Nonconvulsive status epilepticus (NCSE) refers to a prolonged seizure that manifests primarily as altered mental status as opposed to the dramatic convulsions seen in generalized tonic-clonic status epilepticus. There are 2 main types of NCSE, each of which has a different presentation, cause, and expected outcome. In the first type of NCSE, patients present with confusion or abnormal behavior, suggesting the diagnosis of absence status epilepticus (ASE) or complex partial status epilepticus (CPSE). The second type of NCSE (subtle status epilepticus [SSE]) must be considered in comatose patients who present after a prolonged generalized tonic-clonic seizure and who may have only subtle motor manifestations of a seizure, such as facial or hand twitchings. Whereas the morbidity and mortality in patients with prolonged ASE or CPSE is low, the mortality associated with SSE can exceed 30% if the seizure duration is greater than 60 minutes.