Pruritis and Sweating Oxford

Question 1

Pruritis : Pathophysiology

Answer 1

• 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

Question 2

Opioids and Pruritis

Answer 2

• 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

Question 3

Serotonergics and Pruritis

Answer 3

• peripheral serotonin receptors
• SSRI can be useful for itch

Question 4

Clinical evaluation

Answer 4

1. Primary vs Secondary
   - Primary: idiopathic
   - Secondary : due to derm or systemic disease
2. Localized vs generalized
   - Localized: infection, derm disease
   - Generalized : medications, systemic illness, derm disorder

Question 5

Primary Pruritis (idiopathic)

Answer 5

• Diagnosis of exclusion
• Early sign of malignancy (heme)
• Good skin care, topics soothing meds, creams

Question 6

Secondary Pruritis (dermatological)

Answer 6

• Allergic contact dermatitis
• Scabies
• Folliculitis
• Insect Bites
• Atopic dermatitis
• Urticaria
• Pemphigoid

Treatment :

-treat underlying diagnosis

Question 7

Secondary Pruritis : systemic causes

Answer 7

1. Biliary and hepatic disease
2. Chronic renal failure (uremia)
3. Drugs

• opioids
• amphetamines
• cocaine
• asa
• drug sensitivity

4. Endocrine disease

• DM
• DI
• parathyroid
• thyroid disease (hypo, hyper)

5. Hematological disease

• lymphoma
• mastocystosis
• MM
• anemia

6. Infectious disease
   * HIV, syphilis, parasitic, fungal
7. Malignancy
   * carcinoid, breast, stomach, lung
8. Neuro disease

• stroke, peripheral neuropathy, MS, brain mets
• psychosis, parisitosis

Question 8

Topical medications

Answer 8

• localized itch
• Dilute phenol
• menthol
• topical anesthetics
• topical TCA
• topical ketamine
• capsaicin
• steroids

Question 9

Systemic treatments for Pruritis

Answer 9

• 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

Question 10

Treatment for malignancy related pruritis

Answer 10

• severe, refractory
• heme malignancies, lung, gastric, insulinoma, laryngeal tumours

1. SSRI/SNRI (paroxetine, sertraline)
2. Gabapentin/pregab
3. Steroids
4. Others :

• Aprepitant
• thalidomide
• naltrexone

Question 11

Non pharmacological measures for itch

Answer 11

• regular moisturizing with nonfragrant topical emollient lotion
• after bathing
• non irritating, loose clothing
• avoidance of skin irritants
• cool, humidied air

Question 12

Cholestasis

Answer 12

• stenting if possible
• bile acid sequestrants
  
  • cholestyramine
• rifampin
• Naltrexone
• antidepressants (parox, sertraline)

Question 13

Uremia pruritis

Answer 13

• topical emollients
• optimize dialysis
• gabapentin
• hydroxyzine (if not dialyzed)
• sertraline (not if on dialysis)

Question 14

Treatment of Opioid Pruritis

Answer 14

• rotation to lower histamine releasing opioid (fentanyl, oxycodone)
• oral antihistamine

Question 15

Pruritis NYD treatment?

Answer 15

• topical
• SNRI, SSRI
• Gabapentin
• Steroid second-thrid line

Question 16

Sweating physiology

Answer 16

• 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

Question 17

Hyperhydrosis?

Answer 17

• excessive sweating
• night sweats
• localized, primary or secondary

Question 18

List causes of generalized hyperhidrosis

Answer 18

• Endocrine disease
  
  • Dm
  • Acromegaly
  • Thyroid
  • Pheochromocytoma
  • Di
  • Hypopit
  • menopause
• Drugs
  
  • opioids
  • SSRI/SNRI
  • Naproxen
  • Acyclovir
• Malignancy

Question 19

List causes of localized hyperhidrosis

Answer 19

• Neurogenic
  
  • spinal cord injury
  • peripheral neuropathy
  • stroke
• Intrathoraic neoplasm
  
  • Pancoast tumour anhidrosis one side and hyperhidrosis other side
• Cold induced
• Gustatory

Question 20

Hot flashes treatment

Answer 20

• 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

Question 21

Tumour fever treatment

Answer 21

• febrile : antipyretic