Use of simultaneous depth and MEG recording may provide complementary information regarding the epileptogenic region

Simultaneous SEEG-MEG recording has the potential to define the epileptic spike source accurately. We present a case of a 55-year-old female with intractable left temporal lobe epilepsy in whom we evaluated the relationship between the amplitude recorded from SEEG electrodes, inserted in the lateral temporal region, and their distance from the MEG-modelled spike. We found a quadratic fall-off relationship between the amplitude and distance. This result supports the concept that the MEG dipoles reflect the "centre" of spike locations and may provide comprehensive information for SEEG which records spike activities directly but is inherently limited in spatial sampling.