Table 1.
When Should We Perform a Routine EEG?
| Indications | Conclusions | |
|---|---|---|
| Diagnosis and Management of Seizures | First unprovoked seizure | Presence of unequivocal IEDs equates with a new-onset epilepsy diagnosis |
| Classification of focal and generalized epilepsy | IEDs help in the choice of ASM for the seizure type(s) and epilepsies | |
| Diagnosis of epilepsy syndromes | Focal IEDs in focal epilepsy, SSW in epileptic encephalopathies, “fast” GSW in GGE | |
| Selection of ASM and monitoring response to treatment | Reduction in the spike burden of GSW or seizure burden may be present as a response to therapy | |
| Head injury | IEDs may occur that suggest untreated seizures | |
| Brain tumor | Focal slowing loosely correlates with location of abnormality. IEDs suggest a greater potential for seizures | |
| Stroke | May identify IEDs (especially hemorrhagic strokes) to predict a higher incidence of post-infarction seizures | |
| Cognitive and memory problems (e.g., transient epileptic amnesia) | May help suggest seizures as a substrate for cognitive impairment when IEDs are present | |
| Episodic anxiety/mood disturbances | May occur in temporal lobe seizures suggested by anterior temporal IEDs | |
| Diagnosis of Other Neurological Disorders | Paroxysmal neurological events | IEDs suggest seizures independent of bizarre paroxysmal behavior (especially when found in the frontal region) |
| CNS infection | Supports a diagnosis of encephalitis | |
| Encephalopathy | Supported by diffusely slow background | |
| Sleep disorder | Presence of IEDs suggest nocturnal seizures versus parasomnia | |
| Behavioral conditions (e.g., PNES with provocation and normal EEG) | May provide a definitive diagnosis when suggestion during routine EEG provokes a habitual attack to differentiate them from epileptic seizures | |
| Brain death | May be an indirect confirmatory test | |
Abbreviations: ASM = antiseizure medication; CNS = central nervous system; EEG = electroencephalogram; GGE = generalized genetic epilepsy; GSW = generalized spike-and-wave; IED = interictal epileptiform discharges; PNES = psychogenic nonepileptic seizures; SSW = slow spike-and-wave.