The role of brain magnetic resonance imaging on the timing of antiepileptic drugs withdrawal following mesial temporal lobe epilepsy surgery

Objectives:To assess the influence of magnetic resonance imaging (MRI) brain findings on the timing of antiepileptic drugs (AEDs) withdrawal following anterior temporal lobectomy (ATL) in patients with mesial temporal lobe epilepsy (MTLE).Methods:We conducted a retrospective chart review at King Faisal Specialist Hospital and Research Centre, Jeddah, Saudi Arabia from Jan, 2004 – Dec, 2017 of patients with MTLE who underwent ATL and included patients who had a minimum of 2 years of follow-up. We evaluated the association between the time required to start tapering and discontinuing AEDs after ATL in patients with Engel class I outcomes and their preoperative brain MRI.Results:We studied 64 patients who underwent ATL. The majority of patients (63%) had hippocampal sclerosis (HS) on histopathology. Following ATL, the mean time to start tapering AEDs was 10 months and AEDs were discontinued at a mean of 48 months. Abnormal brain MRI was observed in 53 (83%) patients, with findings suggestive of mesial temporal sclerosis (MTS) accounting for 75% of these abnormalities. The presence of any MRI abnormality was associated with a 10-month earlier tapering of AEDs (p<0.01), and an 18-month earlier complete withdrawal of AEDs (p<0.01). The odds of being seizure-free within the first year were higher if MTS was present in the brain MRI (adjusted OR=16). Similarly, this was associated with seizure freedom after the first year (adjusted OR=14.8, p<0.01). The presence of unilateral temporal IEDs on preoperative EEG were also associated with earlier tapering and discontinuation of AEDs as well as a seizure-free state after ATL surgery (OR=8.5 and 4.2, for the first and second year respectively, p<0.01).Conclusion:Patients with abnormal MRI findings and unilateral IEDs had earlier tapering of AEDs with an overall shorter AED discontinuation plan. Moreover, the presence of MTS on MRI, along with unilateral IEDs, were predictors of seizure freedom following ATL.

Anterior temporal lobectomy (ATL) is the standard treatment for medically refractory mesial temporal lobe epilepsy (MTLE), achieving seizure remission in approximately 70% of patients. ^1-3 However, the feasibility and timing of antiepileptic drug (AEDs) withdrawal after ATL are debatable. ⁴ The need for AEDs withdrawal stems from the adverse effects following long-term use, ^5,6 difficulties in maintaining compliance, and their high cost. ^7,8 Moreover, AEDs withdrawal following successful ATL is generally considered safe. ⁴ There are no evidence-based guidelines for managing AEDs withdrawal after resective epilepsy surgery. ^9,10 Moreover, few prospective and retrospective studies have assessed postoperative AEDs management exclusively in patients with MTLE. ^4,11-13 Hence, the timing of AEDs withdrawal after temporal lobectomy is controversial. ^12,14,15 The difficulties faced are how to taper AEDs, how soon it is safe to taper, which clinical profiles favor tapering, and what is the optimal time to start the tapering process. Predicting successful AEDs withdrawal following ATL has been examined in a few studies; however, the results were inconsistent. ^9,12,16-18 In one study, brain magnetic resonance imaging (MRI) findings were associated with seizure outcomes following ATL with successful AEDs discontinuation. ¹² The MRI can detect brain abnormalities, predict postoperative seizure, and AEDs freedom ² Despite this, data are lacking regarding the role of MRI in determining the time to start tapering AEDs postoperatively, as well as the time until AEDs discontinuation in those who do not require postoperative AEDs treatment. These data are essential for establishing guidelines that could assist clinicians with AED management following ATL.We aimed to assess the role of brain MRI in planning the tapering of AEDs and determining when to discontinue AEDs in patients with MTLE following ATL. We also evaluated seizure outcomes in patients with a minimum of 2 years of postoperative follow-up.