Pruritus Flashcards
Give some examples of broad classes of pruritogenic mediators?
Proteases, lipid mediators, neuropeptides, opioids, cytokines (Metz et al. Vet Derm. 2013)
What are some topical agents for treatment of pruritus?
Capsaiscin, calcineurin inhibitors (tacrolimus and pimecrolimus), and cannabinoid agonists (N-palmitoyl ethanol amine. (Metz et al. Vet Derm. 2013)
What are some systemic therapies for pruritus?
Antihistamines, anticonvulsants, opiate receptor antagonist or agonists, antidepressants, ciclosporin, and UV light. (Metz et al. Vet Derm. 2013)
For how long must itch persist for it to be considered chronic pruritus?
More than six weeks (Metz et al. Vet Derm. 2013)
What is the function of pruritus
Serves as an alarm system to effectively remove damaging or harmful substances on the skin (Metz et al. Vet Derm. 2013)
How is pruritus mediated in the skin?
Pruritus is mediated by free nerve endings of non-myelinated nerve fibers that are located at the dermoepidermal Junction and within the epidermis (Metz et al. Vet Derm. 2013)
How do physical stimuli, such as cold and heat, modulate the perception of itching?
Painful heat and cold can significantly diminish itching, while moderate cold intensifies it. (Metz et al. Vet Derm. 2013)
A sub population of Pruritus-specific non-myelinated C fibers exist that respond only to_________
A sub population of Pruritus-specific non-myelinated C fibers exist that respond only to histamine. (Metz et al. Vet Derm. 2013)
What is the gastrin releasing peptide receptor?
A specific receptor in the posterior spinal cord in mice which is exclusively responsible for transmitting the perception of pruritus but not pain or temperature perception
True or false: Pruritus can arise peripherally and then be transmitted to the CNS, but cannot originate in the CNS or spinal cord
False. Pruritus can arise peripherally and then be transmitted to the CNS, or it can originate in the CNS or spinal cord(Metz et al. Vet Derm. 2013)
Intrathecal administration of which substances has been shown to cause scratching, biting and other pruritus related reactions?
Vasoactive intestinal polypeptide, calcitonin gene related peptide, substance P or opioids (Metz et al. Vet Derm. 2013)
What is the gate control theory?
Pruritus is suppressed by mechanical or electrical stimulation of rapid transmitting myelinated A-fibers at the spinal level in favor of transmitting pain sensation. This explains the anti-pruritic effects of scratching. (Metz et al. Vet Derm. 2013)
In mast cells, is histamine preformed or produced following stimulation?
Preformed in large amounts. (Metz et al. Vet Derm. 2013)
Which receptors does histamine stimulate to induce pruritus?
H1 receptors (Metz et al. Vet Derm. 2013)
Which lipid mediators may be involved in pruritus?
Leukotriene B4, Protstaglandin D2, and prostaglandin E2. (Metz et al. Vet Derm. 2013)
Which neuropeptides are the most important mast cell activators?
Vasoactive intestinal polypeptide, calcitonin gene-related peptide and substance P. (Metz et al. Vet Derm. 2013)
The activation of which opioid receptor causes pruritus? The activation of which opioid receptor inhibits pruritus?
ยต-receptor causes pruritus. ๐-receptor inhibits pruritus. (Metz et al. Vet Derm. 2013)
Which interleukins have been associated with pruritus?
IL-2, IL-6, IL-8, and IL-31 (Metz et al. Vet Derm. 2013)
In terms of chronic pruritus, describe the process of peripheral sensitization.
Chronic stimulation of neuroreceptors, such as histamine or capsaicin receptor (TRPV1), bu inflammatory mediators such as bradykinin, prostaglandins and neurotrophins ultimately leads to reduction of stimulus threshold of these receptors. (Metz et al. Vet Derm. 2013)
What is allokinesis?
Itching triggered by normal non-pruritogenic stimulus. (Metz et al. Vet Derm. 2013)
What are the secondary reactive changes to chronic scratching called? What do they look like?
Lichen simplex chronicus, lichen amyloidosus, or prurigo nodularis.
Appears as flat or papular lichenification with hyper or depigmentation and scar formation. Can eventually appear as red or hyper pigmented papule, plaques or nodes.
(Metz et al. Vet Derm. 2013)
What are the four types of etiological classifications of pruritus?
Pruriceptive pruritus, neuropathic pruritus, neurogenic pruritus, and psychogenic pruritus (Metz et al. Vet Derm. 2013)
What is pruriceptive pruritus? Give some examples of causes.
Transmitted through C-fibers, originates directly in the skin, for example, as a consequence of dermatoses, such as psoriasis or excitation eczema. (Metz et al. Vet Derm. 2013)
What is Neuropathic pruritus? Give some examples.
Caused by damage of the itch-transmitting afferents of the peripheral nerves or the spinal cord. Brachioradial pruritus, post-herpetic pruritus and nostalgia paraesthetica. (Metz et al. Vet Derm. 2013)
