B7.005 Prework 1: Pain, Clinical Concepts

Question 1

what is the spinothalamic system

Answer 1

anterolateral system
made up of 1st, 2nd, and 3rd order fibers
moves from periphery through spinal cord, thalamus, and terminates in somatosensory cortex

Question 2

2 types of pain

Answer 2

fast and slow

parallel paths

Question 3

fast pain fibers

Answer 3

larger
have free nerve endings
thermal and mechanical type
-A-delta thinly myelinates
-sharp pricking pain
-accurately localized

Question 4

slow pain fibers

Answer 4

small
polymodal receptors
-C-fibers unmyelinated and slow
-dull burning pain, poorly localized

Question 5

contents of dorsal horn of spinal cord

Answer 5

nociceptive fibers

• C fibers to lamina II
• A delta fibers to Lamina I and V

Question 6

spinothalamic tract

Answer 6

largest tract for pain and temp
crosses the midline at level of entry
ascends in anterolateral funiculus
2 subdivisions
-paleothalamic (slow)
-neothalamic (fast)

Question 7

divisions of the thalamus

Answer 7

medal nuclear group
-wide cortical and basal ganglionic projections
lateral nuclear group
-specific noxious and somatosensory input
-ventrobasal nucleus

Question 8

description of pain sensation in the cortex

Answer 8

less orderly arrangement of nociceptive inputs to the cortex than tactile inputs
large areas of destruction do not result in loss of pain response
wide cortical association areas involved in emotional response to pain

Question 9

chemical mediators of sensitization

Answer 9

released by the damaged tissue and nerve endings to decrease the pain threshold

• histamine
• PGE2
• ATP, ACh, 5HT
• bradykinin
• SP

Question 10

description of visceral pain

Answer 10

similar to slow pain
higher proportion of C fibers
-2 to 1 in skin
-10 to 1 in gut
pain often referred to somatic structures

Question 11

referred pain

Answer 11

pain in deep visceral structures that is felt on the surface of the body

Question 12

mechanism of referred main

Answer 12

convergence of cutaneous and visceral nociceptors onto the same dorsal horn projection neurons
OR
branching pattern of the sensory nerve

Question 13

mechanisms of abnormal pain

Answer 13

abnormal...
sensitization
conduction
modulation
perceptions

Question 14

complex regional pain disorder / reflex sympathetic dystrophy

Answer 14

persistent hyperpathia associated with vasomotor changes after an injury
usually after a period of immobilization
extreme abnormal sensitization

Question 15

signs of complex regional pain disorder

Answer 15

color changes

swelling in limb

Question 16

treatment of complex regional pain disorder

Answer 16

aggressive mobilization
pain control
sympathetic blockade

Question 17

neuralgias

Answer 17

abnormal conduction due to nerve damage
focal area of demyelination with cross talk between bare axons (ephaptic transmission)
usually cryptogenic

Question 18

treatment of neuralgias

Answer 18

carbamezapine
-Na+ channel blocker
surgery

Question 19

most common neuralga

Answer 19

trigeminal

Question 20

deafferentation pain

Answer 20

damage to somatosensory symptoms
associated with numbness
presumed secondary to decreased modulation from deafferentation

Question 21

what is deafferentation

Answer 21

loss of non pain sensory inputs
relative increase of pain: non-pain
pain perceived as a result

Question 22

when can deafferentation be seen

Answer 22

any lesion affecting non-pain sensory inputs

• peripheral nerves
• dorsal columns
• thalamus

Question 23

components of the central pain modulation system

Answer 23

*descends*
periaqueductal gray 
-opiate receptors
rostroventral medulla
-NE, 5HT
dorsal horn
-enkephalin interneurons

Question 24

how to eliminate abnormal pain physiology

Answer 24

decrease sensitization
decrease abnormal conduction
increased modulation
change perception

Question 25

ways to decrease sensitization

Answer 25

early mobility
capsacin (causes substance P release to help deplete it over time)
NSAIDs
steroids

Question 26

ways to decrease pain conduction

Answer 26

nerve block
spinothalamic tractotomy (only in people w short life spans)
“stabilize” nerve
-anti-epilepsy drugs

Question 27

ways to increase modulation

Answer 27

increase non-painful input
-mechanical stimulation
-trans cutaneous stimulator
-posterior column stimulator
-stimulate periaqueductal grey
meds
-antidepressants (upregulate descending pathway)
-opiates

Question 28

ways to change pain perception

Answer 28

focus on behavior
relaxation therapy
biofeedback
treat associated psychopathy
-anxiety
-depression