P1-3-10. Effect of hyperventilation on seizures and EEG findings during routine EEG

Abstract

Hyperventilation (HV) is widely used to induce EEG abnormalities and epileptic seizures. However, it is still controversial how long it should be done in routine EEG. We analyzed 1,184 routine EEG data recorded in our institution between October, 2016 and September, 2017. Among them, 970 patients tried to perform HV lasting 4 min, and 949 patients completed it age mean, range. During HV, interictal epileptiform discharges (IED) were induced in 82 patients (9%). Generalized IED were seen in 70 patients, focal IED in eight, bi-temporal slow wave in three, and rhythmic theta activity (focal) in one. IED appeared only after 3-min HV in 11 patients (13%) out of 82. Epileptic seizures were induced by HV in 25 patients (3%). Absence seizures occurred in 23 patients, and focal seizures in two. Two patients (12%) had seizures after 3-min HV. No adverse event occurred during 4-min HV, not only during this study period, but also more than 40 years of our practice. We concluded that 4-min HV is effective and safe for epilepsy patients.