[PAIN.02] - Pathophysiology of Pain and Pain Assessment V2.pdf

Nociception

What term describes the neural processing of encoding and detecting noxious stimuli?

Pain

What is defined as an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage?

Sensory, emotional, and behavioral factors

What three major factors interact to create the complex perception of pain beyond a simple biological response?

Transduction

Which step in nociception involves converting a mechanical, thermal, or chemical noxious stimulus into an electrical signal?

Transmission

Which step in nociception describes the propagation of electrical signals along primary afferent nerve fibers to the spinal cord?

Ascending pathway

What neural pathway carries pain signals from the dorsal horn of the spinal cord to supraspinal brain centers?

Supraspinal processing

Which step of nociception takes place in the thalamus and cortical areas to subserve sensory and emotional aspects of pain?

Modulation

Which step in nociception involves the alteration of pain signals through descending inhibitory or facilitatory pathways?

Perception

Which step in nociception represents the conscious subjective experience of pain?

Endogenous analgesia

What innate physiological defense mechanism protects the body from an excessive influx of painful stimuli?

Opioid receptors

Which specific receptors in the brain and spinal cord mediate endogenous analgesia?

Substantia gelatinosa

Which dorsal horn region of the spinal cord expresses mu-type opioid receptors and processes incoming nociceptive signals?

Periaqueductal grey, reticular formation, hypothalamus, thalamus, and cortex

Which supraspinal brain regions contain mu-type opioid receptors that overlap with areas involved in pain perception?

Cingulate cortex and cortex

Which cortical regions are highlighted as key supraspinal sites where pain is consciously perceived?

Parabrachial nucleus

Which brainstem nucleus forms part of the ascending pain pathway alongside the reticular formation and periaqueductal gray?

Nociceptors

What are the specialized peripheral sensory receptors activated by mechanical, thermal, or chemical noxious stimuli?

A-delta fibers

Which primary afferent nerve fibers are thinly myelinated and conduct fast nociceptive signals?

C fibers

Which primary afferent nerve fibers are unmyelinated and slowly conduct temperature, burning pain, and itch signals?

A-beta fibers

Which large primary afferent nerve fibers conduct non-noxious mechanical sensory signals such as touch?

Lamina I and Lamina V

In which specific dorsal horn laminae do thinly myelinated A-delta fibers primarily terminate?

Lamina I and Lamina II (predominantly Lamina II)

In which specific dorsal horn laminae do unmyelinated C fibers predominantly synapse?

Withdrawal reflex

Which protective involuntary motor reflex is triggered rapidly via A-delta fiber activation?

Second-order neurons

Which neurons in the dorsal horn receive synaptic inputs from primary afferents and ascend the spinal cord?

Recent onset and short duration

What are the defining temporal characteristics of acute pain?

Persistent pain lasting beyond 3 months after expected tissue healing

What is the traditional temporal definition of chronic pain?

Within 20 minutes post-injury

Within what timeframe after tissue injury does neuronal expression of new genes begin as the foundation for sensitization?

Within a day or so

How quickly after transient nerve ligation do long-term behavioral and histologic changes initiate in the nervous system?

Neuronal plasticity

What term describes structural and functional remodeling of the nervous system that alters future responses to sensory input?

The inability of the body to restore its physiological functions to normal homeostatic levels

According to Loeser and Melzack (1999), what fundamental feature distinguishes chronic pain from acute pain?

The initiation phase of an extensive, persistent nociceptive and behavioral cascade

How should acute pain be conceptualized clinically regarding its role in chronic pain development?

Brief window of opportunity

What critical clinical period does acute pain present for healthcare providers to prevent chronic pain development?

Peripheral sensitization

What process involves an increased responsiveness and reduced activation threshold of peripheral nociceptors following injury?

Ongoing discharge

What spontaneous firing pattern in sensitized primary afferents leads to hyperalgesia and lowered pain thresholds?

ATP, acetylcholine, and serotonin

Which three pain response mediators are released from damaged endothelial cells and platelets at an injury site?

Prostaglandin E2 (PGE2)

Which lipid mediator is synthesized by COX-1 and COX-2 enzymes in damaged cells to sensitize sensory fibers?

Bradykinin

Which peptide released from damaged plasma vessels excites primary afferents and stimulates further prostaglandin synthesis?

Substance P and Calcitonin Gene-Related Peptide (CGRP)

Which two neuropeptides released from primary afferent sensory endings trigger histamine release from mast cells?

Histamine

Which amine released from mast cells by neuropeptides causes additional excitation of peripheral afferent sensory fibers?

Unmasking of silent nociceptors

What peripheral mechanism involves previously unresponsive nociceptors becoming active during inflammation?

Collateral sprouting

What term describes the growth of new nerve terminal branches into damaged or inflamed surrounding tissue?

Sympathetically-mediated pain

What type of pain is maintained spontaneously by sympathetic nervous system signaling following nerve injury?

Alpha-adrenoreceptors

The expression of which receptors on injured and uninjured axons renders them sensitive to circulating catecholamines?

Circulating catecholamines and noradrenaline

Which substances released from postganglionic sympathetic terminals activate injured axons expressing alpha-adrenoreceptors?

Sprouting of sympathetic axons in the dorsal root ganglion

What structural change forms basket-like networks around sensory neuron cell bodies to drive sympathetically-mediated pain?

Ectopic discharge

What term describes abnormal spontaneous action potentials originating from damaged nerve fibers rather than peripheral receptors?

Accumulation of sodium channels

What molecular abnormality in damaged sensory fibers and neuromas generates ectopic action potentials?

Neuromas

What term describes hyperexcitable, swollen regenerating sprouts that form at the proximal end of a transected nerve?

Surgical excision

What surgical procedure is sometimes performed to manage painful neuromas at nerve injury sites?

Local patches of demyelination in the dorsal root ganglia

Besides neuromas, where else in the peripheral nervous system can ectopic discharges arise?

Phantom limb pain and sciatica

What are two clinical examples of neuropathic pain conditions maintained by ectopic activity?

Ephaptic transmission

What process involves action potential transmission jumping across adjacent undamaged sensory fibers from injured fibers?

Cross talk

What colloquial term describes the electrical transfer between adjacent nerve fibers during ephaptic transmission?

Involvement of intact, undamaged nerve fibers in pain transmission

What key distinction separates ephaptic transmission from ectopic discharge?

Central sensitization

What phenomenon is defined as an increased responsiveness of central nervous system neurons to normal or subthreshold afferent input?

Constant bombardment of sensory input from the periphery

What upstream peripheral neural event triggers the wind-up phenomenon and central sensitization?

Wind-up phenomenon

What progressive increase in spinal cord neuronal firing occurs in response to repetitive primary afferent stimulation?

Glutamate

Which excitatory neurotransmitter is released in increasing quantities into the spinal cord during wind-up?

NMDA (N-methyl-D-aspartate) glutamate receptors

The prolonged opening of channels gated by which postsynaptic receptors allows massive ion influx during wind-up?

Calcium and sodium

The influx of which two cations across the postsynaptic membrane produces central neuronal hyperexcitability?

Hyperalgesia

What clinical term describes a heightened pain response to a stimulus that normally causes only mild discomfort?

Spontaneous pain

What term describes pain experienced in the complete absence of an external stimulus?

Expansion of the receptive field

What central phenomenon causes pain perception to spread beyond the original boundaries of tissue injury?

A-beta fiber reorganization

What structural rewiring process occurs when central terminals of intact A-beta fibers sprout into Lamina II of the dorsal horn?

Degeneration of C fiber endings

What peripheral nerve change triggers intact mechanoreceptive A-beta fibers to reroute into superficial dorsal horn layers?

Allodynia

What clinical term describes pain elicited by normally non-noxious stimuli, such as light touch, following A-beta reorganization?

Inhibitory control dysfunction

What pathological state results from the loss of spinal local or descending inhibitory modulation?

GABA and Serotonin (5-HT)

Which two neurotransmitters serve as primary inhibitory mediators in descending spinal control pathways?

Disinhibition

What term describes the removal of tonic descending inhibitory activity, causing increased dorsal horn stimulation?

Pain as the 5th vital sign

Which clinical screening initiative was established to elevate pain awareness and prevent unrelieved pain?

James Campbell, MD (1996)

Which physician stated in 1996 that 'quality care means that pain is measured and treated' as a vital sign?

Every 4 hours

How frequently is routine vital sign and pain screening typically conducted on general inpatient hospital floors?

Further comprehensive pain assessment, prompt clinical intervention, and follow-up evaluation

What three mandatory steps should be triggered immediately by a positive pain score?

1979 IASP definition of pain

Which historical definition described pain as 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage'?

2020 revised IASP definition of pain

Which updated definition describes pain as 'an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage'?

Replaced 'described in terms of such damage' with 'resembling that associated with actual or potential tissue damage'

What was the single major phrase modification in the 2020 IASP revised definition of pain?

To include non-verbal humans and nonhuman animals who experience pain but cannot describe it verbally

Why was the word 'described' removed in the 2020 IASP revision?

Verbal description is only one of several behaviors used to express pain

What key concept regarding pain expression was affirmed in the 2020 IASP notes?

Inability to communicate does not negate the possibility that a human or nonhuman animal experiences pain

What explicit statement did the 2020 IASP notes make regarding individuals with communication barriers?

Biological, psychological, and social factors

According to the 2020 IASP revision, pain is a personal experience influenced to varying degrees by which three factors?

A person's report of an experience as pain should be respected

What fundamental clinical attitude toward patient pain reports is mandated by the 2020 IASP notes?

Pain and nociception are different phenomena, and pain cannot be inferred solely from activity in sensory neurons

How do the 2020 IASP notes distinguish pain from nociception?

Through their life experiences

According to the 2020 IASP notes, how do individuals learn the concept of pain?

Adverse effects on function and social/psychological well-being

Although pain usually plays an adaptive role, what negative impacts can chronic pain exert?

Acute pain

Which temporal pain classification represents a normal, biologically necessary, protective response to noxious stimuli?

Fight-or-flight response

Which evolutionary physiological defense mechanism is activated during acute pain to encourage escape and protection?

Sudden, sharp, intense, and localized

What are the four primary clinical descriptors of acute pain?

Sweating, increased blood pressure, and increased heart rate

Which autonomic physiological changes typically accompany acute pain?

Chronic pain

Which classification describes pain that persists longer than the expected healing time or accompanies progressive disease?

Gnawing, aching, and diffuse

What are the three primary clinical descriptors of chronic pain?

3 months

Pain persisting beyond what duration threshold is defined as chronic pain?

Breakthrough pain

What term describes a transitory exacerbation of pain occurring on a background of otherwise stable pain control?

Rescue dose (or PRN order)

What specific pharmacological treatment strategy is prescribed to manage acute breakthrough pain flares?

Incident pain

Which type of breakthrough pain has a clear, identifiable trigger such as patient movement, coughing, or surgery?

Spontaneous pain

Which type of breakthrough pain occurs unevoked without any identifiable external or physiological trigger?

Nociceptive pain

Which clinical pain classification is triggered by actual or threatened damage to non-neural tissue and activation of nociceptors?

Injury to bone and tissue

In layman's terms, what physical damage characterizes nociceptive pain?

Sharp, cutting, aching, or throbbing

What sensory qualities describe typical nociceptive pain?

Opioids

Nociceptive pain generally exhibits high responsiveness to treatment with which class of medications?

Visceral pain

Which nociceptive pain subtype is poorly localized, paroxysmal, and described by patients as 'all over' the abdomen?

Somatic pain

Which nociceptive pain subtype is constant, well-localized, and usually time-limited?