When children have surgery, anaesthetists carefully monitor the depth of anaesthesia by using sensors on the forehead that measure brain activity, also known as processed electroencephalogram (pEEG). These monitors are routinely used in paediatric anaesthesia; however, investigators do not know if they work accurately in babies and young children with seizure disorders or on anti-seizure medications.

Children with developmental and epileptic encephalopathies may need anaesthesia for tests or procedures. It is important that their treating doctors understand whether these monitors truly reflect how awake or asleep the children are. This study aims to compare a child's electrical brain activity using two commonly used devices in paediatric anaesthesia with the conventional 21-lead EEG patterns in children with seizure disorders. The results of this research may help improve the safety and perioperative care of children with seizure disorders who require general anaesthesia in the future.

There is currently no available data on the reliability of processed electroencephalogram (pEEG) for adequately predicting depth of anaesthesia (DOA) with abnormal electroencephalogram (EEG) and those on anticonvulsant medication. Examples of epilepsy syndromes in which seizures and abnormal EEG (abnormal backgrounds: including excess discontinuity, excess slow, low amplitude, lack of sleep stages, and frequent epileptiform discharges) are predominant features are Early Infantile Developmental and Epileptic Encephalopathy (EIDEE), Epilepsy of infancy with Migrating Focal Seizures (EIMFS), Infantile Spasm Syndrome (IS) and other Epileptic encephalopathies (EE) and Developmental and Epileptic Encephalopathy (DEE). Considering the use of pEEG is common in paediatric anaesthesia and one of the strategies used to precent awareness and excessive anaesthesia provision, it would be pertinent to examine whether pEEG values truly reflect depth of sedation of these infants or if they are artificially low or high. To this end, investigators aim to concurrently measure EEG and pEEG patterns in infants with DEEs with onset in infancy and early childhood. Both pEEG patterns and their values will be measured with two commonly used monitors- the BiSpectral Index (BIS) and Sedline. Data from both pEEG monitors can then be directly compared with contemporaneous conventional EEG patterns on each patient.

This study will be conducted in collaboration with paediatric anaesthetists and neurologists in Perth Children's Hospital, Western Australia and the Hospital das Clínicas, Faculty of Medicine, University of São Paulo, Brazil. The target sample size is 40 participants- 20 from each centre. Participants will be invited to visit the hospital. Each awake participant will be fitted with a 16-lead EEG and additionally a BIS or Sedline monitor, applied consecutively in random order. The measurement period will be 30 minutes for each of the BIS and the Sedline with continuous EEG assessment throughout. This will allow the pEEG data to be measured against a corresponding continuous EEG.

Inclusion Criteria:

• Children (<16 years old) with a confirmed diagnosis of early onset EE or DEE due to any cause (prior to age 2 years).

Exclusion Criteria:

• Language barriers impeding data collection
• Department for Child Protection and Family Support is involved in the care of the child.

20 eligible patients identified by the neurology department at Perth Children's Hospital and 20 eligible patients identified by the neurology department at Hospital das Clinicas HCFMUSP, Faculdade de Medicina, will be approached for the study.