Is an earlier onset of focal epilepsy associated with atypical language lateralization? A systematic review, meta-analysis and new data.
Freya Prentice, Lara Chehabeddine, Maria Helena Eriksson, Jennifer Murphy, Leigh N Sepeta, William D Gaillard, Madison M Berl, Fr��d��rique Li��geois, Torsten Baldeweg
Author Information
Freya Prentice: Developmental Neurosciences Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neuropsychology, Great Ormond Street Hospital for Children, London WC1N 3JH, UK; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA. Electronic address: freya.prentice.19@ucl.ac.uk.
Lara Chehabeddine: Developmental Neurosciences Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK; Clinical Research Institute, Department of Internal Medicine, American University of Beirut, Beirut, Lebanon; Department of Epidemiology and Population Health, American University of Beirut, Beirut, Lebanon; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Maria Helena Eriksson: Developmental Neurosciences Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neuropsychology, Great Ormond Street Hospital for Children, London WC1N 3JH, UK; Program in Neuroscience and Mental Health, The Hospital for Sick Children Research Institute, Toronto, Canada; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Jennifer Murphy: School of Psychology, University of Surrey, Guildford, UK; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Leigh N Sepeta: Center for Neuroscience Research, Children's National Hospital, George Washington University, Washington, DC, USA; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
William D Gaillard: Center for Neuroscience Research, Children's National Hospital, George Washington University, Washington, DC, USA; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Madison M Berl: Center for Neuroscience Research, Children's National Hospital, George Washington University, Washington, DC, USA; Division of Neuropsychology, Children's National Hospital, Washington, DC, USA; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Fr��d��rique Li��geois: Developmental Neurosciences Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Torsten Baldeweg: Developmental Neurosciences Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK; Department of Neuropsychology, Great Ormond Street Hospital for Children, London WC1N 3JH, UK; Departments of Psychiatry and Behavioral Sciences, George Washington University, Washington, DC, USA.
Right and bilateral language representation is common in focal epilepsy, possibly reflecting the influence of epileptogenic lesions and/or seizure activity in the left hemisphere. Atypical language lateralization is assumed to be more likely in cases of early seizure onset, due to greater language plasticity in childhood. However, evidence for this association is mixed, with most research based on small samples and heterogenous cohorts. In this preregistered meta-analysis we examined the association between age at seizure onset and fMRI-derived language lateralization in individuals with focal epilepsy. The pooled effect size demonstrated a correlation between an earlier onset and rightward language lateralization in the total sample (r���=���0.1, p���=���.005, k���=���58, n���=���1240), with no difference in the correlation between age at seizure onset and language lateralization between left and right hemisphere epilepsy samples (Q=62.03, p���=���.302). In exploratory analyses of the individual participant data (n���=���1157), we demonstrated strong evidence that a logarithmic model fits the data better than a linear (BF=350) or categorical model with 6 years of age as a cut-off (BF=36). These findings indicate that there is a small but significant relationship between age at seizure onset and language lateralization. The relationship was consistent with theories of language plasticity proposing an exponential decline in plasticity over early childhood. However, given that this effect was subtle and only found in larger sample sizes, an early age at seizure onset would not serve as a good indicator of atypical language lateralization on the individual patient level.
