Disconnection Surgery for Intractable Epilepsy with a Structural Abnormality in the Medial Posterior Cortex

The lesionectomy is a general surgical procedure for treating focal epilepsy resulting from a structural abnormality, but a favorable outcome cannot be achieved in some patients, especially patients whose symptomatogenic zone is located in remote regions. Herein we propose the surgical disconnection of the seizure propagation pathway, which consists of short and long associating fibers linking the epileptogenic zone to the remote symptomatogenic zone, as an effective method of achieving favorable seizure outcomes in patients with posterior cortex epilepsy.

Three patients with intractable epilepsy showing a structural abnormality in the medial posterior cortex participated in this study. Their habitual seizures were complex partial seizures stemming from remote symptomatogenic zones. Seizure propagation-related fibers were assumed by non-invasive examination and semiology.

Cingulum and superior/inferior longitudinal fasciculus were considered to form main seizure propagation pathway. Based on the preoperative assumption and the intraoperative intracranial electroencephalogram findings, a lesionectomy and corticectomy were performed for 2 patients while a clusterectomy and corticectomy were performed for the remaining patient. The resection area was extended in the direction of the association fibers to disconnect the remote symptomatogenic zone completely from the epileptogenic zone. Engel class I was achieved in all the patients.

The current study suggested that assuming the presence of association fibers was an important factor for achieving a favorable outcome in the surgical treatment of posterior cortex epilepsy. Though further study is required, disconnection surgery is recommended as a treatment option for cases in which the epileptogenic zone is located in an eloquent area.