Route learning impairment in temporal lobe epilepsy

Memory impairment on neuropsychological tests is relatively common in temporal lobe epilepsy (TLE) patients. However, memory has been rarely evaluated in more naturalistic settings. This study assessed TLE (n=19) and control (n=32) groups on a real-world route learning (RL) test. Compared to the controls, the TLE group committed significantly more total errors across the three RL test trials. Route learning errors correlated significantly with standardized auditory and visual memory and visual-perceptual test scores in the TLE group. In the TLE subset for whom hippocampal data were available (n=14), RL errors also correlated significantly with left hippocampal volume. This is one of the first studies to demonstrate real-world memory impairment in TLE patients and its association with both mesial temporal lobe integrity and standardized memory test performance. The results support the ecological validity of clinical neuropsychological assessment.