neuromuscular diseases Flashcards
What are neuromuscular diseases?
disorders that adversely affect muscle function either primarily or via nerve or neuromuscular junction abnormalities
upper motor neurons are
completely contained within the CNS
where do upper motor neuron pathways being and end?
begin: cerebral cortex
end: ventral horn of the spinal cord
primary roles of upper motor neurons
directing, influencing, and modifying reflex arcs, lower level control centers and motor neurons and some sensory
upper motor neurons form
synapses with interneurons which then form synapses with lower motor neurons before projecting to the periphery
the corticospinal tract supplies the
voluntary muscles of the trunk and extremities
where does the corticospinal tract originate?
precentral gyrus
75-90% of the corticospinal tract decussates in the ___ and forms the ____
medulla; lateral corticospinal tract
10-25% of the corticospinal tract makes up the ____
ventral corticospinal tract and travel to the spinal cord
the corticobulbar tract supplies the
voluntary muscles of the head and follow the corticospinal tract until they reach the brainstem
where does the corticobulbar tract originate
in the precentral gyrus next to the lateral fissure of Sylvius
the corticobulbar tract innervates cranial motor nuclei _____ bilaterally except
III, IV, VI, IX, X, XI; except facial and hypoglossal
the corticobulbar tract is involved in
precise motor movements
lower motor neurons are located in
the brain stem or in the spinal cord
the lower motor neurons are responsible for
direct influence on muscles
lower motor neurons send axons out through nerves in the ____ to synapse on and control ____
peripheral nervous system; skeletal muscle cells
the lower motor neurons that pass through the spinal nerves primarily control
muscles of the limbs and the trunk
lower motor neurons that pass through cranial nerves primarily control
the skeletal muscles of the head and the neck
What happens when an action potential arrives and initiates synaptic transmission at the neuromuscular junction
Na+ channels open depolarizing the axon terminal causing VG Ca++ channels to open allowing Ca++ to enter the cell and vesicles to fuse and release ACh into the synaptic cleft, the ACh will bind to receptors on the postsynaptic membrane opening nAChR channels and depolarize the membrane
ACh in the synaptic cleft is broken down by
acetylcholinesterase
upper motor lesion characteristics
muscle groups are affected mild weakness minimal disuse muscle atrophy no fasciculations increased muscle stretch reflex hypertonia spasticity pathological reflexes (+ babinski)
lower motor lesion characteristics
individual muscles may be affected mild weakness marked muscle atrophy fasciculations decreased muscle stretch reflex hypotonia flaccidity (-) babinski sign
Types of lower motor neuron BULBAR diseases
bulbar palsies, amyotrophic lateral sclerosis (ALS- this is mixed upper and lower)
types of lower motor neuron Anterior Horn Cell diseases
poliomyelitis, motor system disease, polyneuritis, amyotrophic lateral sclerosis
types of lower motor neuron primary muscle diseases
muscular dystrophies, myasthenia gravis, polymyositis
causes of upper motor neuron motor cortex diseases
cerebral palsy, neoplasms, trauma, inflammations, ALS
causes of upper motor neuron internal capsule diseases
vascular lesions (CVA, thrombosis, embolism, hemorrhage, aneurysm), neoplasm, trauma inflammations
causes of upper motor neuron brainstem diseases
demyelinating diseases (MS), vascular lesions, neoplasms, trauma, inflammations, degenerative disease (Parkinson’s), ALS
causes of upper motor neuron spinal cord diseases
demyelinating diseases, neoplasms, trauma, inflammations, ALS
which upper motor neuron diseases are we focusing on for exam purposes
cerebral palsy, MS, CVA, Parkinson’s, Huntington’s
Cerebral Palsy is a ____ disorder
non-progressive
cerebral palsy is caused by
injury or abnormal development in the immature brain, before, during, or after birth up to 1 year of age
cerebral palsy is from damage to or defect of
the corticospinal pathway
Signs and symptoms of cerebral palsy
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
vision and hearing impairment, swallowing problems, seizures, intellectual disability, reflux disease, abnormal touch/pain perception, osteopenia
in patients with cerebral palsy symptoms
don’t worsen but become more apparent
cerebral palsy treatment
no cure
Botulinum toxin - prevent release of ACh decreasing spasticity
PT/OT
Surgery - ortho, dental, general, ophthalmology, ENT
(dorsal rhizotomy, antireflux operation, intrathecal baclofen pump)
What does a dorsal rhizotomy treat
treats muscle spasticity, cuts the nerve at the root
anesthetic considerations for cerebral palsy
hold preop sedatives and cautious with opioids, difficult vascular access, difficult airway, decrease MAC need, slow emergence, cautious administration of NDMR
cerebral palsy patients are prone to ____ perioperatively
bleeding, hypothermia, intravascular depletion
what is the main concern (organ system) for cerebral palsy patients?
respiratory
Multiple sclerosis is an ____ disease characterized by ___
autoimmune disease characterized by combo of demyelination, inflammation, and axonal damage of the CNS
which kind of nerves are not affected with MS?
peripheral nerves are not affected
Signs and symptoms of MS
parathesia, muscle fatigue and weakness, painful muscle spasm, visual problems (optic neuritis, diplopia), autonomic instability, bulbar muscle dysfunction, cognitive dysfunction
treatment of MS is directed at and includes
decrease spasticity, tremors, bladder spasticity
- diazepam, dantrolene, baclofen
- glucocorticoids and immunosuppressants
- CD20 monoclonal antibody, interferon B1a or glatiramer acetate
situations that exacerbate the symptoms of MS
stress, increased body temperature, infection, hyponatremia
anesthetic considerations of MS
avoid succinylcholine, scopolamine, and atropine use NDMR cautiously don't have surgery during flare avoid spinal block aspiration risk increase risk of DVT stress dose steroids exaggerated hypotensive effects
CVA is characterized by
sudden neurologic deficits resulting from ischemia or hemorrhage
CVA of the anterior cerebral artery causes
contralateral leg weakness
CVA of the middle cerebral artery causes
contralateral hemiparesis and hemisensory deficit (face and arms), aphasia, contralateral visual field defect
CVA of the posterior cerebral artery causes
contralateral visual field defect and hemiparesis
CVA of the penetrating arteries causes
contralateral hemiparesis, contralateral hemisensory deficits
CVA of the basilar artery causes
oculomotor deficits and/or ataxia, crossed sensory and motor deficits
CVA of the vertebral artery causes
lower cranial nerve deficits and/or ataxia with crossed sensory deficits
CVA is the ___ leading cause of death
4th
Signs and symptoms of CVA
HA, confusion, aphasia, decreased cough/swallow reflex, hemiparesis or hemiplagia, incontinence, seizures, hyperthermia, emotional lability, horner’s syndrome, vomiting, perceptual defects, HTN, apraxia
