Skin Itch Cycle

1. DR ANGELO SMITH
M.D
WHPL

5. ◼ “local discomfort or irritation of the skin,
prompting the sufferer to scratch or rub
the affected area. It is the main symptom
of skin disease”
◼ “a peculiar tingling or uneasy irritation of
the skin that causes a desire to scratch
the affected area”

6. “It feels as though every nerve ending in my
body is attacking me intensely at my
ankles, feet, lower legs, neck, under the
breasts (even the nipples tingle). It's
absolutely horrendous! My hands grow red
as a beet and the itching nearly takes the
skin off my hands as I scratch.”
“ It’s like someone tickling you under
the skin”

7. ◼Debate continues
over whether there
are specific nerve
endings for itch
◼Possibly more than
one mechanism

8. ◼Free nerve endings
fibres most concentrated
in wrists and ankles
Unmyelinated C fibres to
dorsal horn in spinal
cord
◼Scratching is a spinal
reflex response ascends
to cerebral cortex via
spinothalamic tract
◼Skin inflammation
◼Psychological concerns
◼ Chemical mediators
Substance P
Opioid and non-opioid
peptides
Somatostatin
Neurokinin A
Histamine
Serotonin
Prostaglandins
◼ External mediators
Environmental heat or
dryness

11. ◼ History
including onset, duration, pattern, effect
on sleep, previous skin disease, contacts,
other medical problems, drugs, response
to treatment so far.
◼ Skin examination
features of rash, post-inflammatory
changes, signs of scratching
◼ General examination

13. ◼distress
◼excoriation
◼lichenification
◼shiny nails
◼weals
◼nodules

15. ◼age
◼self-control / social setting /
distractions
◼other medical conditions / ability to
scratch
◼site of itch
◼specific skin condition
◼duration

17. ◼skin disorders
◼systemic disorders
◼psychogenic
◼habit / itch-scratch cycle

18. ◼ infestations: scabies, lice,
threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular
urticaria
◼ pityriasis rosea
◼ viral exanthems

19. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

21. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

24. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

26. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

28. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

30. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

32. ◼ infestations: scabies, lice, threadworms
◼ eczemas
◼ urticaria
◼ psoriasis (sometimes)
◼ insect bites – papular urticaria
◼ pityriasis rosea
◼ viral exanthems

33. Slapped face syndrome

35. ◼infestations: scabies
◼eczemas / nodular prurigo/
xerosis
◼urticaria
◼psoriasis (sometimes)
◼lichen planus
◼bullous pemphigoid

37. ◼infestations: scabies
◼eczemas / nodular prurigo/
xerosis
◼urticaria
◼psoriasis (sometimes)
◼lichen planus
◼bullous pemphigoid

41. lesion description additional description
opaleness
owheal opale red
opolycyclic
opurpura

42. ◼infestations: scabies
◼Eczemas / xerosis
◼urticaria
◼psoriasis (sometimes)
◼lichen planus
◼bullous pemphigoid
◼polymorphic light eruption

44. ◼infestations: scabies
◼eczemas /nodular prurigo/ xerosis
◼urticaria
◼psoriasis (sometimes)
◼lichen planus
◼bullous pemphigoid
◼polymorphic light eruption

46. ◼infestations: scabies
◼eczemas/ nodular prurigo/ xerosis
◼urticaria
◼psoriasis (sometimes)
◼lichen planus
◼bullous pemphigoid
◼polymorphic light eruption

48. ◼Eczemas / xerosis
◼urticaria
◼psoriasis (sometimes)
◼infestations: scabies
◼lichen planus
◼bullous pemphigoid
◼polymorphic light eruption

50. ◼ Anogenital/ pruritus ani:
Threadworms, lichen sclerosis, lice, contact
dermatitis
◼ Hands:
eczemas, scabies, contact dermatitis
◼ Flexures:
atopic/ seborrhoeic eczema, scabies
◼ Scalp:
lice, seborrhoeic dermatitis, psoriasis
◼ Any area:
discoid eczema, lichen simplex chronicus, contact
dermatitis

51. ◼liver disease
◼renal failure
◼iron deficiency
◼metabolic:
protein, zinc, calcium, vitamin
deficiencies
◼thyroid disease

52. ◼diabetes
◼malignancies:
lymphoma, PRV, leukaemias,
myeloma
◼pregnancy
◼neurological
◼drugs

53. ◼epidemic forms - hysteria
◼delusional parasitosis
◼habit - itch/scratch cycle

56. ◼Treat the cause
◼Treat the itch

57. ◼keep looking for a cause
◼avoid aggravating factors
temperature, humidity, bedding,
clothing
◼reduce damage from scratching
clothing, bandaging, cut nails

58. ◼topical agents
◼systemic agents
◼psychological
interventions

59. ◼emollients
◼antihistamines - doxepin (Xepin)
◼unknown mechanism -
crotamiton (Eurax)
calamine
◼counter-irritant - capsaicin, menthol
◼local anaesthetics
◼paste bandages

60. ◼Opiod antagonists
◼Ondansetron
◼Rifampicin
◼Cholestyramine
◼Tricyclic antidepressants
◼Thalidomide
◼Phototherapy

61. ◼Biofeedback
◼Behaviour therapy
◼Relaxation techniques
◼Acupuncture
◼Hypnotherapy
◼Homeopathy
◼Self-help groups