Table 1.
EEG-related terminology, acronyms, synonyms, and definitions.
| Terminology (synonym) | Acronym | Definition |
|---|---|---|
| Amplitude-integrated EEG | aEEG | Compressed (amplitude is logarithmic and time is linear) recording of EEG using 2 or several channels, typically of greater than 12 h duration and in ICU settings, with the aim of detecting background changes indicative of encephalopathy or suggestive of seizures. |
| Continuous EEG monitoring | cEEG | ≥16 channels (≥8 in neonates) of EEG recording with simultaneous video recording, typically of greater than 12 h duration and in ICU settings, with the aim of detecting and monitoring seizures, including electrographic (EEG only) seizures. |
| EEG background | The predominant EEG activity, in ICU recordings typically categorised as: normal or sedated sleep; slow and disorganised; discontinuous or burst suppression; or attenuated and featureless.[166], [167], [168], [103] | |
| Electroclinical seizure (clinical seizure, convulsive seizure) | ECSz | A seizure with clinical manifestations and time-locked to an EEG pattern (note: EEG pattern does not need to fulfil electrographic seizure criteria) OR an electrographic seizure and subsequent clinical improvement attributable to suppression of seizures with an ASM.98,169 |
| Electroclinical status epilepticus (clinical or convulsive status epilepticus) | ECSE | An uninterrupted electroclinical seizure lasting 10 min or longer OR recurrent seizures totalling 12 min in any 1-h period (hourly seizure burden ≥20%) OR ≥ 5 min of a convulsive (i.e. with bilateral tonic-clonic motor activity) seizure.13,98,169 |
| Electrographic seizure (EEG seizure) | ESz | An abnormal paroxysmal electrographic event that differs from the background activity, lasts longer than 10 s (briefer if associated with clinical change), has a plausible electrographic field, typically has a frequency of >2.5 Hz, and evolves in frequency, morphology, or spatial distribution (except for neonatal seizures which may not evolve).13,170 |
| Electrographic status epilepticus | ESE | An uninterrupted electrographic seizure lasting 10 min or longer OR recurrent electrographic seizures totalling 12 min in any 1-h period (hourly seizure burden ≥20%)13,169 |
| Ictal-interictal continuum | IIC | An EEG pattern that does not qualify as an electrographic seizure or electrographic status epilepticus, but there is a reasonable chance that it may be contributing to coma, causing other clinical symptoms, and/or contributing to neuronal injury.13 |
| Routine EEG | ≥16 channels (≥8 in neonates) of EEG recording, typically 20–60 min duration with simultaneous video recording, with the aim of detecting abnormalities of EEG background, interictal epileptiform discharges, seizures, and status epilepticus. In ICU settings, routine EEG is considered a screening tool. | |
| Sporadic epileptiform discharges (interictal epileptiform discharges) | SEDs | Non-rhythmic and non-periodic (intermittent) interictal EEG phenomena that are intermixed with the background and are associated with seizures e.g. spikes, polyspikes, sharp waves.13 |
| Total seizure burden | The proportion of time occupied by seizures during cEEG.99 | |
| Video-EEG monitoring | ≥16 channels (≥8 in neonates) of EEG recording with simultaneous video recording, typically greater than 3 h duration and in ward or ambulatory settings, with the aim of recording seizures and other episodic phenomena. In ICU, video-EEG monitoring is generally referred to as cEEG. |