Exam IV: Myasthenia Gravis Flashcards
Chronic disease of _____ _____ (____)
Most _____ neuromuscular disorder
neuromuscular junction (nmj)
prevalent
Ranges ___-____ per 1,000,000 people
3-30
If <50, more _____ than ____ (3:2)
Common in ____
women than men
elderly
Manifested by: (3)
- Increasing skeletal muscle weakness
- Fatigue of muscles with effort
- Partial restoration of strength/function with rest
Decreased # of working ACh receptors _______; ________ ACh pool is normal
postsynaptically
prejunctional
_____ found in 80-85% of MG patients
Antibodies
Unknown promotion production of ___ antibodies—_____ gland seems to play central role
*______ improves symptoms, not curative
IgE
Thymus
Thymectomy
Only a _____ disease - intact sensation, ANS, and cognition
MOTOR
Increased prevalence in those living close to the ______
equator
**Decreased # of working ACh receptors _______; ________ ACh pool is all normal.
postsynaptically
Pre-junctional
Hallmark: _____ _____ that improves with rest; inability to sustain/repeat _____ _____
Generalized weakness
muscular contractions
more movement =
more weakness
Wide range of symptoms — slight ptosis —–> ____ ____
respiratory failure
Eyes, mouth, pharynx, proximal limb, and shoulder girdle muscles =
most often affected
MG exacerbated in 33% of pregnant women with MG, can produce ______________________ (less than 20%)
transitory symptoms in newborns
Exacerbated by:
surgery, electrolyte imbalances, some medications
treatment: ______ inhibitors - (4)
*Pyridostigmine
*(60mg, tid= 2mg IV)
*Immunosuppressants
*Thymectomy
*Plasmapheresis
CHOLINERGIC CRISIS
overdosing of anticholinesterase
Sx: ______ stimulation - excessive ____, _____, _____, ______, _____. Weakness and ____ _____
Muscarinic stimulation: excessive salivation, diarrhea, excessive tearing, bradycardia, miosis
respiratory failure
MYASTHENIC CRISIS
_______ of anticholinesterase
Sx: pupils ______, ______, etc. Weakness and _____ _____.
Underdosing
Pupils normal size, ptosis, etc.
Weakness and respiratory failure
Anesthesia Implications
Evaluate–disease controlled? anticholinesterase dose stable? –> ___ ____ and ____ ____ surgery
sev days
right before
if meds taken DOS - (3)
increased vagal reflex
interferes with muscle relaxants
inhibits plasma cholinesterase
if dose withheld and if disease is advanced/possible deterioration (2)
have aspiration risk
at risk for respiratory failure
Review electrolytes and correct if needed
Hypokalemia can _____ _____ _____
potentiate muscle weakness
When developing plan of care, must consider:
Pharyngeal/laryngeal muscle weakness
Oral secretions—difficulty eliminating
Increased risk of pulmonary aspiration
_____ and _____ muscle dysfunction accounts for much of morbidity of MG
Swallowing and respiratory
_____ or _____ anesthesia preferred
Regional or local
If GA — _____ _____ may decrease muscle tone enough for intubation; may not need muscle relaxants
inhalational agents
Sensitive to ______ NMBA (roc, vec, etc)
nondepolarizing
Reverse MR cautiously to avoid “____ ____”; sugammadex ___ -____ mg/kg if available
cholinergic crisis
2-4
Assess NM blockade at _____ _____ muscle; may overestimate degree of relaxation, but best place to avoid undetected residual weakness
orbicularis oculi
Post Op-EVALUATE FULLY!!!
Muscle strength seems adequate in _____ stages of recovery then can deteriorate ___________ later
early
a few hours
Predictors that post op ventilation may be needed:
transsternal thymectomy
having disease > 6 years
daily pyridostigmine dose > 750 mg
COPD
preop VC <2.9L
Succinylcholine (Sch)
If patient not treated, then ____ to Sch (maybe even 2-3x more _____)
RSI-dose is ___-___ mg/kg vs 1-1.5 mg/kg
resistant
resistant
1.5-2
Succinylcholine (Sch)
If patient on cholinesterase inhibitors, effects of Sch (and _____ local anesthetics) may be _____ (no hydrolysis/breakdown and it lingers)
ester
prolonged
Non-depolarizers (NDMR)
_____ dose or ____
(could be ___-___x more sensitive)
Decrease
avoid
10-100
NDMR - If needed, the use of ____ doses
(____-____ the dose of normal) of shorter acting NDMR is a wiser choice
small
1⁄2-2⁄3
NDMR - Better to titrate dose to allow for _____ _____ than to have to reverse
spontaneous recovery
CAUTION
May produce worsening myasthenic weakness:
- Quinine, quinidine, and procainamide
- Antibiotics: aminoglycosides(gent,neomycin,etc) quinolones (ciprofloxacin,levofloxacin,etc), and macrolides (erythromycin, azithromycin)
- Beta blockers-systemic and ocular
- Calcium channel blockers
- Mag salts (including laxatives with high Mg2+)
- Iodinated contrast
Anticholinesterases - ?impair hydrolysis of ester LA causing prolonged block; _____ _____ of LA appropriate (Lidocaine, Bupiv, Ropiv)
amide class
Lambert-EatonMyasthenic Syndrome (LEMS)
____/____ disorder
Usually occurs in those with _____ -especially those with small cell Ca of bronchi
Rare/autoimmune
malignancy
Lambert-EatonMyasthenic Syndrome (LEMS)
___-___ of people show no evidence of Ca
Most patients = ____ b/t 50 and 70
1/3-1/2
men
Lambert-EatonMyasthenic Syndrome (LEMS)
Seems that the _____ _____ channels are messed up via autoantibodies
presynaptic Ca++
Lambert-EatonMyasthenic Syndrome (LEMS)
Reduction in Ca++ mediated exocytosis of ____ at _____
ACh at nmj
Lambert-EatonMyasthenic Syndrome (LEMS)
Post-junctional AChRs are ______ - unlike _____
unaffected
MG
Lambert-EatonMyasthenic Syndrome (LEMS)
Similar to that of ______ toxicity or _____ poisoning
Mg++
botulism
Clinical Manifestations - LEMS
main features:
- muscle weakness
- fatigue
- hyporeflexia
- proximal limb muscle aches
Clinical Manifestations - LEMS
____ and ____ muscles involved
Diaphragm and resp
Clinical Manifestations - LEMS
Autonomic nervous system dysfunction leads ______ hypotension, impaired gastric _____, _____ retention
orthostatic
motility
urinary
Clinical Manifestations - LEMS
Brief _____ in strength with voluntary contraction
INCREASE
Clinical Manifestations - LEMS
_____ leads to progressive strengthening of muscle
Tetany
LEMS - treatment
No _____
cure
LEMS - treatment
goal is to improve _____ _____, decrease _____ deficits
muscle strength
ANS
LEMS - treatment
__________ — helps some people b/c improves Ca+ influx, thus increasing amt of ACh released
3, 4-Diaminopyridine
LEMS - treatment
_______, _______, IV ________, immunosuppressants help some patients
Plasmapheresis, corticosteroids
immunoglobulin
LEMS - Anesthesia Implications
Must be suspected in patients with hx of _____ ______ and suspected dx of ____ of the lung
muscle weakness
cancer
LEMS - Anesthesia Implications
VERY sensitive to both ______ and ______
depolarizing and NDMR
LEMS - Anesthesia Implications
May use just inhalational agents alone for _____ _____
tracheal relaxation
LEMS - Anesthesia Implications
Can use ______ to reverse
anticholinesterase
LEMS - Anesthesia Implications
Possible to require post op ______/______, must discuss PREOP!
intubation/ventilation
Myotonic Dystrophy
All the “myotonias” have the inability of skeletal muscles to _____ after ______ (chemical or physical)
relax after stimulation
Myotonic Dystrophy
Also called “_____ _____”—is multisystem disease
Steinert’s disease
Myotonic Dystrophy
Skeletal muscles are hypoplastic, dystrophic, and weak — yet ______ _____
persistently contract
Myotonic Dystrophy
Usually occurs ___-___ years old
20-30
Myotonic Dystrophy
Slow, progressive deterioration of ____ _____ ____
all muscle groups
Patho and Tx-Myotonic Dystrophy
Myotonia = persistent _____ of muscle after ______; early in disease
contracture
stimulation
Patho and Tx-Myotonic Dystrophy
Made worse by ____ and _____, warming room temp is helpful
cold and shivering
Patho and Tx-Myotonic Dystrophy
_____, ______, ______ are used to treat myotonic contractures, They delay return of membrane excitation — blocks ____ _____
Phenytoin, procainamide, tocainide
Na+ influx
Patho and Tx-Myotonic Dystrophy
____ do NOT HELP
NDMR
Patho and Tx-Myotonic Dystrophy
____ _____ available for the muscle weakness
NO treatment
MD clinical manifestations:
- Hypoplastic, weak skeletal muscles of face and neck
- Hypersomnolent; Sleep apnea
MD clinical manifestations: Cardiac
- 50-90% have conduction defects
- 1st degree AV block is most common
- Also see bradycardia, atrial flutter/fib
MD clinical manifestations: Respiratory
- Pharyngeal and resp muscle weakness
- Restrictive type impairment
MD clinical manifestations: Gastrointestinal
Intestinal hypomotility; gastric atony
MD Anesthetic Implications:
Abnormal _____ makes them vulnerable to pulm _____
swallowing
aspiration
MD Anesthetic Implications:
AVOID
hypothermia/shivering
MD Anesthetic Implications:
preop ____ and close intraop monitoring
EKG
MD Anesthetic Implications:
_____ — good choice; doesn’t prevent contractures
RA
MD Anesthetic Implications:
Avoid succinylcholine; NDMR are ok but recognize/remember ____ ____
muscle wasting
MD Anesthetic Implications:
be gentle with ____ and careful _____
airway
positioning
Duchenne’s Muscular Dystrophy
Progressive, ______ degeneration and ______ of muscle fibers
painless
necrosis
Duchenne’s Muscular Dystrophy
Pelvic girdle and muscle of thighs affected _____
1st
calf is where its seen first but these are where you notice that something is truly wrong
Duchenne’s Muscular Dystrophy
Mutant gene identified on “X” chromosome in 1987; Error in coding “_____” protein
Duchenne’s – _____ ____
(Becker’s - ______ levels)
dystrophin
no dystrophin
decreased
Duchenne’s Muscular Dystrophy
X-linked ______ — occurs in _____
recessive
males
Duchenne’s Muscular Dystrophy
1 in _____ male births
Most _____ and most _____ of dystrophies
3500
common
severe
DMD-Pathophysiology
Painless and progressive degeneration due to ______ of _____ and ______ tissue in the muscle
*first seen in ____ muscle
infiltration of fat and fibrous
calf
DMD-Pathophysiology
Skeletal muscle-degeneration of _____ _____
respiratory muscles
DMD-Pathophysiology
Cardiac muscle - cardiomyopathy, mitral _____, _____ dysrhythmias
EKG changes - tall R waves (rt) and deep Q waves (left)
Limited activity ____ _____ underlying ____-____ condition
regurg
ventric
may mask
cardio-pulm
DMD-Pathophysiology
smooth muscle -
GI
DMD - ______ sign
Gower’s
Gower’s Sign:
Presents _________
Wheelchair by ________
Death _______
- presents early - 2 to 6 year old
- wheelchair by 12
- death usually in late teens, early adulthood (pneumonia or CHF)
DMD AIs:
_____/_____ anesthesia = ideal; TIVA
Local/regional
DMD AIs:
chronic _____ — be sure to cover during surgery
steroids
DMD AIs:
Opioids, sedatives, GA, patient very sensitive; use ____ _____ possible
smallest amount
DMD AIs:
Careful titration/monitoring with NDMR - _____ effect (___-___ ____)
prolonged
3-6x longer
DMD AIs:
_______ is contraindicated!
Succinylcholine (think MH type symptoms)
DMD AIs:
Carefully titrate fluids d/t risk of _____
CHF (micro drip)
DMD AIs:
______ + ______ = heart failure
Hypotension + tachycardia
DMD AIs:
aspiration risk - consider _____
NGT