Objective:To explore the seizure-onset intracranial electroencephalogram patterns in mesial temporal lobe epilepsy (MTLE) by stereo-electroencephalography (SEEG).Methods:The clinical data of 16 patients with focal epilepsy admitted to Epilepsy Center, Shanghai Deji Hospital from March 2017 to December 2019 were retrospectively analyzed. Tonic discharge was taken as sign of the initial period; transition period from the interictal period to the initial period was named as the preictal period, characterized by clonic discharge that was different from the interictal period. The initial and preictal discharge patterns were described, and their corresponding relationship were studied; at the same time, the spatial distribution and synchrony of the discharges at initial and preictal periods were observed.Results:One hundred and thirty-two seizures were recorded in these 16 patients. Two patterns at initial period were noted: low-voltage fast activity (LVFA)+slow depolarizing shifts (SPSs, n=29, 22%), and rhythmic activity (RA) of low-medium amplitude without SPSs ( n=103, 78%); spatial spread of LVFA+SPSs was much wilder than that of RA. In addition, 3 patterns at preictal period were summarized: hypersynchronous (HYP, n=93, 70.5%, most commonly found in the anterior hippocampus [87/219]), sentinel spike ( n=22, 16.7%), and pattern of smooth transition from the interictal period to the initial period ( n=17, 12.9%). No special correspondence in discharge patterns was noted between the initial period and preictal period. Conclusion:Seizure is a process of gradual evolution from interictal period, preictal period to initial period. HYP potential is the most common pattern of seizure in MTLE at preictal stage, mainly appeared in the anterior hippocampus; RA potential is the most common pattern of seizure in MTLE at initial stage, with lower frequency and more limited spatial spread.

Objective:To explore the seizure-onset intracranial electroencephalogram patterns in mesial temporal lobe epilepsy (MTLE) by stereo-electroencephalography (SEEG).Methods:The clinical data of 16 patients with focal epilepsy admitted to Epilepsy Center, Shanghai Deji Hospital from March 2017 to December 2019 were retrospectively analyzed. Tonic discharge was taken as sign of the initial period; transition period from the interictal period to the initial period was named as the preictal period, characterized by clonic discharge that was different from the interictal period. The initial and preictal discharge patterns were described, and their corresponding relationship were studied; at the same time, the spatial distribution and synchrony of the discharges at initial and preictal periods were observed.Results:One hundred and thirty-two seizures were recorded in these 16 patients. Two patterns at initial period were noted: low-voltage fast activity (LVFA)+slow depolarizing shifts (SPSs, n=29, 22%), and rhythmic activity (RA) of low-medium amplitude without SPSs ( n=103, 78%); spatial spread of LVFA+SPSs was much wilder than that of RA. In addition, 3 patterns at preictal period were summarized: hypersynchronous (HYP, n=93, 70.5%, most commonly found in the anterior hippocampus [87/219]), sentinel spike ( n=22, 16.7%), and pattern of smooth transition from the interictal period to the initial period ( n=17, 12.9%). No special correspondence in discharge patterns was noted between the initial period and preictal period. Conclusion:Seizure is a process of gradual evolution from interictal period, preictal period to initial period. HYP potential is the most common pattern of seizure in MTLE at preictal stage, mainly appeared in the anterior hippocampus; RA potential is the most common pattern of seizure in MTLE at initial stage, with lower frequency and more limited spatial spread.