Myasthenia Gravis and Guillain-Barre Syndrome

Medical-Surgical · Neurology·Updated 2026-10-28

What it is

Myasthenia gravis is an autoimmune disease in which antibodies block acetylcholine receptors at the neuromuscular junction, so voluntary muscles weaken with repeated use and improve with rest; eye and bulbar muscles are affected first. Guillain-Barre syndrome is an acute autoimmune attack on peripheral nerve myelin, often 1 to 3 weeks after a respiratory or gastrointestinal infection, producing symmetric weakness that ascends from the legs with loss of reflexes. Both disorders can paralyze the muscles of breathing and swallowing, so airway protection is the first nursing priority.

What the NCLEX focuses on

Myasthenia gravis: ptosis, diplopia, dysphagia, dysarthria and weakness that worsens with activity and late in the day.
Pyridostigmine (a cholinesterase inhibitor) is given on schedule, 30 to 60 minutes before meals, so chewing and swallowing are strongest while eating.
Myasthenic crisis: undermedication, infection, stress or surgery causes severe weakness and respiratory failure; it improves with more cholinesterase inhibitor, plasmapheresis or IV immunoglobulin.
Cholinergic crisis: overmedication causes excess salivation, tearing, sweating, abdominal cramps, diarrhea, bradycardia and muscle twitching (fasciculations) with weakness; hold the drug and keep atropine available.
Guillain-Barre: ascending symmetric weakness with absent reflexes, paresthesias and pain; consciousness and cognition stay intact.
Guillain-Barre autonomic dysfunction: labile blood pressure, dysrhythmias and urinary retention; treatment is plasmapheresis or IV immunoglobulin early in the illness.
A falling vital capacity, weak cough and difficulty swallowing secretions are the cues to prepare for intubation in both disorders.

Priority nursing actions

Assess breathing and swallowing: vital capacity, negative inspiratory force, respiratory rate, cough strength and ability to handle secretions.
Keep suction and a bag-valve mask at the bedside, elevate the head of the bed, and keep the client NPO if swallowing is impaired.
Notify the provider and prepare for intubation when vital capacity falls.
Give prescribed medications on time: pyridostigmine for myasthenia gravis; plasmapheresis or IV immunoglobulin as prescribed.
Monitor cardiac rhythm and blood pressure for autonomic instability in Guillain-Barre syndrome.
Prevent immobility complications (venous thromboembolism, pressure injury) and set up a communication system.

Numbers to know

Value	Threshold or timing	Why it matters
Vital capacity	Below 20 mL/kg, or a steadily falling trend	Prepare for intubation and mechanical ventilation
Negative inspiratory force	Weaker than -30 cm H2O (for example, -20 cm H2O)	Respiratory muscles are failing
Pyridostigmine	30 to 60 minutes before meals	Peak strength for chewing and swallowing
Guillain-Barre weakness	Peaks within 4 weeks of onset	Respiratory decline is possible throughout this phase

Common exam traps

Choosing an extra dose of pyridostigmine for weakness with drooling, diarrhea and muscle twitching: wrong because these signal cholinergic crisis; hold the drug and support breathing.
Choosing to give pyridostigmine after meals or only when weakness appears: wrong because it is given on schedule and before meals for swallowing strength.
Choosing to wait for a low SpO2 before acting on a falling vital capacity: wrong because oxygen saturation falls late in neuromuscular respiratory failure.
Choosing to limit explanations for a paralyzed client with Guillain-Barre syndrome: wrong because consciousness and hearing are intact; explain all care and set up a blink communication system.

What to teach

Myasthenia gravis: take pyridostigmine on time, never skip or double doses, plan demanding activities for peak drug effect, and rest between them.
Avoid crisis triggers such as infection, emotional stress, heat and alcohol; check with the provider before any new medication, because some antibiotics, magnesium and beta blockers worsen weakness; wear medical identification.
Eat sitting upright, take small bites, and report choking, a weak voice or shortness of breath at once.
Guillain-Barre family: recovery is gradual over months, usually in reverse order of onset, and most clients regain function with rehabilitation.

Try 2 NCLEX-style questions on this topic

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Question 1 · QID F468674C

For each finding in a client with myasthenia gravis, click to specify which crisis it suggests.

	Myasthenic crisis	Cholinergic crisis
History of missed medication doses and a recent infection
Excessive salivation, tearing, and diarrhea
Symptoms began after taking extra medication doses
Improvement expected with MORE cholinesterase inhibitor
Muscle twitching (fasciculations) with the weakness

Question 2 · QID 758F32BE

A client with Guillain-Barré syndrome has weakness that has ascended to the chest. The bedside vital capacity has fallen over the last few hours and the cough is weaker. Which action is the priority?

A. Increase oral fluids and encourage frequent coughing to thin secretions and improve ventilation as the weakness progresses
B. Reduce activity, allow uninterrupted rest overnight, and repeat vital capacity in the morning to determine whether respiratory weakness stabilizes
C. Notify the provider and prepare for ventilatory support
D. Reassure the client that Guillain-Barré weakness is temporary and continue observation while waiting for spontaneous respiratory recovery

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Sources

Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Chronic Neurologic Problems.
Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Spinal Cord and Peripheral Nerve Problems.
Narayanaswami P, Sanders DB, Wolfe G, et al. International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update. Neurology. 2021;96(3):114-122.

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