Pruritus

Question 1

definition of pruritus?

Answer 1

usually unpleasant, poorly localised, non adapting sensation that provokes the desire to scratch

Question 2

name the chemical mediators involved in pruritus in the skin

• transmission of nerve impulses in pruritus
• CNS mediators causing itch
• cells causing itch?

Answer 2

histamine, PGE2, acetylcholine, serotonin, kallikrein, interleukin, substance P, tryptase

• unmyelinated C fibres
• Opiates
• mast cell degranulation stimulated by Substance P, IgE and Codiene

Question 3

name the 4 types of itch

Answer 3

Pruritoceptive- something in the skin triggers itch
Neuropathic- damage to central/peripheral nerves
Neurogenic- caused by the CNS but no damage
Psychogenic- psychological cause with no CNS damage

Question 4

Pruritoceptive itch examples (5)

Answer 4

asteatotic eczema- crazy paving appearance
insect bites
lichen planus
psoriasis
prurigo nodularis- atopic eczema and chronic itch

Question 5

Neuropathic and neurogenic itch (6)

Answer 5

haematological disease
paraneoplastic
Liver and bile duct 
psychogenic
kidney disease
thyroid disease

Question 6

Management (6)

Answer 6

sedative antihistamines
emollients
antidepressants
anti-epileptics
phototherapy
opiate agonists