The aim of the study was to define the usual and pathological modifications arising in the brain following hemispherotomy for intractable epilepsy in children.

Preoperative MRI and postoperative imaging scans (CT in the first week, MRI at 3 months and 1 year after surgery) were reviewed in a series of 52 patients, average age 8 years and 7 months, with intractable epilepsy due to dysplasia, Rasmussen’s encephalitis, ischemic lesions and/or Sturge-Weber disease. The posterior fossa, brain parenchyma, ventricles and subdural space were also analyzed.

Hemispheric scarring was a typical finding on CT and MRI as a consequence of the surgical procedure. Also frequently seen were small subdural effusions, bleeding along the surgical scar on early CT, and chronic subdural effusions with no mass effect on mid-term and late MRI scans. Other features – such as large subdural effusions that required external shunts and hydrocephalus – were rare, but severe, and considered to be postoperative complications. In contrast to the complications associated with other surgical techniques such as hemispherectomy, infection, extensive edema or hemosiderosis were never found in our series.

Hemispherotomy is a surgical technique performed to treat intractable epilepsy. Our findings will help to identify the typical morphology of postsurgical scars, and to differentiate the usual features and complications seen in the postoperative period on CT and MRI brain scans.