Rationale:
Cognitive impairments in people with epilepsy are common and have crucial negative influence on their quality of life. Nonetheless, cognitive dysfunctions of people with epilepsy are still poorly understood. Among them, there are particularly few previous studies on the visual cognitive function in people with epilepsy. In this study, we investigated the relationship between these visual cognitive function in people with epilepsy and their clinical features such as their focal sites of epilepsy and clinical course.
Methods:
The data of visual cognitive performance were obtained from patients with focal epilepsy with no structural abnormalities in occipital lobe, history or coexistence of central nerve system diseases, intellectual disability, psychiatric disorders, or medications that might interfere with cognitive function. We performed Clock Drawing Test (CDT), Rey-Osterrieth Complex Figure Test (ROCFT), and Trail Making Test (TMT) as methods for evaluating visual cognitive functions. We avoided performing the cognitive assessments during or immediately after seizures. We performed multiple regression analyses with cognitive performance scores as dependent variables and clinical features as independent variables. This study was performed in compliance with the Declaration of Helsinki and the study protocol was approved by the Nishiniigata Chuo Hospital Ethics Committee.
Results:
We enrolled 102 patients in the study. A longer duration of epilepsy was associated with a lower score of CDT (β=-0.195, P=0.049). An older age at examination was associated with a lower score of Recall ROCFT (β=-0.229, P=0.018). Structural brain abnormalities (other than occipital lobe) were associated with lower scores of recall ROCFT (β=-0.321, P=0.001), TMT-A (β=0.308, P=0.001) and TMT-B (β=0.172, P=0.046). Occipital lobe Epilepsy was associated with lower scores of TMT-A (β=0.307, P=0.001) and TMT-B (β=0.270, P=0.002). Left mesial temporal lobe epilepsy was associated with a higher score of recall ROCFT (β=0.185, P=0.05).
Conclusions:
This study revealed that the visual cognitive function in people with epilepsy is affected by the long-term course of epilepsy. Although, whether this is more than a normal aging effect requires further investigation. Furthermore, this study showed the relationships between focal sites of epilepsy and visual cognitive tests. However, these results were more complex than we expected, as visual memory function was not impaired in patients with right mesial temporal lobe epilepsy and was better in patients with left mesial temporal lobe epilepsy than in other epilepsy patients. This suggests that the relationships between focal sites of epilepsy and cognitive impairment cannot be simply explained by focal signs.
Funding:
There is no funding for this abstract.