Cognition, change of memory and nonmemory functions, in 147 surgically and 102 medically treated patients with temporal lobe epilepsy was evaluated in a longitudinal study at the University of Bonn, Germany, and the University of Sheffield, UK. Patients were tested at baseline (Tl) and after 2 to 10 years (T3). Surgical patients were also retested 1 year postoperatively (T2). Higher baseline test performance was predictive of better long-term performance and better cognitive outcome. Complete seizure control was obtained in 63% of surgical and 12% of medically treated patients. Significant decline in memory (with little change in nonmemory) function had occurred at T3 follow-up in 50% of medical and 60% of surgical patients. More limited surgical resections were associated with better cognitive outcome and less risk of cognitive decline. Seizure-free surgical patients showed recovery of nonmemory at T2 (p<0.001), and of memory functions at T3 (p=0.03). Psychosocial outcome was better when seizures were controlled. 
COMMENT. Both surgically and medically teated patients with temporal lobe epilepsy (TLE) are at risk of cognitive decline. The degree of cognitive decline is inversely related to seizure control. Surgically treated compared to medically treated patients have better seizure control. When unsuccessful, however, surgery may accelerate the cognitive decline seen with failed medical treatment, especially with left sided temporal lobe resections. When seizures are controlled, either medically or surgically, memory decline is halted or even reversed. Nonmemory functions, related to brain regions distant from the focus, recover more quickly than memory deficits directly associated with the focus. Early and complete control of seizures is necessary to prevent cognitive impairment and adverse effects on quality of life and learning. Memory outcome and that of school or work performance are interrelated, emphasizing the importance of early seizure control. 
The cognitive and behavioral effects of chronic epilepsy have been emphasized in several publications by Deonna T . Some focal epilepsies or purely EEG paroxysmal discharges without clinical seizures can have a chronic adverse effect on cognition and behavior. Treatment should sometimes be directed not only to the control of clinical seizures but also the prevention of cognitive impairments related to focal epileptiform discharges, as for example, epilepsy with so-called benign rolandic spikes. The risks of cognitive decline related to chronic AED treatment are increasingly apparent, especially with temporal lobe epilepsies, emphasizing the importance of early referral of selected patients to our surgical colleagues.