Paediatric EEGs: what NICE didn't say

Electroencephalogram after first unprovoked seizure in children: Routine, unnecessary or case specific

A child is brought into a paediatric emergency unit with an unprovoked, afebrile first seizure. We conduct a clinical assessment of the child and rule out any acute metabolic, traumatic or infectious causes and consequently, make the diagnosis of an epileptic seizure. The International League against Epilepsy (ILAE) suggests that following such a diagnosis, the next step should be the appropriate classification of the seizure type, after which an appropriate syndrome diagnosis should be made. (1) Should an EEG be arranged for this child and if so, should it be arranged within 24 hours or within the next week? If we decide not to arrange an EEG this time and to do so if any further seizures occur, are we practicing evidence based medicine? A recent guideline published by the Royal College of paediatrics and child health (RCPCH) asserted: "There is no need for an EEG following a first simple afebrile seizure". (2) This is a very bold and clear statement but what evidence and what quality of evidence is this statement based upon? This review analyses and discusses prominent literature regarding this widely-discussed topic.

Effect of reducing the recording time of standard EEGs on the detection of EEG-abnormalities in the management of the epilepsies of childhood

PURPOSE

The ILAE recommends baseline recordings of 30 min to detect abnormalities supporting a clinical diagnosis of epilepsy in children. A shorter recording time may be better tolerated by children and be more resource-efficient. Our aim was to determine how many abnormalities supporting a diagnosis of epilepsy would be missed by reducing the recording time of paediatric standard electroencephalograms (EEGs) from 20 to 15 min.

METHODS

We evaluated standard EEGs of 300 patients aged 2 months to 17 years referred consecutively with confirmed or suspected epilepsy. EEGs were recorded for 20 min on digital media. A digital copy of each EEG was truncated to give consecutive sequences of 10 min (sequence "A") and 5 min duration (sequences "B" and "C" respectively). A panel of EEG raters blinded to the children's' details other than age identified these sequences as "normal" or "abnormal" if they contained spike waves, discrete sharp waves or notched slow waves in the respective EEG period.

RESULTS

EEGs of 297 children were analysed (three were omitted for technical reasons). 109 out of 297 EEGs (37%) had specific abnormalities supportive of a diagnosis of an epilepsy. 17 of these EEGs showed the abnormality in EEG sequences "B" or "C" and 7 (95% CI: 1.9-12.2) out of these demonstrated the abnormality in sequence "C" only. 105 out of 297 EEGs had non-specific findings.

CONCLUSION

We conclude that reducing the recording time of standard EEGs to 15 min may miss abnormalities in 2.36% [95% CI: 0.63-4.09%] overall and 6.42% [95% CI: 2.2-11.8%] of those with an abnormality supportive of an epilepsy to explain the reported symptoms. This result should inform any future discussions on seeking resource-efficiencies.