Abstracts

Rationale: Epilepsy surgery is a very successful treatment option for epilepsy patients. There is, however, an increased risk of additional cognitive impairment and there have been fears of an accelerated mental decline in the very long term follow up with normal or even pathological ageing and when seizures are not controlled. Methods: 161 operated (77 right, 84 left temporal) versus a mixed group of 208 medically treated patients with structural epilepsies were re-evaluated in regard to memory, executive functions, and vocational outcome after intervals of 5-22 years (83 yrs.). Patients were prospectively and successively collected under the condition of a past baseline assessment, a one year postoperative examination (surgical), and a follow up visit of > 5 years (all). Medically treated patients were less likely seizure free (17%) than surgical patients (41%) and had somewhat later onsets of epilepsy. The groups did not differ in regard to gender, age, monthly seizure frequency, or number of AED. Results: MANCOVAs of long term change as a function of treatment arm, seizure control, and retest interval revealed a significant effects of "retest by group" and "retest by seizure control" for verbal memory (F=9.6, and F=10.5, df1, p< 0.01) and significant effects of "retest by drug change" and "retest by seizure control" on executive functions (F= 4.3, F=3.4 df1, p < 0.05, p< 0.1). Accordingly seizure free patients (memory & executive) and patients with a reduced drug load (executive) improved and not seizure free patients deteriorated (memory) or showed minor improvement (executive functions). In surgical patients this was independent on whether seizure control was achieved early or late in the follow up. Non-operated patients were less likely seizure free at follow up (>12 months, 17% vs. 41% surgical), The results were confirmed with individual level analyses, according to which in the seizure free group only 3% of the medical, 10% of the right, and 17% of the left temporal patients significantly declined in verbal memory as opposed to 12%, 20%, and 37% of the group with continuing seizures. Executive functions improved in seizure free patients in 26% medical, 19% right, 24% left TLE, as compared to improvement with continuing seizures in 10%, 11%, 6%. Vocational outcome was not different for surgically and medically treated patients (still employed 55%, still unemployed 19%, gain 3%, loss 22%) Conclusions: The results impressively demonstrate favourable cognitive long term outcomes in surgical and medically treated patients depending on seizure control and drug load. If seizure free, surgical patients even recover from one year postoperative drop in memory. No differential effects on vocational status were evident. In the long run there is no evidence of a negative effect of ageing within the evaluated retest interval. One must, however, keep in mind that, due to the natural setting of the long term follow-up evaluations, the patient groups and seizure outcomes in particular are not necessarily equivalent to prospectively selected groups with planned long term follow-up. Funding: no funding