Cognitive outcomes more than 5 years after temporal lobe epilepsy surgery: Remarkable functional recovery when seizures are controlled.

PURPOSE: Epilepsy surgery can be a successful treatment option for temporal lobe epilepsy but there are concerns about accelerated memory decline in long-term follow-up. METHOD: 161 adult operated (77 right, 84 left temporal resections) versus a heterogeneous group of 208 non-operated patients with focal epilepsies were consecutively recruited and re-evaluated focusing on memory, executive functions, and vocational outcome after follow-up intervals of >5 years (5-22 years, mean 8 ± 3 years). RESULTS: Major losses in the operated group manifest early, at one-year follow-up. Few patients declined further. Long-term changes after surgery did not differ from those observed without surgery. The factor "surgery" caused verbal memory decline, "seizure freedom" (operated 48%, non-operated 17%) was associated with recovery of verbal memory, and "drug reduction" positively affected the course of executive functions. In terms of the critical function of verbal memory, only 3-17% of seizure-free patients showed long-term decline whereas 16-20% showed improvement (operated and non-operated). Persistent seizures were associated with decline in 12-37% and improvement in 4-12% of patients. Improvement was related to longer retest intervals and was stronger in younger patients. Independent of surgery or seizure outcome, the vocational status remained unchanged or change was negative (22%) rather than positive (3%). CONCLUSIONS: Patients' cognitive course 5-22 years after surgery is stable and may even be positive if epilepsy is controlled and drug load reduced. Depending on seizure outcome, recovery is more frequently observed than continuing decline. Recovery, however, takes time and age is a limiting factor.

Functional organization of the left inferior precentral sulcus: dissociating the inferior frontal eye field and the inferior frontal junction.

Two eye fields have been described in the human lateral frontal cortex: the frontal eye field (FEF) and the inferior frontal eye field (iFEF). The FEF has been extensively studied and has been found to lie at the ventral part of the superior precentral sulcus. Much less research, however, has focused on the iFEF. Recently, it was suggested that the iFEF is located at the dorsal part of the inferior precentral sulcus. A similar location was proposed for the inferior frontal junction area (IFJ), an area thought to be involved in cognitive control processes. The present study used fMRI to clarify the topographical and functional relationship of the iFEF and the IFJ in the left hemispheres of individual participants. The results show that both the iFEF and the IFJ are indeed located at the dorsal part of the inferior precentral sulcus. Nevertheless, the activations were spatially dissociable in every individual examined. The IFJ was located more towards the depth of the inferior precentral sulcus, close to the junction with the inferior frontal sulcus, whereas the iFEF assumed a more lateral, posterior and superior position. Furthermore, the results provided evidence for a functional double dissociation: the iFEF was activated only in a comparison of saccades vs. button presses, but not in a comparison of incongruent vs. congruent Stroop conditions, while the opposite pattern was found at the IFJ. These results provide evidence for a spatial and functional dissociation of two directly adjacent areas in the left posterior frontal lobe.