Abstracts

Rationale: Mesial temporal lobe epilepsy (MTLE) has long been held to be the most common cause of medically intractable epilepsy in adults. Although epilepsy surgery has been shown to confer clear benefits for patients with MTLE in terms of seizure remission, patients may decline epilepsy surgery or be deemed non-surgical candidates despite being told of post-surgical success rates between 58 - 84% in patients with clear, unilateral mesial temporal sclerosis (MTS). The long-term prognosis of patients who decline surgery is unclear.Methods: In this single-center, prospective, case-control study, the University of Virginia Epilepsy Database of 2,898 patients with documented epilepsy was queried to identify all current patients classified as MTLE with imaging-confirmed MTS. Cases consisted of patients seen within the last 3 years with unilateral MTLE due to MTS, without dual pathology, who declined epilepsy surgery (the “nonsurgical” group) compared to those who underwent anterior temporal lobectomy (ATL, the “surgical” group). Seizure frequency was captured during clinic interviews and recorded over a minimum of 3 years. Durability of seizure freedom was measured in seizure-free patients, defined as continuous months of seizure freedom. In addition, we evaluated demographics, epilepsy risk factors, and treatment-related factors (EEG and MRI findings).Results: A total of 134 out of 2898 patients had MTLE, a prevalence of 4.6%. Of these, 82 patients had unilateral MTS meeting inclusion criteria, with 37 patients in the nonsurgical group and 45 patients in the surgical group. Surgical patients had significantly higher proportions of seizure freedom (71.1% vs 24.3%) and were on fewer anti-epileptic drugs, but risk factors and EEG findings did not significantly differ between groups (Figure 1A). The durability of seizure freedom was robust in both nonsurgical (22.3 ± 8.8 months) and surgical (29.3 ± 12.7 months) groups (Figure 1B).Conclusions: Although ATL provides the greatest chance of seizure freedom in patients with MTLE due to MTS, our results suggest that patients with good outcomes tend to remain seizure-free over time whether or not they have surgery. Up to a quarter of medically treated patients demonstrated sustained seizure freedom greater than 2 years on average, suggesting that the natural history of MTLE is not uniformly a relentless course of pharmacoresistance. Furthermore, there were no significant differences in risk factors between surgical and nonsurgical groups. Further research is needed to determine factors which contribute to good outcomes regardless of surgical treatment.