Complete change of seizure and spike lateralization in temporal lobe epilepsy at two separate monitorings

Objective To report complete change of seizure and spike lateralization over time in bilateral temporal lobe epilepsies (TLE). Methods Repetition of video-EEG monitorings in 115 patients; 2 cases are reported in detail; 113 other severe partial epilepsies were included to estimate retrospectively the frequency of the reported phenomenon. Results In 2 cases, two video-EEG monitorings, separated by several months, revealed the first time one unilateral TL (temporal lobe) seizure and spike focus and the second time a distinct seizure and spike focus located in the opposite TL. The second monitoring was planned for these two patients because of the presence of a discordant lesion or, in the absence of a lesion, of some bilateral or discordant functional (EEG, SPECT and PET) abnormalities. No patient among the other 113 cases had this video-EEG pattern. Conclusions In TLE, two video-EEG sessions may be necessary to disclose two opposite TL epileptogenic foci. Significance In rare bilateral TLE cases, the expression of seizure and spike foci can alternate between hemispheres.