Achieving sleep state during EEG in children; sequence of activation procedures.

Objective: Interictal epileptiform discharges are often enhanced with attainment of sleep during an EEG. Hyperventilation (HV) during an EEG is often followed by drowsiness. However, the effect of intermittent photic stimulation (IPS) on awake/sleep state is unclear. The current study was conducted to determine if the sequence of activation procedures has an impact on acquisition of sleep during a routine, non-sleep deprived EEG.

Methods: Children, scheduled between 9 and 11 a.m., who were not sleep deprived and able to hyperventilate, were included in a 3-month prospective study undertaken at the Neurophysiology Laboratory of a tertiary children's hospital. In the first 48 children evaluated, IPS was started 5 min into the EEG recording and HV was elicited at the end of the session (group I). In the next 48 children, HV was started 5 min into the EEG recording and IPS was presented at the end of the EEG (group II). A third group served as a control group and received both activating procedures at the end of the recording (group III). All 3 groups were assessed for the presence or absence of sleep during their EEG recording.

Results: Only 3 of the 48 (6.2%) children in group I versus 17/48 (35.5%) in group II (P<0.0001), OR=8.68, 95% CI 2.34-32.22) and 11/48 (23%) in group III (P<0.05) attained sleep. The difference between the 3 groups was statistically significant (P=0.02). The children who were hyperventilated at the beginning of the session had an 8-fold increased chance of attaining sleep in comparison with children who received IPS at the beginning of the recording followed by HV at the end.

Conclusions: We recommend that when performing routine non-sleep deprived EEGs in children, HV be performed first with IPS at the end of the EEG in order to maximize the yield of attaining sleep recording during the study.