Abstracts

Rationale: The incidence of atypical handedness in patients with epilepsy has not been well established. Further, any association between handedness and seizure type, side of seizure onset in partial epilepsy, responsiveness to treatment, and brain imaging abnormalities remains unclear. We sought to study the incidence of left- and bi-handedness and any associated factors in patients with epilepsy. Methods: We evaluated the clinical data, EEG, video-EEG monitoring, brain MRI and CT scans in 97 patients with epilepsy (64 female, age 18-81; 51 from US and 46 from Korea). Handedness was established using the Edinburgh handedness inventory defined as left-handed, ambidextrous, or right-handed. Seizure types were classified as complex or simple partial seizures (CPS or SPS), primary generalized epilepsy (PGE), or generalized tonic-clonic seizures (including PGE or CPS with secondary generalization). Results: The overall incidence of left-handedness and bi-handedness were 8.2% and 3%, respectively. These values were higher in US patient (11.7% and 3.9% Vs. 4.3% and 2.2%). The relationship between the two-level handedness variable (R/L) was explored between gender, seizure type, MRI/ ictal/interictal laterality, refractoriness, and seizure frequency. Handedness was not associated with gender (χ2=0.142, p=0.71), seizure type (χ₃2=1.29, p=0.73), MRI laterality (χ₃2= 1.88, p=0.60), ictal laterality (χ₃2=1.16, p=0.76), interictal laterality (χ₃2=4.06, p=0.26), or refractoriness (χ2=1.94, p=0.16). A significant association was observed between handedness and the seizure frequency (χ₂2=8.39, p=0.015); i.e., a greater proportion of those whose seizures were low-frequency (controlled by medication) were left handed or ambidextrous, as compared to the other two status levels (low-frequency, controlled by surgery; uncontrolled). All p-values represent two-sided tests. Conclusions: The overall incidence of left- and bi-handedness in patients with epilepsy is 8.2% and 3%, respectively, which is not significantly different than in general population. There is no relationship between handedness in epilepsy and gender, seizure type, MRI and EEG laterality. Based on this preliminary data there is an association between left-handedness and a lower seizure frequency in response to antiepileptic drug therapy. However, these findings need to be further evaluated using larger number of patients.