Research paperHigh density scalp EEG in frontal lobe epilepsy

- Visual review of hdEEG in frontal lobe epilepsy improves identification of potential candidates for invasive monitoring.
- Early integration of hdEEG in frontal lobe epilepsy may help identify cases with a low yield intracranial monitoring.
- hdEEG in patients with frontal lobe seizures could be a reasonable alternative for SISCOM particularly in resource limited setting.
- When clinically feasible, visual review of hdEEG could potentially augment EEG source localization.
- High density scalp EEG in frontal lobe epilepsy.

PurposeLocalization of seizures in frontal lobe epilepsy using the 10-20 system scalp EEG is often challenging because neocortical seizure can spread rapidly, significant muscle artifact, and the suboptimal spatial resolution for seizure generators involving mesial frontal lobe cortex. Our aim in this study was to determine the value of visual interpretation of 76 channel high density EEG (hdEEG) monitoring (10-10 system) in patients with suspected frontal lobe epilepsy, and to evaluate concordance with MRI, subtraction ictal SPECT co-registered to MRI (SISCOM), conventional EEG, and intracranial EEG (iEEG).MethodsWe performed a retrospective cohort study of 14 consecutive patients who underwent hdEEG monitoring for suspected frontal lobe seizures. The gold standard for localization was considered to be iEEG. Concordance of hdEEG findings with MRI, subtraction ictal SPECT co-registered to MRI (SISCOM), conventional 10-20 EEG, and iEEG as well as correlation of hdEEG localization with surgical outcome were examined.ResultshdEEG localization was concordant with iEEG in 12/14 and was superior to conventional EEG 3/14 (p < 0.01) and SISCOM 3/12 (p < 0.01). hdEEG correctly lateralized seizure onset in 14/14 cases, compared to 9/14 (p = 0.04) cases with conventional EEG. Seven patients underwent surgical resection, of whom five were seizure free.ConclusionshdEEG monitoring should be considered in patients with suspected frontal epilepsy requiring localization of epileptogenic brain. hdEEG may assist in developing a hypothesis for iEEG monitoring and could potentially augment EEG source localization.