Stereo-EEG for Epileptogenic Focus Localization in Schizencephaly: A Single-center Experience in Four Patients.

OBJECTIVE: Schizencephaly is a congenital cerebral malformation characterized by clefts in the hemispheres of the brain, where variations in semiology often make it difficult to localize epileptogenic focus. Here, we report on a series of patients who underwent stereo-encephalography (SEEG) for epileptogenic focus localization and subsequent SEEG-guided surgical intervention. METHODS: Four patients (ages 27, 33, 27, 25 years) with a mean seizure history of 16 years (range 8-22 years) were analyzed. Data pertaining to semiology, video encephalography (EEG), magnetic resonance imaging, positron emission tomography, and invasive EEG studies, surgical intervention and post-surgery outcome were collected and analyzed. RESULTS: All seizure onset zones were within the extent of schizencephaly; however, the limbic system (including the hippocampus, amygdala, cingulate gyrus, or insula) was involved in early spreading. Two patients underwent SEEG-guided radiofrequency thermo-ablation (RFTA) in the seizure onset zone, 1 patient underwent lesionectomy via craniotomy, and 1 underwent neither RFTA nor lesionectomy. At 2 years post-surgery, the outcomes were as follows: Engel grade Ia (n = 2), Ib (n = 1), and III (n = 1). CONCLUSIONS: This article reports on a precise approach to treating patients with schizencephaly dependent of seizure onset zone and functional cortex mapping. Subsequent SEEG-guided surgical interventions (radiofrequency thermo-ablation and lesionectomy) were shown to reduce seizure frequency, while preserving the neurologic functions in drug-resistant epilepsy patients with schizencephaly.

Tadpole-shaped lateralized parietal atretic cephalocele associated with an ipsilateral lacrimal gland fistula and schizencephalic clefts.

BACKGROUND: Parietal atretic cephalocele (AC) and its associated intracranial venous anomalies, such as vertical embryonic positioning of the straight sinus (VEP of SS), have, in previous reports, been exclusively restricted to the midline. CLINICAL PRESENTATION: We report a patient with lateralized parietal AC on the right side. The AC was in the shape of a tadpole, with a large head and a long tail, extending to the proximity of the right external canthus, where a lacrimal gland fistula was observed. The superior sagittal sinus and VEP of SS were also displaced to the right side, although the sagittal suture was located at the midline. Schizencephalic clefts in the right posterior cortex were also observed. CONCLUSION: The parietal AC, which was initially located in the midline, could conceivably have been displaced to the right side by other developmental processes. However, the relationship between lateralized AC and associated multiple anomalies on the ipsilateral side is difficult to explain monogenetically. Our case study indicates that AC might have a broader spectrum of clinical symptoms than was once thought to be the case.

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.

Schizencephaly-diagnostics and clinical dilemmas.

BACKGROUND: Schizencephaly is an uncommon congenital disorder of cerebral cortical development. The defect is characterized by the presence of a cleft in the brain extending from the surface of the pia mater to the cerebral ventricles. The margins of the cleft are lined with heterotropic, dysplastic gray matter. The causes of schizencephaly are heterogeneous and can include teratogens, prenatal infection, maternal trauma, or EMX2 mutations. METHOD: In the present paper, the authors described difficulties in employing diagnostic imaging in differentiating between type II (open-lip) schizencephaly and much more common intracranial fluid spaces of a different origin (arachnoid cysts and hydrocephalus). RESULT: In all the three cases, the treatment consisted in implantation of a shunt system; nevertheless, it should be emphasized that a surgical intervention in the third presented case (type II schizencephaly) aimed at relieving the symptoms of intracranial hypertension-a directly life-threatening condition-since shunting is not a method of treating schizencephaly itself. CONCLUSIONS: Although proper interpretation of the character of intracranial fluid spaces is of significance for further therapeutic management, yet, the key decision as to the surgical intervention is made based on clinical presentation, predominantly on symptoms of intracranial hypertension.