When might hemispheric favouring of epileptiform discharges begin?

PURPOSE EEG studies based on adult populations report interictal epileptiform discharges (EDS) favour the left hemisphere. It is not clear when favouring becomes apparent as similar paediatric studies have not been performed. METHODS The authors reviewed 1,579 paediatric EEG interpretations for evidence of hemispheric favouring of focal epileptiform discharges. Analysis focused on first-time EEG results. RESULTS Right hemispheric favouring of interictal epileptiform discharges occurs in childhood, it remits around 5 years of age whereupon left-sided favouring occurs more frequently (P=0.004, Fisher's Exact). CONCLUSION Hemispheric vulnerabilities to interictal focal epileptiform activity may display discrete age-related favouring. These findings are discussed in context of normal hemispheric maturation.