Comparison of coronal sphenoidal versus standard anteroposterior temporal montage in the EEG recording of temporal lobe seizures

Chronic sphenoidal electrodes were developed to facilitate the recording and localization of temporal lobe seizures during long term monitoring. Many reports demonstrate their utility in displaying temporal interictal epileptiform activity, but there have been few direct comparisons of sphenoidal electrodes and surface temporal recordings ictally. We compared simultaneous portions of 74 EEG recordings of temporal lobe seizures (from 42 patients), with one portion including sphenoidal electrodes in a coronal montage and one with a standard anterior posterior temporal montage. Separated tracings were reviewed by readers blinded to the other portion of the tracing. The coronal sphenoidal montage allowed recognition of temporal lobe seizures inapparent with standard surface temporal electrodes in 19% of seizures and led to an earlier identification (usually by greater than or equal to 5 s) of the onset in 70% of seizures. Indwelling, flexible sphenoidal electrodes assist in ambulatory recording of temporal lobe seizures, both in demonstrating the presence of seizures and in determining the localization and time of seizure onset.