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.