Sensitivity of a 256 channel EEG recording in temporal mesial sclerosis patients and temporal neocortical patients

Purpose: to describe the augmented sensitivity of a 256 channel EEG recording in the epileptiform activity scalp localization by visual inspection of patients affected by temporal mesial sclerosis and neocortical temporal epilepsy. Exploiting 20 left and 20 right electrodes covering face between orbitary floor and the upper margin jaw (anterior and posterior zygomatic electrodes) we underlie the accuracy and non-invasivity of this method. Method: we recorded a rest 256 channel EEG in 14 patients (7 female and 7 male mean age 42 years) affected by temporal epilepsy. We considered six mesial temporal sclerosis patients and three neocortical temporal patients. We then compared the scalp localization of epileptiform abnormalities by visual inspection through the standard 10–20 bipolar and monopolar montages and later through the 256 Topo Plot Average Reference Map e.g. a projection of each electrode's activity on a scalp model. Result: in temporal mesial sclerosis patients, EEG abnormalities observed in fronto temporal standard 10–20 montage are seen with the highest negative peak in anterior zygomatic channels (Topo Plot Map montage), while temporal neocortical patients underling a large field potential are seen in posterior zygomatic electrodes. Conclusion: since the basal temporal cortex is tangential to the lateral surface of the skull and neocortical epilepsy underlies a large field potential, anterior and posterior zygomatic electrodes respectively could be considered at the same time as a non-invasive method and specific tool to increase the maximum peak localization by visual inspection in patients affected by temporal mesial sclerosis and temporal neocortical epilepsy patients.