Patients
The study population consisted of patients with drug-resistant TLE
treated between June 2012 and September 2021. The diagnosis of TLE was
made by experienced epilepsy specialists according to criteria from the
International League Against Epilepsy (ILAE) classification of
epilepsies and epileptic syndromes (Commission on Classification and
Terminology of the International League Against Epilepsy, 2017). All
patients underwent EEG recordings and brain magnetic resonance imaging
(MRI). Seizure origin was confirmed using EEG in all patients.
Drug-resistant epilepsy was defined as the failure of two tolerated and
appropriately chosen anti-seizure drug schedules (whether as
monotherapies or in combination) to achieve sustained seizure inhibition
(Kwan et al., 2010). The exclusion criteria were as follows: (1)
epileptiform discharges over other regions except the temporal lobe on
EEG; (2) concomitant seizures originating in non-temporal regions; (3)
brain MRI revealing obvious lesions in non-temporal areas, which may
influence seizure type or cognition; and (4) complications of other
neurological disorders that may influence seizure or cognition,
including tumor, trauma, stroke, mental retardation, neurodegenerative
disease, and inherited neurological diseases, such as tuberous
sclerosis.
Patients who met the following criteria were included in the abnormal
cognition (AC) group: (1) complaints of cognitive decline, which
interfered with daily routines and work performance; (2) declined
calculation ability (< four correct, subtract 7 from 100,
continued five times); and (3) impaired memory ability (< 2
points, recall the names of three objects learned earlier). The criteria
of normal cognition (NC) group were as follows: (1) no complaints of
cognitive dysfunction, qualified for job, and (2) normal calculation and
memory abilities. The Wechsler Intelligence Scale (WIS) was used in 30
patients in the AC group and 31 patients in the NC group. All patients
underwent video EEG monitoring using a 40-channel video-EEG monitoring
system (Nicolet, USA) at the hospital for over 24 h. We also enrolled 18
sex- and age-matched healthy controls (HC). Recording electrodes were
placed according to the international 10–20 system, densely in the
bilateral temporal regions based on the international 10–10 system,
with a sampling frequency of 512 Hz. The 40 electrodes included Fp1,
Fp2, F3, Fz, F4, F7, F8, C3, Cz, C4, T7, T8, P3, Pz, P4, P7, P8, O1, Oz,
O2, AF7, AF8, F9, F10, FC5, FC6, FT7, FT8, FT9, FT10, C5, C6, T9, T10,
CP5, CP6, TP7, TP8, TP9, TP10.
Hippocampal tissue was available from seven patients who underwent
surgery. There were four patients in the AC group and three in the NC
group. The mini-mental state examination (MMSE) was performed in these
patients for cognitive evaluation. Hippocampal sclerosis was observed in
all the pathology reports.