Pruritus

Question 1

Define Pruritus

Answer 1

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

Question 2

What are some mediators of itch

Answer 2

Chemical mediators in the skin (histamine, acetylcholine, substance P)
Nerve transmission (unmyelinated C fibres
CNS - opiates

Question 3

What are 4 causes of itch

Answer 3

Pruritoceptive: something in skin that triggers
Neuropathic: damage of any sort to central or peripheral nerves causing itch
Neurogenic: no evident damage in CNS but itch caused: opiate effect on CNS receptors
Psychogenic: psychological causes with no CNS damage

Question 4

Name some examples that cause a pruritoceptive itch

Answer 4

psoriasis
eczema
insect bites

Question 5

Name some systemic diseases associated with neurogenic itch

Answer 5

Haematological 
Paraneoplastic 
Liver and bile duct 
Psychogenic
Kidney disease 
Thyroid disease

Question 6

How can we manage a patient with itch

Answer 6

Determine the cause
Treat the cause
Anti-itch treatments (sedative antihitamines, emolluents, antidepressants, Phototherapy, Opiate antagnoists)