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Myasthenia gravis presenting as weakness after magnesium administration
1Emory University School of Medicine, Department of Neurology, Atlanta, Georgia.
Muscle & Nerve
|August 1, 1990
Summary
Parenteral magnesium for preeclampsia can cause temporary paralysis in patients with undiagnosed myasthenia gravis. This case highlights the neuromuscular effects of magnesium and the importance of considering underlying transmission disorders.
Area of Science:
- Neurology
- Pharmacology
- Immunology
Background:
- Preeclampsia treatment involves magnesium sulfate, typically well-tolerated.
- Neuromuscular blockade is a known, rare side effect of magnesium administration.
Observation:
- A patient with preeclampsia developed profound quadriplegia after parenteral magnesium sulfate.
- Electrophysiological studies suggested postsynaptic neuromuscular blockade during weakness.
- Recovery occurred after magnesium discontinuation.
Findings:
- Single-fiber EMG revealed increased jitter and blocking post-recovery.
- Markedly elevated acetylcholine receptor antibodies confirmed myasthenia gravis.
- This represents the initial presentation of myasthenia gravis.
Implications:
- Magnesium-induced paralysis can unmask underlying neuromuscular transmission disorders.
- Patients with unexplained sensitivity to magnesium require thorough neurological evaluation.
- Early diagnosis of myasthenia gravis is crucial for appropriate management.