Atypical handedness in mesial temporal lobe epilepsy

- Atypical pattern of handedness is present in patients with unilateral mesial temporal lobe epilepsy (MTLE).
- There is a significantly increased rate of left-handedness in patients with left-sided MTLE.
- Atypical handedness was associated with early age at epilepsy onset.

ObjectiveThe main aim of our study was to investigate the handedness of patients with mesial temporal lobe epilepsy (MTLE). We also sought to identify clinical variables that correlated with left-handedness in this population.MethodsHandedness (laterality quotient) was assessed in 73 consecutive patients with MTLE associated with unilateral hippocampal sclerosis (HS) using the Edinburgh Handedness Inventory. Associations between right- and left-handedness and clinical variables were investigated.ResultsWe found that 54 (74.0%) patients were right-handed, and 19 (26%) patients were left-handed. There were 15 (36.6%) left-handed patients with left-sided seizure onset compared to 4 (12.5%) left-handed patients with right-sided seizure onset (p = 0.030). Among patients with left-sided MTLE, age at epilepsy onset was significantly correlated with handedness (8 years of age [median; min-max 0.5-17] in left-handers versus 15 years of age [median; min-max 3-30] in right-handers (p < 0.001).ConclusionsLeft-sided MTLE is associated with atypical handedness, especially when seizure onset occurs during an active period of brain development, suggesting a bi-hemispheric neuroplastic process for establishing motor dominance in patients with early-onset left-sided MTLE.