[Intensive care unit-acquired weakness: development of polyneuropathy and myopathy in critically ill patients]

Critically ill patients in the intensive care unit (ICU) often develop ICU-acquired weakness, which is characterized by acute or subacute onset diffuse limb weakness, during the early course of their severe illness and is related to prolonged mechanical ventilation, ICU stay, hospital stay, and even increased mortality. The development of generalized weakness or paralysis may be because of critical illness polyneuropathy (CIP), critical illness myopathy (CIM), and a combination of both. The basic mechanisms underlying these disorders are complex and poorly understood. Several risk factors, including severe sepsis and multiple organ failure, are implicated, whereas the effects of the use of steroids and neuromuscular blocking agents and hyperglycemia on the development of this condition remain to be clarified. Furthermore, whether each risk factor is associated with the development of CIP, CIM, or both has not been clarified thus far. Typically, the condition of patients is diagnosed on the basis of the assessment of risk factors, neurological findings, and electrophysiological examinations, including nerve conduction study and needle electromyography. In addition, muscle biopsy and direct muscle stimulation test can be used to distinguish CIP from CIM. To date, no therapeutic approach has been established for ICU-acquired weakness, and potential preventive measures should be implemented in the daily management of the critically ill patients. Further studies are required to clarify the pathogenesis of these disorders and to identify appropriate therapeutic options.