ELECTROCLINICAL FEATURES OF STATUS EPILEPTICUS

Status epilepticus (SE) is a condition wherein epileptic seizure disch arges are sufficiently prolonged or repetitive so as to produce persis tent alterations in neurologic function and in the underlying physiolo gic and neurochemical activities of the brain. Thus, the definition of SE now includes any disorder in which there is sustained and prolonge d excitation of neurons. Electroencephalographic (EEG) patterns associ ated with specific types of SE are important components in their class ification. Like epileptic seizures, SE can be divided into partial ons et SE and primarily generalized SE. Partial onset SE includes secondar ily generalized convulsive SE (GCSE), complex partial SE (CPSE), simpl e partial SE (SPSE), and the syndromes of epilepsia partialis continua (EPC) and rolandic SE (RSE). Primarily generalized SE includes primar ily GCSE, absence SE, atypical absence SE, generalized myoclonic SE, g eneralized clonic SE, generalized tonic SE, atonic SE, and the syndrom es of electrical SE of sleep (ESES) and minor epileptic SE of Brett. S E is a dynamic disorder. Behavioral and electrical manifestations chan ge over time if seizure activity is allowed to persist without success ful treatment. A progression from overt to subtle convulsive activity occurs in secondarily GCSE and there is also a progression of predicta ble EEG changes in prolonged GCSE. CPSE begins as discrete complex par tial seizures but also progresses behaviorally and electrically throug h a sequence similar to that observed in GCSE. Progressive behavioral and electrical changes have not been reported in primarily generalized forms of SE. EEG is an important tool for verifying successful treatm ent of SE if the patient does not immediately recover neurologic funct ion. EEG recordings also contribute substantially to understanding the mechanisms of, and development of better treatments for, human SE thr ough their use in the study of experimental SE in the laboratory.