- Increasing skeletal muscle weakness - Fatigue of muscles with effort - Partial restoration of strength/function with rest

Exam IV: Myasthenia Gravis Flashcards by Linsley Lloyd

Chronic disease of _____ _____ (____)
Most _____ neuromuscular disorder

neuromuscular junction (nmj)
prevalent

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Ranges ___-____ per 1,000,000 people

3-30

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If <50, more _____ than ____ (3:2)
Common in ____

women than men
elderly

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Manifested by: (3)

Increasing skeletal muscle weakness
Fatigue of muscles with effort
Partial restoration of strength/function with rest

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Decreased # of working ACh receptors _______; ________ ACh pool is normal

postsynaptically
prejunctional

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_____ found in 80-85% of MG patients

Antibodies

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Unknown promotion production of ___ antibodies—_____ gland seems to play central role
*______ improves symptoms, not curative

IgE
Thymus
Thymectomy

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Only a _____ disease - intact sensation, ANS, and cognition

MOTOR

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Increased prevalence in those living close to the ______

equator

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**Decreased # of working ACh receptors _______; ________ ACh pool is all normal.

postsynaptically
Pre-junctional

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Hallmark: _____ _____ that improves with rest; inability to sustain/repeat _____ _____

Generalized weakness
muscular contractions

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more movement =

more weakness

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Wide range of symptoms — slight ptosis —–> ____ ____

respiratory failure

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Eyes, mouth, pharynx, proximal limb, and shoulder girdle muscles =

most often affected

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MG exacerbated in 33% of pregnant women with MG, can produce ______________________ (less than 20%)

transitory symptoms in newborns

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Exacerbated by:

surgery, electrolyte imbalances, some medications

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treatment: ______ inhibitors - (4)

*Pyridostigmine
*(60mg, tid= 2mg IV)
*Immunosuppressants
*Thymectomy
*Plasmapheresis

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CHOLINERGIC CRISIS
overdosing of anticholinesterase
Sx: ______ stimulation - excessive ____, _____, _____, ______, _____. Weakness and ____ _____

Muscarinic stimulation: excessive salivation, diarrhea, excessive tearing, bradycardia, miosis
respiratory failure

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MYASTHENIC CRISIS
_______ of anticholinesterase
Sx: pupils ______, ______, etc. Weakness and _____ _____.

Underdosing
Pupils normal size, ptosis, etc.
Weakness and respiratory failure

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Anesthesia Implications

Evaluate–disease controlled? anticholinesterase dose stable? –> ___ ____ and ____ ____ surgery

sev days
right before

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if meds taken DOS - (3)

increased vagal reflex
interferes with muscle relaxants
inhibits plasma cholinesterase

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if dose withheld and if disease is advanced/possible deterioration (2)

have aspiration risk
at risk for respiratory failure

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Review electrolytes and correct if needed
Hypokalemia can _____ _____ _____

potentiate muscle weakness

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When developing plan of care, must consider:

Pharyngeal/laryngeal muscle weakness
Oral secretions—difficulty eliminating
Increased risk of pulmonary aspiration

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_____ 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

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 -

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

Exam IV: Myasthenia Gravis Flashcards

(98 cards)