liliana tarţău, md, phd. definition of pain (iasp) an unpleasant sensory and emotional experience...

Liliana Tarţău, MD, PhD

Definition of pain (IASP)

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

Pain is subjective. Each individual learns the meaning of the word "pain" through experiences related to injury in early life.

Biologists recognize that those stimuli or illnesses that cause pain are likely to damage tissue.

HistoryHistoryThe ancient Greek believed that pain was associated with The ancient Greek believed that pain was associated with

pleasure because the relief of pain was both pleasurable pleasure because the relief of pain was both pleasurable and emotional.and emotional.

The Romans, coming closer to contemporary thought, The Romans, coming closer to contemporary thought, viewed pain as something that accompanied inflammation.viewed pain as something that accompanied inflammation.

- 2- 2ndnd century, Galen offered the Romans his works on the century, Galen offered the Romans his works on the concepts of the nervous system.concepts of the nervous system.

- 4- 4thth century, successors of Aristotle discovered anatomic century, successors of Aristotle discovered anatomic proof that the brain was connected to nervous system.proof that the brain was connected to nervous system.

- Aristotle’s belief prevailed until the 19- Aristotle’s belief prevailed until the 19 thth century, when century, when German scientist provided irrefutable evidence that the German scientist provided irrefutable evidence that the brain is involved with sensory and motor function.brain is involved with sensory and motor function.

HistoryHistoryModern concepts of pain theory continue to advance from the ideas of Modern concepts of pain theory continue to advance from the ideas of

Aristotle. However, controversy still exists as to which theories are Aristotle. However, controversy still exists as to which theories are correct.correct.

The theories accepted at the turn of the century were the specificity theory The theories accepted at the turn of the century were the specificity theory and the pattern theory, two completely different and seemingly and the pattern theory, two completely different and seemingly contradictory views.contradictory views.

The specificity theory suggests that there is a direct pathway from peripheral The specificity theory suggests that there is a direct pathway from peripheral pain receptors to the brain.pain receptors to the brain.

Proposed by Ronald Melzack and Patrick Wall during the early 1960s, gate Proposed by Ronald Melzack and Patrick Wall during the early 1960s, gate control theory suggests that the spinal cord contains a neurological "gate" control theory suggests that the spinal cord contains a neurological "gate" that either blocks pain signals or allows them to continue on to the brain. that either blocks pain signals or allows them to continue on to the brain. Unlike an actual gate, which opens and closes to allow things to pass Unlike an actual gate, which opens and closes to allow things to pass through, the "gate" in the spinal cord operates by differentiating between through, the "gate" in the spinal cord operates by differentiating between the types of fibers carrying pain signals. the types of fibers carrying pain signals.

General dataGeneral dataPain is a conscious experience that results from brain activity in response to a noxious stimulus and engages the sensory, emotional and cognitive processes of the brain. In general terms we can distinguish two dimensions or components of pain: • sensory - discriminative • affective - emotional.

Nociception is the process by which information about a noxious stimulus is conveyed to the brain. It is the total sum of neural activity that occurs prior to the cognitive processes that enable humans to identify a sensation as pain. Nociception is necessary but not sufficient for the experience of pain.

General dataGeneral data

pain threshold pain threshold – level of noxious stimulus – level of noxious stimulus required to alert an individual of a potential required to alert an individual of a potential threat to tissue.threat to tissue.

pain tolerance pain tolerance – amount of pain a person – amount of pain a person is willing or able to tolerate.is willing or able to tolerate.


Pain is a major health issue. Pain is a major health issue. The number one cause of adult disability in the The number one cause of adult disability in the

US; US;

Prevalence of chronic pain in the general Prevalence of chronic pain in the general population is estimated at population is estimated at 116 million 116 million people.people.

Pain costs an estimated Pain costs an estimated $560 to $635 billion $560 to $635 billion

annually annually in lost workdays, medical expenses, in lost workdays, medical expenses, and other benefit costs. and other benefit costs.

General dataGeneral dataPain diminishes the quality of life for many people,

although it may also be a vital teacher or a warning message to be heeded.

How humans process pain is a complicated, individualized process affected by genetics, personality, life experiences and straightforward physiological processes.

When an injury disrupts homeostasis, and depending upon the extent and severity of the injury, genetically predetermined neural, hormonal, and behavioral programs kick into action.

General dataGeneral dataThe body’s response is as follows:The body’s response is as follows:

The injury triggers a process by which sensory The injury triggers a process by which sensory information is relayed rapidly to the brain, which initiates information is relayed rapidly to the brain, which initiates the complex sequence of events to reinstate the complex sequence of events to reinstate homeostasis.homeostasis.

The body releases cortisol, a hormone produced by the The body releases cortisol, a hormone produced by the adrenal glands, in an effort to re-establish homeostasis. adrenal glands, in an effort to re-establish homeostasis. Cortisol produces and maintains high levels of glucose Cortisol produces and maintains high levels of glucose for quick response following an injury, threat, or other for quick response following an injury, threat, or other form of emergency (such as the fight or flight response). form of emergency (such as the fight or flight response).


Negative consequences of painNegative consequences of paindecreased socializationdecreased socializationwithdrawal from daily lifewithdrawal from daily life fatiguefatiguesleep disturbancesleep disturbance irritabilityirritabilityphysical deconditioning physical deconditioning stressstressdepression.depression.

Congenital analgesiaCongenital analgesiaA well-known case of congenital insensitivity to pain is a girl A well-known case of congenital insensitivity to pain is a girl

referred to as 'miss C' who was a student at McGill referred to as 'miss C' who was a student at McGill university in Montreal in the 1950s. She was normal in university in Montreal in the 1950s. She was normal in every way, except that she could not feel pain. When she every way, except that she could not feel pain. When she was a child she had bitten off the tip of her tongue and was a child she had bitten off the tip of her tongue and had suffered third-degree burns by kneeling on a had suffered third-degree burns by kneeling on a radiator,radiator,

When she was examined by a psychologist she did not feel When she was examined by a psychologist she did not feel any pain when she was given strong electric shocks or any pain when she was given strong electric shocks or when exposed to very hot and very cold water. When when exposed to very hot and very cold water. When these stimuli were presented to her she showed no these stimuli were presented to her she showed no change in heart rate, blood pressure or respiration.change in heart rate, blood pressure or respiration.

Factors affecting painFactors affecting pain

Factors that alter the perception Factors that alter the perception of painof pain

Implications for clinical practiceImplications for clinical practice There is no physiological, imaging, or laboratory test that There is no physiological, imaging, or laboratory test that

can identify or measure pain. Pain is what the patient can identify or measure pain. Pain is what the patient says it is. The clinician must accept the patient's report of says it is. The clinician must accept the patient's report of pain.pain.

The goal of pain therapies is to relieve pain whenever The goal of pain therapies is to relieve pain whenever possible: from nociception to the conscious experience as possible: from nociception to the conscious experience as well as to decrease the emotional response to the well as to decrease the emotional response to the unpleasant experience. Nociception should be treated unpleasant experience. Nociception should be treated even in unconscious patients who appear to be clinically even in unconscious patients who appear to be clinically unresponsive to pain to help prevent sensitization of pain unresponsive to pain to help prevent sensitization of pain pathways which can lead to chronic pain.pathways which can lead to chronic pain.

Pain has a biologically important protective function. The Pain has a biologically important protective function. The sensation of pain is a normal response to injury or disease sensation of pain is a normal response to injury or disease and is a result of normal physiological processes within the and is a result of normal physiological processes within the nociceptive system, with its complex of stages previously nociceptive system, with its complex of stages previously described. described.

There may also be other manifestations of pain related to There may also be other manifestations of pain related to tissue injury including hyperalgesia, an exaggerated tissue injury including hyperalgesia, an exaggerated response to a noxious stimulus, and allodynia, the response to a noxious stimulus, and allodynia, the perception of pain from normally innocuous stimuli.perception of pain from normally innocuous stimuli.

Hyperalgesia and allodynia are the result of changes in either Hyperalgesia and allodynia are the result of changes in either the peripheral or central nervous systems, referred to as the peripheral or central nervous systems, referred to as peripheral or central sensitization, respectively.peripheral or central sensitization, respectively.


General dataGeneral dataPain is a Pain is a multidimensionalmultidimensional phenomenon which is an phenomenon which is an

attention grabbing sensation that can produce attention grabbing sensation that can produce strong emotional reactions that adversely affect a strong emotional reactions that adversely affect a patient's function, quality of life, emotional state, patient's function, quality of life, emotional state, social and vocational status, and general well-being. social and vocational status, and general well-being.

Therefore, pain assessment should also be Therefore, pain assessment should also be multidimensional. multidimensional.

It is important to evaluate these various elements It is important to evaluate these various elements during the interview and examination, and include during the interview and examination, and include them in the diagnostic formulation.them in the diagnostic formulation.

General dataGeneral dataA thorough history and physical exam are essential A thorough history and physical exam are essential

for the medical and pain diagnosis and treatment for the medical and pain diagnosis and treatment planning. planning.

A pain history should include location, quality, A pain history should include location, quality, intensity, temporal characteristics, aggravating intensity, temporal characteristics, aggravating and alleviating factors, impact of pain on function and alleviating factors, impact of pain on function and quality of life, past treatment and response, and quality of life, past treatment and response, patient expectations and goals. patient expectations and goals.

Careful attention to the patient's reported symptoms Careful attention to the patient's reported symptoms will help direct the physical examination and will help direct the physical examination and narrow the pain differential diagnosis.narrow the pain differential diagnosis.

Classification of painClassification of pain- based on pain physiology, intensity, temporal characteristics, - based on pain physiology, intensity, temporal characteristics,

type of tissue affected, and syndrome:type of tissue affected, and syndrome:• pain physiology (nociceptive, neuropathic, inflammatory)pain physiology (nociceptive, neuropathic, inflammatory)• intensity (mild-moderate-severe; 0-10 numeric pain rating intensity (mild-moderate-severe; 0-10 numeric pain rating

scale)scale)• time course (acute, chronic)time course (acute, chronic)• type of tissue involved (skin, muscles, viscera, joints, type of tissue involved (skin, muscles, viscera, joints,

tendons, bones)tendons, bones)• syndromes (cancer, fibromyalgia, migraine, others)syndromes (cancer, fibromyalgia, migraine, others)• special considerations (psychological state, age, gender, special considerations (psychological state, age, gender,

culture).culture).

Classification of painClassification of pain

Acute pain: pain of less than 3 to 6 months Acute pain: pain of less than 3 to 6 months duration.duration.

Chronic pain: pain lasting for more than 3-Chronic pain: pain lasting for more than 3-6 months, or persisting beyond the course 6 months, or persisting beyond the course of an acute disease, or after tissue healing of an acute disease, or after tissue healing is complete.is complete.

Classification of painClassification of painThere are several ways to categorize pain. One is to separate There are several ways to categorize pain. One is to separate

it into acute pain and chronic pain. it into acute pain and chronic pain. Acute pain typically comes on suddenly and has a limited Acute pain typically comes on suddenly and has a limited

duration. It's frequently caused by damage to tissue such duration. It's frequently caused by damage to tissue such as bone, muscle, or organs, and the onset is often as bone, muscle, or organs, and the onset is often accompanied by anxiety or emotional distress.accompanied by anxiety or emotional distress.

Chronic pain lasts longer than acute pain and is generally Chronic pain lasts longer than acute pain and is generally somewhat resistant to medical treatment. This type of somewhat resistant to medical treatment. This type of pain can be the result of damaged tissue, but very often pain can be the result of damaged tissue, but very often is attributable to nerve damage. It's usually associated is attributable to nerve damage. It's usually associated with a long-term illness.with a long-term illness.

Classification of painClassification of pain

Both acute and chronic pain can be debilitating, and both Both acute and chronic pain can be debilitating, and both can affect and be affected by a person's state of mind. can affect and be affected by a person's state of mind.

But the nature of chronic pain - the fact that it's ongoing and But the nature of chronic pain - the fact that it's ongoing and in some cases seems almost constant - makes the in some cases seems almost constant - makes the person who has it more susceptible to psychological person who has it more susceptible to psychological consequences such as depression and anxiety. consequences such as depression and anxiety.

Chronic pain is further subdivided in to two classes: chronic Chronic pain is further subdivided in to two classes: chronic malignant pain and chronic non-malignant pain. malignant pain and chronic non-malignant pain.

At the same time, psychological distress can amplify the At the same time, psychological distress can amplify the pain.pain.

PainPain

About 70% of people with chronic pain treated with About 70% of people with chronic pain treated with pain medication experience episodes of what's pain medication experience episodes of what's called breakthrough pain. called breakthrough pain.

Breakthrough pain refers to flares of pain that occur Breakthrough pain refers to flares of pain that occur even when pain medication is being used regularly. even when pain medication is being used regularly.

Sometimes it can be spontaneous or set off by a Sometimes it can be spontaneous or set off by a seemingly insignificant event such as rolling over seemingly insignificant event such as rolling over in bed. And sometimes it may be the result of pain in bed. And sometimes it may be the result of pain medication wearing off before it's time for the next medication wearing off before it's time for the next dose.dose.

Acute and chronic painAcute and chronic pain

Differences between treatment of acute and chronic painAcute ChronicMedical model of care

Reduced pain intensity is primary goal in order to facilitate recovery and prevent chronic pain

Generally time limited and successful

Treatment ends when pain resolves

Rehabilitation-disease management model of care

Improved function (physical, psychological and social) is often primary goal Patients must actively participate in care

Treatment and pain may never end

Pathophysiological Classification Pathophysiological Classification of Painof Pain

Under this category, pain is divided into two types: Under this category, pain is divided into two types: • nociceptivenociceptive pain pain • neuropathicneuropathic pain. pain.

Nociceptive Pain includes Nociceptive Pain includes somaticsomatic and and visceralvisceral pain pain (directly caused by the stimulation of pain nerve endings (directly caused by the stimulation of pain nerve endings due to tissue injury or tumor infiltration).due to tissue injury or tumor infiltration).

Its represents the normal response to noxious insult or injury Its represents the normal response to noxious insult or injury of tissues such as skin, muscles, visceral organs, joints, of tissues such as skin, muscles, visceral organs, joints, tendons, or bones.tendons, or bones.

Somatic: Somatic: musculoskeletal (joint pain, musculoskeletal (joint pain, myofascial pain), cutaneous; often myofascial pain), cutaneous; often well localized.well localized.

• Somatic painSomatic pain is often described by is often described by patients as dull or aching pain. patients as dull or aching pain. Patients are also able to point directly Patients are also able to point directly to the pain as the location is well to the pain as the location is well defined. Pain is defined. Pain is often worse with often worse with movement. movement.

Common causes of somatic pain include Common causes of somatic pain include cancer metastasis to the bones or cancer metastasis to the bones or muscles due to chemotherapy drugs.muscles due to chemotherapy drugs.


Visceral: hollow organs and smooth Visceral: hollow organs and smooth muscle; usually referred.muscle; usually referred.

Visceral painVisceral pain is difficult to locate and is difficult to locate and the site may be actually distant the site may be actually distant from the source of the pain. from the source of the pain.

It may be determined by distention of It may be determined by distention of ducts leading to major organs, ducts leading to major organs, smooth muscle spasm, muscle smooth muscle spasm, muscle ischemia, obstruction.ischemia, obstruction.


Neuropathic: pain initiated or caused by a primary lesion Neuropathic: pain initiated or caused by a primary lesion or disease in the somatosensory nervous system. or disease in the somatosensory nervous system.

Patients describe this type of pain as sharp, numbing, Patients describe this type of pain as sharp, numbing, burning, or shooting in quality. burning, or shooting in quality.

This type of pain may be seen in patients:This type of pain may be seen in patients:- with poorly controlled diabetes, with poorly controlled diabetes, - after viral infection (herpes zoster, chicken pox). after viral infection (herpes zoster, chicken pox). - with cancer (metastasis to the spinal cord).with cancer (metastasis to the spinal cord).- with spinal cord injury pain, phantom limb pain, and with spinal cord injury pain, phantom limb pain, and

post-stroke central pain.post-stroke central pain.


Aspects of neuropathic painAspects of neuropathic pain

COMPONENT CHARATERS EXAMPLES

Steady, Dysesthetic

• burning, tingling

• constant, aching

• squeezing, itching

• allodynia

• hypersthesia

• diabetic neuropathy

• post-herpetic neuropathy

Paroxysmal, Neuralgic

• stabbing

• shock-like, electric

• shooting

• lancinating

• trigeminal neuralgia

• may be a component of any neuropathic pain


Inflammatory: a result of activation and sensitization of Inflammatory: a result of activation and sensitization of the nociceptive pain pathway by a variety of mediators the nociceptive pain pathway by a variety of mediators released at a site of tissue inflammation.released at a site of tissue inflammation.

The mediators that have been implicated as key players The mediators that have been implicated as key players are proinflammatory cytokines such IL-1-alpha, IL-1-are proinflammatory cytokines such IL-1-alpha, IL-1-beta, IL-6 and TNF-alpha, chemokines, reactive oxygen beta, IL-6 and TNF-alpha, chemokines, reactive oxygen species, vasoactive amines, lipids, ATP, acid, and other species, vasoactive amines, lipids, ATP, acid, and other factors released by infiltrating leukocytes, vascular factors released by infiltrating leukocytes, vascular endothelial cells, or tissue resident mast cellsendothelial cells, or tissue resident mast cells

Examples include: appendicitis, rheumatoid arthritis, Examples include: appendicitis, rheumatoid arthritis, inflammatory bowel disease, and herpes zoster.inflammatory bowel disease, and herpes zoster.

Pain IntensityPain Intensity

Can be broadly categorized as: mild, Can be broadly categorized as: mild, moderate and severe (numeric analogue moderate and severe (numeric analogue scale):scale):

• 0 = no pain0 = no pain• mild: <4/10mild: <4/10• moderate: 5/10 to 6/10moderate: 5/10 to 6/10• severe: >7/10severe: >7/10• 10 is the worst pain imaginable.10 is the worst pain imaginable.

Types of pain in pathologyTypes of pain in pathology

Diagnosis of painDiagnosis of pain

• Medical diagnoses related to the painMedical diagnoses related to the pain: : underlying diagnoses causing pain.underlying diagnoses causing pain.

• Pain typePain type (acute, neuropathic, visceral), (acute, neuropathic, visceral), intensity, impact on quality of life and function.intensity, impact on quality of life and function.

• Medical comorbiditiesMedical comorbidities contributing to pain contributing to pain and/or affecting treatment: cardiovascular, and/or affecting treatment: cardiovascular, cerebro-vascular or neuromuscular diseases.cerebro-vascular or neuromuscular diseases.

• MedicationsMedications that may interfere with the usual that may interfere with the usual choices of drug or nondrug treatments. choices of drug or nondrug treatments.

Psychosocial issuesPsychosocial issues and patient's ability to cope with pain. and patient's ability to cope with pain.

FactorsFactors that impact treatment planning and may affect that impact treatment planning and may affect response to treatment include: response to treatment include: - depression, depression, - anxiety, anxiety, - negative emotions, negative emotions, - past experiences, past experiences, - illness perception, illness perception, - alcohol dependence, alcohol dependence, - substance abuse and substance abuse and - current social situations.current social situations.

Diagnosis of painDiagnosis of pain

Treatment of painTreatment of pain

TreatmentTreatment planning establishes goals, planning establishes goals, expectations, methods and time course for expectations, methods and time course for treatment.treatment.

The goals of pain treatment differ depending The goals of pain treatment differ depending upon the type of pain and the nature of the upon the type of pain and the nature of the individual case. individual case.

Patient and family goals must be informated Patient and family goals must be informated with what is possible and reasonable given with what is possible and reasonable given the situation.the situation.

Treatment of painTreatment of painAcute painAcute pain

The major goals are painThe major goals are pain control and relief control and relief while efforts are while efforts are made to identify and treat the underlying disease and to made to identify and treat the underlying disease and to enhance healing and recovery. Adequate management enhance healing and recovery. Adequate management of acute pain may also prevent the development of of acute pain may also prevent the development of chronic pain.chronic pain.

Analgesics are the mainstay of acute pain treatment, but Analgesics are the mainstay of acute pain treatment, but nondrug methods (patient education, heat/cold, nondrug methods (patient education, heat/cold, massage, distraction/relaxation, others) are essential too. massage, distraction/relaxation, others) are essential too.

In some situations regional analgesia and anesthesia are In some situations regional analgesia and anesthesia are also indicated.also indicated.

Treatment of painTreatment of painChronic painChronic pain

In most cases of chronic pain, multiple mechanisms are at play In most cases of chronic pain, multiple mechanisms are at play and the cause of the pain may be difficult to identify and cannot and the cause of the pain may be difficult to identify and cannot be completely eliminated. Pain relief is still primary but the goals be completely eliminated. Pain relief is still primary but the goals of of improvement in function and quality of life improvement in function and quality of life gain even greater gain even greater importanceimportance. .

In addition to rational multidrug therapy, physical medicine and In addition to rational multidrug therapy, physical medicine and rehabilitation modalities to treat deconditioning and disability, rehabilitation modalities to treat deconditioning and disability, and behavioral/psychological treatment to enhance coping and and behavioral/psychological treatment to enhance coping and improve mood are all important. improve mood are all important.

Aim for maintained or improved daily activity, family life, and Aim for maintained or improved daily activity, family life, and return to work if possible.return to work if possible.

liliana tarţău, md, phd. definition of pain (iasp) an unpleasant sensory and emotional experience...

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