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Pain Assessment

  • Author: Stephen Kishner, MD, MHA; Chief Editor: Erik D Schraga, MD  more...
 
Updated: Jun 13, 2016
 

Practice Essentials

Precise and systematic pain assessment is required to make the correct diagnosis and determine the most efficacious treatment plan for patients presenting with pain.

Technique

Pain must be assessed using a multidimensional approach, with determination of the following:

  • Chronicity
  • Severity
  • Quality
  • Contributing/associated factors
  • Location/distribution or etiology of pain, if identifiable
  • Mechanism of injury, if applicable
  • Barriers to pain assessment

Pain scales

Pain measures fall into 2 categories:

  • Single-dimensional scales - These scales assess a single dimension of pain and, through patient self-reporting, measure only pain intensity; these scales are useful in acute pain when the etiology is clear; see the image below
    Faces Pain Rating Scale. Faces Pain Rating Scale.
  • Multidimensional scales - These measure the intensity, nature, and location of pain, as well as, in some cases, the impact that pain is having on a patient’s activity or mood; multidimensional scales are useful in complex or persistent acute or chronic pain

Pain assessment in the elderly

Pain assessment can be particularly difficult in elderly patients for the following reasons:

  • Underreporting of discomfort because the patient does not want to complain
  • Use of pain to mask other newly developing physical or cognitive disabilities
  • Decreases in hearing and visual acuity, so that pain assessment tools that require extensive explanation or visualization to perform will be more difficult and possibly less reliable

The verbal descriptor scale may be the easiest tool for the elderly to use. It allows patients to use common words to describe what they are feeling.

Pain assessment in infants

The following tools use a combination of behavioral and physiologic measurements to assess pain in infants:

  • CRIES - Uses 5 variables (ie, crying, requires oxygen, increased vital signs, expression, sleeplessness) on a scale of 0-2 points to assess neonatal postoperative pain [1]
  • Modified Behavioral Pain Scale - Uses 3 factors (facial expression, cry, movements); has been validated for children aged 2-6 months [2]

Pain assessment in young children

Limited cognitive or language skills may influence pain measures, as may the positive or negative consequences of a child’s behaviors associated with pain.

In children older than 3-4 years, self-report measures may be used. However, children may underreport their pain to avoid future injections or other procedures aimed at alleviating the pain.

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Overview

Background

Precise and systematic pain assessment is required to make the correct diagnosis and thus establish the most efficacious treatment plan for patients presenting with pain. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience" associated with actual or potential tissue damage.[3] Humans have been equipped with the capability of negative emotion for a purpose. In terms of pain, this capability allows people to be aware of and adjust to tissue trauma.

Pain is an internal, subjective experience that cannot be directly observed by others or by the use of physiological markers or bioassays. Therefore, pain assessment therefore relies largely upon the use of self-report. Much effort has been invested in testing and refining self-report methodology within the field of human pain research.[4, 5, 6]

The Joint Commission on Accreditation of Healthcare Organization in the United States has set standards for the assessment of pain in hospitalized patients.[7] Pain assessment should be ongoing, individualized, and documented. Patients should be asked to describe their pain in terms of the following characteristics: location, radiation, mode of onset, character temporal pattern, exacerbating and relieving factors, and intensity.

It has been stated that the ideal pain measure should be sensitive, accurate, reliable, valid, and useful for both clinical and experimental conditions and able to separate the sensory aspects of pain from the emotional aspects.[8, 9] This topic presents measures for pain assessment.

Technical Considerations

Several brain areas are activated by nociceptive stimulation, including the anterior cingulate cortex, frontal and prefrontal cortices, primary and secondary somatosensory cortices, thalamus, basal ganglia, cerebellum, amygdala, and hippocampus. The primary and secondary somatosensory cortices have a role in the location and intensity of a painful stimulus. The anterior cingulate cortex is involved in the affective aspects of pain (ie, the subjective experience of unpleasantness). The insula seems to serve as an integrator between the two and encodes both intensity/location and affect. The amygdala appears to link sensory experiences to emotional arousal and negative emotional associations.

The use of functional magnetic resonance imaging has shown more frequent and robust activation of the somatosensory cortex, anterior cingulate cortex, and prefrontal cortex in individuals who were highly sensitive to pain versus those who were insensitive to pain, whereas activation in the thalamic relay centers showed no difference.

Pain Etiology

It is possible to describe different types of pain, and they tend to present differently. The history and physical examination help to identify these differences. Because different types of pain tend to respond to different treatments, the identification of pain type during pain assessment is important.

Nociceptive pain arises from activation of nociceptors. Nociceptors are found in all tissues except the central nervous system (CNS). The pain is clinically proportional to the degree of activation of afferent pain fibers and can be acute or chronic (eg, somatic pain, cancer pain, postoperative pain).

Neuropathic pain is caused by nerve injury or disease, as well as by involvement of nerves in other disease processes (eg, tumor, inflammation). Neuropathic pain may occur in the periphery or the CNS.

Sympathetically mediated pain is accompanied by evidence of edema, changes in skin blood flow, abnormal pseudomotor activity in the region of pain, allodynia, hyperalgesia, or hyperpathia.

Deafferentation pain is chronic and results from loss of afferent input to the CNS. The pain may arise in the periphery (eg, peripheral nerve avulsion) or in the CNS (eg, spinal cord lesions, multiple sclerosis).

Neuralgia pain is lancinating and associated with nerve damage or irritation along the distribution of a single nerve (trigeminal) or nerves.

Radicular pain is evoked by stimulation of nociceptive afferent fibers in spinal nerves, their roots, or ganglia, or by ectopic impulse generation. It is distinct from radiculopathy, but the two often arise together.

Central pain arises from a lesion in the CNS, usually involving the spinothalamic cortical pathways (eg, thalamic infarct). The pain is usually constant with a burning, electrical quality. It is exacerbated by activity or changes in the weather. Hyperesthesia and hyperpathia and/or allodynia are invariably present, and the pain is highly resistant to treatment.

Psychogenic pain is inconsistent with the likely anatomic distribution of the presumed generator, or it exists with no apparent organic pathology despite extensive evaluation.

Referred pain often originates from a visceral organ. It may be felt in body regions remote from the site of pathology. The mechanism may be the spinal convergence of visceral and somatic afferent fibers on spinothalamic neurons. Common manifestations are cutaneous and deep hyperalgesia, autonomic hyperactivity, tenderness, and muscular contractions.

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Technique

Approach Considerations

Detailed history and physical examination must be performed, not only to narrow down the diagnoses, but in order to request the appropriate diagnostic and laboratory studies. Mandatory recording of triage pain scores at one emergency department in Australia resulted in a significant decrease in median time to analgesia. Before the scoring intervention, median time from patient arrival to administration of analgesia was 123 minutes. At 1 year, median time to analgesia was reduced to 78 minutes.[10]

Pain Assessment

Pain must be assessed with a multidimensional approach, as follows:

  • Chronicity
  • Severity
  • Quality
  • Contributing/associated factors
  • Location/distribution or etiology of pain, if identifiable
  • Mechanism of injury, if applicable
  • Barriers to pain assessment

Chronicity of Pain

Initial assessment of pain should always include the onset of pain and progression in time. There is no consensus on a specific time period that designates acute pain versus chronic pain. Most clinicians and researchers use durations of either 3 months, 6 months, or (less frequently) 12 months to distinguish between acute and chronic pain.

Recognizing the inception of pain may be crucial in determining its treatment. Onset of pain may be described as abrupt and sudden or insidious and gradual.

Pain is said to be acute when presented within the first 3-6 months from the onset time. It typically has an abrupt start with identifiable associated events, although this may not be always true. It also may resolve within first 6 months without intervention.

Chronic pain does not resolve within 3–6 months of its initiation and progresses beyond 6 months of duration.

Pain may also be described as constant, unrelenting, or intermittent. The timing of pain may also give clinicians clues making differential diagnosis. Symptoms may be most severe in the morning upon waking up, later in the day, or during the night, depending on the etiology of the pain. It is important to document whether the patient complains of disturbance in sleep secondary to the pain.

Severity of Pain

Pain is subjective expression. Objective quantification of pain has been one of the greatest challenges physicians have faced in modern medicine. There is obvious and great variability in the severity of pain among seemingly similar cohort groups. Several methods have been devised to measure pain.

The measures presently available fall into two categories: single-dimensional scales and multidimensional scales. The numbers obtained from these instruments must be viewed as guides and not absolutes. The three most commonly used methods to quantify the pain experience include verbal rating scales, numeric rating scales, and visual analogue scales.

The level of pain often fluctuates with activities of daily living, activity level, and work-related duties. Treatment of pain may be customized depending on the patient's physical activities and its presence at rest.

Quality of Pain

The quality of pain is described by the patient in purely subjective manner. Pain that is stimulated by nociceptive ending is usually characterized as thermal (eg, hot, cold), mechanical (eg, crushing, tearing), and chemical (eg, iodine in a fresh wound, chili powder in the eyes).

Another common quality of pain is attributed by its neuropathic origin. This pain is often described as burning, tingling, electrical, stabbing, or “pins and needles." It has its origin in the nervous system.

Contributing/Associated Factors

Nociceptive symptoms often can be amplified by certain body positions and/or activities. Frequently, patients complain of pain-inducing positions and activities that reduce quality of life in clinical settings.

It is not uncommon to develop antalgic gait or positions in patients who deal with chronic pain. Furthermore, undertreated pain may lead to avoidance of movement, which in turn may cause muscle contractures and adhesive capsulitis.

Psychogenic pain is inconsistent with the likely anatomic distribution of the presumed generator, or it exists with no apparent organic pathology despite extensive evaluation.

Anatomical Etiology of Pain

It is possible to describe different types of pain, and they tend to present differently. The history and physical examination help to identify these differences. Because the different types of pain tend to respond to different treatments, the identification of pain type during pain assessment is important.

Referred pain often originates from a visceral organ. It may be felt in body regions remote from the site of pathology. The mechanism may be the spinal convergence of visceral and somatic afferent fibers on spinothalamic neurons. Common manifestations are cutaneous and deep hyperalgesia, autonomic hyperactivity, tenderness, and muscular contractions.

Mechanism of Injury

If applicable, the mechanism of injury can direct the clinicians in the correct path of diagnosis if there is trauma involved, especially if the symptoms are acute.

Often, however, the mechanism of injury is due to repeated microtrauma over a long period of time. This type of injury may lead to degenerative, insidious, and chronic painful situations. At times, the mechanism of injury is not as obvious, such as with autoimmune diseases, mass effect from neoplastic process, and tissue damage from metabolic processes.

Barriers to Pain Assessment

Barriers to pain assessment occur because of the assessment’s heavy reliance on subjective complaints. Pain assessment becomes even more complicated and difficult in patients who are nonverbal or have communication difficulties. Assessment in pediatric patients is especially troublesome.

Pain threshold is also an issue. There are two thresholds in terms of pain: the perception threshold and the tolerance threshold. The pain perception threshold is the point at which the stimulus begins to hurt, and the pain tolerance threshold is reached when the subject acts to stop the pain. The variability of pain threshold is apparent not only in individual basis within one community, but it is also apparent between patients of different sex, ethnicity, and race.

One of the most difficult challenges in chronic pain management is recognizing patients who are exaggerating their symptoms for secondary gains, including patients who abuse prescription opioids.[11]

Pain Scales

The presently available pain measures fall into two categories: single-dimensional scales and multidimensional scales. The results obtained from these instruments must be viewed as guides and not absolutes.

Single-Dimensional Scales

Single-dimensional scales are a simple way for patients to rate the intensity of their pain. These scales assess a single dimension of pain and measure only pain intensity. Patients report on the intensity of their pain through a self-report. These scales are useful in acute pain when the etiology is clear, such as trauma, pancreatitis, and otitis media. However, they can oversimplify the pain experience.[12] The scales use either numeric, verbal or visual descriptors to quantify pain or to quantify the degree of relief of pain.

Visual scales use pictures of anatomy to describe the location of pain. The Wong-Baker Faces Pain Rating Scale can be used with children, adults, patients with mild to moderate cognitive impairment, and patients with language issues. This scale presents pictures of 6–8 different facial expressions that show a range of emotions, as shown in the image below.

Faces Pain Rating Scale. Faces Pain Rating Scale.

Verbal scales use common words (eg, low, mild, severe) to describe the intensity of the pain. The Melzack and Torgerson scale uses five verbal descriptors: mild, discomforting, distressing, horrible and excruciating.[13]

A verbal numeric pain rating scale is commonly used, in which patients rate their own pain using a scale of 0–10. Advantages of numeric scales are their simplicity, reproducibility, and sensitivity to small changes in pain. Children may use this scale.

Multidimensional Scales

Multidimensional scales measure the intensity, the nature and location of the pain, and in some cases, the impact the pain is having on activity or mood. These are useful in complex or persistent acute or chronic pain when intensity needs to be assessed as well as social support, interference with activities of daily living, and depression.

The McGill Pain Questionnaire assesses pain in three dimensions: sensory, affective, and evaluative. The three major dimensions are subdivided into 20 subclasses that represent varying degrees of pain. This scale takes 5–15 minutes to complete.[14]

The Brief Pain Inventory quantifies both pain intensity and associated disability, addressing the patient's functional status. It is used for patients with cancer, human immunodeficiency virus, and arthritis. It takes 5–15 minutes to complete and uses 11 numeric scales to address pain intensity, mood, ability to work, relationships, sleep, enjoyment of life, and the effect of pain on general activity. The Brief Pain Inventory can measure the progress of a patient with a progressive disease and can show improvement or decline in the patient's mood and activity level. Evaluating function is important in overall pain management.[15, 16]

The Memorial Pain Assessment Card is a rapid multidimensional pain assessment tool for patients with cancer. It consists of three separate visual analog scales and assesses pain, pain relief, and mood. The card includes a set of adjectives to describe pain intensity and takes very little time to administer.[17]

Pain Assessment in the Elderly

Acute pain and chronic pain are both very common in the elderly. Pain management in this population is important because it allows for effective mobilization and functional independence. It also may result in decreased morbidity and health care expenditures.

The multiple medical comorbidities and impaired functional status that may be present in elderly patients present significant challenges in the treatment of pain. The number of medications and ratings of depression may contribute to the amount of pain experienced, and the medications used to control pain can have intolerable side effects in the elderly.

Although treating pain in this population is challenging, the assessment and reporting of pain is the most problematic area in this population. One contributing factor is possible underreporting of discomfort because the patient does not want to complain. Other patients may use pain to mask other newly developing physical or cognitive disabilities.

Pain assessment may also be complicated by decreases in hearing and visual acuity, so tools that require extensive explanation or visualization to perform will be more difficult and possibly less reliable. The verbal descriptor scale may be the easiest tool for the elderly to use. This measure allows patients to describe what they are feeling with common words rather than having to convert how they feel to a number, facial representation, or a point somewhere on a straight line.

An important factor in pain assessment in the elderly is assessing the effect the pain is having on their lives, rather than the intensity of the pain itself. Necessary activities of daily living are often maintained despite severe pain. However, the effect pain has on elective activities, such as social functions or advanced activities of daily living may correlate with severity of pain. With cognitive ability, any baseline impairment in activity may also worsen with significant pain.[18]

Pain Assessment in Infants

Infants are dependent on their caregivers to assess their pain and to determine the effectiveness of management efforts because they cannot verbalize their pain sensations. Facial activity, crying, and body movements are the most studied behavioral responses to pain in neonates. A limited number of facial actions have been studied in infants. The most obvious index is an infant's cry; however, the interpretation is difficult.

Two tools use a combination of behavioral and physiological measurement. CRIES (ie, crying, requires oxygen, increased vital signs, expression, sleeplessness) uses the five variables on a 0–2 point scale to assess neonatal postoperative pain.[1] The Modified Behavioral Pain Scale uses three factors (facial expression, cry, and movements) and has been validated for 2- to 6-month-old children.[2]

Pain Assessment in Young Children

In children, the caregiver must be aware of the developmental stage of the child to best determine the assessment tool. It is important to interpret behavioral observations cautiously and with cultural sensitivity. Limited cognitive or language skills may influence pain measures, as well as the positive or negative consequences a child’s pain reports or behaviors produce. A child sleeping more than usual, for example, may actually be in significant pain without any crying or whimpering.

In children older than 3-4 years, self-report measures may be used. However, children may underreport their pain to avoid future injections or other procedures aimed at alleviating the pain.

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Contributor Information and Disclosures
Author

Stephen Kishner, MD, MHA Professor of Clinical Medicine, Physical Medicine and Rehabilitation Residency Program Director, Louisiana State University School of Medicine in New Orleans

Stephen Kishner, MD, MHA is a member of the following medical societies: American Academy of Physical Medicine and Rehabilitation, American Association of Neuromuscular and Electrodiagnostic Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Julia Ioffe, MD Resident Physician, Department of Physical Medicine and Rehabilitation, Louisiana State University School of Medicine in New Orleans

Disclosure: Nothing to disclose.

Sung Rock Cho, MD, DC Resident Physician, Department of Physical Medicine and Rehabilitation, Louisiana State University School of Medicine in New Orleans

Disclosure: Nothing to disclose.

Chief Editor

Erik D Schraga, MD Staff Physician, Department of Emergency Medicine, Mills-Peninsula Emergency Medical Associates

Disclosure: Nothing to disclose.

References
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  4. Steven D. Waldman, MD, JD. The measurement of pain: Objectifying the Subjective. Pain Management. Saunders Elsevier; 2007. 1: Section 1, Ch. 18.

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  6. Jane Ballantyne, Scott M. Fishman, Salahadin Abdi. Assessment of Pain. Jane Ballantyne, MD. The Massachusetts General Hospital Handbook of Pain Management. second. USA: Lippincott Williams & Wilkins; 2002. pg 58.

  7. [Guideline] The Joint Commission. Pain management standards. Available at http://www.jointcommission.org/assets/1/18/Pain_Management.pdf. Accessed: October 14, 2011.

  8. Spanswick CC, Main CJ. Pain management: an interdisciplinary approach. Edinburgh: Churchill Livingston; 2000. 93.

  9. Melzack R, Wall PD. The challenge of pain. 2nd. New York: Penguin Books; 1996. 17 - 19.

  10. Vazirani J, Knott JC. Mandatory pain scoring at triage reduces time to analgesia. Ann Emerg Med. 2012 Feb. 59(2):134-138.e2. [Medline].

  11. Birnbaum HG, White AG, Reynolds JL, Greenberg PE, Zhang M, Vallow S, et al. Estimated costs of prescription opioid analgesic abuse in the United States in 2001: a societal perspective. Clinical Journal of Pain. 2006. 22(8):667-76.

  12. Marco CA, Nagel J, Klink E, Baehren D. Factors associated with self-reported pain scores among ED patients. Am J Emerg Med. 2011 Feb 28. [Medline].

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  15. Cleeland CS. Salek S. Compendium of Quality of Life Instruments. New York: Wiley; 1998.

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  17. Fishman B, Pasternak S, Wallenstein SL, Houde RW, Holland JC, Foley KM. The Memorial Pain Assessment Card. A valid instrument for the evaluation of cancer pain. Cancer. 1987 Sep 1. 60(5):1151-8. [Medline].

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  19. Lukas A, Barber JB, Johnson P, Gibson SJ. Observer-rated pain assessment instruments improve both the detection of pain and the evaluation of pain intensity in people with dementia. Eur J Pain. 2013 Jun 4. [Medline].

 
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Faces Pain Rating Scale.
 
 
 
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