preparations and as rectal suppositories. It may also be given via subcutaneous, intramuscular, intravenous, or intrathecal injection. Tolerance, and physical and psychological dependence may develop (NIPC 2006, NPEC 2006).

Mu agonists – Opioids that bind to m1 and m2 receptors in the brain, spinal cord and, under certain conditions (e.g., inflammation), the periphery to exert their effects.

Multidisciplinary pain center – An organization, often existing as a component of a medical school or teaching hospital, encompassing healthcare professionals and scientists of varied disciplines, including research, teaching, and patient care related to acute and chronic pain (NIPC 2006).

Multimodal analgesia – Also known as “balanced analgesia,” this approach to pain management involves the use of more than one method or modality of controlling pain (e.g., drugs from two or more classes, drug plus nondrug treatment) to obtain additive beneficial effects, reduce side effects, or both.

Back to Top >


Nerve block – A form of regional anesthesia, in which an anesthetic agent is injected near a nerve to block pain.

Neuroablation – Destruction of tissue, typically by surgical, chemical (e.g., phenol), or heat (e.g., radiofrequency) lesions. The goal of neuroablative procedures is to interrupt signal flow between peripheral sources of pain and the brain or to remove neural structures that contribute to pain.

Neurolysis – A technique for destroying neural tissue that involves injection of a destructive chemical or use of cold (cryotherapy) or heat (radiofrequency coagulation).

Neuralgia – Pain that extends along the course of one or more nerves. It is a form of chronic pain that can be difficult to diagnose (NPEC 2006).

Neuritis – Inflammation of a nerve that can include pain, tenderness, anesthesia and paresthesia, paralysis, wasting, and loss of reflexes (NPEC 2006).

Neuroablative therapy – Use of various injectable substances, for example alcohol or phenol, or the use of controlled heat or cold, to render the nervous system unable to transmit a pain signal. The nerve destruction may be permanent or the nerves may grow back in time; this is usually employed only when other therapies have failed (NPEC 2006, WebMD 2006).

Neuropathic pain  Pain arising from disease or injury to the thermo-nociceptive component of the nervous system at any level (peripheral, central, or both). Peripheral neuropathic pain syndromes include HIV sensory neuropathy, postherpetic neuralgia (PHN), and diabetic neuropathy. Central neuropathic pain includes poststroke pain, spinal cord injury pain, trigeminal neuralgia (5th cranial nerve, one of the largest nerves in the head), and multiple sclerosis pain (NIPC 2006, MedlinePlus 2006).

NMDA receptors – A type of glutamate receptor involved in mediating excitatory neurotransmission. These receptors are thought to play an important role in central sensitization.

Nociceptive pain – Common but misused term (means “painful pain”), which might be replaced by “physiological pain.” This may result from activity in neural pathways caused by potentially tissue-damaging stimuli, including postoperative pain, arthritis, mechanical low back pain, sickle cell crisis, sports/exercise injuries, and others (NIPC 2006).

Nociceptors – Sensory receptors that are preferentially sensitive to tissue trauma or a stimulus that would damage tissue if prolonged.

Nonpharmacologic therapy – Alternative pain management approach that includes biofeedback, relaxation therapy, cognitive/behavioral strategies, acupuncture, and others (NIPC 2006).

Nonsteroidal anti-inflammatory drug (NSAID) – This type of drug, commonly prescribed for the treatment of arthritis or other conditions, for example bursitis or tendinitis, reduces inflammation and pain. NSAIDs block the production of certain body chemicals that can cause inflammation; they also may relieve the pain of bruises or headaches. NSAIDs include aspirin, ibuprofen, naproxen, and many other agents (NIPC 2006, Cleveland Clinic 2004).

Back to Top >


Onset of action – The length of time it takes for a medication to begin working (NPEC 2006).

Opiate – A drug directly derived from opium, for example, morphine (a natural substance extracted from opium poppies) and codeine. Pain is relieved by binding primarily to mu-opioid receptors in the brain and spinal cord (NPEC 2006, 2005, Stedman’s 2000, NIPC 2006).

Opioid – A more inclusive term for naturally derived opiates and synthetic or semisynthetic agents with analgesic properties similar to opiates.

Opioid agreement – This is a consensual, written contract, promise, or accord between the patient and the healthcare provider intended to enhance therapeutic adherence to opioids. Also known as an Opioid Contract or Medication Agreement (NIPC 2006).

Opioid, long-acting – Agents with a half-life of many hours or in extended release formulation, and typically used for persons with chronic pain, for example in cancer, and for management of non-cancer pain associated with arthritis, back disorders, fibromyalgia, and multiple sclerosis (NIPC 2006).

Opioid rotation – Strategy of switching opioids, thereby allowing any opioids causing toxicity or no longer helping to manage pain to be eliminated while still maintaining the analgesic effect. The optimal dose should avoid under-dosing or overdosing, both associated with negative outcomes for the patient. This requires the use of equianalgesic dose tables, to determine new dosage, ensuring that pain is well controlled (NIPC 2006).

Opioid, short acting – Agents typically with a half-life of but a few hours and most commonly used for the treatment of acute (sudden onset) or breakthrough pain, for example, post-operative, dental, or trauma-associated pain (NIPC 2006).

Opium – The gum formed by the drying juice from the unripened fruit (pods) of the poppy (Papaver somniferum). Opium use as an analgesic predates written history; most likely originating in Mesopotamia (NPEC 2006).

Osteoarthritis – A noninflammatory (low-grade) degenerative joint disease, predominately occurring in older persons (80% of people will present with radiographic evidence by age 65). It is characterized by degeneration of articular cartilage (which covers and acts as a cushion inside the joints), hypertrophy (increase in size) of bone at the margins, and changes in the synovial membrane (soft tissue that lines non-cartilaginous surfaces within joints with cavities). Osteoarthritis is accompanied by pain and stiffness, usually after prolonged activity or inactivity (Stedman’s 2000, NPEC 2006, NIPC 2006).

Back to Top >


Pain – A popularly used definition is, “An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage” (Mersky and Bogduk 1994, NIPC 2006).

Pain flares (flare ups) — pain that suddenly erupts or emerges with or without a specific aggravating event or activity.

Pain intensity scales – Systems of rating pain for adults, children, and infants. Some pain scales are: Numeric Rating Scale, Wrong-Baker Faces, COMFORT Scale, CRIES Pain Scale, FLACC Pain Scale, and the Checklist of Nonverbal Indicators (MedlinePlus 2006).

Pain management – The systematic study of clinical and basic science and its application for the reduction of pain and suffering. Pain management emphasizes an interdisciplinary approach to treatment, and combines tools, techniques, and principles from a variety of the healing arts to create a holistic paradigm for the reduction of pain and suffering.

Pain pump – Colloquially, a surgically implanted device in the lower abdomen that provides a steady stream of medication (typically an opioid) to the cerebrospinal fluid ( 2005).

Pain scales — self-report tools that can help a patient describe the intensity of pain to assist healthcare providers in measuring the level of pain for diagnostic and treatment purposes. Three common types of scales include numeric (eg, 1 to 10 scale), verbal (eg, words describing extent of pain), and visual (eg, expressive pictures of faces).

Pain threshold – The least amount of pain which a patient can recognize (Mersky and Bogduk 1994).

Pain tolerance level – The greatest level of pain which a patients is prepared to withstand (Mersky and Bogduk 1994).

Palliative care (hospice) – Comfort and/or medical care that reduces the severity of an incurable disease or slows its progress rather than providing a cure. Typically used to preserve the patient’s quality of life by avoiding aggressive end-of-life treatment. These programs can assist the family or caregiver(s) in making the patient as comfortable as possible, and assistance is usually available around the clock, seven days a week (NIPC 2006, MedlinePlus 2006).

Parenteral administration – Administration of a drug via a route other than the gastrointestinal system, such as by intravenous, intramuscular, or subcutaneous injection.

Paresthesia – An abnormal sensation (e.g., “pins and needles” from a foot “going to sleep”), which may be spontaneous or evoked, and often experienced by patients with neuropathic pain.

Patient-controlled analgesia (PCA) – The self-administration of analgesics by a patient; often involves an intravenous, subcutaneous, or epidural opioid administered via a pump mechanism.

PDN – Painful diabetic neuropathy.

Perioperative pain – Pain that is present in a surgical patient because of preexisting disease, the surgical procedure (e.g., associated drains, chest or nasogastric tubes, complications), or a combination of disease-related and procedure-related sources.

Peripheral neuropathy – A disease or degenerative state in which motor, sensory, and/or vasomotor nerve fibers may be affected. This condition may manifest as muscle weakness and atrophy, pain, and numbness (NIPC 2006).

Peripheral sensitization – A lowering of the stimulus (pain) threshold for nociceptor activation and an increase in the frequency of nerve impulse firing (hyperexcitability). Peripheral sensitization can contribute to pain hypersensitivity found at the site of tissue damage/inflammation (NIPC 2006).

Phantom pain – Pain or discomfort following amputation that feels to the patient as if it comes from the missing limb ( 2005, MedlinePlus 2006).

PHN – Postherpetic neuralgia.

Physical dependence – A physiologic state of adaptation that often includes tolerance and is manifested by a drug class-specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood levels of the drug, and/or administration of an antagonist. This should not be confused with “addiction.”

Physiological pain – Pain arising from a stimulus (e.g., pinprick, heat pulse) that activates the temperature- and pain-transmitting (thermonociceptive) nervous system. (Term sometimes replaces nociceptive pain.)

Polypharmacy – The administration of multiple drugs sometimes resulting in excessive medication (NIPC 2006).

Postherpetic neuralgia (PHN) – A painful condition caused by the varicella zoster virus in the area governed by a specific sensory nerve after an attack of herpes zoster. PHN usually manifests after vesicles associated with skin rash have crusted over and begun to heal. See also, shingles (NIPC 2006).

Potency – The dose or concentration of a drug required to produce a particular effect (e.g., pain relief).

Preemptive analgesia – A pharmacologic intervention performed before a noxious event (e.g., surgery) that is intended to minimize the impact of the stimulus by preventing peripheral and central sensitization.

Primary afferent (nerve) fibers – Axons of primary afferent (or “first order”) neurons that transmit impulses from the periphery toward the central nervous system. Each neuron has a cell body that resides in sensory ganglia (e.g., dorsal root ganglia) and a bifurcated axon. One branch extends along a peripheral nerve and ends in a sensory receptor; the other branch projects to the spinal cord, where it synapses with a spinal neuron (e.g., interneuron, projection neuron).

Projection neurons – Neurons in the dorsal horn of the spinal cord with nerve fibers that project to the brain in tracts. These neurons are responsible for transmitting nociceptive information from the spinal cord to higher centers.

Pruritus  Severe itching; sometimes a side effect of opioid therapy.

Pseudoaddiction – An iatrogenic syndrome that may be created by the undertreatment of pain. It is characterized by patient behaviors such as anger and escalating demands for more or different medications. Apparent “drug seeking” can be mistaken for addiction and result in suspicion and avoidance by staff. Pseudoaddiction can be distinguished from true addiction in that the behaviors normally resolve when pain is effectively treated (Alford et al. 2006).

Pseudo-opioid resistance – patients with adequate pain control may continue to report pain or exaggerate its presence, as if they have become resistant to opioid analgesic effects, to prevent reductions in their currently effective doses of medication (Alford et al. 2006).

Pseudotolerance – The need to increase analgesic dosage that is not due to tolerance, but due to other factors such as: disease progression, new disease, increased physical activity, lack of compliance, change in medication, drug interaction, addiction, or deviant behavior. When a once-fixed opioid dose is no longer effective, the above conditions should be reviewed to exclude pseudotolerance.

Psychogenic pain – Sometimes pejorative and usually unhelpful term related to unclassified pain experienced by psychiatric patients.

Psychological dependence – Generally refers to the mental/cognitive manifestations of substance dependence or abuse whereby the patient believes there is a need for the drug to maintain comfort or stability, possibly in the absence of any physiologic benefit.

Back to Top >


Radiculopathy – Caused by compression, inflammation, and/or injury to a spinal nerve root in the lower back. Also known as radicular pain or sciatica, the causes of this type of pain include herniated disc with nerve compression, foraminal stenosis, diabetes, nerve root injuries, and scar tissue from previous spinal surgery (NPEC 2006, NIPC 2006).

Referred pain – Pain felt in a part of the body other than where the cause is situated. As different nerve networks converge to common neurons, which relay information to higher never centers, the brain is not always able to distinguish where activity initiated (NPEC 2006, NIPC 2006).

Reflex sympathetic dystrophy (RSD) – More recently known as CRPS (complex regional pain syndrome) this disorder has been recognized for the past 2,500 years and accepted as valid for the past 150, but it has yet to be understood. These syndromes can be characterized by discrete sensory, motor, and autonomic findings, but many patients with CRPS continue to suffer for years without a diagnosis. The role of the sympathetic nervous system in maintaining these syndromes and its appropriateness as a target for treatment continue to be subjects of controversy (Bennett and Brookoff 2006).

Regional anesthesia – This interrupts the sensory nerve conductivity to a specific region of the body. When produced by injection of an anesthetic agent close to the specific nerve, it is called a nerve block (NPEC 2006).

Responsiveness – The probability of achieving adequate pain relief with an analgesic without encountering unmanageable side effects.

Rheumatism – Any of a variety of disorders marked by inflammation, degeneration, or metabolic derangement of the connective tissue structures of the body. It is attended by pain, stiffness, or limitation of motion in joints and related structures, including muscles, bursae, tendons, and fibrous tissue (NPEC 2006).

Rheumatoid arthritis (RA) – This is an inflammatory disorder, considered an autoimmune disease that causes pain, swelling, stiffness, and loss of function in the joints. It has several features that make it different from other kinds of arthritis, for example, RA generally occurs in a symmetrical pattern, meaning that if one knee or hand is involved, the other one also is. While the disease often affects the wrist joints and the finger joints closest to the hand, it can also affect other parts of the body besides the joints. Many people with RA develop anemia, or a decrease in the production of red blood cells. In addition, people with rheumatoid arthritis may have fatigue, occasional fevers, and a general sense of malaise (NPEC 2006, NIPC 2006, MedlinePlus 2006).

RSD – reflex sympathetic dystrophy, also known as CRPS (complex regional pain syndrome) can be characterized by discrete sensory, motor, and autonomic findings, but many patients continue to suffer for years without a diagnosis. The role of the sympathetic nervous system in maintaining these syndromes and its appropriateness as a target for treatment continue to be subjects of controversy. Recent insights into how the nervous system responds to injury are beginning to explain some of the “impossible” neurological findings that are characteristic of RSD/CRPS. Case-series studies suggest that spinal cord stimulation is a safe and effective treatment for many people with advanced RSD/CRPS who have not obtained adequate relief with other treatments (Bennett and Brookoff 2006).

Back to Top >


Sciatica (see also Radiculopathy) – A syndrome characterized by pain radiating from the back into the buttock and lower extremity along its posterior or lateral aspect. It is most commonly caused by protrusion of a low lumbar intervertebral disk, but the term can be used to refer to pain anywhere along the sciatic nerve (NPEC 2006).

Selective serotonin reuptake inhibitors (SSRIs) – Medications used to relieve depression by increasing the availability of serotonin in the brain. By increasing this chemical’s availability, these drugs modify neuronal pathways involved in regulating mood ( 2005, MedlinePlus 2006).

Shingles – An acute viral inflammation of the sensory ganglia of spinal and cranial nerves caused by reactivation of the virus causing chicken pox, herpes zoster, and resulting in dermatitis with vesicular eruptions and neuralgic pain, usually on one side of the body (NIPC 2006, MedlinePlus 2006).

Sicca syndrome — An autoimmune disease, also known as Sjögren syndrome, that classically combines dry eyes, dry mouth, and another disease of connective tissue such as rheumatoid arthritis (most common), lupus, scleroderma, or polymyositis. About 90% of Sjögren syndrome patients are female, usually in middle age or older. Inflammation of the the lacrimal glands leads to decreased tears and dry eyes. Inflammation of the salivary glands leads to dry mouth. The syndrome can consequently be complicated by infections of the eyes, breathing passages, and mouth.

Sjögren syndrome — see Sicca syndrome (above).

Somatic pain – Pain arising from tissues such as skin, muscle, tendon, joint capsules, fasciae, and bone.

Somatosensory cortex – A subdivision of the sensory cortex.

Spinal cord stimulator – As a therapy for certain types of chronic neuropathic pain, the spinal cord is electrically stimulated to cause a new sensation, for example, tingling, to block pain from being perceived by the brain ( 2005, NIPC 2006).

Spinal stenosis – Narrowing of the vertebral canal, nerve root canals, or intervertebral foramina of the lumbar spine, usually resulting from soft tissue and bony encroachment of the spinal canal and nerve roots. Symptoms include pain, paresthesias, and neurogenic claudication (non-specific limb symptoms) (NPEC 2006, WebMD 2006).

Spondylitis – Name given to a group of chronic diseases that are forms of inflammatory arthritis primarily affecting the spine (NPEC 2006, MedlinePlus 2006).

Spinothalamic tract (STT) – Major pathway by which nociceptive information travels from the dorsal horn of the spinal cord to the thalamus.

Stellate ganglion block – A procedure to relieve pain caused by overactivity of the sympathetic nervous system (automatic regulation system, operating without the intervention of conscious thought) in the upper extremities, head, or neck. A local anesthetic is injected in the front of the neck; sympathetic nerves are blocked, while sensory pathways are not ( 2005).

“Stress hormone” response – A series of responses to an acute injury or stress that leads to an increase in the metabolic rate, blood clotting, and water retention; impaired immune function; and a “fight or flight” alarm reaction with autonomic features. These responses minimize further damage and blood loss, promote healing, prevent or fight infection, and reduce blood flow to vital organs, among other functions.

Substance P – A neuropeptide that activates spinal neurons and enhances their responsiveness to excitatory amino acids, thus facilitating nociception.

Superficial (cutaneous) somatic pain – A type of somatic pain associated with ongoing activation of nociceptors in the skin, subcutaneous tissue, or mucous membranes.

Sympathetic (nervous system) hyperactivity – Symptoms and signs of sympathetic (autonomic) nervous system hyperactivity include increased heart rate, blood pressure, and respiratory rate; sweating; pallor; dilated pupils; nausea; vomiting; dry mouth; and increased muscle tension.

Sympathetic nerve block – Injection of anesthetic to relieve pain resulting from abnormal activity in the sympathetic nervous system (see stellate ganglion block) ( 2005).

Back to Top >


Temporomandibular Joint (TMJ) Disorder – A condition causing pain and dysfunction in the lower jaw joint and muscles that control jaw movement. It is often associated with restricted jaw movement, clicking or popping sounds, muscle spasms, and grinding of teeth. Trauma to the jaw or temporomandibular joint plays a role in some TMJ disorders but in most cases the exact cause of the condition is not clear (NPEC 2006, MedlinePlus 2006).

Thalamus – A portion of the brain that relays impulses from the sensory nerves, which, in turn, enables people to feel objects they touch as well as pain ( 2005).

Therapeutic dependence – sometimes patients exhibit what is considered drug-seeking because they fear the reemergence of pain and/or withdrawal symptoms from lack of adequate medication therapy; their ongoing quest for more analgesics is in the hopes of insuring a tolerable level of comfort (Alford et al. 2006).

Thermonociceptive – Relating to the temperature- and pain-sensing components of the nervous system.

Tolerance – A state of adaptation in which repetitive exposure to a drug induces changes that result in a diminution of one or more of the drug’s effects over time.

Topical agents – Medication applied to the skin rather than ingested or injected ( 2005).

Transdermal – Medication absorbed into the bloodstream via the skin ( 2005, NIPC 2006).

Tricyclic antidepressants (TCAs) – Any of a group of antidepressant drugs that contain three fused benzene rings, which increase the effectiveness of norepinephrine or serotonin by inhibiting their uptake by nerve endings, but do not inhibit monoamine oxidase. TCAs were the most popular antidepressants until the advent of SSRIs. They are still prescribed for certain types of severe depression that do not respond to SSRIs (NIPC 2006).

Trigger point injection – A procedure used to relax a tender muscle, or to reduce muscle pain and inflammation. The targeted muscle is injected with a local anesthetic (for example, Lidocaine) and corticosteroid. Also called field block injection ( 2005).

Trigger zone/point – Hypersensitive area on the body where touch or pressure elicits pain (NPEC 2006).

Triptans – A class of drugs for the treatment of migraine that act as agonists for 5-hydroxtryptamine (5-HT) receptors. The triptans also help relieve other migraine symptoms, such as nausea, vomiting, and sensitivity to light, noise, and motion. While triptans can be effective in relieving migraine for some patients, they do not prevent future attacks or lessen their frequency (NIPC 2006, MedlinePlus 2006).

Back to Top >


Visceral pain – Pain arising from visceral organs (e.g., heart, lungs, gastrointestinal tract, liver, gallbladder, kidneys, bladder).

Waddell signs –First described in 1984, they are thought to be indicators of a psychological component to pain. Also called inorganic or nonorganic signs, these are behavioral responses during physical examination. The eight original signs include: 1) superficial tenderness; 2) nonanatomic tenderness, 3) pain in response to axial loading (vertical downward pressure on the top of the head when standing); 4) back pain in response to simultaneous rotation of the shoulders and pelvis; 5) improved straight leg raise response when distracted; 6) weakness not consistent with normal neurologic function; 7) sensory loss that does not follow a dermatomal pattern (area of skin supplied by cutaneous branches from a single spinal nerve); and 8) “overreaction” to the physical examination. Historically and sometimes inappropriately they have been used to detect and/or accuse patients with back pain as “malingering” (Fillingim 2005, Stedman’s 2000).

Wind-up pain – Nerve cells in the spinal cord may release chemicals that intensify the pain, affecting the strength of the pain signal that reaches the brain. Also known as sensitization (NIPC 2006).

Withdrawal – The uncomfortable physical or psychological state experienced when certain substances or medications are discontinued suddenly in an habituated individual. Therapeutic medication withdrawal is done gradually over time to minimize uncomfortable symptoms ( 2005, Stedman’s 2000).

Back to Top >


Ziconotide – A calcium channel blocker with analgesic and neuroprotective effects that has been used to help relieve chronic intractable pain. It is a synthetic analog of a constituent of the venom from a tropical marine snail of the genus Conus (C. magus). The brand name for the drug is Prialt®. (NIPC 2005).

Back to Top >


Reference Sources
The definitions above were derived or adapted from the following sources:

Alford DP, Comptom P, Samet JH. Acute pain management for patients receiving maintenance methadone or buprenorphine therapy. Ann Intern Med. 2006;144:127-134.

American Academy of Pain Medicine (AAPM), American Pain Society (APS), American Society of Addiction Medicine (ASAM). Definitions Related to the Use of Opioids for the Treatment of Pain. Glenview, IL: APS; 2001.

American Psychiatric Association (APA). Diagnostic and Statistical Manual of Mental Diorders. 4th ed – Text Revision. (DSM-IV-TR.) Washington, DC: APA; 2000.

American Society for Pain Management Nursing. ASPMN Position Statement: Pain Management in Patients with Addictive Disease. Pensacola, FL: ASPMN; 2002.

Backonja M-M. Conceptualizing pain and improving pain diagnosis and assessment. P&T Digest. 2005;30(12):9-14.

Bennett DS, Brookoff D. Complex regional pain syndromes (reflex sympathetic dystrophy and causalgia) and spinal cord stimulation. Pain Med. 2006;7(Suppl 1):S64-S96.

Cherny NI . Opioid analgesics: Comparative features and prescribing guidelines. Drugs. 1996 May;51(5):713-737.

Cleveland Clinic. The Cleveland Clinic Department of Rheumatic and Immunologic Diseases [website]. Available at: Access checked September 30, 2006.

Compton P. Substance abuse. In McCaffery M, Pasero C. Pain: Clinical Manual. 2nd ed. St. Louis: Mosby; 1999:428-466.

Dunbar SA, Katz NP. Chronic opioid therapy for nonmalignant pain in patients with a history of substance abuse: Report of 20 cases. J Pain Symptom Manage. 1996;11:163-171.

Fillingim RB. Concise Encyclopedia of Pain Psychology. New York: Haworth Press; 2005.

Iocolano CF. Perioperative pain management in the chemically dependent patient. J Perianesthesia Nurs. 2000;15(5),329-347.

Krames E. Battling Back: Overcoming the Undertreatment of Chronic Pain. WebMD [online serial]. Available at: Access checked September 30, 2006.

Maizels M, McCarberg B. Antidepressants and Antiepileptic Drugs for Chronic Non-Cancer Pain. Am Fam Physician. 2005;71:483-490.

MedlinePlus. Available at: Access checked September 30, 2006.

Mersky H, Bogduk N, eds. Classification of Chronic Pain. Seattle, WA; IASP Press; 1994.

National Pharmaceutical Council, Inc. in collaboration with the American Pain Society (APS). Pain: Current Understanding of Assessment, Management, and Treatments. December 2001.

NIPC (National Initiative on Pain Control). The Pain; Glossary. Available at: Access checked April 24, 2010.

NPEC (National Pain Education Council). Pain Glossary.

Pereria J, Lawlor P, Vigano A, Dorgan M, Bruera, E. Equianalgesic dose ratios for opioids. A critical review and proposals for long-term dosing. J Pain Symptom Manage. 2001;2:672-687.

Portenoy RK, Payne R. Acute and chronic pain. In Lowinson JH, Ruiz P, Millman RB, Langrod JG (eds). Substance abuse: A comprehensive Textbook. Baltimore: Williams & Wilkins; 1992:563-589.

Stedman’s Medical Dictionary. 27th ed. Baltimore MD: Lippincott Williams & Wilkins; 2000.

Stimmel B. Pain and its Relief without Addiction. Haworth Press: Binghamton, NY; 1997.

Uretsky, S. Antidepressant Drugs. In: The Gale Group, Inc. Gale Encyclopedia of Medicine. Detroit MI: The Gale Group Inc.; 2002. Available at: Access checked September 30, 2006.

WebMD. Available at: Access checked September 30, 2006.

Compiled and edited by Stewart B. Leavitt, MA, PhD
and Scottie Kersta-Wilson, MFA

Back to Top >