pruritis Flashcards
types of pruritis
1- systemic - itch from a non - cutaneous organ system , no peripheral nerve input, associated with Opoid receptors, ILs and neuropeptides imbalance
2- psychogenic - itch due to disease of the mind
3- neuropathic - itch from central or peripheral nerve damage
4- pruritoceptive - unmyelinated group c fibres are involved
dermatogenic pruritis
mediators of pruritis
histamine
serotonin
substance P
IL
opioid peptides
tryptase
PGE
receptors inhibiting and stimulating itch
stimulating itch : u opioid receptor
inhibiting itch: k opioid receptors
aetiology of each type of pruritus
systemic - myeloproliferative disease, hepatic disease, choleasthasis
psychogenic - Obsessive-compulsive disorder, depression, anxiety, somatic symptom disorders, psychosis, substance use
delusions of parasitosis
neuropathic - Postherpetic neuralgia, brachioradial pruritus, notalgia paresthetica
puritoceptive - Xerosis, scabies, urticaria, reactions to insect bite, atopic dermatitis, wool fibers
what is notalgia paresthetica ?
Likely due to neuropathy secondary to entrapped spinal nerves
more commonly seen in older females
C/P of notalgia paresthetica
- A characteristic finding is a well-circumscribed hyperpigmented patch
- The erythema seen here is due to rubbing and scratching
- Interscapular is most common location
brachioradial pruritis
Defined as a chronic, uncommon, intermittent pruritus of the arm superior to the elbow
Cumulative solar damage, presence of a cervical rib, or cervical nerve root impingement may be contributory factors.
mechanism of pruritis in CKD ?
- Xerosis
- 2ndry hyperparathyroidism
- Iron deficiency anaemia
- Neuropathy
- Increased serum histamine levels
Tx of pruritus in CKD
naltrexone
presentation of primary biliary cirrhosis
- Women above 30
- itching
- Jaundice and hyperpigmentation
TX of pruritis in primary billiary cirrohsis
Naltrexone, cholestyramine
presentatioin of polycythemia vera
pruritis induced by changes in temperature or after bathing
treatment for pruritis associated with PV
Aspirin, PUVA, nb-UVB,
Paroxetine
scabies
causative organism
mode of transmission
causative: Sarcoptes scabiei var. hominis , lives in the epidermis of the skin
mode of transmission : direct close contact with an infested person or sexual contact
life cycle of the mites
30 day life cycle entirely spent in the epidermis
2-3 eggs laid a day , totalling of about 60-90 eggs
which take 10 days to mature
incubation period of scabies
days to months (2-6 weeks)
where is substance P produced in pruritis
c fibres
pathognomonic lesions in scabies
furrows and burrows
portal of entryy and exit of the mites
site and distribution oof scabies
Cutaneous lesions are symmetrical. Typical sites of involvement include the interdigital webbing of the hands, the
flexural aspect of the wrists, axillae, buttocks and belt area
sekc parts of males and females
scabies appearing in HIV patients
Norwegian scabies
scabies following misuse of topical steroids
scabies incognito
scabies that persists after months of scabies treatment
nodular scabies - a local hypersensitivity reaction
Tx of scabies
generally - all family members to bee treated even if they show no signs of pruritis
medically :
permethrin cream day 1 and day 8
Ivermectin oral on day 1 and 14
Post scabeitic pruritus
pruritis that persists after succesful treatment
3adii - reassuree patient
body still reacting to dead scabies ( give it 2 weeks )
