Ch 4 Pruritus

Question 1

Classic skin findings from chronic pruritus?

Answer 1

1. Lichen simplex chronicus

2. Prurigo nodularis

Question 2

What’s lichen simplex chronicus?

Answer 2

• Skin colored, pink or hyperpigmented
• plaques
• exaggerated skin markings
• leathery appearance

Question 3

Distribution or lichen simplex chronicus?

Answer 3

1. Posterior neck
2. occipital scalp
3. Anogenital region
4. Ankles
5. Extensor arms + legs

Question 4

Rx of (LSC)?

Answer 4

• Symptomatic = topical anesthetics (pramoxine)

* Topical CS under occlusion

Question 5

Describe prurigo nodularis?

Answer 5

Discrete firm papulonodules with central scale-crust.

Question 6

Distribution of prurigo nodularis?

Answer 6

• Extensor extremities

- upper back + buttocks

Question 7

Rx of prurigo nodularis?

Answer 7

• CS
• phototherapy
• Thalidomide

Rx depends of # of lesions

Question 8

Syndromes of neuropathic itch

Answer 8

Trigeminal trophies syndrome (TTS)

Radiculopathies

Notalgia paresthetica

Brachioradial pruritus

Meralgia paresthetica

Small fiber polyneuropathy

Question 9

What’s neuropathic itch?

Answer 9

Itch syndrome due to CNS or PNS disorder

Question 10

Distribution of neuropathic itch?

Answer 10

Head and neck > lower body

Question 11

Quality of itch in neuropathic syndromes?

Answer 11

Affected Pt’s want to “dig at” or “gouge out” their skin

Question 12

Rx of neuropathic itch syndrome?

Answer 12

Don’t respond to antihistamine

Ice packs offers relief

Question 13

What’s trigeminal trophic itch?

Answer 13

Intractable facial itch characterized by painless scratching to the point of self harm + ulceration.

Question 14

Distribution of trigeminal trophic syndrome?

Answer 14

Nasal ala

NB: Nasal tip is spared (?) nerve supply is derived from external branch of anterior ethmoidal nerve.

Question 15

Clinical picture of trigeminal trophic syndrome?

Answer 15

Small crust develops into crescentic ulcer over nasal ala. extends to cheeks + upper lip.

Question 16

Cause of trigeminal trophic itch?

Answer 16

Impingement of trigeminal nerve

Secondary to:
1- iatrogenic
2- infection = VZV, HSV
3- CNS tumor

Question 17

Rx of trigeminal trophic syndrome?

Answer 17

Protective barrier
Surgical consult
Oral pimozide + carbamazepine

Question 18

What’s rediculopathy?

Answer 18

Focal neurological dysfunction caused by injury to single sensory nerve root, resulting in pruritus.

Question 19

Injuries to sensory nerve root causing pruritic radiculopathy?

Answer 19

1. Impingement from spinal osteoarthritis
2. Distal impingement by inflamed muscle
3. Infection (VZV, leprosy, Lyme)
4. Tumors (schwannoma, mets), vascular malformation, cysts.

Question 20

Clinical picture of pruritic radiculopathy?

Answer 20

Unilateral + on the side of damaged SNR.

Question 21

When to do MRI for pruritic radiculopathy?

Answer 21

1. Sever, sudden pruritus

2. Worsening pruritus

Question 22

Rx of pruritic radiculopathies ?

Answer 22

1. Symptomatic Rx:
   - Topical: anesthetics + capsaicin

• Oral neuromedulators ( gabapentin, pregablin)
• physical + acupuncture
• Botox

Question 23

Classical radiculopathies in derm?

Answer 23

1. Shingles - Post herpetic neuralgia | post herpetic itch.
2. Notalgia paresthetica
3. Brachioradial pruritus
4. Meralgia parenthetic

Question 24

Clinical picture of notalgia paresthetica?

Answer 24

Focal intense pruritus of upper back, along the medial scapular boards (+/- pain or burning)

Hyper pigmented patch result of chronic rubbing.

Question 25

DDx of notalgia paresthetica?

Answer 25

``` Macular amyloidosis Sipple syndrome (esp in childhood) ```

Question 26

Rx of notalgia paresthetica?

Answer 26

Topical capsaicin 5x/day for 1 week then 3xday for 3-6 weeks Anesthetics Gabapentin Acupuncture

Question 27

What's brachioradial pruritus?

Answer 27

Chronic intermittent pruritus of dorsal forearm + elbows (+/- shoulder) With excoriation / prurigo simplex lesions or scaring in affected area.

Question 28

Association with brachioradial pruritus?

Answer 28

Photo damaged skin + degenerative cervical spine

Question 29

Diagnostic sign of brachioradial pruritus?

Answer 29

1. Patient can delineate affected area with pen. | 2. Ice pack sign = only relief

Question 30

Rx of brachioradial pruritus?

Answer 30

1. Sun protection 2. Cold packs 3. Topicals (pramoxine, capsaicin) 4. Oral (gabapentin, amitriptyline)

Question 31

What's meralgia paresthetica?

Answer 31

Pruritus of anterolateral thigh + numbness / burning pain

Question 32

Cause of meralgia paresthetica?

Answer 32

Impingement of lateral femoral cutaneous nerve as it passes through inguinal ligament

Question 33

Predisposing factors of meralgia paresthetica?

Answer 33

Obesity Pregnancy Tight cloths Rarely: tumors or hemorrhage.

Question 34

Rx of meralgia paresthetica?

Answer 34

Removal of cause of compression Focal nerve block Surgical decompression

Question 35

Role of neuromedulator agents in meralgia paresthetica?

Answer 35

Not helpful

Question 36

What's small fiber polyneuropathy?

Answer 36

Most common cause of pruritus with bilateral distribution.

Question 37

Distribution of small fiber polyneuropathy?

Answer 37

Stock-glove

Question 38

Dx of small fiber polyneuropathy?

Answer 38

Sensory sx Intact muscle R/o potential causes Dx test: 1. Immunohistochemical staining (anti-PGP9.5) 2. Autoimmune function test

Question 39

Treatable causes of pruritus?

Answer 39

1. DM = HA1c , FPG 2. Anemia = B12, folate, copper, homocysteine 3. Gammopathy = SPEP + UPEP, immunofixation, serum-free light chain analysis. 4. Hematological Ca = CBC + PLT

Question 40

Dysesthesia syndromes?

Answer 40

Burning mouth syndrome (orodynia) Burning scalp syndrome (scalp dysesthesia) Dysesthetic anogenital syndrome