APS Glossary of Pain Terminology

The following glossary of terminology is provided to assist visitors who are unfamiliar with some of the specific terms used to discuss basic mechanisms and treatment of pain. These terms were compiled from APS Clinical Practice Guidelines appendices.

Ablative surgery. Surgical procedures performed on peripheral nerves, the spinal cord, the brain, or brain stem that relieve pain by permanent disruption of nerve pathways.

Acupuncture. A procedure in which specific body areas associated with peripheral nerves are pierced with fine needles to produce anesthesia, relieve pain, and promote therapy.

Acute pain. Pain that has a sudden onset and commonly declines over a short time (i.e., days, hours, minutes). Follows injury to the body and generally disappears when the bodily injury heals. It is often, but not always, associated with objective physical signs of autonomic nervous system activity such as tachycardia, hypertension, diaphoresis, mydriasis, and pallor (APS, 1999).

Addiction. A primary, chronic, neurobiologic 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 medication use, compulsive use, continued use despite harm, and craving (APS, AAPM, & ASAM, 2001).

Adjuvant analgesic medication. A medication that is not a primary analgesic but rather a medication that research has shown to have independent or additive analgesic properties (e.g., antidepressant, anticonvulsant).

AHCPR. Agency for Health Care Policy and Research (now the Agency for Health Care Research and Quality) was created by Congress in 1989 to develop multidisciplinary evidence-based clinical practice guidelines.

Allodynia. A condition in which a nonpainful stimulus is felt as painful in spite of normal-appearing tissue.

Anxiolysis. Sedation or hypnosis used to reduce anxiety, agitation, or tension.

Anxiolytic. Medication used to reduce anxiety, agitation, or tension.

Arthritis. A generic term that describes more than 100 different conditions. A disorder of a joint where two bones meet, which may be manifested on physical examination by swelling, redness, warmth, or tenderness in the joint or may be demonstrated on radiograph by loss of the joint space, formation of spurs, erosions, or cysts in the bone.

Arthrocentesis. A procedure in which a needle is inserted into the joint to either drain fluid for diagnostic purposes or to inject medications or other materials into the joint.

Arthrodesis. The surgical removal of articular joint surfaces with fixation of bone ends. After bony union, the two bones function as one and there is no motion at the prior joint.

Arthroplasty. Implantation of a prosthesis in a joint.

Arthroscopy. The insertion of an endoscope within a joint. Surgical procedures are then percutaneously performed, guided by visualization through the arthroscope. It may be used for diagnostic evaluations as well as treatments.

ATC. Around-the-clock administration.

Best-evidence synthesis. Evidence based on the best-evidence principle as used in law, in which the same evidence that would be essential in one case might be disregarded in a second case because better evidence is available.

Biofeedback. A process in which a person learns to influence reliably physiologic responses of two kinds: those that are not ordinarily under voluntary control and those that ordinarily are easily regulated but for which regulation has broken down because of trauma or disease.

Biologic agents. A new category of therapy in rheumatic diseases involving the synthesis of substances that interfere with the basic biologic mechanisms of the disease process. These agents interrupt the natural cascade of events that occur in a particular disease. They may work in part by binding to various biologic messengers that are produced in disease states, or may block receptor sites where these messengers attach to induce further disease.

Body mass index (BMI). A measure of fitness and health that takes both weight and height into account. To calculate BMI, (a) multiply weight (in pounds) by 704.5, (b) square height (in inches), then (c) divide number from Step a by number from Step b.

Breakthrough pain. Intermittent exacerbations of pain that can occur spontaneously or in relation to specific activity; pain that increases above the level of pain addressed by the ongoing analgesics; includes incident pain and end-of-dose failure.

Cancer pain. May be acute, chronic, or intermittent and often has a definable etiology, usually related to tumor recurrence or treatment. Chronic cancer pain rarely is accompanied by signs of sympathetic nervous system arousal.

Case study design. A nonexperimental study that extensively explores a single unit (a unit may be a person, family, or group) or a very small number of units.

Catastrophize. The tendency to ruminate upon, focus on, and worry about pain and to evaluate one’s ability to control pain in an overly negative fashion.

Chronic pain (nonmalignant). Generally considered to be pain that lasts more than 6 months, is ongoing, is due to non-life-threatening causes, has not responded to current available treatment methods, and may continue for the remainder of the person’s life. (Wall & Melzack, 1999)

Cognitive reappraisal. A coping strategy in which patients are taught to monitor and evaluate negative thoughts and replace them with more positive thoughts and images.

Combination therapy. Method of treating disease through the simultaneous use of a variety of medications to eliminate or control the biochemical cause of the disease.

Condylectomy. The removal of a condyle, which is a prominent part of the bone at a joint and which may cause a pressure area, particularly in the foot.

Conscious or moderate sedation. “Light sedation” during which the patient retains airway reflexes and responses to verbal stimuli.

Constitutive. Normally present.

Counterirritant. An agent that is applied to produce irritation at one site so as to decrease perception of pain at the same or a distant site.

Counterstimulant. Application of a moderate to intense sensory stimulation, such as with cold, heat, rubbing, pressure, or electrical current, so as to decrease perception of pain at the same or a distant site.

Cryoanalgesia. The destruction of peripheral nerves by extreme cold to achieve prolonged pain relief.

Cryotherapy. The therapeutic use of cold to reduce discomfort, limit progression of tissue edema, or break a cycle of muscle spasm. Cryotherapy is a form of counterirritation.

Cyclooxygenase. Refers to a particular enzyme involved in the formation of prostaglandins in the body. The enzyme may be important in the natural physiology in a particular organ or cell or may be involved in the formation of prostaglandins that induce inflammation in a joint, in which case it may be detrimental.

Cyclooxygenase-1 (COX-1). An enzyme that is normally present in the body for physiologic reasons. It is also called constitutive cyclooxygenase, COX-1 is produced physiologically in the stomach and protecs the lining of the stomach.

Cyclooxygenase-2 (COX-2). The “inducible” form of cyclooxygenase that arises with joint inflammation and is involved in the diseases of the joints. COX-2 is produced in the joint when “induced” by inflammation.

Deafferentation pain. Pain due to loss of sensory input into the central nervous system, as occurs with avulsion of the brachial plexus or other types of lesions of peripheral nerves or because of pathology of the central nervous system.

Descriptive study. A nonexperimental study in which variables or subject characteristics are examined as they naturally occur for the purpose of describing or comparing samples or examining relationships among a set of variables.

Dysautonias. Postural tachycardia syndrome or neurally mediated hypotension.

Dysesthesia. An unpleasant abnormal sensation, whether spontaneous or evoked; impairment of sensation, especially touch.

Dysphoria. An emotional state marked by anxiety, depression, and restlessness.

Effect size. A measure of the magnitude of a relationship (e.g., the size of the relationship between an independent and dependent variable in an experimental study).

Epidural. Situated within the spinal canal, on or outside the dura mater (the tough membrane surrounding the spinal cord); synonyms are extradural and peridural.

Equianalgesic. Having equal analgesic effect; morphine sulfate 10 mg parenterally is generally used for opioid analgesic comparisons.

Eutectic mixture of local anesthetics (EMLA). An ointment that contains local anesthetics so that topical application causes local anesthesia without the need for injection.

Exostectomy. The removal of a fragment of bone.

Experimental study (randomized controlled trial or randomized clinical trial). An experiment that uses random assignment to create treatment and control groups so that changes can be attributed to the experimental treatment.

Fibromyalgia syndrome (FMS). The most common chronic, widespread pain syndrome characterized by a set of well-defined symptoms. Etiologic or pathologic findings are not established.

Goniometer. An instrument for measuring angles (as of a joint).

Hyaluronic acid. A substance in the synovial fluid that is responsible for the viscosity of joint fluid. It is important in the lubrication process and in the protection of the joint and allows for smoother motion of the joint.

Hyperalgesia/allodynia. Increased sensitivity to pain or enhanced intensity of pain sensation.

Hyperpathia. A painful syndrome characterized by increased reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold.

Hypnosis. A state of heightened awareness and focused concentration that can be used to manipulate the perception of pain.

Hyporeflexia. A condition characterized by diminished or weakened reflexes.

Iatrogenic. Induced inadvertently by medical treatment or procedures.

Imagery. A cognitive-behavioral strategey that uses mental images produced by memory or imagination for relaxation or for distraction, depending on the content of the imagery.

Incident pain. A type of breakthrough pain that is related to a specific activity, such as eating, defecating, socializing, or walking; also referred to as movement-related pain.

Inducible. Able to initiate or increase the production of an enzyme or other protein at the level of genetic transcription; produced in the joint by inflammation.

Interpleural. Situated between the membrane surrounding the lungs and the membrane lining the thoracic cavity.

Intrathecal. The area that lies between the arachnoid membrane and pia mater and contains the cerebral spinal fluid (CSF). This subarachnoid space is commonly known as the space where “spinal taps” are performed.

Juvenile chronic arthritis. A group of systemic inflammatory disorders affecting children younger than 16 years of age. Three major subsets are described: (a) pauciarticular onset—four joints or less involved, (b) polyarticular onset—more than four joints involved and (c) systemic onset—with fever, rash, and arthritis.

Lancinating. Characterized by piercing or stabbing sensations.

Loading dose. The initial dose administered for a pain episode.

Local nerve block. Infiltration of a local anesthetic around a peripheral nerve so as to produce anesthesia in the area supplied by the nerve.

Maintenance dose. The medication dosage required to produce a given level of analgesia.

Meta-analysis. The process of combining the results of several related studies to obtain more reliable conclusions.

Mixed opioid agonist-antagonist. A compound that has an affinity for two or more types of opioid receptors and blocks opioid effects on one receptor type while producing opioid effects on a second receptor type.

Movement-related pain. A type of breakthrough pain that is related to a specific activity, such as eating, defecating, socializing, or walking; also referred to as incident pain.

MU (μ) Agonist. Type of opioid; relieves pain by binding to the µ receptor sites in the nervous system.

Mucositis. Inflammation of a mucous membrane. Oral mucositis is a common complication of chemotherapy and radiation therapy.

Music therapy. A form of distraction that uses music as an aid to relaxation.

Myofascial pain. A large group of muscle disorders characterized by the presence of hypersensitive points, called trigger points, within one or more muscles and/or the investing connective tissue, together with a syndrome of pain, muscle spasm, tenderness, stiffness, limitation of motion, weakness, and occasionally autonomic dysfunction.

Neurolytic block. The injection of a chemical agent to cause destruction and consequent prolonged interruption of peripheral somatic or sympathetic nerves, or in some cases, the neuraxis.

Neuropathic pain. Pain that results from a disturbance of function or pathologic change in a nerve; in one nerve, mononeuropathy; in several nerves, mononeuropathy multiplex; if diffuse and bilateral, polyneuropathy.

Neuropathy. A disease or abnormality of the nervous system, especially one affecting the cranial or spinal nerves.

Nociception. The process of pain transmission, usually relating to a receptive neuron for painful sensations.

Nociceptive pain. Pain resulting from actual or potential tissue damage; pain resulting from the ongoing activation of primary afferent neurons by noxious stimuli. (The nervous system is intact.)

Nonsteroidal anti-inflammatory drug (NSAID). Aspirin-like medication that reduces inflammation (and hence pain) arising from injured tissue.
COX-2 selective NSAID: An NSAID that inhibits the COX-2 isoform of cyclooxygenase, but not the COX-1 form.
Nonselective NSAID: An NSAID that inhibits both COX-1 and COX-2 isoforms of cyclooxygenase.

Number needed to treat (NNT) to prevent one additional adverse outcome. A number which gives an estimate of how many people need to receive a treatment before one person would experience the beneficial outcome (e.g., if you need to give a stroke prevention drug to 20 people before one stroke is prevented, then the NNT for that stroke prevention drug is 20).

Opiate receptor. Opiate-binding sites found throughout primary afferents and the neuraxis.

Opioid. A morphine-like medication that produces pain relief. The term opioid is preferred to the term narcotic; it refers to natural, semisynthetic, and synthetic medications that relieve pain by binding to opioid receptors in the nervous system. Opioid is also preferred to the term opiate because it includes all agonists and antagonists with morphine-like activity, as well as naturally occurring and synthetic opioid peptides.

Opioid agonist. Any morphine-like compound that produces bodily effects including pain relief, sedation, constipation, and respiratory depression.

Opioid agonist-antagonist. A medication that acts as an agonist at one type of opioid receptor and as an antagonist at another receptor.

Opioid partial agonist. A compound that has an affinity for and stimulates physiological activity at the same cell receptors as opioid agonists but that produces only a partial (i.e., submaximal) bodily response.

Osteoarthritis (OA). A disease of the cartilage that progressively produces a local tissue response, mechanical change, and failure of function. The disease typically affects weight-bearing joints asymmetrically. It is the most common form of arthritis.

Osteotomy. The sectioning or cutting of bone. This may be used to change angular alignment of a joint surface to relieve diseased areas of weight-bearing stress.

Oximetry. Determination of the oxygen saturation of arterial blood, typically by means of an external probe applied around a finger or tie.

Pain. An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. (International Association for the Study of Pain, 1994)

Pain affect. The affective unpleasantness and emotional arousal caused by pain.

Pain threshold level. The level of intensity at which pain becomes appreciable or perceptible.

Paradoxical reaction. A response (e.g., to a medication) that is the opposite of the usual response, such as agitation produced in an individual patient by a drug normally considered to be a sedative.

Paraneoplasia. Hormonal, neurological, hematological, and other chemical and biochemical disturbances associated with malignant neoplasms but not directly related to invasion by the primary tumor or its metastases.

Paraparesis. Partial paralysis of the lower extremities.

Paresthesia. A skin sensation, such as burning, prickling, itching, or tingling, with no apparent physical cause.

Patient-controlled analgesia (PCA). Analgesics self-administered by a patient who has received instruction in doing so; usually refers to self-dosing with an intravenous, subcutaneous epidural opioid (e.g., morphine) administered by means of a programmable pump.

Peer review. Evaluation of the present guideline document by an interdisciplinary panel of experts using the Institute of Medicine (Field and Lohr 1992) attributes of clinical practice guidelines as evaluation criteria.

Peridural. Situated within the spinal canal, on or outside the dura mater (the tough membrane surrounding the spinal cord); synonyms are epidural and extradural.

Perineural. Surrounding a nerve.

Persistent pain. Constant pain that lasts for long periods.

Phalangectomy. The partial or complete removal of the phalanges (i.e., bones of the fingers and toes). This aids in correction of deformities and relief of pressure areas.

Physical dependence. A state of adaptation that is manifested by a medication class–specific withdrawal syndrome that can be produced by abrupt cessation, rapid dose reduction, decreasing blood level of the medication, and/or administration of an antagonist (APS, AAPM, & ASAM, 2001).

Physical modalities. Physical methods such as heat, cold, massage, or exercise to relieve pain.

Plexopathy (brachial). Decreased movement or sensation in the arm and shoulder, casued by impaired function in the brachial plexus, a nerve area that affects the arm.

Polyarthritis. Refers to inflammation in multiple joints.

PRN. As needed.

Progressive muscle relaxation. A cognitive-behavioral strategy in which muscles are alternately tensed and then relaxed in a systematic fashion.

Pseudoaddiction. Pattern of medication-seeking behavior of patients receiving inadequate pain management that can be mistaken for addiction.

Psychosocial intervention. A therapeutic intervention that uses cognitive, cognitive-behavioral, behavioral, and supportive interventions to relieve pain. These include patient education, interventions aimed at aiding relaxation, psychotherapy, and structured or peer support.

QTc. The corrected QT interval. The length of the QT interval varies inversely with heart rate and therefore shortens as heart rate increases. To compare QT intervals over time for an individual, it is necessary to return the measured interval to normal for heart-rate effects. Correctional formulas generate a corrected QT interval, or an interval adjusted for heart rate.

Quasi-experimental study (includes nonrandomized controlled trial or nonrandomized clinical trial). A design that does not use random assignment to create treatment and control groups but uses other methods to control validity threats so that changes can be inferred or attributed to the experimental treatment.

Randomized controlled trial (RCT). See “experimental study.”

Refractory pain. Pain that is resistant to ordinary treatment.

Relaxation. A state of relative freedom from both anxiety and skeletal muscle tension.

Relaxation methods. A variety of techniques to help decrease anxiety and muscle tension; these may include imagery, distraction, and progressive muscle relaxation.

Rescue dose. A bolus or extra dose of medication given as needed (prn) to relieve pain that breaks through despite a regimen of medication that is given at regularly scheduled intervals.

Rheumatoid arthritis (RA). A chronic inflammatory condition in which the body’s immune system attacks cartilage, bone, and sometimes internal organs, usually causing joint disease. Joints become inflamed which leads to swelling, pain, stiffness, and the possible loss of function. It is characterized by a symmetrical pattern of synovitis of the joints leading to progressive destruction.

Scientific review. An exhaustive literature search to define and critically evaluate the knowledge base for a subject (e.g., pain assessment and intervention).

Self-statement. The substitution by patients of positive thoughts for negative thoughts like “I can’t stand this” or “How much longer will this go on?”

Substance P. A short chain polypeptide that functions as a neurotransmitter, especially in the transmission of pain impulses from peripheral receptors to the central nervous system.

Subtalar joint. The major point in the hindfoot beneath the ankle. This joint allows eversion and inversion of the foot in concert with the midfoot articulation (talonavicular and calcaneocuboid joints).

Suffering. Threat or damage to sense of self; a state of severe distress associated with events that threaten the intactness of the person.

Synovitis. Inflammation of the synovial lining tissue of the joint as is seen in inflammatory arthritis.

Tactile strategies. Strategies that provide comfort through the sense of touch, such as stroking or massage.

Tapering or weaning. A process in which a medication is gradually withdrawn from a patient who is physically dependent on the medication.

Titration. The incremental adjustment of a medication in subsequent doses until a desired effect is achieved.

Titration to relief. A gradual increase in pain medication until the highest pain relief is obtained, making the pain as tolerable as possible while minimizing short- and long-term negative effects.

Tolerance. A state of adaptation in which exposure to a medication induces changes that result in a diminution of one or more of the medication’s effects over time (APS, AAPM, & ASAM, 2001)

Torsade de pointes. Paroxysms of ventricular tachycardia in which the electrocardiogram shows a steady undulation in the QRS axis in runs of 5 to 20 beats and with progressive changes in direction.

Transcutaneous electrical nerve stimulation (TENS). A method of producing electroanalgesia through electrodes applied to the skin.

Tumor necrosis factor (TNF). Important immune mediator that may be involved in the mechanisms contributing to disease in rheumatoid arthritis. The ability to block TNF with recent biologic agents has helped in control of active disease in patients with rheumatoid arthritis.

Viscosupplementation. A procedure currently approved for use in osteoarthritis in which viscous fluid is injected into a joint (currently the knee joint), which results in decreased pain and increased mobility.

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These definitions were originally published in the following American Pain Society guidelines: Guideline for the Management of Fibromyalgia Syndrome Pain in Adults and Children (2005), Guideline for the Management of Cancer Pain in Adults in Children ( 2005), and Guideline for the Management of Pain in Osteoarthritis, Rheumatoid Arthritis, and Juvenile Chronic Arthritis (2002).