PURPOSE:To investigate spatial and metabolic changes associated with frontal lobe seizures. METHODS:Functional near-infrared spectroscopy combined with electroencephalography (EEG-fNIRS) recordings of patients with confirmed nonlesional refractory frontal lobe epilepsy (FLE). KEY FINDINGS:Eighteen seizures from nine patients (seven male, mean age 27 years, range 13-46 years) with drug-refractory FLE were captured during EEG-fNIRS recordings. All seizures were coupled with significant hemodynamic variations that were greater with electroclinical than with electrical seizures. fNIRS helped in the identification of seizures in three patients with more subtle ictal EEG abnormalities. Hemodynamic changes consisted of local increases in oxygenated (HbO) and total hemoglobin (HbT) but heterogeneous deoxygenated hemoglobin (HbR) behavior. Furthermore, rapid hemodynamic alterations were observed in the homologous contralateral region, even in the absence of obvious propagated epileptic activity. The extent of HbO activation adequately lateralized the epileptogenic side in the majority of patients. SIGNIFICANCE:EEG-fNIRS reveals complex spatial and metabolic changes during focal frontal lobe seizures. Further characterization of these changes could improve seizure detection, localization, and understanding of the impact of focal seizures.