Does Hyperventilation Increase the Diagnostic Yield of the Routine Electroencephalogram: A Retrospective Analysis of Adult and Pediatric Cohorts

PURPOSE: While hyperventilation (HV) increases the diagnostic yield of EEG in children, there is conflicting evidence to support its application in adults. For the first time in history, a large cohort of patients has undergone EEGs without HV during the COVID-19 pandemic. Utilizing this opportunity, we sought to investigate whether HV increases the diagnostic yield of EEG in children compared with adults. METHODS: Patients aged six years and above who had routine EEGs at Monash Health between January 2019 and December 2020 were studied. The cohort was divided into two, pediatric (younger than 18 years) and adult (18 years or older). Epileptiform abnormalities (ictal and interictal) were the outcomes investigated. The effect of HV was examined with logistic regression to determine odds ratios with 95% confidence intervals. RESULTS: In total, we studied 3,273 patients (pediatric = 830, adult = 2,443). In the pediatric cohort, HV significantly increased the diagnostic yield of absence seizures ( p = 0.01, odds ratios 2.44, 95% confidence intervals 1.21-4.93). In adults, HV did not increase the yield of absence seizures ( p = 0.34, odds ratios 0.36, 95% confidence intervals 0.05-2.88). Interictal epileptiform discharges during HV were significantly more frequent in children compared with adults ( p < 0.001, odds ratios 3.81, 95% confidence intervals 2.51-5.77). CONCLUSIONS: Hyperventilation is useful to increase the yield of interictal epileptiform discharges and absence seizures in pediatric patients but not in adults. Hence, routine EEG may be recorded in adults without HV when it is unsafe to perform.