- International League Against Epilepsy (ILAE): “seizure that persists for a sufficient length of time or is repeated frequently enough that recovery between attacks does not occur"
- Sufficient time: Seizure lasting greater than 30 minutes or 2 or more repetitive seizures without recovery of the baseline level of consciousness between attacks
- However many authors have suggested that a duration of 5 minutes or more should be defined as a status epilepticus.
- Categorized by motor manifestations:
- Convulsive status epilepticus: Any kind of motor manifestations
- Nonconvulsive status epilepticus: Without motor manifestations
- Categorized by portion of cerebral cortex involved:
- Partial status epilepticus
- Generalized status epilepticus
- A generalized status epilepticus that starts with a focal seizure is usually due to a focal brain dysfuntion or lesion (symptomatic epilepsy)
- A status that starts with generalized epileptic activity is usually due to genetic causes or idiopathic.
- Classically the seizures starts with flattening of the normal background rhythms, followed by generalized low voltage fast activity or Polyspikes that increase in amplitude and decrease in frequency until these patterns become obscured by muscle and movement artifact. As the seizure clinically moves into the clonic phase, the EEG shows rhythmic alternating muscle artifacts corresponding to the rhythmic jerking of the patient. After the seizure or between seizures, the EEG shows diffuse suppression of cerebral activity.
- Nonconvulsive (or electrographic) seizure may be demonstrated by any electrographic pattern lasting at least 10 seconds and satisfying any 1 of the following 3 primary criteria:
- Repetitive generalized or focal Spikes and sharp waves, Spike slow wave complex, or Sharp wave slow wave complex at a frequency of 3 or more per second.
- Repetitive generalized or focal Spikes and sharp waves, Spike slow wave complex, or Sharp wave slow wave complex at a frequency of 3 or less per second AND one of the secondary criteria below:
- Sequential rhythmic, periodic, or quasi-periodic waves at 1 or more per second and unequivocal evolution in: (1) frequency (increasing or decreasing by at least 1/sec), (2) morphology, or (3) location. Of note, evolution in amplitude alone is not sufficient to meet the criteria for evolution. Additionally, change in sharpness of the waveform without other change in morphology is also not adequate to qualify as evolution of morphology.
- An electrographic or nonconvulsive seizure may be additionally demonstrated by significant improvement in the patient’s clinical state or the appearance of previously-absent normal EEG patterns temporally coupled to the acute administration of a rapidly-acting antiepileptic drug such as a benzodiazepine.
Generalized status epilepticus that starts with focal spikes, sharp waves and Spike slow wave complexes, wich generalized to rhytmic discharges increasing in amlitude and muscle artifacts (average)
- Chong DJ, Hirsch LJ. Which EEG patterns warrant treatment in the critically ill? Reviewing the evidence for treatment of periodic epileptiform discharges and related patterns. J Clin Neurophysiol. 2005 Apr. 22(2):79-91