Pain

Question 1

What is pain?

Answer 1

An unpleasant sensory or emotional experience. Purely a perception, no way to quantify. Whatever the patient says it is, need a sense of emotion to sense pain

Question 2

How is tissue damage related to pain? How is pain related to the number of nerves involved?

Answer 2

May not be proportional

Also not proportional to the number of nerves involved (except on the skin).

Question 3

What is the issue of the subjective nature of pain?

Answer 3

Undertreatment

Question 4

How can a functional MRI be used with pain?

Answer 4

Can determine whether or not pain is actually being felt

Question 5

What are the 3 effects of pain on the body?

Answer 5

Amplifies the body’s stress response (SNS) to traumatic injury
Stimulates endocrine and metabolic systems, causes abnormalities
Retards patient’s recovery from trauma, surgery and disease

Question 6

What is acute pain?

Answer 6

Pain lasting less than 6 months and subsides once the healing process is accomplished

Question 7

What is chronic pain?

Answer 7

Complex. Involves altered anatomy and neural pathways. Constant and prolonged, lasting longer than 6 months.

Question 8

What is the cousins’ pain theory?

Answer 8

Severe, unrelieved acute pain results in abnormally enhanced physiological responses that lead to pronounced and progressively increasing pathophysiology.
Will increase organ dysfunction, increasing morbidity and mortality

Question 9

What is the pathophysiology of pain?

Answer 9

SNS stimulation causes the heart to beat more and harder (needs more oxygen) but less oxygen is being delivered.
Arterial hypoxemia and suppression of immune functions (predisposition to infections and sepsis)
Infections could also be due to lifestyle changes

Question 10

What causes chronic pain syndrome?

Answer 10

Result of acute, unrelieved pain like multiple trauma, phantom limb pain, repeated back surgeries (get up and walk around after)
Neuromuscular disorders like fibromyalgia, rheumatoid arthritis, MS
May be from a known or unknown cause

Question 11

What causes pain to be felt?

Answer 11

Specialized receptors on free nerve endings (almost all nerves) are stimiulated by mechanical damage, extreme temperature or chemical irritation.

Question 12

What are the 2 types of neurons involved in pain and what do they feel?

Answer 12

A-delta for the initial quick, sharp pain that causes the body to withdraw (mom, protective pain)
C for the second dull pain (dad) that has learning and behavioural modifications and causes immobilization

Question 13

What is transduction in the pain pathway?

Answer 13

Local biochemical changes released by damaged tissue in the nerve ending that generate a signal
Nociceptors distinguish between noxious and innocuous stimuli
Na channels cause cell depolarization

Question 14

What is transmission in the pain pathway?

Answer 14

Movement of the signal from the site of pain to the spinal cord and central strucures in the brain
Requires neurotransmitters

Question 15

What is perception in the pain pathway?

Answer 15

Synthesis and analysis in the brain to generate emotional responses (only in vertebrates above fish)
Can change in your head via training

Question 16

What is modulation in the pain pathway?

Answer 16

Endogenous systems (endorphins) in place that can inhibit pain at any point along the pathway, modulating transmission and perception
Serotonin also modulates perception

Question 17

What are the substances released by damaged tissue during transduction?

Answer 17

Bradykinin
Serotonin
Substance P (well known pain transmitter)
Histamine (inflammation and exacerbation)
Prostaglandin (NSAIDS target)

Question 18

What drugs help stop transduction?

Answer 18

NSAIDS like aspirin, ibuprofen, diclofenac minimize prostaglandins
Corticosteroids (cortisone, dexamethasone) inhibits prostaglandins and other inflammatory mediators

Question 19

What do opioids do?

Answer 19

Bind to receptors and inhibit the release neurotransmitters

Endorphins or medical

Question 20

What are the size and speed differences between the pain transmission fibres?

Answer 20

A delta: Large diameter, fast signal transfer

C: Small diameter

Question 21

Which fibres are involved in chronic pain?

Answer 21

C fibres

Question 22

Where are endorphins released?

Answer 22

Descending fibres in the spinal tract and higher cortical centres.

Question 23

Why do antidepressants decrease pain?

Answer 23

Because they interfere with the reuptake of serotonin and norepinephrine which can modulate pain perception.

Question 24

How can endorphins play a role in chronic pain syndromes?

Answer 24

Many people with chronic pain disorders have messed up endorphins.

Question 25

What activates the descending pain modulation system?

Answer 25

Stress, fear, hunger, thirst, fatigue, prolonged motor activity (exercise) and hypnosis

Question 26

What is the gate control theory?

Answer 26

There are spinal gates in each dorsal horn that only allow only a certain amount of heat, touch or pain to be transmitted at each point at one time
Vibration trumps all

Question 27

What is nociceptic pain?

Answer 27

Normal pain with tissue damage

Injury, trauma, infection, post operative pain, mechanical lower back pain

Question 28

What is neuropathic pain?

Answer 28

Primary lesion or dysfunction of the peripheral or central nervous system
Could be known or unknown cause, trigeminal neuralgia, polyneuropathy

Question 29

What is visceral pain?

Answer 29

Arising from an internal organ and is massively amplified in the brain
MI, appendicitis, small bowel obstruction

Question 30

What are some examples of mixed type pain?

Answer 30

Postherpetic neuralgia, neuropathic lower back pain, arthritis, sports/exercise injuries

Question 31

What is hyperalgesia?

Answer 31

Intense pain in response to mildly painful stimulus

type of neuropathic pain.

Question 32

What is allodynia?

Answer 32

Pain in response to completely innocuous stimulus

Type of neuropathic pain