With the continuous improvement in the survival of critical patients, new neuromuscular syndromes are being described. The clinical finding is an acute-subacute onset of generalised weakness with difficulty in weaning the patient from the ventilator, due to polyneuropathy, myopathy, prolonged neuromuscular blockade or a combination of these disorders. Although having a multifactorial ethiopathology, the major risk factors in the development of these disorders are multiple organ failure and sepsis for polyneuropathy; corticosteroids and neuromuscular junction blocking agents (NMB) for myopathy; and NMB and renal and liver failure for prolonged neuromuscular blockade. No specific treatment exists, which is why--due to the high incidence of these syndromes and their poor prognosis, with a mortality rate higher than 50%--we should recognise, diagnose and avoid, where possible, the conditions that help the development of these disorders.