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Alcohol abuse is a common cause of seizures resulting in admission to the intensive care unit. The cause of the alcohol-related seizures (ARS) is usually abstinence in a chronic alcoholic, although some patients may still have detectable levels of alcohol in their blood. ARS generally occur between 7 and 48 h after abstinence. Approximately half of patients presenting with ARS will have recurrent seizures (usually two to four) within a vulnerable 6-h period following the initial ARS. Although patients with ARS rarely enter status epilepticus (SE), alcohol withdrawal is a common contributing factor in many cases of SE. Evaluation involves searching for a focal cause of the seizure as well as looking for comorbid conditions, including delirium tremens, that may complicate the management of chronic alcohol abusers. Treatment of ARS is similar to general management of alcohol withdrawal, with benzodiazepines being the mainstay of treatment. Treatment of alcohol-related SE is similar to that of other causes of SE. Phenytoin is not indicated for treatment of ARS unless the patient enters SE.

Critically ill patients are subjected to numerous medication effects during their stay in the intensive care unit (ICU). Some of them have epileptogenic potentials. The most common pathophysiologic mechanism is through blockade of the γ-aminobutyric acid (GABA) receptor, and the most commonly used family of ICU drugs, reducing the seizure threshold, is the antibiotics. The exact role of these medications in inducing a clinical or subclinical seizure, in the context of cerebral injury or other multiorgan failure, is in many cases unclear. Fortunately, the ability to prevent seizures in critically ill patients is within our grasp. However, the intensivist should always seek a medication as the cause of the witnessed seizure and should consider replacing it with another having less epileptogenic potential.

To minimize seizures, the same cautious measures used to minimize or eliminate any unwanted drug side effect should be followed. Always attempt to start and keep the patient on the lowest dose of the medication necessary to exert the desired therapeutic effect. When upward titration in dosage is necessary, increase slowly, keeping a watchful eye on all laboratory and clinical indicators of success or failure. Free levels of antiepileptic or other medications must be considered in the critically ill because of the numerous factors affecting their final action on the target in the central nervous system. A GABAergic receptor agonist antiepileptic drug should be used as first-line antidote in most of the cases.

Seizures caused by ingestion of drugs and toxins require specific treatment aiming to terminate epileptiform activity and to eliminate the toxin. Withdrawal from regularly ingested drugs can also be accompanied by seizures requiring admission to an intensive care unit. This chapter discusses diagnostic and therapeutic particulars of seizures induced by illicit drugs of abuse, environmental toxins, and heavy metals.

There are multiple approaches to the treatment of seizures and status epilepticus (SE) in the intensive care unit (ICU). With only one seizure, the focus should be more on defining the etiology than on treating the patient with antiepileptics; but with more prolonged or recurrent seizures, both approaches should be pursued in parallel. If delayed or untreated, SE carries a grave prognosis, and every ICU should have a protocol for rapid response to this neurological emergency. Continuous electroencephalographic monitoring should become mandatory in the treatment of SE because of the late dissociation between clinical convulsions and electrographic seizures and the inability to use the clinical examination as guide to the treatment. Focal and nonconvulsive SE have etiology and prognosis different from those of generalized convulsive SE and the treatment also differs. Several medications are available for treating seizures, but only few are available for parenteral, fast administration in the treatment of SE. Therefore, the experience from using the newer antiepileptics in the case of resistant SE is limited. Interactions between antiepileptics and common ICU medications may be significant, and concurrent multiorgan failure may alter their metabolism.