Syncope is often mistaken for generalized tonic-clonic seizures because of the prominent motor manifestations that may occur in the midst of the attack. Distinguishing features include the initial syncopal symptoms, facial pallor, and prompt recovery.
The sequential EEG changes during a syncopal attack consist of alpha suppression, low-voltage beta activity, diffuse theta increasing in voltage, then highvoltage delta that gradually decreases in amplitude followed by diffuse attenuation (suppression). Tonic and then clonic activity may accompany the decreasing delta and attenuation phases (92). As cerebral blood flow regains its normal quantity, brain waves reappear in reverse order of disappearance. More abbreviated sequences may accompany relatively minor attacks. Breathholding spells produce a similar sequence of changes (92), as may the apneic spells induced by crying in children (93). Because the semeiology of such spells is far more diagnostic than the electroencephalogram, any interparoxysmal EEG abnormality in either children or adults is very likely irrelevant (94).
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