Memory guided saccades in mesial temporal lobe epilepsy with hippocampal sclerosis

Objective Mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) may involve extrahippocampal areas of structural and functional damage. The incidence and the features of this damage are still a matter of debate and vary depending on the method applied. Memory guided saccades (MGSs) with a memorization delay longer than 20 s can be used reliably to evaluate the parahippocampal cortex. Methods MGSs with 3 and 30 s memorization delays were recorded with the search coil technique in six patients affected by right MTLE-HS, and in 13 healthy controls. Results The patients were not able to reduce the MGSs residual amplitude error after the first saccade with a 30 s memorization delay. This finding was more evident with leftward saccades. Conclusions MGS abnormalities suggested the functional involvement of the right parahippocampal cortex in most of the patients with MTLE-HS, and this supports the clinical and anatomopathological heterogeneity of the disease. Significance MGSs can be used in patients with right MTLE-HS to detect a possible functional involvement of the ipsilateral parahippocampal cortex.