Acute metabolic encephalopathy: a review of causes, mechanisms and treatment.

Acute encephalopathy is a relatively common problem: one of the causes is metabolic disorders. A detailed history, examination and investigations performed during the acute illness (blood sugar, blood gases, plasma ammonia, blood lactate, plasma ketones, plasma amino acids, liver function tests, and urinary organic acids) should identify those patients in whom a metabolic disorder is likely. More detailed studies may be needed to establish a precise diagnosis. The mechanism of the acute brain dysfunction is multifactorial. Factors that contribute include changes in blood flow and, initially, a disturbance in neurotransmitter function followed by failure of energy metabolism and cellular depolarization. Treatment of these conditions is largely supportive, with special attention to the management of cerebral perfusion pressure.