Non-Convulsive Status Epilepticus (NCSE): Definition, Recognition, Electroencephalographic Findings, and Diagnosis

Non-convulsive status epilepticus (NCSE) is being increasingly recognized in many patient populations, especially in patients with altered mental status (AMS) admitted to the intensive care unit (ICU), where its frequency is the highest. Because of the paucity of signs and symptoms, the diagnosis of NCSE needs a prolonged electroencephalography (EEG) recording which may take more than 24 hours. Once the diagnosis is established, an urgent treatment should be initiated. This chapter will review the history and definition, the EEG, and clinical manifestations of NCSE and will also focus on the many factors including the newly described ictal-interictal continuum which all contribute to an increase in the frequency of NCSE.