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
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
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
4
Q
corticospinal synapse with
A
spinal nerves
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
6
Q
corticobulbar tract innervates these cranial motor nuclei bilaterally
A
3, 4, 6, 9, 10, 11
7
Q
corticobulbar tract innervates these cranial motor nuclei unilaterally
A
7 (facial), 12 hypoglossal)
8
Q
steps to neuromuscular junction synapses
A
- action potential arrives and initiates synaptic transmission
- sodium channels open, depolarizing axon terminal membrane
- depolarization of the terminal membrane causes VgCa channels to open
- calcium centers the cells and triggers fusion of Ach vesicles with presynaptic membrane
- Ach molecules diffuse across synaptic cleft and bind to receptors on postsynaptic membrane
- Ach receptors open chemically gated channels and depolarize postsynaptic membrane. this spreading depolarization fires an AP in postsynaptic membrane
- Ach in synaptic cleft is broken down by the enzyme acetylcholinesterase and the compounds are taken back up by the presynaptic cell for resynthesis
- after synaptic transmission, Ach and vesicles are recycled
9
Q
where are lower motor neuron problems usually located
A
neuromuscular junction
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)
11
Q
type of cells and location of upper motor neurons
A
pyramidal cells, motor cortex
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
13
Q
lower motor neurons are located in these two areas
A
ventral horn (spinal cord) and motor nuclei (brainstem)
14
Q
lower motor neuron diseases that involve the bulbar region
A
bulbar palsies
ALS
15
Q
lower motor neuron diseases that involve the myoneural junction
A
MG
16
Q
5 diseases that involve upper motor neurons
A
cerebral palsy multiple sclerosis CVA parkinsons huntingtons
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
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)
19
Q
CP associated problems
A
vision and hearing impairment swallowing problems seizures intellectual disability reflux disease abnormal pain perceptions
20
Q
CP treatment
A
surgical (ortho, dental, general, opthomalogy, ENT) dorsal rhizotomy anti reflux operation intrathecal baclofen pumps botulinum toxin PT OT ST
21
Q
dorsal rhizotomy for CP
A
tx muscle spasticity, cut nerves at root
22
Q
botulinum toxin for CP
A
prevent release of Ach in NMJ to decrease spasticity
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)
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.
25
s/sx of MS
```
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
```
26
MS includes which pathways
somatic motor
somatic sensory
autonomic
higher brain neurons
27
MS spares which nerves
peripheral
28
MS tx
decrease spasticity, tremors, bladder spasticity
diazepam, dantrolene, baclofen
glucocorticoids
immunosuppressants
CD20 monoclonal antibody interferon B1a or glatiramer acetate
29
situations that may exacerbate sx of MS
stress
increase body temperature
infection
hyponatremia
30
MS anesthetic considerations
```
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
```
31
CVA to anterior cerebral artery sx
contralateral leg weakness
32
CVA to middle cerebral artery sx
contralateral hemiparesis and hemisensory deficit (face and arm > leg)
aphasia
contralateral visual field deficit
33
CVA to posterior cerebral artery sx
contralateral visual field deficit and hemiparesis
34
CVA to penetrating arteries sx
contralateral hemiparesis
| contralateral hemisensory deficits
35
CVA to basilar arteries sx
oculomotor deficits and/or ataxia
| crossed sensory and motor deficits
36
CVA to vertebral artery sx
lower cranial nerve deficits
| and/or ataxia with crossed sensory deficits
37
CVA tx
aspiring
TPA
surgery (crani/cerebellar resection)
38
anesthesia considerations for CVA
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
CVA and coming back for another surgical procedure
need to restore auto regulation and vasomotor response to CO2. literature differs on 3 v 6 months
40
parkinson's disease definition
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
s/sx of parkinson's disease
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
parkinson's disease tx
```
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
parkinson's disease anesthetic considerations
```
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
parkinson's disease and ketamine
ok if patient on levodopa. if not, increased SNS response to ketamine
45
parkinsons and hyperdynamics
use direct acting for HoTN like neo versus indirect like ephedrine
46
huntingtons disease definition
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
huntingtons disease sx
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
huntingtons disease tx
tx of choreiform movements (tremor/jerkins) with haldol or dopa antagonist/dopa store depletor
antidepressants
PT OT ST
49
huntingtons disease anesthetic considerations
```
aspiration risk (RSI)
prolonged response to succ
sensitive to NDMR
consider avoiding reglan and anticholinergics
glyco>atropine (BBB)
autonomic dysfunction (labile BP)
```
50
lower motor neuron diseases
```
MG (lambert eaton)
muscular dystrophy (duchenne, Becker)
myotonic dystrophy
mitochondrial DO
gillian barre
spinal muscular atrophy
```
51
myasthenia gravis definition
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
MG s/sx
```
diplopia, ptosis
fluctuating fatigue and weakness that improves after rest
muscle weakness of mouth and throat
dyspnea with exerrtion
proximal muscle weakness
```
53
MG tx
```
cholinesterase inhibitor (physostigmine)
plasmapharersis (r/t resp pharyngeal weakness)
coticosteroids
immunosuppressants, immunoglobins
thymectomy
```
54
situations that exacerbate MG sx
```
pregnancy
infection
electrolyte imbalance
surgical and psychological stress
amino glycoside abx
BB or higher doses of steroids (stress dose) can also exacerbate
```
55
MG anesthetic considerations
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
lambert eaton definition
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
s/sx LEMS
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
LEMS tx
```
3,4 DAP
guanidine hydrochloride
corticosteroids
immunosuppressants
plasmapharesis
```
59
LEMS anesthetic considerations
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
duchenne muscular dystrophy definition
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
s/sx duchennes
```
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
becker muscular dystrophy defintion
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
becker muscular dystrophy s/sx
```
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
duchenne/becker MD dx
```
genetic testing
CK levels (10-100x normal)
muscle biopsy (rare)
```
65
duchenne/becker MD tx
```
surgery (ileus, scoliosis, contractures)
PT
steroids (can delay progression)
biphosphates
nystatin inhibitors
gene modification
protease inhibitors
stem cell infusions
```
66
muscular dystrophy anesthetic considerations
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
myotonic dystrophy definition
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
myotonic dystrophy s/sx
```
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
myotonic dystrophy triad in males
frontal balding, cataracts, testicular atrophy
70
myotonic dystrophy tx
```
procainamide
phenytoin
mexiletine
baclofen
dantrolene
carbamazepine
cardiac pacemaker
```
71
anesthetic considerations for myotonic dystrophy
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
mitochondrial DO definition
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
mitochondrial DO s/sx
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
mitochondrial DO dx
hallmark: ragged red fiber
| accumulation of mitochondria under sarcolemma, increased lactate to pyruvate ratio
75
mitochondrial DO tx
administration of metabolites and co factors
sodium bicarbonate/dichloracetate
ketogenic diet
76
anesthetic considerations mitochondrial DO
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
guillian barre definition
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
guillian barre s/sx
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
guillcian barre tx
plasmapheresis (contradicted in active bleeding or dynamic instability)
IVIG: admin when you cannot do plasmapheresis
steroids are not useful
80
guillian barre anesthetic considerations
```
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
spinal muscular atrophy definition
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
spinal muscular atrophy SMA I
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
spinal muscular atrophy SMA II
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
spinal muscular atrophy SMA III
juvenile form that develops after age 2. patients develop weakness of proximal limb muscles with relative sparing of bulbar muscles
85
spinal muscular atrophy tx
```
spinraza
zolgensma
evyrsdi
PT
surgery
abx (low threshold with these patients)
```
86
spinal muscular atrophy anesthetic considerations
```
pulmonary consultation
difficult intubation
avoid succ**
varying sensitivity to NDMR (longer DOA)
regional (controversial)
cautious with opioids
postop resp support
```
87
ALS (upper and lower motor neurons) definition
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
ALS s/sx
```
spasticity
hyperreflexia, loss of coordination
muscle weakness
fasciculations
atrophy often begins in hands
orthostatic hypotension
resting tachycardia
sensation remains intact
```
89
ALS tx
riluzole (NMDA receptor antagonist, only drug that reduces mortality)
edaravone (decrease decline in ADL's)
smasmolytics
analgesics
90
ALS anesthetic considerations
```
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
```
