Neurology

Myasthenia gravis

An autoimmune neuromuscular-junction disorder causing fluctuating, fatigable weakness with particular risk to ocular, bulbar and respiratory muscles.

Definition

Myasthenia gravis is an autoimmune disorder of neuromuscular transmission causing fluctuating, fatigable weakness, usually affecting ocular, facial, bulbar, neck, limb and sometimes respiratory muscles.

First principles

The problem is failed postsynaptic transmission

Autoantibodies most often target the acetylcholine receptor or MuSK at the neuromuscular junction. This reduces the number or function of effective postsynaptic receptors and narrows the safety margin, so a normal nerve impulse may fail to trigger muscle contraction.

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