Week 3 Pain management

Question 1

hyperalgesia

Answer 1

enhanced response to noxious (tissue damaging) stimuli; applied heat to sunburnt area b/c damage- overreaction

Question 2

allodynia

Answer 2

non-noxious input is coded as painful; something usually not perceived as pain is painful

Question 3

Exaggerated pain

Answer 3

Caused by central sensitization via NMDA(glutamate receptor in ion channel of neurons) receptor; NMDA receptor normally closed- opens up (Mg2+ plug removed) after strong enough depolarization- why pain lasts for a while

Question 4

Postherpetic Neuralgia (PHN)

Answer 4

Shingles; long lasting pain; >1mth after rash has resolved; localized to the DRG; damaged DRG leads to degeneration of peripheral & spinal axons; dermatomal distribution is the thoracic dermatomes; pain= burning, aching,dull, paroxysmal, stabbing, elctric-like

Question 5

Complex Regional Pain Syndrome (CRPS)

Answer 5

variety of painful conditions following injury- appears regionally and exceeds in magnitude adn duration of initial tisse injury event; results in motor impairment-variable progression over time; brain injury>heart attack=peripheral nerve injury>fractures- incidence

Question 6

Type I CRPS

Answer 6

following noxious event; mostly in one extremity; increase in pain, loss of sensation, autonomic abnormalities; eating and motor dysfxn

Question 7

Type II CRPS

Answer 7

same as Type I; except lesions of nerve structures & subsequent focal deficits are MANDATORY for diagnosis- difference between the two

Question 8

Anti-depressants (amytriptyline/desipramine)

Answer 8

Treats: PHN, CRPS Iⅈ moderate outcome; increased BP, sedation, nausea, serotonin syndrome; MOA: noradrenergic & serotonergic release & selective norepinephrine blockers

Question 9

Gabapentin & pregabalin

Answer 9

Treats: PHN (1st line treatment), CRPS Iⅈ moderate outcome; sedation, ataxia; Ca2+ N-channel blocker

Question 10

Opioids (morphine/methadone)

Answer 10

Treats: PHN; moderate outcome; physical tolerance, psychological dependence; MOA: opioid receptor

Question 11

Topical Agents (capsaicin, lidocaine)

Answer 11

Treats: PHN, CRPS Iⅈ moderate outcome; acute discomfort; MOA: reversible sensory nerve terminal degeneration (inhibit substance P), Na+ channel blocker;adhesive patches

Question 12

Vaccination

Answer 12

PHN; excellent outcome; preventative measure

Question 13

Steroids- oral prednisone

Answer 13

CRPS Iⅈ excellent outcome; elelvated blood glucose, depression, anxiety; synthetic corticosteroid immunosuppressant

Question 14

Lacosamide, alfinamide

Answer 14

Neuropathic pain; very good outcome; no side effects; MOA: nonselective Na+ channel blockers