Spike dipole analysis using SEP dipole as a marker

In dipole localization analysis many problems remain which affect the accuracy of localization. We performed dipole estimation of spikes and SEP components in identical patients. The subjects are 8 cases of benign childhood epilepsy with centrotemporal spikes (BCECS), and two cases of temporal lobe epilepsy (TLE). In 8 of 10 cases, we also investigated dipoles using a 3-layer model in addition to a single layer (homogenous) model. Results: 1) In 8 cases of BCECS, the spike dipoles were concentrated at the central line near the SEP dipoles, at a slightly fronto-lateral-downward position to the latter. The spike dipoles seemed to be situated at the bottom of the sensory cortex. 2) In two cases of TLE, the spike dipoles were located at the same coronal plane with the SEP dipoles, and more deeply seated mesially. The spike dipoles seemed to be at the bottom of the mesial temporal area. 3) Using 3-layer models, both the spike dipoles and the SEP dipoles located more superficially, while conserving the positional relationship with each other. Conclusion: It is possible to more accurately define spike dipoles by using the SEP dipole as a marker.