Sixty-three neonates were investigated using prolonged video/EEG monitoring to identify seizures and determine the diagnostic efficiency of clinical observation and short duration EEGs at the Department of Paediatric Neurology, Prince of Wales Children’s Hospital, Sydney, NSW, Australia. Thirty-two patients had seizures confirmed. Clinical observations after anticonvulsant treatment identified seizures in 66%, and a 60 min EEG revealed electrographic seizures in 76%, after phenobarbital treatment, and in 50% after addition of phenytoin. Short duration EEG avoids misdiagnoses in most patients with ambiguous clinical signs and aids substantially in the identification of neonatal seizures. 
COMMENT. When clinical signs of seizures are controlled by anticonvulsants, a 60 min EEG is required to uncover subclinical neonatal seizures, and in some cases, especially when phenytoin has been given in addition to phenobarbital, prolonged video/EEG monitoring may be necessary in diagnosis. An EEG after infusion of anticonvulsant does not gaurantee seizure identification, but the probability of diagnosis increases in relation to the length of the recording. In a study at the Magee-Womens Hospital, Pittsburgh, PA, more than 50% of 92 neonates with seizures had only electrographic expression of seizures, and 16% exhibited electroclinical dissociation. (see Progress in Pediatric Neurology II, PNB Publishers, 1994, pp 11-16).