Ch 4 Pruritus Flashcards
Classic skin findings from chronic pruritus?
- Lichen simplex chronicus
2. Prurigo nodularis
What’s lichen simplex chronicus?
- Skin colored, pink or hyperpigmented
- plaques
- exaggerated skin markings
- leathery appearance
Distribution or lichen simplex chronicus?
- Posterior neck
- occipital scalp
- Anogenital region
- Ankles
- Extensor arms + legs
Rx of (LSC)?
- Symptomatic = topical anesthetics (pramoxine)
* Topical CS under occlusion
Describe prurigo nodularis?
Discrete firm papulonodules with central scale-crust.
Distribution of prurigo nodularis?
- Extensor extremities
- upper back + buttocks
Rx of prurigo nodularis?
- CS
- phototherapy
- Thalidomide
Rx depends of # of lesions
Syndromes of neuropathic itch
Trigeminal trophies syndrome (TTS)
Radiculopathies
Notalgia paresthetica
Brachioradial pruritus
Meralgia paresthetica
Small fiber polyneuropathy
What’s neuropathic itch?
Itch syndrome due to CNS or PNS disorder
Distribution of neuropathic itch?
Head and neck > lower body
Quality of itch in neuropathic syndromes?
Affected Pt’s want to “dig at” or “gouge out” their skin
Rx of neuropathic itch syndrome?
Don’t respond to antihistamine
Ice packs offers relief
What’s trigeminal trophic itch?
Intractable facial itch characterized by painless scratching to the point of self harm + ulceration.
Distribution of trigeminal trophic syndrome?
Nasal ala
NB: Nasal tip is spared (?) nerve supply is derived from external branch of anterior ethmoidal nerve.
Clinical picture of trigeminal trophic syndrome?
Small crust develops into crescentic ulcer over nasal ala. extends to cheeks + upper lip.
Cause of trigeminal trophic itch?
Impingement of trigeminal nerve
Secondary to:
1- iatrogenic
2- infection = VZV, HSV
3- CNS tumor
Rx of trigeminal trophic syndrome?
Protective barrier
Surgical consult
Oral pimozide + carbamazepine
What’s rediculopathy?
Focal neurological dysfunction caused by injury to single sensory nerve root, resulting in pruritus.
Injuries to sensory nerve root causing pruritic radiculopathy?
- Impingement from spinal osteoarthritis
- Distal impingement by inflamed muscle
- Infection (VZV, leprosy, Lyme)
- Tumors (schwannoma, mets), vascular malformation, cysts.
Clinical picture of pruritic radiculopathy?
Unilateral + on the side of damaged SNR.
When to do MRI for pruritic radiculopathy?
- Sever, sudden pruritus
2. Worsening pruritus
Rx of pruritic radiculopathies ?
- Symptomatic Rx:
- Topical: anesthetics + capsaicin
- Oral neuromedulators ( gabapentin, pregablin)
- physical + acupuncture
- Botox
Classical radiculopathies in derm?
- Shingles - Post herpetic neuralgia | post herpetic itch.
- Notalgia paresthetica
- Brachioradial pruritus
- Meralgia parenthetic
Clinical picture of notalgia paresthetica?
Focal intense pruritus of upper back, along the medial scapular boards (+/- pain or burning)
Hyper pigmented patch result of chronic rubbing.
DDx of notalgia paresthetica?
Macular amyloidosis Sipple syndrome (esp in childhood)
Rx of notalgia paresthetica?
Topical capsaicin 5x/day for 1 week then 3xday for 3-6 weeks
Anesthetics
Gabapentin
Acupuncture
What’s brachioradial pruritus?
Chronic intermittent pruritus of dorsal forearm + elbows (+/- shoulder)
With excoriation / prurigo simplex lesions or scaring in affected area.
Association with brachioradial pruritus?
Photo damaged skin + degenerative cervical spine
Diagnostic sign of brachioradial pruritus?
- Patient can delineate affected area with pen.
2. Ice pack sign = only relief
Rx of brachioradial pruritus?
- Sun protection
- Cold packs
- Topicals (pramoxine, capsaicin)
- Oral (gabapentin, amitriptyline)
What’s meralgia paresthetica?
Pruritus of anterolateral thigh + numbness / burning pain
Cause of meralgia paresthetica?
Impingement of lateral femoral cutaneous nerve as it passes through inguinal ligament
Predisposing factors of meralgia paresthetica?
Obesity
Pregnancy
Tight cloths
Rarely: tumors or hemorrhage.
Rx of meralgia paresthetica?
Removal of cause of compression
Focal nerve block
Surgical decompression
Role of neuromedulator agents in meralgia paresthetica?
Not helpful
What’s small fiber polyneuropathy?
Most common cause of pruritus with bilateral distribution.
Distribution of small fiber polyneuropathy?
Stock-glove
Dx of small fiber polyneuropathy?
Sensory sx
Intact muscle
R/o potential causes
Dx test:
- Immunohistochemical staining (anti-PGP9.5)
- Autoimmune function test
Treatable causes of pruritus?
- DM = HA1c , FPG
- Anemia = B12, folate, copper, homocysteine
- Gammopathy = SPEP + UPEP, immunofixation, serum-free light chain analysis.
- Hematological Ca = CBC + PLT
Dysesthesia syndromes?
Burning mouth syndrome (orodynia)
Burning scalp syndrome (scalp dysesthesia)
Dysesthetic anogenital syndrome
