Lateralization effect on memory and executive functions in mesial temporal lobe epilepsy

Summary: Purpose: The patients who were diagnosed with mesial temporal lobe epilepsy (MTLE) were included to the study. The aim of this study was to compare patients with right or left hippocampal sclerosis (HS) among memory and executive functions and to search if there is lateralization effect on these functions. Materials and methods: Patients were classified according to 2017 ILAE Classification of Seizures criteria. 79 patients with MTLE-HS who were diagnosed according to seizure history, EEG, neuropsychological tests and MRI findings and 30 healthy controls were enrolled in the study. The patients with right or left HS were compared in terms of memory and executive functions. Tests evaluating memory and executive functions were performed to all participants. Results: Forty-nine (62%) female and 30 (38%) male patients with MTLE-HS, and 14 (46.7%) female and 16 (53.3%) male controls participated in the study. The mean age of the patients and controls was 33.53±9.60 (range, 18-57) years and 35.90±7.98 (range, 18-56) years, respectively. 40 patients (50.6%) had right HS while 39 (49.4%) had left HS. When comparing patients with controls, scores of tests evaluating memory, attention and other executive functions were found significantly lower in patients than controls (p<0,05). Recall score of Verbal Memory-Recall, Recognition, Total Learning-Tests (VMT) was significantly lower while recognition scores were higher in left HS patients than right HS patients (p=0,001). There were no significant differences between right and left HS patients concerning visual memory scores or executive functions (p>0,05). Conclusion: In our study, the lower recall scores of VMT in left HS suggested us that deficits in verbal memory tests could be lateralized to the left, however finding no difference in visual memory function would not always be lateralized to the right similar to conflicting results in the literature. There were no significant differences between right and left HS concerning attention and other executive functions. Thus, we suggested that defisits in these functions would not help us to lateralize the disorder