Pain

Question 1

What is the definition of pain?

Answer 1

An unpleasant sensory and emotional experience associated with actual or potential tissue damage.

Question 2

What nerve fibres are responsible for immediate pain and persisting pain?

Answer 2

Immediate - a delta,

Persisting - C fibres

Question 3

what is the withdrawal reflex?

Answer 3

It occurs where there is a painful stimulus. This information travels to the spinal cord and causes a flexor reflex and a crossed extensor reflex which causes the limb/body part to move away from the stimulus.

Question 4

How do we perceive pain?

Answer 4

Via spinothalamic tracts.

Question 5

What are features of A-delta fibres?

Answer 5

They are myelinated.
Conduct sharp, localised pain.
Fast Conduction.
Minority of nociceptors

Question 6

What are features of C fibres?

Answer 6

Unmeylinated.
Conduct dull, throbbing and diffuse pain.
Majority of nociceptors,
Slow conduction

Question 7

Explain the transduction of pain

Answer 7

1st there is conversion of noxious stimulus (heat, mechanical or chemical) into action potential in a nociceptor. Therefore the nociceptors respond to stimuli that will potentially damage tissue. The sensation may extend beyond point of assault

Question 8

Explain the transmission of pain?

Answer 8

Occurs via spinothalamic tracts. First order neurons release Glutamate, substance P or CGRP which binds to either AMPA, NMDA or G-protein coupled receptors to cause a response. There is no single excitatory substance or pain receptor

Question 9

How can pain be modulated?

Answer 9

Via decending inhibition which has 3 mechanisms; GABA and glycinergic interneurons, decending inhibition from PAG, rostral ventral medulla and dorsal horn, and lastly endogenous opioids.
Also modulated by higher order brain function

Question 10

What is the gate control theory?

Answer 10

Theory of pain modulation. Based on presynaptic inhibition of pain information produced by mechanical stimuli (mechanoreceptor fibres excite an inhibitory interneuron which inhibits nociceptor fibres before they synapse at the spinal cord)

Question 11

Describe what can occur when the neuronal activity of pain becomes a conscious experiance?

Answer 11

• Past experiences, current situation and understanding modulate the conscious experience.
• Reticular system then elicits an autonomic response and the limbic system links perception of pain with mood

Question 12

Describe features of visceral pain?

Answer 12

• Visceral nociceptors respond to distention or ischaemia,
• The pain is more diffuse (less well localised).
• Referred pain can occur

Question 13

What are associated symptoms of pain?

Answer 13

-Sweating,
-Pallor,
-Nausea,
-Tachycardia,
-Hypertension
(THINK AUTONOMIC NS)

Question 14

Describe the prevention and preparation of pain

Answer 14

• Anticipation and simple adjustments (let the patient know they may experience some pain).
• Distraction,
• Education,
• Challenge patients misconception,
• Rebranding (eg, tender or pressure)

Question 15

How do you assess pain?

Answer 15

• SOCRATES,
• Red flags,
• Co-morbidities,
• Psycho-social history and awareness of yellow flag

Question 16

What is the WHO treatment of cancer pain ladder?

Answer 16

1- Mild pain give simple analgesics.
2 - Moderate pain give mild opioid and continue analgesics,
3 - Severe pain give strong opioid and continue simple analgesics

Question 17

What drug is used for neuropathic pain?

Answer 17

Amitriptyline or gabapentin

Question 18

What is the difference with the WHO treatment lader for acute nociceptive pain?

Answer 18

• Start with the strong opioids and continue with analgesics and then work down to mild opioids and simple analgesics and then use simple analgesics on their own

Question 19

What is neuropathic pain?

Answer 19

Pain arising as a direct consequence of a lesion or disease affecting somatosensory system. Spontaneous and evoked pains and allodynia

Question 20

What are some causes of neuropathic pain?

Answer 20

Trauma, diabetic neuropathy, postherpetic neuralgia, trigeminal neuralgia and post-stroke neuralgia.

Question 21

What is the definition of chronic pain?

Answer 21

Pain persisting beyond the usual healing time of the acute injury (usually beyong 12 weeks)

Question 22

What causes chronic pain?

Answer 22

Peripherally there are prolonged inflammatory responses which results in decreased pain threshold in primary afferents, increased production of substance P and CGRP and recruitment of NMDA receptors.
Spinal cord - Changes in gene and receptor expression in DRG and dorsal horn neurons

Question 23

What are the non-modifiable risk factors for chronic pain?

Answer 23

• Gender,
• Age,
• Genetic predisposition,
• Lower-socio-economic status,
• History of abuse,
• Compensation from having said injury

Question 24

What are the modifiable risk factors for chronic pain?

Answer 24

• Past experiences of pain,
• Anxiety and depression,
• Catastrophizing beliefs,
• surgical approach,
• attitudes,
• communication

Question 25

What are complex regional pain syndromes?

Answer 25

• Severe continuous neuropathic pain which causes abnormal sensation, vasomotor change, sudomotor change, trophic change