35-year-old man presents by EMS with seizures. According to family at the scene, he has a history of seizures but has not been taking his medication recently. He has been seizing for 30 minutes, despite treatment of intravenous lorazepam by EMS. On arrival, he is obtunded, foaming at the mouth, and exhibiting generalized tonic-clonic seizure activity.

Clinical Question

» How should status epilepticus be diagnosed?

The diagnosis and management of status epilepticus are essential skills for emergency physicians. Should emergency physicians rely on standard textbooks for diagnostic and treatment regimens? Or should recent literature guide diagnosis and management?

Status epilepticus has previously been defined as seizure(s) greater than or equal to 30 minutes in which the patient does not regain normal mental status between seizures. Alternatively, the Neurocritical Care Society defines it as a seizure with five minutes or more of continuous clinical or EEG seizure activity, or recurrent seizure activity without recovery between seizures.¹

History and physical examination have been the cornerstone of seizure diagnosis in the emergency department (ED). History taking, which relies on patient or witness accounts of the seizure event, can provide critical clues to differentiate seizures from other episodic disorders; however, its sensitivity is limited by the accuracy and completeness of the recollection, which can be affected by the patient’s postictal state or the observer’s understanding of seizure manifestations. Physical examination, including the assessment of postictal signs such as Todd’s paralysis, tongue bite marks, or loss of bladder control, offers additional diagnostic clues but also lacks specificity for seizure diagnosis.

These issues are compounded in the diagnosis of nonconvulsive seizures in critically ill patients. This subset of seizures lacks the dramatic convulsive movements typically associated with seizures, instead manifesting with either subtle clinical signs or altered mental status without any overt seizure-like activity. These seizures are detectable only with EEG monitoring and, similar to convulsive seizures, nonconvulsive seizures that are prolonged or repetitive can present a neurological emergency termed nonconvulsive status epilepticus.² A study of routine EEG in the ED in 2013 found that five percent of ED patients with altered mental status had nonconvulsive seizures (of whom 75 percent were in nonconvulsive status epilepticus).³ A systematic review of nonconvulsive seizures and status epilepticus in the intensive care unit (ICU) reported a pooled prevalence of 15 percent using continuous EEG; however, this prevalence varied considerably according to the clinical context or underlying etiology (eight percent among patients with coma, 10 percent in sepsis, 15 percent in stroke, 23 percent post-cardiac arrest, 33–48 percent following treatment of convulsive status epilepticus).⁴ With the increasing utilization of EEG, especially continuous EEG, nonconvulsive seizures have been increasingly recognized and diagnosed as a cause of altered mental status in critically ill patients.