Rapidly Progressive Weakness

Abstract

The first step in evaluating a patient with rapidly progressive weakness is to ensure respiratory stability, intubating the patient if necessary. Measurements of negative inspiratory force and forced vital capacity help to determine which patients are in urgent need of intubation or closer respiratory monitoring. Once respiratory stability is ensured, identifying the initial pattern of weakness is the next step in establishing the diagnosis. Nerve conduction studies, electromyography, and other laboratory tests can then be used to differentiate among the various causes of weakness. The most important causes of rapidly progressive weakness are Guillain-Barre syndrome (GBS) and myasthenic crisis. Less common causes of rapidly progressive weakness include botulism, poliomyelitis, and spinal cord infarction. Critical illness neuromyopathy is a common source of failure to wean from the ventilator seen in patients who have undergone prolonged treatment in the ICU.