Electrolyte Disturbances and Critical Care Seizures

Abstract

Electrolyte disorders are common in critically ill patients. The brain is only partially protected from these imbalances by the blood–brain barrier. Neuronal excitability and synaptic transmissions are affected by changes in extracellular ion concentration and osmolality. Hyponatremia is by far the most common cause of seizures due to an electrolyte imbalance. The risk depends on the severity and the rate of onset. Prompt recognition and careful treatment are required to avoid irreversible complications. Seizures can also occur in the setting of hypernatremia but are most often due either to an extra-pontine demyelination syndrome or an excessively rapid correction of sodium levels. Hypocalcemia can also cause seizures, mainly in neonates. Hypercalcemia and hypomagnesemia are also associated with acute seizures, although a direct causal relationship is less likely and associated complications, especially a posterior reversible encephalopathy syndrome, should be actively sought as an alternative etiology. Acid-base disorders are common in the critically ill but they do not appear to be a major cause of acute seizures. Acute acidosis can be the consequence of seizures or suggests an acute intoxication as the etiology. On the other hand, acute inhalation of 5% CO₂ is a potent anti-seizure agent.