Antiseizure agents in critical illness

Seizures are a common problem in intensive care units (ICU) and the advent of continuous electroencephalography is demonstrating that the incidence of seizures is still underestimated. Many patients considered encephalopathic from any cause are now found to be in non-convulsive status epilepticus. While the significance of non-convulsive seizures remains unclear, there is little disagreement that these seizures should be treated with antiseizure agents and prevention of any type of seizure is a reasonable therapeutic goal. Many antiseizure agents have been studied in ICU populations and extensive experience exists with drugs such as phenytoin, valproate, or pentobarbital. Since the previous edition of this textbook, several new antiseizure agents have been introduced. Levetiracetam, topiramate, and lacosamide have been established as reasonable pharmacologic options, in particular for treatment of status epilepticus. Patients with seizures in the ICU often present with challenging clinical scenarios, which influence the choice of antiseizure agents. For example, reduced liver or renal function, especially if needing continuous renal replacement therapy or intermittent haemodialysis, has an impact on drug level variability and susceptibility to seizure development. ICU patients will typically require a multitude of pharmacological agents for their specific clinical situation and drug–drug interactions must be considered. Additionally, many medications used in ICUs are associated with seizures, in particular, certain antibiotics. Overall, the development of new drugs and better monitoring methods will undoubtedly improve our ability to control seizures in ICU patients, but currently no treatment has been shown to be universally effective for challenges, such as refractory status epilepticus.