Also known as Myasthenic Syndrome – Not to be confused with Myasthenia Gravis

Respiratory Failure – Weakness can lead to respiratory failure post operatively. Do a thorough evaluation and prepare for respiratory interventions if you think the patient will need them.

Improvement with activity – Patients with this condition tend to improve throughout the day and/or with exercise

Drugs – Anticholinesterase drugs (eg. Neostigmine) are ineffective.

Paralytics – Sensitive to depolarizing AND nondepolarizing neuromuscular blocking agents (NMBAs)

Treatment – Short term relief can be achieved with  plasmapheresis and immunoglobulins. Drugs that can be effective at treating the disorder include Guanidine hydrochloride and 3,4 Diaminopyridine (DAP).  These drugs increase the release of acetylcholine.  Also, effective adjuncts include corticosteroids and azathioprine. 

3,4 DAP – should be continued until the time of surgery. If the patient has been treated with 2,3 DAP or an anticholinesterase, reversal of neuromuscular blockade may be ineffective

Immune-mediated. Autoantibodies attack the presynaptic voltage-gated calcium channels.

These patients are typically male > 40 years of age.

Muscle weakness and increased fatigability is typically in the proximal limb muscles. The most common muscles affected are the lower limbs. Other symptoms may include dry mouth, impotence, constipation, reduced sweating, autonomic dysfunction

Associated with small cell lung carcinoma and idiopathic autoimmune disease