However, in certain instances an EEG recording or monitoring help considerably. Recording a clinically typical seizure by EEG is the most helpful circumstance as it not only affirms that the attacks are seizures but may identify the seizure type. However, if no EEG change occurs in association with a clinically typical attack, this does not mean it is nonepileptic in nature. Attacks confined to inferior and mesial surfaces may not be recorded by scalp electrodes. Muscle and movement artifact may obscure EEG potentials.
Interictal spikes correlate well with a seizure disorder.
Spike discharges may be found in other conditions that are not epilepsy, including occipital spikes in congenitally blind children and in some children with encephalopathies without epilepsy. Nonepileptiform abnormalities are usually not helpful but if they are prominent, they should encourage the performance of additional EEGs in search of epileptiform potentials. Such phenomena include bursts of rhythmic delta activity and abnormal focal slow waves in the theta or delta range. Rarely, an event will have no perceptible specific electrographic change but will be followed by focal or regional delta activity suggesting that some type of acute event, possibly a seizure, has occurred. If a single EEG fails to contain diagnostic information and yet the clinical issue remains in doubt, repeat recordings, occasionally using sleep, may be most helpful.