Successful surgery for refractory seizures associated with bilateral schizencephaly: two case reports and literature review.

Schizencephaly is a rare malformation of cortical development resulting from cell migration defects that occur unilaterally or bilaterally. The type of the schizencephalic cleft can be open lip or closed lip. Patients suffering from refractory seizures secondary to schizencephaly should be considered for surgical treatment. In this paper, we retrospectively analyzed two patients with confirmed schizencephaly and intractable seizures. The evaluation methods included a medical history assessment, a neurological examination and magnetic resonance imaging (MRI). Continuous intracranial video-electroencephalogram (vEEG) monitoring with surface electrodes and deep electrodes was evaluated to confirm the epileptogenic zones associated with the schizencephalic lesions. Cortical electrical stimulation was performed to evaluate the neurophysiology of the relevant brain regions. Epileptic focus resection was performed close to the schizencephalic cleft according to the results of intracranial EEG and stimulation while preserving neurological functions. MRI revealed bilateral open lip schizencephaly in one patient and closed lip schizencephaly in the other patient. The epileptogenic zones were localized close to the schizencephalic clefts. The seizure outcome was Engel's class Ia in both patients at 1-year follow-up. No significant neurological deficits were found, and their activities of daily life were significantly improved. We conclude that abnormal cortex near the schizencephalic clefts may display an extrinsic epileptogenicity. Accurate localization of the epileptogenic zones using intracranial EEG and electrical stimulation can lead to a seizure-free outcome in patients with refractory epilepsy associated with schizencephaly.