Longitudinal changes in developmental trajectory following early hemispherotomy in early infantile developmental and epileptic encephalopathy.

Early infantile developmental and epileptic encephalopathy (EIDEE) associated with extensive unilateral structural abnormalities is frequently characterized by drug-resistance and poor developmental outcomes. Although epilepsy surgery is recognized as a treatment option, the optimal timing of intervention in early infancy and detailed longitudinal postoperative developmental trajectories remain insufficiently characterized. We report a male infant with EIDEE due to extensive unilateral hemispheric malformation who underwent hemispherotomy at four months of age for persistent epileptic spasms with a suppression-burst pattern. The patient achieved sustained seizure freedom over five years and discontinued antiseizure medications two years postoperatively. Longitudinal developmental assessments showed continued acquisition of cognitive, language, and motor skills. Raw developmental measures increased steadily over time, whereas age-normed standardized scores remained below age-adjusted norms, indicating a gradual shift in developmental trajectory rather than normalization within the expected range. This case suggests that early consideration of surgical intervention may be associated with a favorable developmental trajectory in selected infants with EIDEE due to congenital structural abnormalities, particularly when drug-resistance is anticipated. Further investigation is needed to define optimal timing and patient selection.