Hyperventilation maneuver during EEG in children with epilepsy after the Covid-19 pandemic. Is a routine procedure necessary?

Summary Objective Hyperventilation (HV) is one of the main and basic activation methods during ambulatory electroencephalogram (EEG), unless medical reasons contraindicate it During the COVID-19 pandemic, with the high risk of human-to-human infection, local guidelines and recommendations have been developed that suggest not to perform the HV manoeuvre routinely Our objective was to characterize patients who present positive HV in an epilepsy center Methods We analyzed retrospectively all the ambulatory EEGs performed during one year in our specialized ambulatory child and adolescent epilepsy center, and describe patients with positive maneuver Results A total of 305 EEGs were performed Patients under 3 years and 11 months were excluded as well as all patients that did not fill up the criteria for epilepsy diagnosis From the 252 EEGs that were included in the study, 194 EEGs (77%) were classified as abnormal and 58 (23%) as normal From these same 252 EEGs, 150 EEG finished correctly the HV maneuver Physiological slowing response was found in 54 EEGs (36%), no changes (negative) in 83 (55%) and abnormal response (positive) in 13 EEGs (9%) The 13 HV positive EEGs showed 4 patients with an increase of epileptiform activity, 3 patients experienced an increase of basal pre-registered abnormal slowing and 6 EEGs showed trigger of bilaterally synchronous and symmetric 2?4 Hz spike-and-slow wave discharges and absences None of these last 6 patients needed more than 3 minutes to elicit the paroxysmal discharge Significance Based on these findings and according with other studies the low positivity and high specificity of the HV maneuver supports the idea that HV could be excluded during the Covid-19 pandemic situation, and also re-evaluate if it could be changed to a complementary maneuver, restricted only for cases where absence epilepsy is suspected Larger studies will be needed to reaffirm this proposal