Neuromuscular Flashcards Preview

AS - N935 Advanced Patho II > Neuromuscular > Flashcards

Flashcards in Neuromuscular Deck (66)
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1
Q

Upper Motor Neurons

A

Cerebral cortex → ventral motor horn
Direct, influence, & modify reflex arcs
Form synapses w/ interneurons & lower motor neurons before projecting to periphery

2
Q

Corticospinal Tract

A

Motor transmission
Receives information from sensory cortex
AP to 1° motor neuron
Synapses w/ 2° efferent motor neuron
Decussates at medulla & travels down the spinal cord via the anterolateral tract
2° motor nerve synapses w/ 3° efferent motor neuron at ventral horn
3° (lower motor neuron) projects down to the skeletal muscle

3
Q

Corticobulbar Tract

A

Cranial nerves
Bilaterally III, IV, VI, IX, X, XI
Unilateral facial VII & hypoglossal XII
Involved in precise motor movements

4
Q

Lower Motor Neurons

A

Neurons located in brain stem & spinal cord
Direct influence on muscles
Send axons into PNS to synapse one & control skeletal muscle cells
Lower motor neurons that pass through the spinal nerves 1° control limb & trunk muscles
Pass through cranial nerves 1° control the head & neck skeletal muscles

5
Q

NMJ

A

Neuromuscular junction
AP initiates synaptic transmission
Na+ channels depolarize the axon terminal membrane
Depolarization causes VGCa2+ channels to open
ACh diffuses across the synaptic cleft & binds to receptors on postsynaptic membrane
Depolarizes post-synaptic AP
ACh uptake to resynthesize/recycle

6
Q

Upper Motor Lesions

A
Motor cortex
Muscle groups are affected
 Mild weakness
Minimal diffuse muscle atrophy
No fasciculations
↑muscle stretch reflex
Hypertonia & spasticity
Pathological reflexes
7
Q

Lower Motor Lesions

A
Ventral horn (spinal cord) & motor nuclei (brainstem)
Individual muscles affected
Mild weakness
Severe muscle atrophy
Fasciculations
↓muscle stretch reflex
Hypotonia & flaccidity
- Babinski sign
8
Q

Upper Motor Neuron Disorders

A
Cerebral palsy
Multiple sclerosis
CVA
Parkinson's
Huntington's
9
Q

Cerebral Palsy

A

Non-progressive disorder caused by injury or abnormal development in the immature brain
Before, during, or after birth up to 1yo
Damage or defects in the corticospinal pathway

10
Q

CP S/S

A
Muscle weakness
Loss fine motor control
Impaired speech
Drooling
Exaggerated deep tendon reflexes
Spasticity
Extremity rigidity
Scoliosis, contractures, joint dislocation
Vision or hearing impairment
Swallowing problems
Seizures
Intellectual disability
Reflux disease
11
Q

CP Treatment

A
No cure
↑ADLs
Surgery (ortho, dental, general, ophthalmology, ENT)
- Dorsal rhizotomy
- Antireflux operation
- Intrathecal baclofen pump
Botulinum toxin
PT/OT
12
Q

CP Anesthetic Considerations

A
Hold preop sedative
Caution w/ opioids
Difficult vascular access
Airway concerns d/t dentition, secretions, TMJ, ankylosis, & contractures
Potential RSI
Succinylcholine does not ↑K+ release
Cautious NDMR admin
↓MAC 20-30%
Prone to bleeding, hypothermia, & intravascular depletion
Slow emergence
13
Q

Multiple Sclerosis

A

Autoimmune disease characterized by combination demyelination, inflammation, & CNS axonal damage
Peripheral nerves not affected

14
Q

MS S/S

A
Parethesias (face, arms, fingers, legs)
Muscle weakness/fatigue
Painful muscle spasms
Visual problems (optic neuritis & diplopia)
Autonomic instability
Bulbar muscle dysfunction
Cognitive dysfunction (advanced MS)
15
Q

MS Treatment

A
↓spasticity, tremors, bladder spasms
Diazepam
Dantrolene
Baclofen
Glucocorticoids
Immunosuppressants
CD20 monoclonal antibody - interferon B1a of glatiramer acetate

S/S exacerbated by stress, ↑body temp, infection, hyponatremia

16
Q

MS Anesthetic Considerations

A
AVOID SUCCINYLCHOLINE
Caution w/ NDMR admin
Avoid surgery during flare
Avoid spinal block
Epidurals safe
Aspiration risk
↑risk DVT
Stress-dose steroids
Exaggerated hypotensive effects
17
Q

Cerebrovascular Accident

A

Stroke characterized by sudden neurologic deficits resulting from ischemia 88% or hemorrhage 12%

18
Q

CVA S/S

A

Anterior cerebral artery - contralateral leg weakness
Middle cerebral artery - contralateral hemiparesis & sensory deficit (face/arms > legs), aphasia, contralateral visual field defect
Posterior cerebral artery - contralateral visual field defect & hemiparesis
Penetrating arteries - contralateral hemiparesis & contralateral hemisensory deficits
Basilar artery - oculomotor deficits and/or ataxia & crossed sensory & motor deficits
Vertebral artery - lower cranial nerve deficits & ataxia w/ crossed sensory deficits

19
Q

CVA Treatment

A

Aspirin
TXA (IV admin or VIR direct infusion)
Surgery (crani/cerebellar resection)

20
Q

CVA Anesthetic Considerations

A

Aspiration & DVT risk
Maintain blood glucose
Blood pressure maintenance

21
Q

Parkinson’s Disease

A

Neurodegenerative disorder
Unknown cause
Loss dopaminergic fibers in the basal ganglia
Regional dopamine concentrations are also depleted
Results in diminished neuron inhibition controlling the extrapyramidal motor system & unopposed ACh stimulation

22
Q

Parkinson’s S/S

A

Skeletal muscle rigidity (pill-rolling) - more prominent during rest & disappears during voluntary movement
Rigidity
Akinesia - loss voluntary movement
Diaphragmatic spasms
Dementia
Depression
Facial immobility (infrequent blinking & paucity emotional expressions)

23
Q

Parkinson’s Treatment

A
Levidopa - dopamine precursor
Carbidopa - peripheral dopa decarboxylase inhibitor
Amantadine 
Selegline & Rasgiline
Rpinirole - dopamine agonist
Entacapone - COMT inhibitor
Donepezil & Taurine - AChEi
Amatadine - antiviral
24
Q

Parkinson’s Anesthetic Considerations

A
Continue Levidopa therapy
Aspiration/airway risk
Hypertension
Post-extubation laryngospasm
Avoid benzodiazepines
Ideal volatile agent = Sevoflurane
NDMB less effective
Use Sugammadex
Avoid indirect-acting NT releaser (Ephedrine)
Hypotension & cardiac dysrrhythmias
25
Q

Huntington’s Disease

A

DNS degenerative disease characterized by marked caudate nucleus atrophy & putamen & globus pallidus to lesser degree
Autosomal dominant

26
Q

Huntington’s S/S

A

Progressive dementia
Chorea (involuntary jerking or writhing movement)
Tremors
Rigidity & contractures
Depression, aggressive outburst, mood swings
Difficulty w/ speech & swallowing

27
Q

Huntington’s Treatment

A

Treat the choreiform movements
Antidepressants (Haldol)
Physical, occupational, & speech therapy

28
Q

Huntington’s Anesthetic Considerations

A
Aspiration risk → RSI
Prolonged response to Succinylcholine
Sensitive to NDMR
Avoid anticholinergics & Reglan
Glycopyrrolate > Atropine
29
Q

Lower Motor Neurons Disorders

A
Myasthenia gravis
Lambert-Eaton
Muscular dystrophy
Myotonic dystrophy
Mitochondrial disorders
Guillain-Barre
Spinal muscular atrophy
30
Q

Myasthenia Gravis

A

Autoimmune destruction IgG antibodies against nAChR
Inactivation postsynaptic ACh receptors at NMJ
↓receptors & function degradation
complement-mediated damage to postsynaptic end plate

31
Q

MG S/S

A
Diploplia & ptosis
Fluctuating fatigue & weakness that improves after rest
Mouth & throat muscle weakness
Dyspnea w/ exertion
Proximal muscle weakness
32
Q

MG Treatment

A
Cholinesterase inhibitor (Pyridostigmine)
Plasmapheresis
Corticosteroids
Immunosuppressants & immunoglobins
Thymectomy

S/S exacerbated by pregnancy, infection, electrolyte imbalance, surgical & psychological stress, aminoglycoside antibiotics

33
Q

MG Anesthetic Considerations

A
Aspiration risk
Sensitive to NDMR
Regional preferred (amide LAs)
Avoid block > mid thoracic or interscalene or supraclavicular block d/t phrenic nerve paralysis
RESISTANT to  Succinylcholine 2mg/kg
DOA ↑5-10min
34
Q

Lambert-Eaton

A

Pre-synaptic defect
Antibodies attach to voltage-gated Ca2+ channels on the nerve terminal
↓ACh release at the motor end plate
Affects males > females

35
Q

LEMS S/S

A

Proximal muscles 1° affected
Weakness generally worse in the morning & improves throughout the day
Respiratory & diaphragm muscles become weak
ANS dysfunction
- Orthostatic hypotension
- Delayed gastric motility
- Urinary retention

36
Q

LEMS Treatment

A
3,4 DAP
Guanidine hydrochloride
Corticosteroids
Immunosuppressants
Plasmapheresis
37
Q

LEMS Anesthetic Considerations

A

Sensitive to Succinylcholine & NDMR
Inadequate reversal w/ AChE
High risk postop respiratory failure
60% small cell carcinoma

38
Q

Duchenne Muscular Dystrophy

A
X-linked recessive disorder
Results from abnormal protein dystrophin production
Affects males > females
Presents between 3-5yo
Rarely live past 30yrs
39
Q

Duchenne MD S/S

A

Symmetric proximal muscle weakness manifested as gait disturbance “Gower sign”
Fatty infiltration typically causes muscle enlargement (particularly the calves)
Kyphoscoliosis
Respiratory muscle weakness
Cardiac muscle degeneration
Impaired GI hypo-motility, airway reflexes, &cardiac conduction
Cognitive impairment
Pulmonary HTN

40
Q

Becker Muscular Dystrophy

A

X-linked recessive disorder
Partial dystrophin
Less common than Duchenne

41
Q

Becker MD S/S

A
Present later in life (adolescence)
Disease progresses more slowly
Less severe
Intellectual disability less common
Proximal muscle weakness
Prominent calf pseudohypertrophy
Cardiac muscle degeneration
Death r/t respiratory complications
42
Q

MD Diagnosis

A

Genetic testing
↑CK levels
Muscle biopsy (rare)

43
Q

MD Treatment

A
Surgery
Physical therapy
Steroids delay disease progression
Biphosphates
Mystatin inhibitors
Gene modification
Protease inhibitors
Stem cell infusions
44
Q

MD Anesthetic Considerations

A

Pre-anesthesia testing PFTs, echo, EEG, sleep apnea study
Avoid Succinylcholine & volatile anesthetics
Malignant hyperthermia syndrome characterized by rhabdomyolysis & hyperkalemia
Avoid preop w/ benzodiazepines & opioids
Positioning complications d/t kyphoscoliosis
Sensitive to NDMR - prolonged DOA
Local & regional anesthesia preferable
Aspiration risk

45
Q

Myotonic Dystrophy

A

Hereditary skeletal muscle degenerative disease
Results in dysfunctional Ca2+ sequestration by SR
Na+ & Cl¯ channel dysfunction

46
Q

Myotonic Dystrophy S/S

A

Weakness - facial, thoracic, intercostal, diaphragm, sternocleidomastoid, & distal limb
Inability to release/relax hand grip (myotonia)
Cardiomyopathy
Conduction defects 1st degree AV block
Dysphagia & slowed gastric emptying
Endocrine dysfunction
Central sleep apnea
Ptosis
Males (triad) - frontal balding, cataracts, & testicular atrophy

47
Q

Myotonic Dystrophy Treatment

A
Procainamide
Phenytoin
Mexiletine
Baclofen
Dantrolene
Carbamazepine
Cardiac pacemaker
48
Q

Myotonic Dystrophy Anesthetic Considerations

A

Avoid Succinylcholine
Aspiration risk
Volatile anesthetics may produce exaggerated myocardial depression
High volatile anesthetic concentrations potential to abolish myotonia
Questionable d/t association w/ MH
Anesthesia & surgery could aggravate cardiac conduction problems via ↑vagal tone
Neostigmine & Physostigmine aggravate myotonia
Sensitive to respiratory depressant
Maintain normothermia & avoid shivering
PFTs & EKG
Transthoracic pacing readily available

49
Q

Mitochondrial Disorder

A

Heterogenous groups
Skeletal muscle energy metabolism disorders
Mitochondria produce energy required by skeletal muscle cells through the oxidation-reduction reactions of the electron transport chain & oxidative phosphorylation → ADP

50
Q

Mitochondrial Disorder S/S

A

Abnormal fatigue w/ sustained exercise
Skeletal muscle pain & progressive weakness
Hearing loss & impaired vision
Balance & coordination problems
Seizures
Learning deficits
Organ problems - heart, liver, kidney, brain

51
Q

Mitochondrial Disorder Treatment

A
Symptomatic
Admin metabolites & cofactors
Sodium bicarbonate
Dichloroacetate
Ketogenic diet
52
Q

Mitochondrial Disorder Anesthetic Considerations

A
Prone to acidosis & dehydration
Lactate level (avoid LR)
Avoid continuous infusion Propofol
Avoid Succinylcholine 
Maintain normothermia
Use NDMR & LAs w/ caution
Avoid Bupivacaine
Avoid prolonged tourniquets
53
Q

Guillain-Barre

A

Immunologic assault on myelin in the peripheral nerves particularly lower motor neurons
AP unable to be conducted
Motor endplate does not receive the incoming signal
Upward progression 2wks
Full recovery 4wks w/ some permanent paralysis remaining

54
Q

Guillain-Barre S/S

A
Flaccid paralysis 
Begins in distal extremities & ascends bilaterally
Intercostal muscle weakness
Facial & pharyngeal weakness
Sensory deficits
Autonomic dysfunction common
Cognition intact
55
Q

Guillain-Barre Treatment

A

Plasmapheresis
IVIG
Steroids not useful

56
Q

Guillain-Barre Anesthetic Considerations

A
Avoid Succinylcholine
NDMR sensitivity
↑DVT risk
Aspiration risk
Exaggerated response to indirect sympathomimetics (A-line)
Assess Na+ levels
Slow position changes
Avoid barbiturates → CV depression (autonomic dysfunction)
Postop ventilation
57
Q

Spinal Muscular Atrophy

A

Deletions or mutations in survival motor neuron gene on chromosome 5q13
SMN gene involved in RNA complex formation & trafficking out nucleus
Loss SMN function promotes apoptosis lower motor neurons - affects anterior spinal cord horn

58
Q

SMA Type I

A
Most severe
Infantile spinal muscular atrophy
Autosomal recessive disorder
Manifests w/in 3mos
Rapidly progressive leading to death from respiratory complications usually by age 3

Difficulty sucking, swallowing, breathing, atrophy & fasciculation in tongue & limb muscles

59
Q

SMA Type II

A

Autosomal recessive inheritance
Begins 6mos-1yo
Progressive more slowly than infantile form
Able to survive into adulthood

60
Q

SMA Type III

A

Juvenile form
Develops after age 2

Weakness proximal limb muscles w/ relative sparing bulbar muscles (cranial nerves)

61
Q

SMA Treatment

A
Spinraza
Zolgensma 2019
Evrysdi 2020
PT
Surgery
Antibiotics
62
Q

SMA Anesthetic Considerations

A

Pulmonary consultation
Difficult intubation d/t secretions, muscle weakness, contractures, & aspiration risk
Avoid Succinylcholine
Varying sensitivity to NDMR (longer DOA)
Regional controversial - neuraxial difficult/unreliable
Cautious w/ opioids
Postop respiratory support

63
Q

Amyotrophic Lateral Sclerosis

A

Mixed motor neuron disease - upper & lower motor
Rapidly progressive motor neuron degeneration in corticospinal tract (1° descending upper motor neurons) & lower motor neurons in anterior spinal cord gray matter
Astrocytic gliosis replaces the affected motor neurons

64
Q

ALS S/S

A
Spasticity
Hyperreflexia & loss coordination
Muscle weakness
Fasciculations
Atrophy often begins in hands
Orthostatic hypotension
Resting tachycardia
Sensation remains intact
Cognition WNL
Bladder & bowel function not typically affected
65
Q

ALS Treatment

A
Riluzole (NDMA receptor antagonist)
- Only drug that reduces mortality
Edaravone ↓ADLs decline
Spasmolytics
Analgesics
66
Q

ALS Anesthetic Considerations

A
Avoid Succinylcholine
Hyperkalemia risk
↑NDMR sensitivity
Aspiration risk
Consider postop mechanical ventilation
↑sensitivity to respiratory depressants
Autonomic dysfunction w/ hemodynamic instability risk (A-line)
Avoid spinal anesthesia d/t demyelination
Induction → PEA