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ABA Pain Medicine study materials
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ABA Pain Medicine practice questions

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Question 1Anatomy, Physiology, and Pharmacology of Pain

Which Rexed lamina of the spinal dorsal horn is known as the substantia gelatinosa and is a key site of nociceptive processing?

  1. Lamina IX
  2. Lamina II Correct answer.
  3. Lamina IV
  4. Lamina VII

Explanation

The substantia gelatinosa corresponds to lamina II of the dorsal horn and receives dense input from small-diameter A-delta and C nociceptive afferents. It contains interneurons that modulate transmission to deeper laminae and to ascending tracts.

Question 2Anatomy, Physiology, and Pharmacology of Pain

Which primary afferent fiber type is thinly myelinated and conveys rapid, sharp, well-localized pain?

  1. A-beta fibers
  2. C fibers
  3. B fibers
  4. A-delta fibers Correct answer.

Explanation

A-delta fibers are thinly myelinated group III fibers that conduct at moderate velocity and mediate first pain, which is sharp and well localized. Unmyelinated C fibers conduct more slowly and produce dull, poorly localized second pain.

Question 3Anatomy, Physiology, and Pharmacology of Pain

At what level do most fibers of the lateral spinothalamic tract cross the midline?

  1. In the medulla near the cuneate nucleus
  2. At the internal capsule
  3. In the midbrain near the red nucleus
  4. In the anterior white commissure Correct answer.

Explanation

Nociceptive fibers synapse in the dorsal horn, and second-order axons decussate through the anterior white commissure within one or two segments of entry. This crossing pattern explains why cord lesions can produce contralateral sensory loss.

Question 4Anatomy, Physiology, and Pharmacology of Pain

Which opioid receptor subtype is primarily responsible for the analgesic effects of morphine?

  1. Nociceptin receptor
  2. Mu receptor Correct answer.
  3. Kappa receptor
  4. Delta receptor

Explanation

Morphine and most clinically used strong opioids produce analgesia mainly through mu-opioid receptor agonism. Mu receptors are concentrated in the periaqueductal gray, dorsal horn, and other pain-modulating regions.

Question 5Anatomy, Physiology, and Pharmacology of Pain

Local anesthetics produce nerve block primarily by inhibiting which target?

  1. N-methyl-D-aspartate receptors
  2. Gamma-aminobutyric acid type A receptors
  3. Voltage-gated sodium channels Correct answer.
  4. Voltage-gated potassium channels

Explanation

Local anesthetics bind the inner pore of voltage-gated sodium channels and stabilize the inactivated state, preventing action potential propagation. This effect is most pronounced in small, unmyelinated or thinly myelinated fibers.

Question 6Anatomy, Physiology, and Pharmacology of Pain

Which enzyme is the principal target through which nonsteroidal anti-inflammatory drugs reduce prostaglandin synthesis?

  1. Phospholipase A2
  2. Cyclooxygenase Correct answer.
  3. Acetylcholinesterase
  4. Lipoxygenase

Explanation

NSAIDs inhibit cyclooxygenase, the enzyme that converts arachidonic acid to prostaglandin H2 and downstream prostanoids. Reduced prostaglandin production lowers nociceptor sensitization and inflammation.

Question 7Anatomy, Physiology, and Pharmacology of Pain

Capsaicin produces burning pain and desensitization by activating which receptor?

  1. ASIC3
  2. P2X3
  3. Nav1.7
  4. TRPV1 Correct answer.

Explanation

Capsaicin is a selective agonist of transient receptor potential vanilloid 1 (TRPV1), a heat- and proton-sensitive ion channel on nociceptors. Sustained activation leads to calcium influx, receptor desensitization, and reduced pain signaling.

Question 8Anatomy, Physiology, and Pharmacology of Pain

According to gate control theory, which afferent input tends to inhibit nociceptive transmission in the dorsal horn?

  1. Large-diameter A-beta input Correct answer.
  2. Visceral vagal input to the brainstem
  3. Sympathetic efferent input to the skin
  4. Silent C-fiber input to the dorsal horn

Explanation

Gate control theory proposes that large-diameter A-beta afferents activate inhibitory dorsal horn interneurons and reduce transmission of small-fiber nociceptive signals. This principle underlies therapies such as transcutaneous electrical nerve stimulation.

Question 9Anatomy, Physiology, and Pharmacology of Pain

The periaqueductal gray produces descending analgesia in part by projecting to which structure?

  1. Locus coeruleus
  2. Ventral posterolateral thalamus
  3. Nucleus tractus solitarius
  4. Rostral ventromedial medulla Correct answer.

Explanation

Periaqueductal gray neurons project to the rostral ventromedial medulla, which in turn sends descending projections through the dorsolateral funiculus to the dorsal horn. This pathway modulates nociceptive transmission via serotonin and norepinephrine.

Question 10Anatomy, Physiology, and Pharmacology of Pain

Gabapentin and pregabalin exert their analgesic effect by binding to which target?

  1. Sodium channel Nav1.8 in nociceptors
  2. Mu-opioid receptor in the dorsal horn
  3. Serotonin transporter in descending tracts
  4. Alpha-2-delta calcium channel subunit Correct answer.

Explanation

Gabapentinoids bind the alpha-2-delta auxiliary subunit of presynaptic voltage-gated calcium channels. This reduces calcium influx and neurotransmitter release from hyperexcited nociceptive terminals.

Question 11Anatomy, Physiology, and Pharmacology of Pain

Ketamine produces analgesia and antihyperalgesia mainly through antagonism at which receptor?

  1. Alpha-2 adrenergic receptor
  2. NMDA receptor Correct answer.
  3. Mu-opioid receptor
  4. Cannabinoid CB1 receptor

Explanation

Ketamine is a noncompetitive NMDA receptor antagonist that reduces central sensitization and windup. This mechanism underlies its use for refractory pain and opioid-tolerant states.

Question 12Anatomy, Physiology, and Pharmacology of Pain

Tricyclic antidepressants such as amitriptyline relieve neuropathic pain chiefly by inhibiting reuptake of which neurotransmitters?

  1. Dopamine and acetylcholine
  2. Glutamate and aspartate
  3. GABA and glycine
  4. Norepinephrine and serotonin Correct answer.

Explanation

Tricyclic antidepressants block norepinephrine and serotonin transporters, increasing monoamine availability in descending inhibitory pathways. This action strengthens descending modulation independently of antidepressant effect.

Question 13Anatomy, Physiology, and Pharmacology of Pain

Calcitonin gene-related peptide (CGRP) is best characterized in which role related to pain?

  1. A voltage-gated sodium channel isoform
  2. A vasoactive trigeminal peptide Correct answer.
  3. An endogenous opioid receptor agonist
  4. A postsynaptic GABA receptor subunit

Explanation

CGRP is released from activated trigeminal and dorsal root nociceptors and contributes to neurogenic inflammation and migraine pain. CGRP-targeted monoclonal antibodies are used for migraine prevention.

Question 14Anatomy, Physiology, and Pharmacology of Pain

Which mediator is most directly responsible for prostaglandin-mediated sensitization of peripheral nociceptors?

  1. Brain-derived neurotrophic factor
  2. Substance P
  3. Adenosine triphosphate
  4. Prostaglandin E2 Correct answer.

Explanation

Prostaglandin E2 is produced at sites of inflammation and binds EP receptors on nociceptor terminals. It lowers activation thresholds by enhancing tetrodotoxin-resistant sodium currents and other excitatory conductances.

Question 15Anatomy, Physiology, and Pharmacology of Pain

Windup of dorsal horn neurons during repetitive C-fiber stimulation is a model of which process?

  1. Gate control inhibition
  2. Motor neuron recruitment
  3. Peripheral demyelination
  4. Central sensitization Correct answer.

Explanation

Windup is a frequency-dependent increase in dorsal horn neuron firing during repeated C-fiber input, reflecting NMDA receptor-dependent central sensitization. It contributes to hyperalgesia and tactile allodynia.

Question 16Anatomy, Physiology, and Pharmacology of Pain

Which thalamic nucleus relays nociceptive information from the face and oral cavity?

  1. Ventral posteromedial nucleus Correct answer.
  2. Mediodorsal nucleus
  3. Lateral geniculate nucleus
  4. Ventral posterolateral nucleus

Explanation

The ventral posteromedial nucleus receives trigeminothalamic fibers carrying facial nociception. The ventral posterolateral nucleus serves the contralateral body via the spinothalamic tract.

Question 17Anatomy, Physiology, and Pharmacology of Pain

Codeine requires metabolic activation by which cytochrome P450 enzyme to produce significant analgesia?

  1. CYP3A4
  2. CYP1A2
  3. CYP2D6 Correct answer.
  4. CYP2C9

Explanation

Codeine is a prodrug converted to morphine primarily by CYP2D6. Poor metabolizers may obtain little analgesia, while ultrarapid metabolizers risk opioid toxicity.

Question 18Anatomy, Physiology, and Pharmacology of Pain

Beta-endorphin is derived from which precursor protein?

  1. Preproenkephalin
  2. Proopiomelanocortin Correct answer.
  3. Prodynorphin
  4. Preprotachykinin

Explanation

Beta-endorphin is cleaved from proopiomelanocortin, the same precursor that yields ACTH and melanocyte-stimulating hormone. It acts preferentially at mu-opioid receptors in central pain-modulating circuits.

Question 19Anatomy, Physiology, and Pharmacology of Pain

Which statement best describes the dorsal root ganglion cell that gives rise to a primary nociceptive afferent?

  1. Anaxonic and releasing transmitter in the ganglion
  2. Pseudounipolar with peripheral and central axons Correct answer.
  3. Multipolar with dendrites in the dorsal horn
  4. Bipolar with synapses inside the ganglion

Explanation

Dorsal root ganglion neurons are pseudounipolar: a single stem axon divides into a peripheral branch to the tissue and a central branch to the spinal cord. The cell body in the ganglion serves a trophic role and does not form a synapse.

Question 20Anatomy, Physiology, and Pharmacology of Pain

In complex regional pain syndrome, which feature most directly reflects sympathetic nervous system involvement?

  1. Elevated cerebrospinal fluid beta-endorphin
  2. Upward plantar reflex
  3. Vasomotor and sudomotor asymmetry Correct answer.
  4. Positive Romberg sign

Explanation

CRPS frequently shows regionally altered blood flow, temperature, and sweating due to sympathetic dysregulation. These vasomotor and sudomotor changes help distinguish CRPS from simple neuropathic pain.

Question 21Anatomy, Physiology, and Pharmacology of Pain

The spinoreticular tract is best described as projecting to which region and serving which function?

  1. Hypothalamus, supporting thermoregulation only
  2. Reticular formation, supporting arousal and affect Correct answer.
  3. Primary somatosensory cortex, supporting localization
  4. Cerebellar cortex, supporting motor adaptation

Explanation

The spinoreticular tract ascends with the anterolateral system to the brainstem reticular formation. It participates in arousal, autonomic, and affective-motivational aspects of pain rather than precise localization.

Question 22Anatomy, Physiology, and Pharmacology of Pain

Activation of mu-opioid receptors on nociceptive neurons typically produces which intracellular change?

  1. Increased cyclic AMP formation via Gs coupling
  2. Opening of voltage-gated sodium channels
  3. Increased calcium influx through L-type channels
  4. Adenylyl cyclase inhibition via Gi coupling Correct answer.

Explanation

Mu receptors are Gi/o-coupled; activation inhibits adenylyl cyclase, reduces cyclic AMP, and closes voltage-gated calcium channels. It also opens potassium channels, hyperpolarizing the neuron.

Question 23Anatomy, Physiology, and Pharmacology of Pain

In an inflamed, acidic tissue, why does a local anesthetic such as lidocaine show reduced potency?

  1. More charged drug cannot cross membranes Correct answer.
  2. Acidosis increases sodium channel expression
  3. Tissue acidity increases hepatic drug clearance
  4. Acidosis raises the fraction of uncharged base

Explanation

In acidic tissue, more lidocaine exists as the protonated, charged form, which crosses lipid membranes poorly. Fewer molecules reach the intracellular channel binding site, reducing block.

Question 24Anatomy, Physiology, and Pharmacology of Pain

Which glial-derived mediator has been implicated in enhancing dorsal horn pain transmission during neuroinflammation?

  1. Brain-derived neurotrophic factor Correct answer.
  2. S100B calcium-binding protein from astrocytes
  3. Glial fibrillary acidic protein from astrocytes
  4. Myelin basic protein from oligodendrocytes

Explanation

Activated microglia and astrocytes release BDNF, cytokines, and other mediators that enhance dorsal horn excitability. BDNF in particular modulates chloride homeostasis and NMDA receptor signaling in nociceptive circuits.

Question 25Anatomy, Physiology, and Pharmacology of Pain

Presynaptic N-type voltage-gated calcium channels contribute to nociceptive transmission by doing which action?

  1. Maintaining resting potential in motor neurons
  2. Clearing glutamate from the synaptic cleft
  3. Triggering transmitter release from nociceptor terminals Correct answer.
  4. Generating the upstroke of A-beta fiber action potentials

Explanation

N-type calcium channels are concentrated at presynaptic terminals of nociceptors, where calcium entry triggers release of glutamate and substance P. Ziconotide, a cone snail peptide, blocks these channels to produce analgesia.

Question 26Anatomy, Physiology, and Pharmacology of Pain

At which level does the lateral spinothalamic tract decussate?

  1. In the medulla oblongata after dorsal column ascent
  2. In the midbrain immediately before the thalamus
  3. Within the spinal cord near the entry segment Correct answer.
  4. At the thalamus before cortical projection

Explanation

Nociceptive and temperature primary afferents synapse in the dorsal horn, and the second-order axons cross the midline through the anterior white commissure within a few spinal segments of entry. The crossed fibers then ascend in the lateral spinothalamic tract to the thalamus.

Question 27Anatomy, Physiology, and Pharmacology of Pain

Which primary afferent fiber type is most responsible for the sharp, well-localized first pain after a pinprick?

  1. C fibers
  2. Preganglionic B fibers
  3. A-beta fibers
  4. A-delta fibers Correct answer.

Explanation

A-delta fibers are thinly myelinated and conduct rapidly, producing the sharp first pain of a pinprick. C fibers are unmyelinated and slower, producing the delayed burning second pain.

Question 28Anatomy, Physiology, and Pharmacology of Pain

Which neurotransmitter is released by primary nociceptive afferents at their central terminals in the dorsal horn?

  1. Glutamate Correct answer.
  2. Dopamine
  3. Glycine
  4. GABA

Explanation

Primary nociceptive afferents use glutamate as their principal fast excitatory neurotransmitter at dorsal horn synapses and often co-release peptides such as substance P. GABA and glycine are mainly inhibitory transmitters in local dorsal horn circuits.

Question 29Anatomy, Physiology, and Pharmacology of Pain

A local anesthetic is infused near a nerve that is firing repetitively. Its blocking effect strengthens with each action potential because the drug binds more readily to open or inactivated sodium channels. This property is called:

  1. Reverse use dependence
  2. Competitive antagonism at the sodium channel pore
  3. Use-dependent block Correct answer.
  4. Closed-state block

Explanation

Local anesthetics preferentially bind sodium channels in open or inactivated states, so rapidly firing nerves accumulate more block. This frequency- or use-dependent behavior explains why painful, repetitively firing nerves are especially susceptible.

Question 30Anatomy, Physiology, and Pharmacology of Pain

Acetaminophen produces analgesia chiefly through which mechanism?

  1. Blockade of voltage-gated sodium channels
  2. Inhibition of central prostaglandin synthesis Correct answer.
  3. Irreversible acetylation of platelet cyclooxygenase-1
  4. Direct activation of mu-opioid receptors

Explanation

Acetaminophen reduces pain and fever mainly by inhibiting prostaglandin synthesis within the central nervous system, with little peripheral anti-inflammatory effect. This contrasts with aspirin, which irreversibly acetylates cyclooxygenase in platelets.

Question 31Anatomy, Physiology, and Pharmacology of Pain

Which brainstem nucleus is the principal source of descending noradrenergic fibers that inhibit nociceptive transmission in the dorsal horn?

  1. Raphe magnus
  2. Substantia nigra pars compacta
  3. Locus coeruleus Correct answer.
  4. Nucleus ambiguus

Explanation

The locus coeruleus supplies noradrenergic projections to the spinal dorsal horn that dampen nociceptive transmission. The raphe magnus is better known for serotonergic descending modulation.

Question 32Anatomy, Physiology, and Pharmacology of Pain

A child has episodes of severe burning pain and redness of the extremities, and genetic testing shows a gain-of-function mutation in a sodium channel preferentially expressed in nociceptors. Which channel is most likely affected?

  1. Nav1.7 Correct answer.
  2. Nav1.9
  3. Nav1.4
  4. Nav1.5

Explanation

Gain-of-function mutations in Nav1.7 cause inherited erythromelalgia, characterized by burning pain and redness of the extremities. Nav1.7 is highly expressed in peripheral nociceptors and amplifies their excitability.

Question 33Anatomy, Physiology, and Pharmacology of Pain

Which endogenous lipid mediator is synthesized on demand, activates cannabinoid CB1 receptors, and is degraded primarily by fatty acid amide hydrolase?

  1. Substance P
  2. Nerve growth factor
  3. Anandamide Correct answer.
  4. Bradykinin

Explanation

Anandamide is an endocannabinoid lipid mediator that acts at CB1 receptors and is broken down mainly by fatty acid amide hydrolase. Its on-demand synthesis allows it to modulate nociceptive signaling locally.

Question 34Anatomy, Physiology, and Pharmacology of Pain

In the dorsal horn, which receptor mediates the slow, prolonged excitatory action of substance P released from nociceptive afferents?

  1. Ionotropic AMPA glutamate receptor
  2. Metabotropic GABA-B inhibitory receptor
  3. Neurokinin-1 (NK1) receptor Correct answer.
  4. Gi-coupled mu-opioid receptor

Explanation

Substance P acts at the Gq-coupled neurokinin-1 receptor to produce a slow, prolonged excitatory postsynaptic potential in dorsal horn neurons. Glutamate acting at AMPA receptors provides the faster excitatory component.

Question 35Pain Assessment, Diagnosis, and Evaluation

Which instrument is most appropriate for rating pain intensity in a patient with severe visual impairment?

  1. Visual analog scale
  2. McGill Pain Questionnaire
  3. Faces Pain Scale-Revised
  4. Verbal numeric rating scale Correct answer.

Explanation

A verbal numeric rating scale requires only that the patient state a number from 0 to 10, so it does not depend on vision or reading ability. Visual analog and faces scales require the patient to see the scale, and the McGill questionnaire requires reading and abstract verbal descriptors.

Question 36Pain Assessment, Diagnosis, and Evaluation

A 3-year-old child cannot self-report pain after surgery. Which tool is designed for this situation?

  1. Short-form McGill Pain Questionnaire
  2. DN4 questionnaire
  3. Numeric rating scale
  4. FLACC scale Correct answer.

Explanation

The FLACC scale rates Face, Legs, Activity, Cry, and Consolability and is validated for children aged 2 months to 7 years who cannot self-report. It relies on observed behavior rather than on the child's own rating.

Question 37Pain Assessment, Diagnosis, and Evaluation

The McGill Pain Questionnaire primarily adds which dimension to pain assessment beyond intensity?

  1. Sensory and affective quality Correct answer.
  2. Psychological distress screening
  3. Neuropathic grading
  4. Functional capacity

Explanation

The McGill Pain Questionnaire was designed to capture the sensory, affective, and evaluative qualities of pain in addition to intensity. Its word descriptors allow characterization of pain quality that a simple intensity score cannot provide.

Question 38Pain Assessment, Diagnosis, and Evaluation

Pain evoked by a normally nonpainful stimulus such as light touch is termed:

  1. Hyperalgesia
  2. Dysesthesia
  3. Hyperpathia
  4. Allodynia Correct answer.

Explanation

Allodynia is pain produced by a stimulus that does not normally provoke pain, such as light brushing of the skin. It reflects altered central processing and is a hallmark of neuropathic pain.

Question 39Pain Assessment, Diagnosis, and Evaluation

A patient with neck pain radiating into the arm has symptoms reproduced by cervical extension, lateral bending, and axial compression. This maneuver is the:

  1. Spurling test Correct answer.
  2. Phalen test
  3. Adson test
  4. Lhermitte sign

Explanation

The Spurling test applies cervical extension, ipsilateral lateral bending, and axial downward compression to narrow the neural foramen. Reproduction of radicular arm pain constitutes a positive test.

Question 40Pain Assessment, Diagnosis, and Evaluation

Which finding on straight-leg raise is most specific for lumbar radiculopathy?

  1. Low back pain only during the maneuver
  2. Reproduction of leg pain below the knee Correct answer.
  3. Pain at 60 degrees of elevation
  4. Hamstring tightness limiting elevation

Explanation

Reproduction of pain radiating below the knee during straight-leg raise is the finding most specific for lumbar nerve root irritation, though sensitivity is only moderate. Crossed straight-leg raise is even more specific but less sensitive.

Question 41Pain Assessment, Diagnosis, and Evaluation

Phantom limb pain is best described as:

  1. Pain perceived in the missing body part Correct answer.
  2. Painful cramping in the residual limb
  3. Nonpainful tingling in the amputated limb
  4. Pain evoked by touching the stump

Explanation

Phantom limb pain is pain perceived in a body part that has been amputated. It is distinct from phantom sensation, which is a nonpainful awareness of the missing part.

Question 42Pain Assessment, Diagnosis, and Evaluation

The lowest stimulus intensity at which a subject perceives pain is the:

  1. Conditioned pain modulation threshold
  2. Wind-up threshold
  3. Pain detection threshold Correct answer.
  4. Pain tolerance threshold

Explanation

The pain detection threshold is the lowest stimulus intensity that the subject perceives as painful. It is distinguished from the pain tolerance threshold, which is the maximum intensity the subject is willing to endure.

Question 43Pain Assessment, Diagnosis, and Evaluation

Which score on the DN4 questionnaire indicates neuropathic pain?

  1. 7 or more out of 10
  2. 4 or more out of 10 Correct answer.
  3. 19 or more out of 38
  4. 12 or more out of 24

Explanation

The DN4 consists of 7 sensory descriptor items and 3 bedside examination items, with a total score out of 10. A score of 4 or more suggests neuropathic pain.

Question 44Pain Assessment, Diagnosis, and Evaluation

Which painDETECT score suggests a likely neuropathic component?

  1. 4 or higher
  2. 30 or higher
  3. 19 or higher Correct answer.
  4. 10 or higher

Explanation

painDETECT uses 9 items and yields a score from -1 to 38, with scores of 19 or higher indicating a likely neuropathic component. Scores of 13 to 18 are considered uncertain.

Question 45Pain Assessment, Diagnosis, and Evaluation

A patient has pain in a plausible neuroanatomic distribution, sensory signs in that distribution, and confirmatory diagnostic testing. Under the NeuPSIG framework this represents:

  1. Probable neuropathic pain
  2. Unlikely neuropathic pain
  3. Definite neuropathic pain Correct answer.
  4. Possible neuropathic pain

Explanation

NeuPSIG defines definite neuropathic pain as pain in a plausible neuroanatomic distribution with a history of a relevant lesion or disease plus confirmatory objective evidence, including sensory signs and a diagnostic test. Probable requires clinical signs without confirmatory testing.

Question 46Pain Assessment, Diagnosis, and Evaluation

Budapest criteria for complex regional pain syndrome require which combination?

  1. Symptoms in 4 of 4 categories and no signs
  2. Symptoms in 2 of 4 categories and signs in 4 of 4
  3. Symptoms in 3 of 4 categories and signs in 2 of 4 Correct answer.
  4. Symptoms in 1 of 4 categories and signs in 1 of 4

Explanation

Budapest criteria require at least one symptom in three of four categories and at least one sign in two of four categories, plus no other diagnosis that better explains the findings. The categories are sensory, vasomotor, sudomotor or edema, and motor or trophic.

Question 47Pain Assessment, Diagnosis, and Evaluation

Under the 2016 fibromyalgia criteria, which combination satisfies the widespread pain index and symptom severity threshold?

  1. WPI 2 and SS 10
  2. WPI 7 and SS 6 Correct answer.
  3. WPI 5 and SS 4
  4. WPI 3 and SS 3

Explanation

The 2016 fibromyalgia criteria are met by either widespread pain index of 7 or more with symptom severity of 5 or more, or WPI 4 to 6 with SS of 9 or more, in the absence of another explanation. WPI 7 with SS 6 therefore satisfies the first pathway.

Question 48Pain Assessment, Diagnosis, and Evaluation

Which set of findings is most consistent with nonorganic Waddell signs?

  1. Unilateral calf atrophy
  2. Dermatomal sensory loss and weakness
  3. Reproducible pain with straight-leg raise at 40 degrees
  4. Widespread superficial tenderness, pain on simulated rotation, and disproportionate grimacing Correct answer.

Explanation

Waddell signs are grouped into tenderness, simulation, distraction, regional disturbance, and overreaction. Widespread superficial tenderness, pain on simulated axial loading or rotation, and disproportionate grimacing illustrate several of these categories.

Question 49Pain Assessment, Diagnosis, and Evaluation

Referred pain from visceral structures is best explained by:

  1. Peripheral sensitization of nociceptors
  2. Convergence of visceral and somatic afferents onto the same dorsal horn neurons Correct answer.
  3. Loss of A-beta fibers
  4. Ectopic discharge in dorsal root ganglia

Explanation

Visceral and somatic afferents converge onto the same second-order dorsal horn neurons. Because the brain cannot distinguish the source, visceral pain is often referred to the somatic dermatomes sharing the same spinal segment.

Question 50Pain Assessment, Diagnosis, and Evaluation

A progressive increase in pain rating during repeated identical noxious stimuli delivered at 0.33 Hz or faster is called:

  1. Temporal summation Correct answer.
  2. Diffuse noxious inhibitory control
  3. Habituation
  4. Conditioned pain modulation

Explanation

Temporal summation refers to the progressive increase in perceived pain when identical noxious stimuli are delivered at a frequency of at least 0.33 Hz. It is a psychophysical correlate of wind-up in dorsal horn neurons.