Undiagnosed myasthenia gravis unmasked by neuromuscular blockade.

Myasthenia gravis is an uncommon autoimmune disease resulting in destruction of the postsynaptic nicotinic receptors at the neuromuscular junction. We describe a 43-yr-old, 95 kg patient who presented for elective laparoscopic cholecystectomy. She was given vecuronium 10 mg to facilitate tracheal intubation. At the end of the procedure the patient could not maintain adequate spontaneous ventilation despite administration of two doses of neostigmine 2.5 mg. Subsequent investigation led to a diagnosis of myasthenia gravis. We discuss the investigation, diagnosis, and subsequent management of such a patient and emphasize that tactile estimation of the train-of-four ratio is not a reliable indicator of adequate recovery of neuromuscular function.