General Considerations in the Diagnosis of Neuromuscular Disorders

Neuromuscular disorders are commonly encountered in the critical care setting. Patients with known neuromuscular disorders, such as Guillain-Barré syndrome or myasthenia gravis, are admitted when weakness compromises the patient’s ability to protect his or her airway or threatens ventilatory failure. Patients admitted with ventilatory failure of unknown cause may be diagnosed with a neuromuscular disorder such as amyotrophic lateral sclerosis or myasthenia gravis. Rarely, treatment may unmask a pre-existing neuromuscular disorder, as when drugs with neuromuscular blocking properties are given to patients with myasthenia gravis. Finally, patients with nonneuromuscular critical illnesses frequently develop neuromuscular weakness as a result of their illness or its treatment (1). Intensive care physicians need to be familiar with the principles underlying diagnosis and management of patients with neuromuscular disease. Because electrophysiologic testing is often necessary to diagnose neuromuscular disorders in the intensive care setting, they should also have a basic appreciation of the techniques and indications for these studies. They should be familiar with the common neuromuscular disorders that require intensive care; Guillain-Barré syndrome and myasthenia gravis are considered in some detail because they are prevalent and treatable, and because, with proper treatment, they often carry a favorable prognosis. Finally, the intensive care physician will be responsible for recognizing and managing neuromuscular disorders that result from critical illness, which are now the neuromuscular disorders most commonly encountered in the intensive care setting (2).