Lecture 1 Flashcards

1
Q

Functions of pain

A
  • Warning

- Support of healing process

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2
Q

Acute vs. Chronic pain

A
  • Persists longer than 6 months
  • Lost its warning function
  • Occurs even in the absence of noxious stimuli
  • Occurs even after successful healing
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3
Q

Pain is

A

An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. - ISAP (international association for the study of pain)

Sensory and affective component:

  • How intense, what quality?
  • How unpleasant, annoying, distressing?
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4
Q

What are the multiple response levels of pain?

A
  • Brain
  • Reflexes
  • Facial expressions
  • VNS (vegetative nervous system)
  • Report
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5
Q

What is nociception?

A
  • Processing and transmission of signals detected by nociceptors
  • Sensory basis for adaptive protective behavior
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6
Q

What are nociceptors?

A
  • Specific sensors with high sensory threshold, only excited by stimulation which is tissue-damaging or threat of tissue damage.
  • Free-ending nerve fibres (Aδ- and C-fibers)
  • Mostly polymodal
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7
Q

How are nociceptors polymodal?

A

They respond to:

  • Thermal
  • Mechanical
  • And chemical stimulation
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8
Q

What is not pain?

A

Activity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain.

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9
Q

How is pain described?

A
  • It is always a psychological phenomenon

- It is highly subjective

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10
Q

Nociception vs Pain

A

Nociception: detection and processing of noxic (harmful) stimuli by highly specialized part of the somatosensory system (nociceptive system)

Pain: conscious experience of this perception, emerging from cognitive and emotional evaluation of the information gathered through the nociceptive system

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11
Q

What is the nociceptive system?

A

Somatosensory system

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12
Q

What is the prevalence of pain in Europe?

A
  • 19% of the European population
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13
Q

What are the most common places where people experience chronic pain?

A
  • Back
  • Lower back
  • Knee
  • Head
  • Leg
  • Joints
  • Shoulder
  • Neck
  • Hip
  • Hand
  • Upper back
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14
Q

What are the most common causes of pain?

A
  • Arthritis/osteoarthritis
  • Hemiated/deteriorating diacs
  • Traumatic injury
  • Rheumatoid arthitis
  • Migraine headache
  • Fracture/detoriation of spine
  • Nerve damage
  • Cartilage damage
  • Whiplash
  • Surgery
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15
Q

What are the phases of nociceptive pain?

A
  • Transduction
  • Conduction
  • Transmission
  • Perception
  • Modulation

In slides:
Trauma > signal > pain

Painful event is detected by nociceptors, transmitted along nerves to the spinal cord and from there to the brain.

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16
Q

What are nociceptors (neurobiologically)?

A
  • Specialized neurons which respond to intense, noxious stimuli
  • Found in every tissue of the human body (skin, muscles, inner oorgans, bones)
  • Polymodal (react to thermal, chemical, mechanical stimulation)
17
Q

What are the stations of nociceptive signaling?

A
  • Nociceptor
  • Peripheral Nerve
  • Spinal Cord
  • Brain
18
Q

What are the ascending pathways?

A
  • Afferent nociceptive information enters the brain from the spinal cord.
  • Afferent spinal pathways include the spino-thalamic, and the spino-amygdaloid pathways.
  • Nociceptive information from the thalamus is projected to the insula, anterior cingulate cortex (ACC), primary somatosensory cortex (S1) and secondary somatosensory cortex (S2).
  • Nociceptive information from the amygdala (AMY) is projected via the Prefrontal Cortex (PFC), and from there to the basal ganglia (BG).
19
Q

What is the lateral pain system?

A

Lateral nuclei of the thalamus, S1, S2 > sensory/discriminatory component of pain

20
Q

What is the medial pain system?

A

Medial nuclei of the thalamus, (anterior) cingulate cortex (ACC), prefrontal cortex (PFC) > affective-motivational pain component

21
Q

What does the insula do?

A

Integrates sensory and affective pain components, crucial for the representation of body (integrity)

22
Q

What is the pain-matrix?

A
  • Lateral pain system
  • Medial pain system
  • Insula
23
Q

What is the descending pain modulatory system?

A

The ascending pain signals can be modulatted (i.e. enhanced or inhibited) via descending pathways:

  1. Descending input from the anterior cingulate cortex (ACC) to the prefrontal cortex (PFC) and ten to the periaqueductal gray (PAG)
  2. Descending input from the insula via the amygdala to the PAG
  3. Descending pathway from the PAG through the rostroventral medulla (RVM) to the dorsal horn of the spinal cord influences nociceptive afferent transmission
24
Q

What are experimental pain paradigms?

A
  • Electrical stimulation
  • Thermal stimulation (e.g. thermode laser, cold pressor test)
  • Mechenical stimulation (e.g., pressure pain)
  • Chemical stimulation: capsaicin, NaCl-injection
  • Ischemic stimulation: arresting blood flow with a tourniquet
25
Q

How do we measure pain?

A
  • Subjective:
  • Questionnaires
  • Self-report scales
  • Motor/behavioral:
  • Reflexes
  • Avoidance behacior
  • Physiology
  • Peripheral
  • Neurpohysiological
26
Q

What are common pain measurements?

A
  • Number scale
  • 4-point category scale
  • Visual analog scale
  • Combined verbal-numerical scale

Assessment of the two dimensions of pain (sensory and affective):

  • Radio Metaphor by Price: How loud vs. how annoying is the sound?
  • Intensity = How painful?
  • Unpleasantness = How unpleasant?
27
Q

What questionnaires do we use?

A
  • West Haven-Yale Multidimensional pain inventory (Kerns, Turk & Rudy)
  • McGill Pain Questionnaire (MPQ) (Melzack et al. 1971)
28
Q

How do we decode the facial expressions caused by pain?

A
  • FACS: Facial Action Coding System (Ekman)
  • Action Units (AU): Smallest entity of muscular facial response
  • Pain face: brow lowering (AU4), orbit tightening (AU6) and levator contraction (AU10), eyelids closing (AU43)
  • Video tape participants, decode facial activity (AU + Intensity)
29
Q

How kind of techniques do we use to measure activity in the brain?

A
  • Structural imaging techniques:
  • MRI / CT (e.g. stroke)
  • Functional imaging techniques (spatial vs. temporal resolution)
  • EEG / MEG
  • fMRI
  • PET