Somatosensory function (pain)

Question 1

examples of pain types

Answer 1

nociceptive
muscle
superficial somatic
visceral
referred 
neuropathic.

Question 2

types of muscular pain

Answer 2

	Metabolic		
	Overuse		
	Tension		
	Compression		
	Ischaemia		
	Tearing		
	Viral infection
	Fibromyalgia
	Angina

Question 3

what are the typical features of pain?

Answer 3

Aching
Burning (lactic acidosis)
Cramping
Tightness
Crushing
Tenderness

Question 4

why is visceral pain vague, diffused and poorly localised?

Answer 4

low density of sensory innervation

Question 5

visceral pain

Answer 5

may be referred
often midline
associated with autonomic symptoms
may show visceral hyperalgesia, viscerovisceral cross-talk

Question 6

types of somatic pain

Answer 6

	Often nociceptic	
	Related to skin	
	Pressure		
	Too hot/cold		
	Inflammation		
	Injury		
	Infection		
	Burns

Question 7

features of somatic pain

Answer 7

Well-localised
Sharp
Stinging
Aching
Burning
Throbbing
Tightness
Sensitive

Question 8

where does referred pain often occur?

Answer 8

at sites of the body wall where innervation enters the spinal cord at the same level as the organ
pain is sharper and better localised than visceral pain

e.g in angina

Question 9

what are Wind Dynamic neurones

Answer 9

o Receive input from A, A and C fibres.
o The most populous cell whose soma is located in the dorsal horn.
o Respond to a full range of stimuli (touch, heat and chemical) but fire more frequently to noxious stimuli.
o They fire APs in a graded fashion.
o Exhibit “wind-up”.

Question 10

what is the Wind-Up phenomenon

Answer 10

exponentially progressive increase in firing of WDR neurons with repeated stimulation

increase in pain intensity over time when a given stimulus is delivered repeatedly above a critical rate

o Short-lasting synaptic plasticity.
o Repetitive stimulation of WDRs which induce increased evoked response and post discharge with each stimulus.
o May precipitate long-term potentiation (LTP) – i.e. long lasting increase in efficacy of synaptic transmission.
o Wind-up and LTP related to neuropathic sensitisation.

Question 11

what are the two types of sensitisation?

Answer 11

peripheral and central

Question 12

peripheral sensitisation

Answer 12

injury in late nerve

small area of sensitisation

Question 13

central sensitisation

Answer 13

injury in the early nerve in spinal cord

possible large area of sensitisation if in tracts

Question 14

what is neuropathic pain

Answer 14

pain source in the somatosensory nervous system

pain in area of neuronal dysfunction
sharp, burning, electric shcck and squeezing pain
has poor response to usual analgesic drugs
can last after an area has completely healed

Question 15

allodynia

Answer 15

pain due to stimulus that does not usually cause pain

Question 16

hyperalgesia

Answer 16

increased pain from a stimulus that normally causes pain

Question 17

hypoalgesia

Answer 17

decreased pain from a stylus that normally causes pain

Question 18

what is sensitisation?

Answer 18

increased responsiveness of nociceptive neurones to their normal input

Question 19

hyperpathia

Answer 19

painful syndrome caused by abnormally painful reaction to a stimuli
especially a repetitive stimulus and an increased threshold

Question 20

paraesthesia

Answer 20

abnormal sensation (spontaneous or evoked)

pins and needles

Question 21

dysaesthesia

Answer 21

unpleasant abnormal sensation (spontaneous or evoked)

Question 22

examples of neuropathic pain

Answer 22

complex regional pain (CRPS) syndrome

phantom limb pain
sciatica

Question 23

Complex Regional Pain Syndrome

Answer 23

o Sensory, vasomotor, pseudomotor/oedema, motor/trophic symptoms must be present.
 Characterised by neurogenic inflammation.
 Displays overexpression of nociceptive nerve endings.

Question 24

phantom limb pain

Answer 24

common among amputees
stump neuroma association
may be due to remapping of brain

treatment:
o Antidepressants – Amitriptyline, Nortriptyline, Duloxetine.
o Anticonvulsants – Gabapentin, Pregabalin.
o Opioid trial – Tramadol, Buprenorphine, Methadone, Morphine.
o Hybrid – Tapentadol.
o Topical – 5% Lidocaine, Capsaicin 0.075% cream and capsaicin 8% patches.