Lambert-Eaton Myasthenic Syndrome (LEMS)

Profound NMB sensitivity - Patients are exquisitely sensitive to BOTH depolarizing and nondepolarizing neuromuscular blockers (unlike myasthenia gravis, which resists succinylcholine). Give greatly reduced doses or avoid relaxants entirely, and titrate to quantitative train-of-four (TOF).

Unreliable reversal - The response to anticholinesterase reversal is blunted and unpredictable; sugammadex has been used but recovery can still be prolonged. Confirm full, sustained reversal before extubation.

Respiratory reserve - Weakness plus residual blockade risks postoperative respiratory failure; plan monitored recovery and possible ventilation.

Reduced anesthetic and sedative requirement - Sensitivity extends to sedatives and opioids; titrate carefully.

Aspiration and autonomic features - Bulbar and autonomic involvement warrant aspiration precautions; also pursue the underlying malignancy workup (small-cell lung cancer).

An autoimmune disorder in which antibodies against presynaptic voltage-gated calcium channels at the neuromuscular junction reduce acetylcholine release. The result is proximal muscle weakness that characteristically IMPROVES with repeated effort - the opposite of myasthenia gravis - along with autonomic features such as dry mouth. It is frequently paraneoplastic, most often associated with small-cell lung cancer. The key anesthetic point is a profound, unpredictable sensitivity to neuromuscular blocking drugs of both classes.