Pruritus

Question 1

How is the sensation of itch transmitted?

Answer 1

Unmyelinated C-fibres, processed in forebrain and maybe hypothalamus

Question 2

Name three chemical mediators of itch in the skin.

Answer 2

Histamine
PGE2
Serotonin
Interleukin-2
Tryptase
Substance P

Question 3

What are the four types of itch?

Answer 3

Pruritoceptive- inflammation in skin
Neuropathic- damage to peripheral/central nerve fibres
Neurogenic- no evident nerve damage, e.g. effect of opiods in CNS
Psychogenic- psychological cause

Question 4

What category of itch does
a) dermatographism
b) bile duct obstruction
come under?

Answer 4

a) pruritoceptive

b) neurogenic

Question 5

How is pruritus managed?

Answer 5

Determine the cause
Treat the cause (so for pruritoceptive- treat inflammation in skin)
Other treatments: sedative antihistamines, emollients, antidepressants, opioid antagonists