Neuromuscular weakness is a common occurrence in patients who are critically ill, developing in ≥25 percent of patients who are in the intensive care unit (ICU) and ventilated for at least seven days . Weakness is partly a consequence of improved survival in patients with multiorgan failure and sepsis, but is also a consequence of treatments administered in the ICU, including intravenous glucocorticoids and sometimes paralytic agents.
Neuromuscular weakness in the ICU is most often due to critical illness myopathy or to critical illness polyneuropathy. This topic will review the peripheral neuromuscular disorders of critical illness.
In a critically ill patient who develops flaccid generalized weakness, the major considerations in the differential diagnosis are critical illness myopathy and critical illness polyneuropathy, or a combination of the two. Prolonged neuromuscular junction blockade is rare. Each of these disorders is discussed in detail below.
Other acute and subacute myopathies can occur in critically ill patients, including rhabdomyolysis and cachectic myopathy. In addition, rare acute neuropathies such as Guillain-Barré syndrome can also develop in the ICU.
Rhabdomyolysis — Some critically ill patients develop rhabdomyolysis due to their illness or medications . (See "Clinical manifestations and diagnosis of rhabdomyolysis".)