Seizures after Hemispherectomy: The Role of the Insula

• Published in: Neuropediatrics
• Main Authors: Polster, T., Kalbhenn, T., Korenke, C., Cloppenborg, T., Herting, A., Woermann, F. G.
• Format: Conference Proceeding
• Language: English
• Published: 20.04.2016
• ISSN: 0174-304X; 1439-1899
• DOI: 10.1055/s-0036-1583619

Background: Functional hemispheric disconnections are an important treatment for pharmacoresistant structural epilepsies in early childhood. Persisting seizures after surgery raise two main questions: Was the hypothesis of a unihemispheric epileptogenic zone correct? Did the surgical disconnection include all relevant structures of the operated hemisphere? Especially the insular cortex is a matter of discussion. Methods: We report the case of a 12-year-old girl with right hemispheric epilepsy with focal cortical dysplasia type IIa and give a review of the literature. Results: The girl had focal tonic seizures from her first day of life. MRI revealed a right frontal malformation, but a right frontal lobe resection did not lead to seizure freedom. Seizures were tonic, involving mainly the left hemibody, and could evolve into status epilepticus. She also had atonic seizures. A functional hemispherectomy stopped all tonic seizures and status epilepticus, but atonic seizures persisted. Video-EEGs documented an ictal pattern with spike-waves in the left centro-parietal region. Resection of suspected residual insular cortex overlying the right basal ganglia (less than 2 × 2 cm) leads to sustained seizure freedom; actual follow-up is more than 18 months. Conclusion: Insular cortex, even with circumscribed extension on basal ganglia, can be connected with the contralateral hemisphere and be the reason for persisting seizures after hemispheric epilepsy surgery. In case of prior surgery, the electro-clinical findings are of limited value for the identification of the epileptogenic zone. The most important criterion for an additional surgical intervention is the MR-based decision about the anatomically complete disconnection.