COMPARISON OF EEG DERIVED FROM SPHENOIDAL, INFRAZYGOMATIC, ANTERIOR TEMPORAL, AND MIDTEMPORAL ELECTRODES DURING COMPLEX PARTIAL SEIZURES

A prospective study was performed to determine whether complex partial seizures are better, or differently, recorded by sphenoidal (SP) or i nfrazygomatic (IZ) electrodes. Two seizures in each of 20 patients wer e recorded from radiographically documented SP and IZ, as well as ante rior temporal (AT) and midtemporal (MT) electrodes. Initial ictal bipo lar EEG changes appeared at means of 0.57 s (SP) and 0.16 s (IZ) befor e, and 0.06 s (AT) and 2.36 s (MT) after, the onset of clinical signs. Mean first lateralized ictal bipolar EEG discharges appeared 0.11 s ( SP), 0.88 s (IZ), 2.98 s (AT), and 3.94 s (MT) after behavioral seizur e onsets. These changes occurred earlier (statistically significant) a t SP than at other electrodes. Referentially, mean first ictal EEG cha nges occurred 0.28 s (SP) before to 0.20 s (MT) after, and ictal later alization appeared 0.68 s (IZ) to 1.19 s (MT) after, the appearance of clinical seizure onsets. Ictal EEG amplitudes were largest (statistic ally significant) at SP and progressively smaller at IZ, AT, and MT el ectrodes. Overall, however, SP electrodes closer to the foramen ovale did not consistently reveal earlier ictal features or higher EEG ampli tudes than SP electrodes farther from this landmark. For clinical purp oses, SP and IZ electrodes were virtually equivalent.