Purpose
To evaluate preoperative factors influencing unilateral and bilateral interictal discharges in TLE, and ictal diffusion patterns in scalp EEG during onset of the seizure.Methods
This was a retrospective analysis of 129 patients with TLE who had undergone surgery; cases were classified into two groups of unilateral and bilateral discharge groups according to interictal discharge patterns in the EEG. In this study, unilateral interictal discharges meaned that the discharge was confined to one hemisphere, while bilateral interictal discharges meaned that the discharge involved both hemispheres. Differences between the two groups in age, gender, duration of disease, frequency of seizures, MRI findings, origin of TLE, antiepileptic drug administration, and ictal diffusion patterns during seizures were statistically analyzed. In addition, the differences in ictal diffusion patterns between left and right TLE were statistically analyzed.Results
There were a total of 74 cases of unilateral discharges, including unilateral discharges in the temporal region, anterior head including both temporal and frontal regions, and unilateral hemispheric discharges, and there were another 55 cases of bilateral discharges, including bilateral temporal area, bilateral anterior heads, and bilateral hemispheric multi-brain areas. There were 60 cases of left TLE and 69 cases of right TLE. There were no statistically significant differences in gender, duration of disease, frequency of seizures, MRI manifestations, administration of antiepileptic drugs, and ictal diffusion patterns between interictal unilateral and bilateral discharge groups, but, there were statistically significant differences in age and side of origin of the TLE. Scalp EEG recorded 11 different ictal diffusion pattern types, and the difference in terms of whether the EEG recorded the diffusion pattern to be confined to the same hemisphere or spread to both hemispheres was statistically significant between the left and right temporal lobes.Conclusion
Age and side of origin of TLE affects the TLE interictal discharge patterns. Older patients are more prone to bilateral discharges. Bilateral discharges are more common in right TLE, and the onset of EEG more likely to bilateral diffusion in right TLE.