Nonconvulsive Status Epilepticus in Adults: Types, Pathophysiology, Epidemiology, Etiology, and Diagnosis

AbstractNonconvulsive status epilepticus (NCSE) is defined by permanent electroclinical nonconvulsive epileptic activity or a series of nonconvulsive seizures without recovery to baseline. This “silent” manifestation of lasting neurological symptoms, like aphasia, confusion, etc., impedes easily recognizing NCSE. The most important diagnostic step often is to consider the possibility of NCSE. NCSE can only be confirmed by an immediate EEG recording. Epidemiological studies show slight preponderance of convulsive status epilepticus (CSE) over NCSE (60:40%); however, this might result from lack of recognition of NCSE because of its very unspectacular manifestation. Regarding pathophysiology, the neuronal mechanisms are identical for both NCSE and CSE, but they spare the primary motor neurons. Permanent hyperexcitability may damage the neurons involved in NCSE the same way as the motor neurons in CSE. However, NCSE is spared from the life-threatening secondary pathophysiological sequelae of CSE (lactic acidosis, respiratory exhaustion, rhabdomyolsis, etc.). Nevertheless, autonomic dysregulation (arrhythmias (ventricular tachycardia/asystolia), apneas) may also expose the patient to su