Neurological problems are common among critically ill patients; they often signal that other organs are failing, but are themselves important causes of morbidity and mortality. Cognitive function may suffer as a consequence of septic encephalopathy, the pathophysiology of which is poorly understood; however, the affected patients usually return to their baseline when sepsis resolves. Seizures and cerebrovascular disorders are also common in the intensive care unit. Neuromuscular complications are important causes of failure to wean from mechanical ventilation and lead to substantial long-term morbidity.