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Chapter 24
Drugs for Neuromuscular Disorders:
Myasthenia Gravis, Multiple Sclerosis,
and Muscle Spasms
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
Myasthenia Gravis (MG)

Pathophysiology






Autoimmune disorder
Lack of nerve impulses and muscle responses at
myoneural junction
Inadequate secretion of acetylcholine (ACh)
Loss of ACh because of an increase in the
enzyme acetylcholinesterase
Thymus gland
Characteristics


Muscular weakness and fatigue
Respiratory muscle paralysis, ptosis, difficulty
chewing and swallowing
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Acetylcholinesterase
Inhibitors/Cholinesterase Inhibitors

Acetylcholinesterase inhibitors (AChE
inhibitors)


Neostigmine (Prostigmin): short-acting
Edrophonium (Tensilon): ultrashort-acting for
diagnosing
 Pyridostigmine (Mestinon): intermediate-acting
 Ambenonium (Mytelase): long-acting
 Action
• Transmission of neuromuscular impulses by preventing
destruction of Ach

Use
• Control and treat MG
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Patients Not Responding to
Acetylcholinesterase Inhibitors



Prednisone
Plasma exchange
Intravenous immune globulin (IVIG) or
immunosuppressive drugs

Azathioprine (Imuran)
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AChE Inhibitors

Overdosing and underdosing







Similar symptoms
Muscle weakness, dyspnea
Dysphagia, abdominal cramping
Drooling, increases tearing, sweating
Bradycardia
Myasthenia crisis: underdosed
Cholinergic crisis: overdosed
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Myasthenia Gravis (Cont.)

Myasthenic crisis

Severe muscle weakness
• May involve diaphragm and intercostal muscles
 Triggers:
• Inadequate dosing
• Infection
• Emotional stress
• Menses, pregnancy
• Surgery, trauma
• Hypokalemia, alcohol intake
• Medication interactions
 Improves after edrophonium (Tensilon) and
neostigmine (Prostigmin)
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Myasthenia Gravis (Cont.)

Cholinergic crisis

Usually occurs within 30 to 60 minutes after taking
anticholinergic medications
 Severe muscle weakness
• Possible respiratory paralysis and arrest
• Abnormal pupil constriction
• Excess salivation
• Pallor, sweating, vertigo
• GI distress
• Bradycardia
• Fasciculations
 Worsens after edrophonium chloride (Tensilon)
 Triggers
• Overdosing
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AChE Inhibitors (Cont.)

Side effects







GI disturbances (nausea, vomiting, diarrhea,
abdominal cramps)
Increased salivation
Tearing
Miosis (constricted pupil of the eye)
Blurred vision
Bradycardia
Hypotension
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Nursing Process: AChE Inhibitors




Assessment
Nursing diagnosis
Planning
Nursing interventions



Patient teaching
Cultural considerations
Evaluation
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Nursing Process: AChE Inhibitors

Nursing interventions





Administer doses on time.
Take drug before meals if possible.
Monitor drug effectiveness.
Have antidote available for cholinergic crisis.
• Atropine
Encourage patient to wear medical identification.
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10
Multiple Sclerosis (MS)

Pathophysiology




Autoimmune disorder
Attacks myelin sheath of nerve fibers in brain and
spinal cord
Causes lesions or plaques
Characteristics




Remissions and exacerbations
Weakness
Spasticity in extremities
Diplopia
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Multiple Sclerosis (Cont.)

Diagnosis



No specific diagnostic test
McDonald Criteria
Laboratory tests that may suggest MS include
• Elevated immunoglobulin G (IgG) in the cerebrospinal
fluid
• Increased IgG/albumin ratio
• Multiple lesions observable through MRI
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Multiple Sclerosis Treatment



Acute attack: tapering course of
glucocorticoids (prednisone),
adrenocorticotropic hormone (ACTH) (H.P.
Acthar)
Remission-exacerbation: biologic (immune)
response modifiers (BRMs)
Chronic progressive: immunosuppressant
therapy
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Skeletal Muscle Relaxants

Spasticity (Centrally acting)



Baclofen (Lioresal)
Tizanidine (Zanaflex)
Spasticity (Direct acting)

Dantrolene sodium (Dantrium)
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Skeletal Muscle Relaxants (Cont.)
Centrally acting muscle relaxants





Carisoprodol (Soma)
Chlorzoxazone (Parafon forte DSC)
Methocarbamol (Robaxin)
Metaxalone (Skelaxin)
Orphenadrine citrate (Norflex)
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Skeletal Muscle Relaxants (Cont.)

Depolarizing muscle relaxants (adjunct to
anesthesia)




Pancuronium bromide (Pavulon)
Succinylcholine (Anectine)
Vecuronium (Norcuron)
Tubocurarine
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Skeletal Muscle Relaxants (Cont.)

Cyclobenzaprine (Flexeril)


Action
• Relax skeletal muscles
Use
• Alleviates muscle spasm associated with acute painful
musculoskeletal conditions

Side effects
• Anticholinergic effects
• Drowsiness; dizziness
• Headache
• Fever
• Abdominal pain; vomiting; diarrhea; flatulence
• Erectile dysfunction
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Nursing Process: Skeletal Muscle
Relaxants




Assessment
Nursing diagnoses
Planning
Nursing interventions



Patient teaching
Cultural considerations
Evaluation
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Nursing Process: Skeletal Muscle
Relaxants (Cont.)

Nursing Interventions





Take with food.
Monitor liver function.
Check vital signs.
Advise patient not to drive.
Inform patient that most centrally acting muscle
relaxants are prescribed for no longer than 3
weeks.
 Teach patient not to stop abruptly.
• Discontinue over 1 week to avoid rebound spasms.
 Have patient avoid alcohol and other depressants.
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Case Study
A patient with myasthenia gravis comes to the
emergency department in respiratory distress.
He has been diagnosed with myasthenic crisis.
The nurse anticipates administration of which
drug?
A.
B.
C.
D.
Diazepam (Valium)
Baclofen (Lioresal)
Edrophonium (Tensilon)
Neostigmine (Prostigmin)
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Case Study
The patient is prescribed pyridostigmine
(Mestinon). To avoid development of
myasthenic crisis in the future, the nurse should
include which information in the patient
teaching?
A. Take muscle relaxants for cramps.
B. Take medication with meals.
C. It may take 2-3 days before improvement of
symptoms occur.
D. Medication should be taken at the time of day when
you feel the weakest.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Case Study
The patient is readmitted to the emergency
department a few weeks later with cholinergic
crisis. The nurse anticipates administration of
A.
B.
C.
D.
atropine sulfate.
baclofen (Lioresal).
edrophonium (Tensilon).
neostigmine (Prostigmin).
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Case Study
A student nurse asks the ED nurse which
symptom is most likely to differentiate
myasthenic crisis from cholinergic crisis. The
ED nurse should say that even though the
symptoms of the two conditions are similar,
which is most likely to occur with cholinergic
crisis?
A.
B.
C.
D.
Drooling
Muscle weakness
Dyspnea
Dysphagia
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Practice Question #1
A patient with myasthenia gravis comes to the
emergency department in respiratory distress.
To determine if the patient is in myasthenic
crisis or cholinergic crisis, the nurse anticipates
administration of which drug?
A.
B.
C.
D.
Diazepam (Valium)
Baclofen (Lioresal)
Edrophonium (Tensilon)
Neostigmine (Prostigmin)
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Practice Question #2
The nurse identifies which patient as being least
likely to experience adverse effects of
clobenzaprine (Flexaril) therapy? The patient
A.
B.
C.
D.
who is taking an MAOI.
with a history of narrow-angle glaucoma.
who has a history of myasthenia gravis.
who is prescribed an oral antidiabetic agent.
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Practice Question #3
A patient with myasthenia gravis is prescribed
neostigmine bromide (Prostigmin). The nurse
identifies that the medication is effective when
the patient experiences?
A.
B.
C.
D.
Increased muscle strength
Decrease in sweating and salivation
Changes in vital signs to within normal limits
Decrease in generalized pain
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Practice Question #4
A patient with multiple sclerosis is being treated
with large doses of corticosteroids. Which
nursing diagnosis would be the priority at this
time?
A.
B.
C.
D.
Alteration in nutrition: less than body requirements
Risk for infection
Ineffective individual coping
Fatigue
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Practice Question #5
A child with cerebral palsy is ordered to receive
baclofen (Lioresal). The nurse is aware that this
medication is prescribed to
A.
B.
C.
D.
induce sleep and rest.
increase appetite.
reduce muscle spasticity.
increase bowel function.
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