pruritis

Question 1

types of pruritis

Answer 1

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

Question 2

mediators of pruritis

Answer 2

histamine
serotonin
substance P
IL
opioid peptides
tryptase
PGE

Question 3

receptors inhibiting and stimulating itch

Answer 3

stimulating itch : u opioid receptor
inhibiting itch: k opioid receptors

Question 4

aetiology of each type of pruritus

Answer 4

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

Question 5

what is notalgia paresthetica ?

Answer 5

Likely due to neuropathy secondary to entrapped spinal nerves
more commonly seen in older females

Question 6

C/P of notalgia paresthetica

Answer 6

• A characteristic finding is a well-circumscribed hyperpigmented patch
• The erythema seen here is due to rubbing and scratching
• Interscapular is most common location

Question 7

brachioradial pruritis

Answer 7

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.

Question 8

mechanism of pruritis in CKD ?

Answer 8

• Xerosis
• 2ndry hyperparathyroidism
• Iron deficiency anaemia
• Neuropathy
• Increased serum histamine levels

Question 9

Tx of pruritus in CKD

Answer 9

naltrexone

Question 10

presentation of primary biliary cirrhosis

Answer 10

• Women above 30
• itching
• Jaundice and hyperpigmentation

Question 11

TX of pruritis in primary billiary cirrohsis

Answer 11

Naltrexone, cholestyramine

Question 12

presentatioin of polycythemia vera

Answer 12

pruritis induced by changes in temperature or after bathing

Question 13

treatment for pruritis associated with PV

Answer 13

Aspirin, PUVA, nb-UVB,
Paroxetine

Question 14

scabies
causative organism
mode of transmission

Answer 14

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

Question 15

life cycle of the mites

Answer 15

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

Question 16

incubation period of scabies

Answer 16

days to months (2-6 weeks)

Question 17

where is substance P produced in pruritis

Answer 17

c fibres

Question 18

pathognomonic lesions in scabies

Answer 18

furrows and burrows
portal of entryy and exit of the mites

Question 19

site and distribution oof scabies

Answer 19

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

Question 20

scabies appearing in HIV patients

Answer 20

Norwegian scabies

Question 21

scabies following misuse of topical steroids

Answer 21

scabies incognito

Question 22

scabies that persists after months of scabies treatment

Answer 22

nodular scabies - a local hypersensitivity reaction

Question 23

Tx of scabies

Answer 23

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

Question 24

Post scabeitic pruritus

Answer 24

pruritis that persists after succesful treatment
3adii - reassuree patient
body still reacting to dead scabies ( give it 2 weeks )

Question 25

medications that cause itching

Answer 25

ace inhibitors
statins
calcium channel blockers