Pain assessment forms the cornerstone of the therapeutic alliance between physician and patient. A patient gets to tell his or her story, while the physician tries to characterize the pain, infer its etiology, and develop a treatment plan. If a patient has multiple problems, it is advisable to prioritize problems and deal with each problem in turn. In addition to evaluating the physical characteristics of the pain, a physician should assess physical and psychosocial comorbidities, as well as the degree of disability caused by the pain.
The next 2 slides deal with the elements of a comprehensive pain assessment, composed of a detailed history, physical examination, and appropriate laboratory and radiologic tests. The pain history should include not only information about the current pain, but also any past history of persistent pain. The patient’s current functional status and degree of inactivity should be evaluated. Information gathered from the history and physical exam is used to guide the selection of laboratory and imaging studies. Referrals to other medical specialists may also be made.
This schema depicts the interaction among the physical and psychosocial aspects of chronic pain. Pain cannot be viewed as an isolated physical symptom. Intervening variables, such as psychologic functioning, social support, coexisting symptoms, and physical impairment, converge to produce a range in patients’ degree of disability. Disability can be assessed by measuring disturbance in activities of daily living, sleep, energy level, mood, motivation, and interpersonal relations. In optimal circumstances, both assessment and treatment are best provided by an interdisciplinary team.
This slide lists characteristics of clinical relevance. The temporal features can help to distinguish acute (well-defined, sudden-onset, short-lived or expected to be short-lived) from chronic pain. Waxing and waning of intense pain are common in the latter group. The physician should assess the presence of breakthrough pain. Pain intensity is easily measured with simple, valid questionnaires and should be frequently reassessed. Pain location gives further clues as to pain distribution in the body, while pain quality can suggest its etiology. Clarification of activities that lessen or worsen the pain can further refine a clinician’s thinking about causality and help with formulation of the treatment plan.
Nociceptive pain is viewed as an appropriate response to evident or inferred tissue damage. Somatic pain, a subset of nociceptive pain, tends to be well localized in areas of the skin, bone, or muscle, and it may be described as aching, sharp, stabbing, or throbbing. Neuropathic pain is sustained by abnormal somatosensory processing in the peripheral nervous system (PNS) or central nervous system (CNS). Nerve entrapment, injury, and inflammation are all included. Neuropathic pain can be further subdivided: Deafferentation pain is thought to be generated in the CNS and may be caused by injury to the peripheral nerves, the brain, or the spinal cord. Painful mononeuropathy or polyneuropathy is presumed to be generated in peripheral nervous structures. Sympathetically-maintained pain is sustained by afferent function in the sympathetic nervous system. The term “psychogenic pain” is applied when there is evidence of a major psychologic component to the pain.
Pain intensity scales have been shown to be reliable and valid. To depict pain severity, verbal rating scales use a range from “no pain” to “worst possible pain.” Numeric scales capture the same information using numeric anchors, with 0 indicating no pain, 5 signifying moderate pain, and 10 representing the worst possible pain. The visual analogue scale is a single line with 2 endpoints: The extreme left signifies no pain, and the extreme right signifies pain as bad as it could be. Scales for children generally use graphics, such as happy and sad faces, to capture pain.
Acute pain is transient in nature, may have a sudden or recent onset, and can usually be linked to an injury, surgical procedure, or other identifiable cause. Chronic pain is pain that persists for a period of time, at least months. A useful definition in describing chronic pain is pain that persists beyond the usual course of healing for that illness or injury, pain that recurs for a period of months, or pain that is associated with a lesion that is unlikely to remit. Breakthrough pain can be severe or excruciating, and it can occur along with the other pain syndromes. These distinctions are useful when making treatment decisions.
Several pain syndromes are named for their location in the body. Syndrome identification is useful in defining the need for additional evaluation, suggesting specific treatments, and prognostication. There are numerous defined syndromes.
A thorough assessment of a patient for confirmatory diagnosis of the suspected cause of neuropathic pain should consist of careful medical history-taking and physical, neurologic, regional examination. The diagnostic workup includes imaging studies, laboratory tests, electromyography/nerve-conduction velocity studies, and nerve and skin biopsies. For more information, please see Pain Assessment.
During the medical history-taking, physicians should focus on the onset, duration, progression, and nature of the patient’s complaints. For example, complaints of persistent numbness/weakness in an area or body part or progressive inability to do something that was once an ordinary task, such as opening jars, may be suggestive of neurologic deficits. Complaints such as pain evoked by touch, intermittent abnormal sensations, and spontaneous or shooting pains are suggestive of sensory dysfunction. Important clinical information about pain can be obtained from the presence of other concomitant systemic complaints, such as urinary frequency, fatigue, weight loss, etc. These complaints could provide clues as to the etiology of the neuropathic condition and help reach a more specific pain diagnosis.
During physical examination, inspection of the symptomatic region is essential, with focus on the anatomic pattern and localization of the abnormal sensory symptoms and neurologic deficits.
When evaluating a patient for neuropathic pain, a thorough diagnostic workup is essential to delineate its cause and the potential mechanisms involved in generating the pain. Laboratory studies, samples from skin and nerve tissue, and anatomic and neurophysiologic studies have a role in the evaluation of chronic neuropathic pain. Necessary are a complete blood cell count (CBC), an erythrocyte sedimentation rate (ESR), a general chemistry profile, thyroid-function tests, vitamin B 12 and folate serum levels, fasting blood glucose (FBG), and glycosylated hemoglobin (HbA 1c ). Also important (according to the clinical presentation) are serum protein electrophoresis with immunofixation, Lyme disease antibody titers, hepatitis B and C screening titers, HIV screening, antinuclear antibodies (ANA), rheumatoid factor, Sjögren’s syndrome titers (SS-A, SS-B), and antineutrophil cytoplasmic antibody.
In addition to the aforementioned laboratory tests, the complete diagnostic workup also should include cryoglobulins, antisulfatide IgM antibody titer, anti-HU titers, serum and urine screening for heavy metals, and cerebrospinal fluid (CSF) to rule out the demyelinating neuropathies (eg, Guillain-Barré syndrome) and polyradiculopathies related to meningeal carcinomatosis.
Besides the many laboratory tests necessary to a thorough workup, the EMG-NCV studies and quantitative sensory testing (QST) may identify or localize a lesion. Also, they may indicate an axonal versus a focal segmental demyelinating process, or they may help detect diffuse abnormalities, indicating a polyneuropathy.
For nerve biopsy, usually the sural nerve is selected because the sensory deficit following the procedure is limited to the dorsolateral aspect of the ankle and foot. The biopsy is useful for the diagnosis of vasculitis, amyloidosis, tumor infiltration, IgM monoclonal gammopathies, chronic inflammatory demyelinating polyradiculopathies, and small-fiber neuropathies, among others. Skin biopsy is considered promising for evaluating the density of unmyelinated fibers within the dermis and epidermis. Immunostaining with a panaxonal marker has been used to demonstrate the intraepidermal network of C-fibers.
A careful history taking and physical examination are often necessary for the diagnostic evaluation of a patient with back pain and sciatica. A medical history of unexplained weight loss, fever, cancer, infection, etc, may give clues to an underlying systemic disease. Family and psychosocial history such as depression, substance abuse, job dissatisfaction, etc, may be associated with persistent and unexplained back-pain syndrome. Response to previous pharmacologic therapy is helpful in assessing future management strategies. Physical examination should consist of musculoskeletal and neurologic evaluations. Clinicians should focus on musculoskeletal deformities, areas of tenderness, range of motion, and neurologic function.
To help with the differential diagnosis, the assessment of pain should consist of the following: description, duration, and intensity of pain, along with an account of any alleviating or aggravating factors.
Neurologic evaluation should include examination of the deep tendon reflexes (DTRs), strength, sensation, and gait. The spine and leg should be examined for underlying pathologic conditions. Sciatic- and femoral-nerve stretching tests consist of: The straight-leg-raising (SLR) test, which is performed with the patient lying supine, the examiner holding the leg straight and, with the other hand, lifting the heel to 30 degrees. A patient testing positive will have pain below the knee during this maneuver. This test is sensitive for disk herniations. Pain on raising the contralateral leg is less sensitive, but more specific. A reverse SLR test is performed with the patient lying prone and the leg extended at the hip. This test may be positive, with disk herniations occurring at a higher lumbar level (eg, L2 – L3).
Other mechanical joint-disease tests include: Truncal flexion (forward bending), which compresses the disk, and truncal extension (backward bending), which compresses the facet joints. These tests help determine the causes of pain. Patrick’s maneuver is performed after a positive SLR test to differentiate hip disease from radicular disease. During this test, the leg is raised with the knee bent and the thigh rotated laterally. Simultaneous flexion, abduction, and external rotation (FABER) on both hips will stress the sacroiliac joints bilaterally. If unilateral hip and/or gluteal pain arise while performing this bilateral maneuver, clinically significant SI joint disease (ipsilateral to the pain) can be suspected. Of note, all these provocative maneuvers are of diagnostic value if they can elicit an exacerbation of the patient’s typical and predominant pain complaint.
While a variety of imaging techniques are available for use, the early and frequent use of these techniques is discouraged because degenerative, bulging, and herniated disks are as common in asymptomatic adults as they are in patients with back pain. However, these imaging tests should be obtained promptly for patients who present with “red flags” (ie, patients in whom there is strong clinical suggestion of underlying disease). In a study by Jensen’s group (1994) evaluating magnetic resonance imaging (MRI) of the lumbar spine in people without back pain, the MRI examination showed that of 98 asymptomatic subjects, 36% had normal disks at all levels, 52% had a bulge disk at least at 1 level, 27% had a protrusion, and 1% had an extrusion. Both computed tomography (CT) and MRI have been used in detecting herniated disks and spinal stenosis, but the MRI is better at defining soft tissues and showing disk morphology. Although CT and MRI have largely supplanted myelography, used in conjunction with CT, myelography can provide detailed images of intradural disease.
Facet injections with an anesthetic agent are used to rule out pain that originates from a degenerated facet joint. Discogenic pain may be provoked by injecting dye into the disk under fluoroscopic control (diskogram). The clinically relevant outcome of the procedure is based on the quality and radiation of the pain elicited by the disk injection. The diskogram is called positive if the pain provoked by the injection is concordant with a patient’s usual and predominant pain complaint. At that point, the anatomic location of the patient’s pain generator can be inferred. Of note, a “normal” disk should always be injected for control and the patient should be “blind” as to what disk is being injected.
“ Red flags” that are indicative of underlying serious conditions (neoplasm, diskitis, epidural abscess, cauda-equina syndrome, compression fracture [Fx]) include nighttime pain, fever, weight loss, history of cancer or trauma, intravenous drug abuse, leg weakness, and bladder or bowel dysfunction.
An MRI of the spine is indicated in the following situations: — “ Red flags” — Neurologic deficits or progressive neurologic signs and symptoms — Pain persisting more than 6 weeks
Although obtaining a headache history from someone with a severe headache may be particularly challenging, a thorough history, whenever feasible, is essential. Factors to consider include the duration, onset, and frequency of the headache. Is the person coming for evaluation for the first time despite experiencing headaches for many years? Is the patient a known migraineur whose headaches have suddenly changed in character? Has the patient experienced the first and only headache of his/her life but is coming for evaluation because it was severe? Such a headache may be indicative of a subarachnoid hemorrhage (sentinel headache). Does the patient awaken with the headache? This may point to migraine, hypertension, sleep apnea, and other causes. Is the headache getting progressively worse (suggesting brain neoplasm)? Is the headache getting less responsive to treatment (possible analgesic overuse)? Are any causes of headache known for that individual? The location of the headache may help to distinguish among various types/causes. Two-thirds of migraine headaches are unilateral. Cervicogenic headaches often present with suboccipital pain. Associated symptoms—including visual changes, sensory and motor changes, cognitive impairment, and others—are important to recognize.
Some characteristics of a patient’s headache should alert the clinician to the possibility of serious illness. These include rash, meningeal signs, or fever, all of which may be associated with a systemic illness; onset of headache after age 50 or onset in a person with human immunodeficiency virus (HIV) infection or cancer; worsening headaches; abrupt onset of headache; and signs of focal neurologic disease. When evaluating a patient with headache, clinicians must use appropriate judgment to determine what laboratory tests and/or neuroimaging tests might be appropriate. Decisions should be based on the history and age of a patient, other medical diagnoses, family history, physical/neurologic examination findings, and other factors. Laboratory tests are especially important if assessing for the possibility of secondary headache. If one suspects the diagnosis of temporal arteritis (generally in patients older than 50), an erythrocyte sedimentation rate should be sent. If a patient has focal neurologic signs and/or symptoms, magnetic resonance imaging (MRI) is the most sensitive tool to evaluate for the possibility of a structural intracranial lesion. If a central nervous system (CNS) infection is suspected, a lumbar puncture (LP) needs to be performed, unless it is contraindicated. Computed tomography (CT) remains the best tool to assess for an acute hemorrhagic event in an emergency setting.
Assessment and Diagnosis of Pain Disorders
Assessment and Diagnosis of Pain Disorders
Pain Assessment: Goals <ul><li>Characterize the pain </li></ul><ul><li>Identify pain syndrome </li></ul><ul><li>Infer pathophysiology </li></ul><ul><li>Evaluate physical and psychosocial comorbidities </li></ul><ul><li>Assess degree and nature of disability </li></ul><ul><li>Develop a therapeutic strategy </li></ul>
Pain and Disability <ul><li>Nociception </li></ul><ul><li>Other physical symptoms </li></ul><ul><li>Physical impairment </li></ul><ul><li>Neuropathic Psychologic Social isolation </li></ul><ul><li>mechanisms processes Family distress </li></ul><ul><li>Sense of loss or inadequacy </li></ul><ul><li>Adapted with permission from Portenoy RK. Lancet . 1992;339:1026. </li></ul>Pain Disability
Pain History <ul><li>Temporal features — onset, duration, course, pattern </li></ul><ul><li>Intensity — average, least, worst, and current pain </li></ul><ul><li>Location — focal, multifocal, generalized, referred, superficial, deep </li></ul><ul><li>Quality — aching, throbbing, stabbing, burning </li></ul><ul><li>Exacerbating/alleviating factors — position, activity, weight bearing, cutaneous stimulation </li></ul>
Pathophysiology <ul><li>Nociceptive pain </li></ul><ul><li>Neuropathic pain </li></ul><ul><li>Idiopathic pain </li></ul><ul><li>Psychogenic pain </li></ul><ul><li>Commensurate with identifiable tissue damage </li></ul><ul><li>May be abnormal, unfamiliar pain, probably caused by dysfunction in PNS or CNS </li></ul><ul><li>Pain, not attributable to identifiable organic or psychologic processes </li></ul><ul><li>Sustained by psychologic factors </li></ul>
Pain Syndromes <ul><li>Acute pain </li></ul><ul><li>Chronic pain </li></ul><ul><li>Breakthrough pain </li></ul><ul><li>Recent onset, transient, identifiable cause </li></ul><ul><li>Persistent or recurrent pain, beyond usual course of acute illness or injury </li></ul><ul><li>Transient pain, severe or excruciating, over baseline of moderate pain </li></ul>
Neuropathic Pain: Clinical Assessment <ul><li>A comprehensive diagnostic approach to patients affected by neuropathic pain </li></ul><ul><ul><li>Medical history </li></ul></ul><ul><ul><li>Examinations: general, neurologic, regional </li></ul></ul><ul><ul><li>Diagnostic workup: imaging studies, laboratory tests, nerve/skin biopsies, electromyography/nerve-conduction velocity (EMG-NCV) studies, selected nerve blocks </li></ul></ul>
Medical History <ul><li>Ask patient about complaints suggestive of </li></ul><ul><li>Neurologic deficits: persistent numbness in a body area or limb-weakness, for example, tripping episodes, inability to open jars </li></ul><ul><li>Neurologic sensory dysfunction: touch-evoked pain, intermittent abnormal sensations, spontaneous burning and shooting pains </li></ul>
Neurologic and Regional Examinations <ul><li>In patients with neuropathic pain, examination should focus on the anatomic pattern and localization of the abnormal sensory symptoms and neurologic deficits </li></ul>
Diagnostic Workup: Lab Tests <ul><li>Complete blood cell count with differential, erythrocyte sedimentation rate, chemistry profile </li></ul><ul><li>Thyroid-function tests, vitamin B 12 and folate, fasting blood sugar, and glycosylated hemoglobin </li></ul><ul><li>Serum protein electrophoresis with immunofixation </li></ul><ul><li>Lyme titers, hepatitis B and C, HIV screening </li></ul><ul><li>Antinuclear antibodies, rheumatoid factor, Sjögren’s titers (SS-A, SS-B), antineutrophil cytoplasmic antibody </li></ul>
Diagnostic Workup: Lab Tests <ul><li>Cryoglobulins </li></ul><ul><li>Antisulfatide antibody titers, anti-HU titers </li></ul><ul><li>Heavy metals serum and urine screens </li></ul><ul><li>Cerebrospinal fluid study for demyelinating diseases and meningeal carcinomatosis </li></ul>
Diagnostic Workup: Electrophysiologic Studies <ul><li>EMG-NCV and QST </li></ul><ul><li>To localize pain-generator/nerve or root lesion </li></ul><ul><li>To rule out </li></ul><ul><ul><li>Axonal vs focal segmental demyelination </li></ul></ul><ul><ul><li>Underlying small-fiber or mixed polyneuropathy </li></ul></ul>
Biopsies <ul><li>Nerve (eg, sural nerve): to diagnose vasculitis, amyloidosis, sarcoidosis, etc. </li></ul><ul><li>Skin: to evaluate density of unmyelinated fibers within dermis and epidermis </li></ul>
Back Pain and Sciatica: Comprehensive Assessment <ul><li>History </li></ul><ul><ul><li>Medical </li></ul></ul><ul><ul><li>Psychosocial </li></ul></ul><ul><ul><li>Family </li></ul></ul><ul><ul><li>Previous trials </li></ul></ul><ul><li>General examination </li></ul><ul><ul><li>Musculoskeletal </li></ul></ul><ul><ul><li>Neurologic </li></ul></ul>
Back Pain and Sciatica: Pain Assessment <ul><li>Description </li></ul><ul><li>Duration </li></ul><ul><li>Intensity </li></ul><ul><li>Alleviating factors </li></ul><ul><li>Aggravating factors </li></ul>
Assessment of Patients With Low Back, Hip, and Leg Pain <ul><li>Neurologic exam </li></ul><ul><ul><li>DTRs, strength, sensitivity, gait </li></ul></ul><ul><li>Regional exam of spine and leg </li></ul><ul><ul><li>Inspection for scoliosis or skin rash, palpation for bone tenderness </li></ul></ul><ul><li>Sciatic- and femoral-nerve stretching tests </li></ul><ul><ul><li>SLR, reverse and contralateral SLR maneuver </li></ul></ul>
Assessment of Patients With Low Back, Hip, and Leg Pain <ul><li>Provocative mechanical joint tests </li></ul><ul><ul><li>Truncal flexion for discogenic pain or spine instability </li></ul></ul><ul><ul><li>Truncal extension for facet joint disease </li></ul></ul><ul><ul><li>Patrick’s maneuver for hip disease (FABER test of both hips for SI joint disease) </li></ul></ul>
Back Pain and Sciatica: Imaging Evaluation <ul><li>Lumbosacral x-ray studies with flexion/ extension/oblique views </li></ul><ul><li>MRI of the spine </li></ul><ul><li>CT with 3-D reconstruction </li></ul><ul><li>CT plus myelography </li></ul>
Assessment of Chronic Back Pain and Sciatica: Diagnostic Blocks <ul><li>Facet blocks to rule out facet joint pain </li></ul><ul><li>Provocative diskograms or disk blockade to rule out discogenic pain and pain associated with segmental spinal instability </li></ul><ul><li>Selective root blocks to determine location of root pain generator </li></ul>
Assessment of Acute Back Pain and Sciatica: “Red Flags” <ul><li>Nighttime pain, fever, weight loss, history of cancer </li></ul><ul><li>Fever, IV drug abuse </li></ul><ul><li>Bladder, bowel dysfunction; leg weakness </li></ul><ul><li>Trauma </li></ul><ul><li>Neoplasm </li></ul><ul><li>Infection (diskitis, epidural abscess) </li></ul><ul><li>Cauda-equina syndrome </li></ul><ul><li>Compression Fx </li></ul>History Possible Diagnosis
Back Pain and Sciatica <ul><li>MRI of the spine if patient demonstrates </li></ul><ul><li>“ Red flags” </li></ul><ul><li>Neurologic deficits or progressive neurologic signs and symptoms </li></ul><ul><li>Pain persisting more than 6 wk </li></ul>
Headache Evaluation <ul><li>History (duration, onset, frequency) </li></ul><ul><li>Is there a family history of headache? </li></ul><ul><li>Are there any known causes of headache? </li></ul><ul><li>What is the typical location(s)? </li></ul><ul><li>What does the pain feel like? </li></ul><ul><li>What makes it worse? </li></ul><ul><li>What makes it better? </li></ul><ul><li>What are the results of past evaluations? </li></ul><ul><li>Are there associated symptoms? Exam findings? </li></ul><ul><li>What is the patient’s sex? </li></ul>
Headache: Diagnostic Red Flags <ul><li>Rash, meningeal signs, or fever </li></ul><ul><li>Onset after age 50 </li></ul><ul><li>Onset in a person with HIV or cancer </li></ul><ul><li>Abrupt onset </li></ul><ul><li>Worsening pain </li></ul><ul><li>Signs of focal neurologic disease </li></ul>