Neuromuscular diseases Flashcards
Define neuromuscular disorders.
Disorders that adversely affect muscle function either primarily or via nerve or neuromuscular junction abnormalities
The primary roles of upper motor neurons are
directing, influencing, and modifying reflex arcs, lower-level control centers and motor neurons, and some sensory
Upper motor neurons are
motor pathways completely contained within the CNS
begin in the cerebral cortex and end in the ventral horn of the spinal cord
Describe the neuron pathway from upper motor neurons to lower motor neurons
upper motor neurons synapse with interneurons which then form synapses with lower motor neurons before projecting to the periphery
The corticospinal tract originates in the
precentral gyrus
The corticospinal tract goes through the
internal capsule, midbrain, and pons
The corticospinal tract supplies
the voluntary muscles of the trunk & extremities
Describe decussation in the corticospinal tract.
75-90% decussate in the medulla and form the lateral corticospinal tract
- at each cord level some leave and enter the ventral horn grey matter and synapse with lower body neurons
10-25% that do not decussate in the medulla make up the ventral corticospinal tract and travel to the spinal cord. they cross over before synapsing with lower motor neurons
The corticobulbar tract supplies the
voluntary muscles of the head and follows the corticospinal tract until they reach the brainstem
The corticobulbar tract is involved in
precise motor movements
The corticobulbar tract innervates
cranial motor nuclei bilaterally except FACIAL & HYPOGLOSSAL
The corticobulbar tract originates in the
precentral gyrus next to the lateral fissure of Sylvius
Lower motor neurons are located in
the brain stem or the in the spinal cord
Lower motor neurons are responsible for
direct influence on muscles
Lower motor neurons that pass through cranial nerves primarily control the
skeletal muscles of the head & the neck
The lower motor neurons that pass through the spinal nerves primarily control
muscles of the limbs & trunk
Lower motor neurons send axons out through
nerves in the peripheral nervous system to synapse on and control skeletal muscle cells
Briefly describe the AP at the NMJ.
- AP arrives & synaptic transmission begins
- Na+ channels open and depolarize
- Ca2+ enter cell and triggers vesicles to fuse presynaptically
- Ach diffuses across the cleft
- Ach binds to nachr and releases Na
- Ach, vesicles are recycled
With upper motor lesions-
muscle groups are affected mild weakness minimal disuse muscle atrophy no fasciculations increased muscle stretch reflex hypertonia, spasticity pathological reflexes
With lower motor lesions
occur in ventral horn (spinal cord) & motor nuclei (brainstem) -individual muscles may be affected mild weakness marked muscle atrophy fasciculations decreased muscle stretch reflex hypotonia, flaccidity no Babinski sign
Upper motor neuron diseases include
cerebral palsy, multiple sclerosis, CVA, Parkinson’s, and Huntingto’s
Cerebral palsy is a
non-progressive disorder caused by injury or abnormal development in the immature brain before, during, or after birth up to 1 year of age. it is damage or defects in the corticospinal pathway
The cause of cerebral palsy is
still unknown although sources point to infection vs. anoxic brain injury
Signs & symptoms of cerebral palsy include
muscle weakness, loss of fine motor control, impaired speech, drooling, exaggerated deep tendon reflexes, spasticity, rigidity of extremities, scoliosis, contractures, joint dislocation
Associated problems with cerebral palsy include
vision & hearing impairment, swallowing problems, seizures, intellectual disability and reflux disease
Treatment for cerebral palsy includes:
no cure
treat symptoms to increase ADLs- surgical (ortho, dental, general, ophthalmology, ENT)–> may see dorsal rhizotomy, antireflux operation, intrathecal baclofen pumps
Medications–> botulinum toxin
-physical & OT
Anesthesia considerations for the cerebral palsy patient include.
hold preop sedatives and cautious with opioids (give short-acting)
difficult vascular access
difficult airway- dentition, secretions, TMJ ankylosis, contractures
consider RSI
Succ does not produce increased K release
cautious administration of NDMR
decreased MAC need (20-30%)
prone to bleeding, hypothermia, & intravascular depletion
slow emergences
prone to latex allergies
careful w/ positioning & regional d/t contractures & scoliosis
Multiple sclerosis is an
autoimmune disease characterized by combination of demyelination, inflammation, and axonal damage of the CNS. peripheral nerves are not affected
T Cell mediated autoantiboides
_________ anesthesia is generally not recommended for the MS patient
spinal
Signs & symptoms of MS include
paresthesia, muscle fatigue/weakness, painful muscle spasms, autonomic instability, bulbar muscle dysfunction, visual problems (optic neuritis & diplopia), cognitive dysfunction (advanced MS)
Multiple sclerosis typically affects
women 20-40 or 45-60
etiology is unknown
MS affects the
somatic motor
somatic sensory
and autonomic systems
Treatments for MS include
decrease spasticity, tremors, bladder spasticity
diazepam, dantrolene, or baclofen
glucocorticoids
immunosuppressants
CD20 monoclonal antibody, interferon B1a or glatiramer acetate
Situations that exacerbate symptoms of MS include
stress
increased body temperature
infection
& hyponatremia
Anesthetic considerations for MS icnlude
avoid succinylcholine, scopolamine, & atropine NMDR- 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
CVA is characterized by
sudden neurologic deficits resulting from ischemia (88% of cases) or hemorrhage (12% of cases)
The presentation of CVA depends on
where it is located
Patients who have a CVA of the anterior cerebral artery have
contralateral leg weakness
Patients who have a CVA of the middle cerebral artery have
aphasia, contralateral visual field defect
contralateral hemiparesis & hemisensory deficit
Patients who have a CVA of the posterior cerebral artery have
contralateral visual field defect & hemiparesis
Patients who have a CVA of the vertebral artery have
lower cranial nerve deficits
and/or ataxia with crossed sensory deficits
Patients who have a CVA of the basilar artery have
oculomotor deficits and/or ataxia
crossed sensory & motor deficits
Patients who have a CVA of the penetrating arteries have
contralateral hemiparesis
contralateral hemisensory deficits
Stroke survivors represent the
highest rate of disability
Treatment for CVA includes
aspirin
TPA (IV administration or direct infusion)
surgery (crani/cerebellar resection)
Anesthesia considerations for CVA include
aspiration risk DVT risk BS maintenance BP maintenance avoid: hyperglycemia, dehydration, hypothermia, infections statins aspirin therapy regional, MAC- reduce incidence of stroke because it decreases BP swings
Patients who have had a CVA should wait to come back for surgery for
3 months because they need the time to heal and have cerebral autoregulation restored
Parkinson’s disease is 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 in Parkinson’s disease results in
diminished inhibition of neurons controlling the extrapyramidal motor system and unopposed stimulation by acetylcholine
Signs & symptoms of Parkinson’s disease include
skeletal muscle tremor (pill rolling) more prominent during rest & disappear during voluntary movement
rigidity
akinesia
diaphragmatic spasms
dementia
depression
facial immobility (infrequent blinking & paucity of emotional expressions)
Treatment for Parkinson’s disease include
levodopa, carbidopa, amantadine, selegiline & rasagiline, surgery
acetylcholinestarse inhbitiors
antiviral agents–> prolongs QT
dopamine agonist
For patients with Parkinson’s disease who take seregine, we need to avoid
meperidine because it can lead to serotonin syndrome
Anesthetic considerations of the patient with Parkinson’s disease include
levodopa therapy continued hypotension & cardiac dysrhythmias -droperidol/haldol airway risk aspiration risk risk of HTN prone to post-extubation laryngospasm avoid benzos sevo is agent of choice NDMB is less effective if patient on anticholinergic for dementia/uses sugammedex
Huntington’s disease is a
degenerative disease of the CNS characterized by marked atrophy of the caudate nucleus and to a lesser degree the putamen & globus pallidus
Signs & symptoms of Huntington’s disease include
progressive dementia, chorea (involuntary jerking or writhing movements), tremors, rigidity/contractures, depression, aggressive outburst, mood swings, difficulty with speech & swallowing
Treatment of Huntington’s disease includes
treat the choreiform movements/jerking
antidepressants
physical, occupational, & speech therapy
Anesthetic considerations for the patient with Huntington’s disease includes
high aspiration risk prolonged response to succinylcholine sensitive to NDMR consider avoiding (Reglan & anticholinergics) -glyco>atropine difficult IV access autonomic dysfunction (labile BP)
Anesthetic considerations for all patients who have upper motor neuron diseases includes
thorough assessments
check meds
disease severity & systemic involvement
need to be alert before you can pull tube to ensure they can protect their airway
Diseases of the lower motor neuron include
myasthenia gravis, lambert-eaton, muscular dystrophy, myotonic dystrophy, mitochondrial disorder, Guillain-Barre, spinal muscular atrophy
Myasthenia gravis is an
autoimmune destruction (IgG antibodies against the nicotinic acetylcholine receptor) or inactivation of postsynaptic acetylcholine receptors at the neuromuscular junction leading to reduced numbers of receptors and degradation of their function and to complement-mediated damage to the postsynaptic end plate
Signs & symptoms of myasthenia gravis include
diplopia, ptosis, fluctuating fatigue & weakness that improves after rest, muscle weakness of mouth and throat, dyspnea with exertion, proximal muscle weakness
Treatment for myasthenia gravis includes
plasmapheresis, corticosteroids, immunosuppressants, immunoglobins, thymectomy, cholinesterase inhibitor
Situations that exacerbate symptoms of myasthenia gravis include
pregnancy, infection, electrolyte imbalance, surgical & psychological stress, aminoglycoside antibiotics
Anesthetic considerations for the patient with myasthenia gravis includes
aspiration risk
sensitive to NDMR
sensitive to respiratory depressants
regional preferred (amide locals not esters)
-avoid >mid thoracic or interscalene or supraclavicular blocks
resistant to succinylcholine (2mg/kg)–> DOA increased by 5-10 min.
Lambert-Eaton disease is a
presynaptic defect of the neuromuscular transmission in which antibodies to voltage-gated calcium channels on the nerve terminal markedly reduce the quantal release of acetylcholine at the motor end plate
Signs & symptoms of Lambert-Eaton disease includes
proximal muscles are mostly affected
weakness generally worse in the AM and improves through the day
respiratory & diaphragm muscles become weak
autonomic nervous system dysfunction- orthostatic hypotension, slowed gastric mobility, & urinary retention
Treatment of Lambert-Eaton includes
3,4 DAP, Guanidine hydrochloride, corticosteroids, immunosuppressants, plasmapharesis
Anesthetic considerations for the patient with Lambert-Eaton includes
Sensitive to succinylcholine & NDMR
inadequate reversal with anticholinesterase
high risk of postop respiratory failure
60% have small cell carcinoma
Duchenne’s muscular dystrophy is a
X-linked recessive disorder that results from production of abnormal protein dystrophin
Duchenne’s muscular dystrophy is more likely to affect
males>females, & presents between 3-5 years of age and rarely live past 30 years
S&S of Duchenne’s muscular dystrophy include
symmetric proximal muscle weakness that is manifested as a gain disturbance-"Gower sign" fatty infiltration typically causes enlargement of muscles, particularly the calves kyphoscoliosis respiratory muscle weakness degeneration of cardiac muscles impaired GI hypo-motility impaired airway reflex impaired cardiac conduction cognitive impairment pulmonary hypertension
Becker’s disease is a
X-linked recessive disorder but less common than Duchenne’s
still have dystrophin just lower
Becker’s disease is typically found in
males
presents later in life (adolescence) than Duchenne’s and progresses more slowly
S/S of Becker’s disease includes
intellectual disability is less common, proximal muscle weakness, prominent calf pseudohypertrophy, degeneration of cardiac muscles
death d/t respiratory compromise
Diagnosis of Duchenne’s & Becker’s Muscular dystrophy includes
genetic testing, CK levels, muscle biopsy (rare)
Treatment of Duchenne’s & Becker’s muscular dystrophy includes
surgery physical therapy steroids biphosphates mystatin inhibitors gene modification protease inhibitors stem cell infusions
Anesthetic considerations for includes Duchenne’s & Becker’s muscular dystrophy include
association with malignant hyperthermia (TIVA)- avoid succinylcholine & inhalation agents
preoperative pre-medications with opioid and benzos should be avoided
intraoperative position complications due to kyphoscoliosis
sensitive to NMDR
local & regional preferable
aspiration risk
Myotonic dystrophy is a
hereditary degenerative disease of the skeletal muscle that results in the dysfunctional calcium sequestration by the sarcoplasmic reticulum
sodium & chloride channel dysfunction is implicated as well
Myotonic dystrophy symptoms include
weakness- facial, thoracic, intercostal, diaphragm, sternocleidomastoid, & distal limb
inability to relax hand grip (myotonia)
cardiomyopathy, conduction defects (1st degree AV block)
dysphagia, slowed gastric emptying
endocrine dysfunction
central sleep apnea
Ptosis
Triad in males includes- frontal balding, cataracts, & testicular atrophy
Treatment for myotonic dystrophy includes
procainamide, phenytoin, mexiletine, baclofen, dantrolene, carbamazepine, & cardiac pacemaker
Anesthetic considerations for the patient with myotonic dystrophy include
avoid succinylcholine
aspiration risk
volatile anesthetic may produce exaggerated myocardial depression but high concentrations can abolish myotonia. still questionable d/t MH
anesthesia & surgery can aggravate cardiac conduction problems by increasing vagal tone
neostigmine & physostigmine can aggravate myotonia
sensitive to respiratory depressant
maintain normothermia & avoid shivering
pulmonary function test, ECG, and transthoracic pacing should be readily available
Mitochondrial disorders are a
heterogenous group of disorders of skeletal muscle energy metabolism. mitochondria produce the energy required by skeletal muscle cells through the oxidation-reduction reactions of the electron transfer chain and oxidative phosphorylation thereby generating ADP
Signs & symptoms of mitochondrial disorders include
abnormal fatigability with sustained exercise, skeletal muscle pain and progressive weakness, hearing loss, impaired vision, balance & coordination problems, seizures, learning deficits, organ problems for the heart, liver, kidney & brain
Treatment for mitochondrial diseases include
treat the symptoms
administration of metabolites and cofactors
sodium bicarbonate/dichloroacetate
ketogenic diet
Anesthetic considerations for the mitochondrial disorders include
prone to acidosis & dehydration, lactate level, avoid propofol for continuous infusion, avoid succinylcholine & LR, maintain normothermia, use with caution- NDMR & local anesthetics, avoid prolonged tourniquets, avoid bupivacaine
Guillain-Barre is an
immunologic assault on myelin in the peripheral nerves particularly lower motor neurons
APs cannot be conducted so the motor endplate does not receive the incoming signal
persists for 2 weeks and ends with full recovery in 4 weeks with some permanent paralysis remaining
Guillain-Barre signs & symptoms include
flaccid paralysis that begins in the distal extremities and ascends bilaterally, intercostal muscle weakness, facial and pharyngeal weakness, sensory deficits, autonomic dysfunction is common
One of the most likely causes of Guillain-Barre is
the flu
Treatment for Guillain-Barre includes
plasmapheresis, IVIG, steroid not useful therapy
Anesthetic considerations for the patient with Guillain-Barre includes
avoid succinylcholine, sensitivity to NDMR, increase risk of DVT, risk of aspiration, exaggerated response to indirect sympathomimetics (A-line)
avoid respiratory depression
risk for postop mechanical ventilation
assess Na+ d/t risk for SIADH
Spinal muscular atrophy is due to
deletions or mutations in the survival motor neuron gene on chromosome 5q13
The 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
Spinal muscular atrophy affects the
anterior horn of spinal cord
SMA III is a
juvenile form that develops after age 2. patients develop weakness of proximal limb muscles with relative sparing of bulbar muscles
SMA II has an
autosomal recessive mode of inheritance and begins in the latter half o the first year of life
it progresses more slowly than the infantile form and patients may survive into adulthood
SMA I is an
infantile spinal muscular atrophy, an autosomal recessive disorder that manifests usually within the first 3 months of life
infants with this condition have difficulty sucking, swallowing, and breathing
atrophy & fasciculation are found in the tongue & limb muscles
rapidly progressive, most usually die by age 3
Treatment for spinal muscular atrophy includes
PT, surgery, low threshold for antibiotics, spinraza, zolgensma, evrysdi
Anesthetic considerations for the patient with spinal muscular atrophy include
pulmonary consultation
difficult intubation d/t increased secretions
avoid succinylcholine
varying sensitivity to NDMR (longer DOA)
regional (controversial)
cautious with opioids
postop respiratory support is a high likelihood
Mixed motor neuron disease include
amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis is a
rapidly progressive degeneration of motor neurons to the corticospinal tract (primary descending upper motor neurons) and the lower motor neurons in the anterior horn gray matter of the spinal cord. Astrocytic gliosis replaces the affected motor neurons
S/S of ALS include
spasticity, hyperreflexia, loss of coordination, muscle weakness, fasciculations, atrophy often begins in hands, orthostatic hypotension, resting tachycardia, sensation remains intact
cognitive, bladder, & bowel function not usually affected
Treatment for ALS includes
No known tx
analgesics, spasmolytics, edaravone-decrease decline in ADLs
riluzole (NMDA receptor antagonist)- is the only drug that reduces mortality
Anesthetic considerations for the patient with ALS include
avoid succinylcholine
increase sensitivity to NDMR
aspiration risk
Consider postoperative mechanical ventilation
increase sensitivity to respiratory depressants
autonomic dysfunction with risk for hemodynamic instability
spinal anesthesia avoided
Patients with myasthenia gravis will be: A. sensitive to rocuronium B. Sensitive to succinylcholine C. Resistant to rocuronium D. Resistant to succinylcholine
A & D
Characteristics of lower motor neuron lesion A. pathological reflexes B. fasciculations C. spasticity D. flaccidity E. disuse muscle atrophy
B & D
