Most generalized tonic-clonic SE consists of partial seizures that have secondarily generalized; primary generalized SE is less common [5]. Most patients do not convulse continuously. Instead, seizures of a few minutes’ duration may be followed by a prolonged period of unconsciousness that leads to the next seizure. During convulsive SE, massive autonomic discharge occurs with tachycardia and hypertension. Corneal and pupillary reflexes are lost and plantar reflexes may be extensor. As SE continues, the motor manifestations may evolve into more subtle activity such as low-amplitude focal twitching, nystagmus, eye deviation, or recurrent pupillary hippus. This is sometimes called subtle generalized SE [4]. SE may also present in this more subtle form, without initial convulsive activity, in patients who are very encephalopathic; electroencephalography (EEG) is required to confirm the diagnosis. Myoclonic SE is often classified as a form of convulsive SE; it can occur in children with chronic epilepsy and mental retardation. It is characterized by repetitive, asynchronous myoclonus with variable clouding of consciousness and may evolve into generalized tonic-clonic SE. In adults, the myoclonic syndromes that occur are usually secondary to toxic or metabolic encephalopathies, most commonly severe cerebral anoxia [6]. The patients are usually comatose, and the prognosis is poor. In both forms of myoclonic SE, the EEG shows repetitive generalized epileptiform discharges.

Simple partial status epilepticus is the second most common form of SE, after generalized tonic-clonic SE [4]. In partial motor SE, focal clonic or tonic-clonic activity is localized to the face or an extremity. This activity may spread, corresponding to the somatotopic organization of the motor cortex, known as a Jacksonian march. Alternatively, the partial motor seizures may be multifocal, in this case often precipitated by metabolic disorders, such as hyperglycemia with a hyperosmolar nonketotic state [7]. Epilepsia partialis continua refers to a form of partial motor SE characterized by continuous, highly localized seizures that do not secondarily generalize and in which consciousness is maintained.

NCSE is an under-recognized cause of coma. In a recent study, NCSE was documented in 8% of all comatose patients, without signs of seizure activity [8]. In additional studies, 31% to 37% of patients with unexplained altered mental status in intensive care units were in NCSE. NCSE is more likely to occur in the setting of acute medical problems, both systemic and neurologic [8,9,10].

Nonconvulsive SE includes absence and complex partial SE [4]. Clinically, both absence and complex partial SE present with a prolonged period of altered behavior and can masquerade as a psychiatric fugue state. Absence SE involves a variable level of altered consciousness, which may be accompanied by subtle myoclonic movements of the face, eye blinking, and occasional automatisms of the face and hands. The EEG is diagnostic, revealing continuous or discontinuous generalized spike and slow-wave activity. Complex partial SE involves either a series of complex partial seizures with staring, unresponsiveness, and motor automatisms, separated by a confusional state, or a more prolonged state of partial responsiveness and semipurposeful automatisms. In both of these forms of SE, the patient is partially or totally amnestic for the episode.