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N935 Pathophysiology > Neuromuscular Disorders > Flashcards

Neuromuscular Disorders Flashcards

1
Q

upper motor neurons are contained in ______ and begin/end where?

A

contained within the CNS and begin in the cerebral cortex/end in vertebral horn of spinal cord

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2
Q

corticospinal tract
supplies
originates in
goes through which parts of brain

A

supplies voluntary muscles of trunk and extremities
originates in precentral gyrus
goes through internal capsule, midbrain, pons

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3
Q

corticospinal tract decussation details

A

75-90% decussate in medulla and form lateral corticospinal tract.
10-25% that do no decussate in medulla make up ventral corticospinal tract and travel to spinal cord. cross over before synapsing with lower motor neurons

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4
Q

corticospinal synapse with

A

spinal nerves

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5
Q

corticobulbar tract
supplies
originates in
involved in what kind of movements

A

supply voluntary muscles of head and follow corticospinal tract until they reach brainstem
originate in precentral gyrus next to lateral fissure of sylvius
precise motor movements

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6
Q

corticobulbar tract innervates these cranial motor nuclei bilaterally

A

3, 4, 6, 9, 10, 11

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7
Q

corticobulbar tract innervates these cranial motor nuclei unilaterally

A

7 (facial), 12 hypoglossal)

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8
Q

steps to neuromuscular junction synapses

A
  1. action potential arrives and initiates synaptic transmission
  2. sodium channels open, depolarizing axon terminal membrane
  3. depolarization of the terminal membrane causes VgCa channels to open
  4. calcium centers the cells and triggers fusion of Ach vesicles with presynaptic membrane
  5. Ach molecules diffuse across synaptic cleft and bind to receptors on postsynaptic membrane
  6. Ach receptors open chemically gated channels and depolarize postsynaptic membrane. this spreading depolarization fires an AP in postsynaptic membrane
  7. Ach in synaptic cleft is broken down by the enzyme acetylcholinesterase and the compounds are taken back up by the presynaptic cell for resynthesis
  8. after synaptic transmission, Ach and vesicles are recycled
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9
Q

where are lower motor neuron problems usually located

A

neuromuscular junction

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10
Q

upper motor neuron lesions (corticospinal, corticobulbar) sx

A 
muscle groups are affected
mild weakness
minimal disuse muscle atrophy 
no fasciculations
increased muscle stretch reflex
hypertonia, spacticity
pathological reflexes (positive babinski sign, toes flare out)
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11
Q

type of cells and location of upper motor neurons

A

pyramidal cells, motor cortex

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12
Q

lower motor neuron lesions sx

A 
individual muscles may be affected
mild weakness
marked muscle atrophy
fasciculations
decreased muscle stretch reflex
hypotonia, faccidity
negative babinski sign
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13
Q

lower motor neurons are located in these two areas

A

ventral horn (spinal cord) and motor nuclei (brainstem)

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14
Q

lower motor neuron diseases that involve the bulbar region

A

bulbar palsies

ALS

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15
Q

lower motor neuron diseases that involve the myoneural junction

A

MG

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16
Q

5 diseases that involve upper motor neurons

A 
cerebral palsy
multiple sclerosis
CVA
parkinsons
huntingtons
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17
Q

cerebral palsy definition

A

non progressive DO caused by injury or abnormal development in immature brain before, during, or after birth up to 1 year of age. damage or defects in corticospinal pathway

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18
Q

s/sx of CP (varies alot)

A

muscle weakness, loss of fine motor control
impaired speech
drooling
exaggerated deep tendon reflexes
spacticity
rigidity of extremities
scoliosis, contractures, joint dislocation (can get worse as they age)

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19
Q

CP associated problems

A 
vision and hearing impairment
swallowing problems
seizures 
intellectual disability
reflux disease
abnormal pain perceptions
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20
Q

CP treatment

A 
surgical (ortho, dental, general, opthomalogy, ENT)
dorsal rhizotomy
anti reflux operation
intrathecal baclofen pumps
botulinum toxin
PT OT ST
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21
Q

dorsal rhizotomy for CP

A

tx muscle spasticity, cut nerves at root

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22
Q

botulinum toxin for CP

A

prevent release of Ach in NMJ to decrease spasticity

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23
Q

CP anesthesia considerations

A

hold preop sedatives and cautious with opioids (give short acting)
difficult vascular access (dehydrated, contracted)
difficult airway (dentition, secretions, TMJ ankylosis, contractures)
consider RSI*
succ does not produce risk of K increase but weight risk/benefit
cautious admin of NDMR (may be on anticonvulsants, resistant to NDMR’s)
decrease MAC need (20-30%)
prone to bleeding, hypothermia, intravascular depletion
slow emergences
careful with positioning (some may have scoliosis)

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24
Q

MS definition

A

autoimmune disease characterized by combination of demyelination, inflammation, and axonal damage of CNS. peripheral nerves are not affected. T cell mediated autoantibodies, demyelination. exacerbation and remission.

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25
Q

s/sx of MS

A 
paresthesias (face, legs, arms, fingers)
visual problems (optic neuritis and diplopia)
muscle fatigue, weakness
autonomic instability
cognitive dysfunction (advanced stages)
painful muscle spasms
bulbar muscle dysfunction
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26
Q

MS includes which pathways

A

somatic motor
somatic sensory
autonomic
higher brain neurons

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27
Q

MS spares which nerves

A

peripheral

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28
Q

MS tx

A

decrease spasticity, tremors, bladder spasticity
diazepam, dantrolene, baclofen
glucocorticoids
immunosuppressants
CD20 monoclonal antibody interferon B1a or glatiramer acetate

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29
Q

situations that may exacerbate sx of MS

A

stress
increase body temperature
infection
hyponatremia

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30
Q

MS anesthetic considerations

A 
avoid succ, scopolamine, atropine
NDMR: use cautiously
surgery avoided during flare
avoid spinal block
epidural safe to use
aspiration risk
increase risk of DVT
stress dose steroids
exaggerated hypotensive effects
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31
Q

CVA to anterior cerebral artery sx

A

contralateral leg weakness

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32
Q

CVA to middle cerebral artery sx

A

contralateral hemiparesis and hemisensory deficit (face and arm > leg)
aphasia
contralateral visual field deficit

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33
Q

CVA to posterior cerebral artery sx

A

contralateral visual field deficit and hemiparesis

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34
Q

CVA to penetrating arteries sx

A

contralateral hemiparesis

contralateral hemisensory deficits

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35
Q

CVA to basilar arteries sx

A

oculomotor deficits and/or ataxia

crossed sensory and motor deficits

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36
Q

CVA to vertebral artery sx

A

lower cranial nerve deficits

and/or ataxia with crossed sensory deficits

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37
Q

CVA tx

A

aspiring
TPA
surgery (crani/cerebellar resection)

38
Q

anesthesia considerations for CVA

A

aspiration risk
DVT risk (bridging pt on anticoagulant therapy)
BG maintenance 20% of baseline
BP maintenance (dont rapidly drop BP. keep pressure up until revascularization where the surgeon will give you a range)
regional/MAC- reduce incidence of CVA
dysphagia may incite FVD
ASA theapy

39
Q

CVA and coming back for another surgical procedure

A

need to restore auto regulation and vasomotor response to CO2. literature differs on 3 v 6 months

40
Q

parkinson’s disease definition

A

neurodegenerative disorder of unknown cause marked by a characteristic loss of dopaminergic fibers in the basal ganglia, regional dopamine concentrations are also depleted. depletion of dopamine results in diminished inhibition of neurons controlling extrapyramidal motor system and unopposed stimulation by Ach

41
Q

s/sx of parkinson’s disease

A

skeletal muscle tremor (pill rolling, more prominent during rest and disappear during voluntary movement)
rigidity
akinesia (loss of voluntary movement)
diaphragmatic spasms
dementia
depression
facial immobility (infrequent blinking and paucity of emotional expressions)

42
Q

parkinson’s disease tx

A 
levodopa
carbidopa (d carboxylase inhibitor)
amandatine (antiviral, prolong QT)
selegeline and rasagiline (avoid meperidine)
surgery (DBS)
ropinrole (dopa agonist)
AchE (donepezil, tacrine)
COMT inhibitors entacopine. (check liver enzymes)
ARV: cimantadine (prolong QT)
43
Q

parkinson’s disease anesthetic considerations

A 
levodopa therapy continued
hypotension and cardiac dysrhythmias
avoid droperidol/haldol- antagonizes dopa
aspiration 
HTN risk
prone to post extubation laryngospasm
avoid benzos
sevo: agent of choice
NMDB less effective of anticholinergics. use sugammadex
44
Q

parkinson’s disease and ketamine

A

ok if patient on levodopa. if not, increased SNS response to ketamine

45
Q

parkinsons and hyperdynamics

A

use direct acting for HoTN like neo versus indirect like ephedrine

46
Q

huntingtons disease definition

A

degenerative disease of CNS characterized by marked atrophy of the caudate nucleus and to a lesser degree the putamen and globes pallid us
-autosomal dominant transmission with onset of 30-40 years

47
Q

huntingtons disease sx

A

progressive dementia
chorea (involuntary jerking or writhing movements)
tremors
rigidity/contractures
depression, aggressive outburst, mood swings
difficulty with speech and swallowing (pharyngeal involuntary movement)

48
Q

huntingtons disease tx

A

tx of choreiform movements (tremor/jerkins) with haldol or dopa antagonist/dopa store depletor
antidepressants
PT OT ST

49
Q

huntingtons disease anesthetic considerations

A 
aspiration risk (RSI)
prolonged response to succ
sensitive to NDMR
consider avoiding reglan and anticholinergics
glyco>atropine (BBB)
autonomic dysfunction (labile BP)
50
Q

lower motor neuron diseases

A 
MG (lambert eaton)
muscular dystrophy (duchenne, Becker)
myotonic dystrophy
mitochondrial DO
gillian barre
spinal muscular atrophy
51
Q

myasthenia gravis definition

A

autoimmune destruction (IgG antibodies against the nicotinic acetylcholine receptor) or inactivation of postsynaptic acetylcholine receptors at the NMJ leading to reduced numbers of receptors and degradation of their function, and to complement mediated damage to postsynaptic end plate

52
Q

MG s/sx

A 
diplopia, ptosis
fluctuating fatigue and weakness that improves after rest
muscle weakness of mouth and throat
dyspnea with exerrtion
proximal muscle weakness
53
Q

MG tx

A 
cholinesterase inhibitor (physostigmine)
plasmapharersis (r/t resp pharyngeal weakness)
coticosteroids
immunosuppressants, immunoglobins
thymectomy
54
Q

situations that exacerbate MG sx

A 
pregnancy
infection
electrolyte imbalance
surgical and psychological stress
amino glycoside abx
BB or higher doses of steroids (stress dose) can also exacerbate
55
Q

MG anesthetic considerations

A

aspiration risk
sensitive NDMR “start small”
sensitive to respiratory deperssants
regional preferred (amide locals not esters)
avoid mid thoracic or inter scalene supraclavicula blocks
resistant to succinylcholine 2mg/kg
DOA of succ increases by 5-10 minutes (decreased functional Ach receptors)
volatiles OK, helps relax c/o or with less paralytics
regional still preferred

56
Q

lambert eaton definition

A

presynaptic defect of neuromuscular transmission in which antibodies to voltage gated calcium channels on the nerve terminal markedly reduce the quantal release of Ach at the motor end plate (males > females)

57
Q

s/sx LEMS

A

proximal muscles mostly affected
weakness generally worse in morning and improves throughout the day
resp and diaphragm muscles become weka
ANS dysfunction: orthostatic hypotension, slowed gastric motility, urinary retention
begins in LE’s
dry mouth, impotence, small cell carcinoma

58
Q

LEMS tx

A 
3,4 DAP
guanidine hydrochloride
corticosteroids
immunosuppressants
plasmapharesis
59
Q

LEMS anesthetic considerations

A

sensitive to succinylcholine and NDMR
inadequate reversal with AchE (if not on AchE agent like DAP)
high risk of postop respiratory failure
60% have small cell carcinoma

60
Q

duchenne muscular dystrophy definition

A

most severe, dystrophin completely not working
x linked recessive DO that results from production of abnormal protein dystrophin. affects males > females and presents between 3-5 years of age and rarely lives past 30 years

61
Q

s/sx duchennes

A 
symmetric proximal muscle weakness that is manifested as a gait disturbance "gower sign"
fatty infiltration typically causes enlargement of muscles, particularly the calves
kyphoscoliosis
resp muscle weakness
degeneration of cardiac muscles
impaired GI hypomotility
impaired airway reflex
impaired cardiac conduction
cognitive impairment 
pulmonary HTN (as they progress)
large tongue
pseudo hypotonia of calves
dont usually begin walking until about 18 months
death is cardiopulmonary demise in 30's
62
Q

becker muscular dystrophy defintion

A

dystrophin remains partially functioning
x linked recessive DO but less common (dystrophin lower)
sx 5-15 years
death is respiratory related in 4th-5th decade

63
Q

becker muscular dystrophy s/sx

A 
common to duchenne but usually present later in life and progress more slowly
intellectual disability less common
proximal muscle wekaness
primininet calf pseudo hypertrophy
degeneration of cardiac muscles
64
Q

duchenne/becker MD dx

A 
genetic testing
CK levels (10-100x normal)
muscle biopsy (rare)
65
Q

duchenne/becker MD tx

A 
surgery (ileus, scoliosis, contractures)
PT
steroids (can delay progression)
biphosphates
nystatin inhibitors
gene modification
protease inhibitors 
stem cell infusions
66
Q

muscular dystrophy anesthetic considerations

A

association with MH (do TIVA, avoid succ)
preop medications with opioid and benzos should be avoided (NO VERSED)
intraop position complications due to kyphoscoliosis
sensitive to NDMR (prolonged 4x norm)
local and regional preferable (hard r/t scoliosis/contracture)
aspiration risk
dilated and hypertrophic cardiomyopathy
get echo, EEG, PFT’s

67
Q

myotonic dystrophy definition

A

a hereditary degenerative disease of skeletal muscle that results in dysfunctional calcium sequestration by SR. sodium channel and chloride channel dysfunction is implicated as well. inability of skeletal muscle to relax. ex) grab door handle and cant let go

68
Q

myotonic dystrophy s/sx

A 
weakness: facial, thoracic, intercostal, diaphragm, sternocleidomastoid and distal limb
inability to relax hand grip (myotonia)
cardiomyopathy and conduction defects (1st degree AVB)
dysphagia, slowed gastric emptying 
endocrine dysfunction
central sleep apnea
ptosis
uterine atony in pregnant women
69
Q

myotonic dystrophy triad in males

A

frontal balding, cataracts, testicular atrophy

70
Q

myotonic dystrophy tx

A 
procainamide
phenytoin
mexiletine
baclofen
dantrolene
carbamazepine
cardiac pacemaker
71
Q

anesthetic considerations for myotonic dystrophy

A

avoid succinylcholine!!
aspiration risk
volatile anesthetics may produce exaggerated myocardial depression but high concentrations of volatile anesthetics may abolish myotonia. still questionable r/t MH
anesthesia and surgery could aggravate cardiac conduction problems by increasing vagal tone
neostigmine and physostigmine can aggravate myotonia
sensitive to respiratory depressant
maintain normothermia and avoid of shivering
PFT, ECG, trans thoracic pacing should be readily available

72
Q

mitochondrial DO definition

A

heterogenous group of DO’s of skeletal muscle energy metabolism. mitochondria produce energy required by skeletal muscle cells through oxidation reduction reactions of electron transfer chain and oxidative phosphorylation thereby generating ADP

73
Q

mitochondrial DO s/sx

A

abnormal fatiguability with sustained exercise “poor stamina”
skeletal muscle pain and progressive weakness
hearing loss, impaired vision
balance and coordination problems
seizures
learning deficits
organ problems

74
Q

mitochondrial DO dx

A

hallmark: ragged red fiber

accumulation of mitochondria under sarcolemma, increased lactate to pyruvate ratio

75
Q

mitochondrial DO tx

A

administration of metabolites and co factors
sodium bicarbonate/dichloracetate
ketogenic diet

76
Q

anesthetic considerations mitochondrial DO

A

prone to acidoses and dehydration (first case)
lactate level
avoid propofol for continuous infusion (PRIS)
avoid succ and LR
maintain normothermia
use NDMR and LA’s with caution (sevo best)
avoid prolonged tourniquets
avoid bupivicaine

77
Q

guillian barre definition

A

immunologic assault on myelin in peripheral nerves particularly lower motor neurons. action potential cannot be conducted, so motor endplate does not receive incoming signal. persist for 2 weeks and ends with full recovery in 4 weeks with some pernanent paralysis remaining

78
Q

guillian barre s/sx

A

flaccid paralysis that begins in distal extremities and ascends bilaterlly
intercostal muscle weakness
facial and pharyngal weakness
sensory deficits
autonomic dysfunction common
paresthesias, impaired ventilation, hyperdynamic

79
Q

guillcian barre tx

A

plasmapheresis (contradicted in active bleeding or dynamic instability)
IVIG: admin when you cannot do plasmapheresis
steroids are not useful

80
Q

guillian barre anesthetic considerations

A 
avoid succ****(K increase)
sensitivity to NDMR
increase risk of DVT
risk of aspiration
exaggerated response to indirect sympathomimetics (aline)
SIADH possible, assess NA
avoid rapid position changes
avoid barbs/resp depressants/phenothiazines/CV depression
MV risk postop
81
Q

spinal muscular atrophy definition

A

due to deletions or mutations in survival motor neuron gene on chromosome 5q13. SMN gene product is involved in the formation of RNA complexes and their trafficking out of the nucleus. loss of SMN function promotes apoptosis of lower motor neurons. affect anterior horn of spinal cord

82
Q

spinal muscular atrophy SMA I

A

infantile spinal muscular atrophy, an autosomal recessive DO that manifests usually within first 3 months of life. infants with this condition have difficulty sucking, swallowing, breathing. atrophy and fasciculation are found in tongue and limb muscles. disorder is rapidly progressive, leading to death from respiratory complications by age 3

83
Q

spinal muscular atrophy SMA II

A

autosomal recessive mode of inheritance and begins in latter half of first year of life. it progresses more slowlyy than in infantile form, and patients may survive into adulthood

84
Q

spinal muscular atrophy SMA III

A

juvenile form that develops after age 2. patients develop weakness of proximal limb muscles with relative sparing of bulbar muscles

85
Q

spinal muscular atrophy tx

A 
spinraza
zolgensma
evyrsdi
PT
surgery
abx (low threshold with these patients)
86
Q

spinal muscular atrophy anesthetic considerations

A 
pulmonary consultation
difficult intubation
avoid succ**
varying sensitivity to NDMR (longer DOA)
regional (controversial)
cautious with opioids
postop resp support
87
Q

ALS (upper and lower motor neurons) definition

A

rapidly progressive degeneration of motor neurons in corticospinal tract (directly to motor nerves, primary descending upper motor neurons) and the lower motor neurons in the anterior horn gray matter of the spinal cord. astrocytic gloss replaces affected motor neurons

88
Q

ALS s/sx

A 
spasticity
hyperreflexia, loss of coordination
muscle weakness
fasciculations
atrophy often begins in hands
orthostatic hypotension
resting tachycardia
sensation remains intact
89
Q

ALS tx

A

riluzole (NMDA receptor antagonist, only drug that reduces mortality)
edaravone (decrease decline in ADL’s)
smasmolytics
analgesics

90
Q

ALS anesthetic considerations

A 
avoid succ*
increase sensitivity to NDMR
aspiration risk
consider postoperative mechanical ventilation
increase sensitivity to resp depressants
autonomic dysfunction with risk for hemodynamic instability
spinal anesthesia avoided
orthostatic hypotension and tachycardia
PEA after induction a thing

N935 Pathophysiology (12 decks)

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