Abstract
ObjectivesTo investigate the long-term postoperative outcomes and predictive factors associated with poor surgical outcomes in mesial temporal lobe epilepsy (MTLE).Materials and methodsWe enrolled patients with MTLE who underwent resective surgery at single university-affiliated hospital. Surgical outcomes were determined using a modified Engel classification at the 2nd and 5th years after surgery and the last time of follow-up.ResultsThe mean duration of follow-up after surgery was 7.6 ± 3.7 years (range, 5.0–21.0 years). 334 of 400 patients (83.5%) were seizure-free at the 5th postoperative year. Significant predictive factors of a poor outcome at the 5th year were a history of generalized tonic clonic (GTC) seizures (odds ratio, OR; 2.318), bi-temporal interictal epileptiform discharge (IED) (OR; 3.107), bilateral hippocampal sclerosis (HS) (OR; 5.471), unilateral HS and combined extra-hippocampal lesion (OR; 5.029), and bi-temporal hypometabolism (BTH) (OR; 4.438). Bi-temporal IED (hazard ratio, HR; 2.186), BTH (HR; 2.043), bilateral HS (HR; 2.541) and unilateral HS and combined extra-hippocampal lesion (HR; 2.75) were independently associated with seizure recurrence. We performed a subgroup analysis of 208 patients with unilateral HS, and their independent predictors of a poor outcome at the 5th year were BTH (OR; 5.838) and tailored hippocampal resection (OR; 11.053).ConclusionThis study demonstrates that 16.5% of MTLE patients had poor long-term outcomes after surgery. Bilateral involvement in electrophysiological and imaging studies predicts poor surgical outcomes in MTLE patients.
Highlights
The rate of complete remission of seizures after epilepsy surgery for mesial temporal lobe epilepsy (MTLE) is only 60% to 70%.[1]
Significant predictive factors of a poor outcome at the 5th year were a history of generalized tonic clonic (GTC) seizures, bi-temporal interictal epileptiform discharge (IED) (OR; 3.107), bilateral hippocampal sclerosis (HS) (OR; 5.471), unilateral HS and combined extra-hippocampal lesion (OR; 5.029), and bi-temporal hypometabolism (BTH) (OR; 4.438)
Patients were diagnosed as having MTLE if (a) HS was seen on an magnetic resonance imaging (MRI) and mesial temporal ictal onset was identified during video-EEG monitoring, or (b) the MRI was normal or another definite pathologic lesion was found in the temporal or extratemporal regions on MRI, but video-EEG monitoring and other functional neuroimaging, including PET and single photon emission computed tomography (SPECT), confirmed exclusive mesial temporal ictal onset
Summary
The rate of complete remission of seizures after epilepsy surgery for mesial temporal lobe epilepsy (MTLE) is only 60% to 70%.[1] Almost one third of patients continue to have seizures after surgery. The long-term outcome is worse than the short-term outcome, with 48 to 58 percent continuing to experience seizures 5 years after surgery.[2,3] It is important to develop reliable predictors of surgical outcomes for MTLE and selecting proper surgical candidates remains a challenge. Clinical predictors for long-term surgical outcomes differ from the variables that predict short-term outcomes.[2,3,4,5,6,7] A history of secondarily generalized tonic-clonic seizures (SGTCS) is associated with recurrent seizures in both the short- and long-term after surgery.[4,5] The presence of SGTCS was independently associated with poor 2-year outcomes but not with 5-year outcomes;[2] in that study, epilepsy duration was the only important negative predictor for 5-year outcomes. The significant relationship between epilepsy duration and surgical outcome existed only in TLE with a temporal tumor or gliosis,[6] not in non-lesional TLE patients.[7]
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