Hazards of neostigmine in patients with neuromuscular disorders

In a 57-yr-old female with dystrophia myotonica, attempts to reverse residual non-depolanzmg block with neostigmine 1.0 mg were only partially effective and the administration of a further dose (0.5 mg) produced long-lasting muscle weakness. The train-of-four response of thi « patient resembled that of a depolarizing block and suggested an alteration in the electrical properties of the muscle membrane A 50-yr-old male with a 30-yr history of progressive muscle dystrophy, exhibited a tonic response to neosugmine in the evoked mechanomyogram during recovery from partial neuromuscular block. It is concluded that the type of reaction to neostigmme in patients with neuromuscular disease is unpredictable. On account of their tonic response to depolarizing neuromuscular blocking drugs, various types of myotonia represent a source of potential hazard during general anaesthesia (Orndahl, 1962a; Pater