side by side comparison
Myasthenia Gravis vs Guillain-Barré Syndrome: Descending vs Ascending Weakness
Both diseases cause progressive weakness that can paralyze the diaphragm, but one starts at the eyes and works down while the other starts at the feet and climbs up. Picking the wrong direction on NCLEX means you'll miss the respiratory decline trajectory and choose the wrong intervention.
Comparison
Side-by-side2 compared
Dimension
Myasthenia Gravis
Guillain-Barré
Pathophysiology & onset
- Autoimmune anti-AChR antibodies at NMJ
- Chronic, relapsing-remitting onset
- Post-infectious demyelination (Campylobacter)
- Acute; peaks at 2–4 weeks
Signs & symptoms
- DESCENDING: ptosis/diplopia → bulbar → limbs
- ★Worsens with use, improves with rest
- ★ASCENDING: feet/legs → trunk → arms
- Constant weakness; no rest improvement
Diagnostics
- Edrophonium (Tensilon) test confirms MG
- Anti-AChR antibodies present
- ★CSF: ↑ protein, normal WBC
- Areflexia — absent reflexes
Respiratory priorities
- Monitor serial NIF & vital capacity
- Myasthenic crisis: sudden vent failure
- Monitor serial NIF & vital capacity
- Intubate if VC < 15 mL/kg
Treatment
- Pyridostigmine; thymectomy
- Plasmapheresis or IVIG
- Plasmapheresis or IVIG
- ★NO anticholinesterases
Patient teaching
- Take pyridostigmine on time, before meals
- Pace activity; rest between tasks
- Recovery is gradual over weeks–months
- PT/OT, DVT prevention during paralysis
Crisis — escalate
- Myasthenic crisis: undermedication
- Cholinergic crisis: overmed (SLUDGE)
- Respiratory failure from ascending paralysis
- Autonomic instability: BP/HR swings
Prognosis
- Chronic — managed not cured; normal lifespan
- 80% regain full function over wk–mo
Pathophysiology & onset
Myasthenia Gravis
- Autoimmune anti-AChR antibodies at NMJ
- Chronic, relapsing-remitting onset
Guillain-Barré
- Post-infectious demyelination (Campylobacter)
- Acute; peaks at 2–4 weeks
Signs & symptoms
Myasthenia Gravis
- DESCENDING: ptosis/diplopia → bulbar → limbs
- ★Worsens with use, improves with rest
Guillain-Barré
- ★ASCENDING: feet/legs → trunk → arms
- Constant weakness; no rest improvement
Diagnostics
Myasthenia Gravis
- Edrophonium (Tensilon) test confirms MG
- Anti-AChR antibodies present
Guillain-Barré
- ★CSF: ↑ protein, normal WBC
- Areflexia — absent reflexes
Respiratory priorities
Myasthenia Gravis
- Monitor serial NIF & vital capacity
- Myasthenic crisis: sudden vent failure
Guillain-Barré
- Monitor serial NIF & vital capacity
- Intubate if VC < 15 mL/kg
Treatment
Myasthenia Gravis
- Pyridostigmine; thymectomy
- Plasmapheresis or IVIG
Guillain-Barré
- Plasmapheresis or IVIG
- ★NO anticholinesterases
Patient teaching
Myasthenia Gravis
- Take pyridostigmine on time, before meals
- Pace activity; rest between tasks
Guillain-Barré
- Recovery is gradual over weeks–months
- PT/OT, DVT prevention during paralysis
Crisis — escalate
Myasthenia Gravis
- Myasthenic crisis: undermedication
- Cholinergic crisis: overmed (SLUDGE)
Guillain-Barré
- Respiratory failure from ascending paralysis
- Autonomic instability: BP/HR swings
Prognosis
Myasthenia Gravis
- Chronic — managed not cured; normal lifespan
Guillain-Barré
- 80% regain full function over wk–mo
★ marks the fact that sets a column apart.
Clinical Pearl
MG drops Down from the eyes; GBS Gets up from the Ground — both can stop breathing.
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