Epileptic seizures in critically ill patients

Abstract

The aim of this article - to review the causes, clinical signs, pathophysiology, consequences, and treatment of seizures and status epilepticus in critically ill patients. Only 25% of people, who have seizures and status epilepticus, have epilepsy as well. In the intensive care settings, seizures and status epilepticus are a common neurologic complication, which is attributable to primary neurologic pathology (stroke, hemorrhage, tumor, central nervous system infection, head trauma) or secondary to critical illness (anoxic brain damage, intoxications, metabolic abnormalities) and clinical management. There are three main subtypes of status epilepticus in intensive care units: generalized convulsive status epilepticus, focal motor status epilepticus, and nonconvulsive status epilepticus. A seizure is a consequence of electrical neurological derangement because of sudden imbalance between the inhibitory and excitatory forces within the network of cortical neurons. The main inhibiting neurotransmitter in the brain is gamma-aminobutyric acid (GABA), which binds to GABA-A and GABA-B receptors. The main excitatory neurotransmitter is glutamate, which binds to N-methyl-D-aspartate receptors. Different ions (Cl-, K+, Na+, Ca2+) also play a role in the pathophysiology of seizures. Prolonged status epilepticus may lead to different systemic and neurologic consequences. Generalized convulsive status epilepticus is one of the most common emergencies encountered in clinical practice, which requires immediate treatment. The first-line drugs are benzodiazepines (lorazepam, diazepam), the second-line ones - phenytoin and fosphenytoin. For the treatment of refractory status epilepticus, barbiturates (phenobarbital, pentobarbital, thiopental), valproate, midazolam, propofol, and isoflurane are used. The dosage of drugs and parameters to monitor are referred in the article. The mortality from generalized convulsive status epilepticus is 15-50%; the main factors, influencing prognosis, are the cause and the duration of status epilepticus and age of a patient.