NeurologyPending review

Myasthenia gravis

An autoimmune attack on the postsynaptic acetylcholine receptor at the neuromuscular junction reduces the safety margin for transmission, so muscle strength fails progressively with repeated use, fatigable weakness, because each successive nerve impulse recruits an ever smaller pool of intact receptors.

In a nutshell

MG is antibody-mediated loss of postsynaptic acetylcholine receptors, narrowing the neuromuscular junction's safety margin so that strength fails with repeated use, fatigable weakness, hitting the eye and bulbar muscles first because their safety margin is smallest.

Classic presentation

Fatigable ptosis and diplopia worsening through the day and with sustained upward gaze, improving with rest, sometimes with proximal limb or bulbar weakness.

Key points

Weakness is fatigable, not fixed; it worsens with sustained or repeated use and improves with rest, unlike most other causes of weakness.

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Educational content pending clinical review. Not medical advice.