Pruritis and Sweating Oxford Flashcards
Pruritis : Pathophysiology
- release of stimuli
- physical (pressure, thermal, electrical, caustic)
- Chemical (histamine, proteases, PGs)
- Stimuli of nerve fibres
- Type A and Type C unmyelinated
- Itch receptor on C fibres
- Transmission to CNS
- Synapse on second order neurons dorsal horn
- Spinothalamic tract to thalamus and cortex
Opioids and Pruritis
- excitatory and inhibitory effects on pruritis
- peripheral stimulation of mast cell degranulations and histamine release
- spinal cord level opioids are inhibitory
- CNS level - opioids directly trigger itch
Serotonergics and Pruritis
- peripheral serotonin receptors
- SSRI can be useful for itch
Clinical evaluation
- Primary vs Secondary
- Primary: idiopathic
- Secondary : due to derm or systemic disease - Localized vs generalized
- Localized: infection, derm disease
- Generalized : medications, systemic illness, derm disorder
Primary Pruritis (idiopathic)
- Diagnosis of exclusion
- Early sign of malignancy (heme)
- Good skin care, topics soothing meds, creams
Secondary Pruritis (dermatological)
- Allergic contact dermatitis
- Scabies
- Folliculitis
- Insect Bites
- Atopic dermatitis
- Urticaria
- Pemphigoid
Treatment :
-treat underlying diagnosis
Secondary Pruritis : systemic causes
- Biliary and hepatic disease
- Chronic renal failure (uremia)
- Drugs
- opioids
- amphetamines
- cocaine
- asa
- drug sensitivity
- Endocrine disease
- DM
- DI
- parathyroid
- thyroid disease (hypo, hyper)
- Hematological disease
- lymphoma
- mastocystosis
- MM
- anemia
- Infectious disease
* HIV, syphilis, parasitic, fungal - Malignancy
* carcinoid, breast, stomach, lung - Neuro disease
- stroke, peripheral neuropathy, MS, brain mets
- psychosis, parisitosis
Topical medications
- localized itch
- Dilute phenol
- menthol
- topical anesthetics
- topical TCA
- topical ketamine
- capsaicin
- steroids
Systemic treatments for Pruritis
- generalized pruritis
- poor evidence for all
1. Anti-inflammatories
-steroids, histamine blockers, ASA
2. Vasoactive drugs
-propranolol
3. Anesthetics
-Ketamine
4. Antidepressants
-Sedative, TCA, opioid antagonists, SNRI (paroxetine), SSRI (sertraline)
5. GABA agonists
-gabapentin, pregab
6. Sequestrants
-cholestyramine
Treatment for malignancy related pruritis
- severe, refractory
- heme malignancies, lung, gastric, insulinoma, laryngeal tumours
- SSRI/SNRI (paroxetine, sertraline)
- Gabapentin/pregab
- Steroids
- Others :
- Aprepitant
- thalidomide
- naltrexone
Non pharmacological measures for itch
- regular moisturizing with nonfragrant topical emollient lotion
- after bathing
- non irritating, loose clothing
- avoidance of skin irritants
- cool, humidied air
Cholestasis
- stenting if possible
-
bile acid sequestrants
- cholestyramine
- rifampin
- Naltrexone
- antidepressants (parox, sertraline)
Uremia pruritis
- topical emollients
- optimize dialysis
- gabapentin
- hydroxyzine (if not dialyzed)
- sertraline (not if on dialysis)
Treatment of Opioid Pruritis
- rotation to lower histamine releasing opioid (fentanyl, oxycodone)
- oral antihistamine
Pruritis NYD treatment?
- topical
- SNRI, SSRI
- Gabapentin
- Steroid second-thrid line
Sweating physiology
- physiologic response
- thermoregulation
- inappropriate sweating because of cancer and treatment
- thermosensitive neurons in hypothalamus
- Thermoreceptors in skin, spinal cord, brain stem
- temperature set point
- altered by hypercapnia, plasma osmolality, intravasc volume, chemical mediators
Autonomic control of thermoregulation
- heat production (shivering)
- heat dissipation (sweating)
Behavioural thermoregulation
- posture
- voluntary movement
- clothing, environment
Hyperhydrosis?
- excessive sweating
- night sweats
- localized, primary or secondary
List causes of generalized hyperhidrosis
-
Endocrine disease
- Dm
- Acromegaly
- Thyroid
- Pheochromocytoma
- Di
- Hypopit
- menopause
-
Drugs
- opioids
- SSRI/SNRI
- Naproxen
- Acyclovir
- Malignancy
List causes of localized hyperhidrosis
- Neurogenic
- spinal cord injury
- peripheral neuropathy
- stroke
- Intrathoraic neoplasm
- Pancoast tumour anhidrosis one side and hyperhidrosis other side
- Cold induced
- Gustatory
Hot flashes treatment
- estrogen depletion in breast cancer.
- Premature Ovarian Failure from anti estrogens, aromatase inhibitors
SSRI
- venlafaxine, paroxetine, citalopram
- tamoxifen CYP 2D6 may interact
Gabapentin/Pregabalin
Hormonal agents :
- progresterone
- not for hormone receptor positive breast ca
Tumour fever treatment
- febrile : antipyretic
