Clinical characteristics and multimodal imaging can help diagnosing and treating mild malformation of cortical development with oligodendroglial hyperplasia and epilepsy.

OBJECTIVE: Mild malformation of cortical development with oligodendroglial hyperplasia and epilepsy (MOGHE) is a recently described, histopathologically and molecularly defined (SLC35A2-mutated) type of cortical malformation. Although increasingly recognized, the diagnosis of MOGHE remains a challenge. We present the characteristics of the first six patients diagnosed in Bulgaria, with the aim to facilitate identification, proper presurgical evaluation, and surgical treatment approach in this disease. METHODS: Revision of histopathological specimens of 202 patients operated on for drug-resistant focal epilepsy identified four cases with MOGHE. Another two were suggested, based on clinical characteristics and subsequently, were histologically confirmed. Sanger SLC35A2 sequencing on paraffin-embedded or fresh-frozen brain tissue was performed. Analysis of seizure types, neuropsychological profiles, electroencephalographic (EEG), imaging features and epilepsy surgery outcomes was done. RESULTS: Three out of the six cases (50%) harbored pathogenic SLC35A2 mutations. One patient had a heterozygous somatic variant with uncertain significance. Clinical characteristics included epilepsy onset in infancy (in 100% under 3 years of age), multiple seizure types, and moderate or severe intellectual/developmental delay. Epileptic spasms with hypsarrhythmia on EEG were the initial seizure type in five patients. The subsequent seizure types resembled those in Lennox-Gastaut syndrome. The majority of the patients (n = 4) presented prominent and persisting autistic features. Magnetic resonance imaging (MRI) showed multilobar (n = 6) and bilateral (n = 3) lesions, affecting the frontal lobes (n = 5; bilaterally in three) and characterized by increased signal on T2/fluid-attenuated inversion recovery (FLAIR). Voxel-based morphometric MRI post-processing and positron emission tomography helped determining the localization and extent of the lesions and presumed epileptogenic zones. After surgery, four patients (66.7%) were seizure-free ≥2 years. Interestingly, all seizure-free patients carried somatic SLC35A2-alterations. SIGNIFICANCE: Epileptic spasms, early prominent neuropsychological disturbances, MRI-T2/FLAIR hyperintense lesions with cortico-subcortical blurring, frequently multilobar and especially frontal, can preoperatively help to suspect MOGHE. Epilepsy surgery is still the only successful treatment option in MOGHE.

Three-dimensional neuronavigation in SEEG-guided epilepsy surgery.

OBJECTIVES: Epilepsy surgery is mainly cortical surgery and the precise definition of the epileptogenic zone on the complex cortical surface is of paramount importance. Stereoelectroencephalography (SEEG) may delineate the epileptogenic zone even in cases of non-lesional epilepsy. The aim of our study was to present a technique of 3D neuronavigation based on the brain surface and SEEG electrodes reconstructions using FSL and 3DSlicer software. PATIENTS AND METHODS: Our study included 26 consecutive patients operated on for drug-resistant epilepsy after SEEG exploration between January 2015 and December 2017. All patients underwent 1.5 T pre-SEEG MRI, post-SEEG CT, DICOM data post-processing using FSL and 3DSlicer, preoperative planning on 3DSlicer, and intraoperative 3D neuronavigation. Accuracy and precision of 3D SEEG reconstruction and 3D neuronavigation was assessed. RESULTS: We identified 125 entry points of SEEG electrodes during 26 operations. The accuracy of 3D reconstruction was 0.8 mm (range, 0-2 mm) with a precision of 1.5 mm. The accuracy of 3D SEEG neuronavigation was 2.68 mm (range, 0-6 mm). The precision of 3D neuronavigation was 1.48 mm. CONCLUSION: 3D neuronavigation for SEEG-guided epilepsy surgery using free software for post-processing of common MRI sequences is possible and a reliable method even with navigation systems without a brain extraction tool.

Bilateral pallidotomy for Meige syndrome.

Meige syndrome (MS) is usually described as a combination of blepharospasm with oromandibular dystonia. There are a large number of case reports of deep brain stimulation (DBS) of the globus pallidus internus (GPI) for MS and only one report of unilateral pallidotomy (PT). We report the first case of staged bilateral PT for treatment of a patient with MS using intraoperative high-frequency stimulation in order to predict and prevent postoperative deficit. There was a significant improvement of the Burk-Fahn-Marsden dystonia rating scale from 26 to 3. There were no adverse postoperative neurological and neuropsychological events.

Stereoelectroencephalography Using Magnetic Resonance Angiography for Avascular Trajectory Planning: Technical Report.

BACKGROUND: Stereoelectroencephalography (SEEG) requires high-quality angiographic studies because avascular trajectory planning is a prerequisite for the safety of this procedure. Some epilepsy surgery groups have begun to use computed tomography angiography and magnetic resonance T1-weighted sequence with contrast enhancement for this purpose. OBJECTIVE: To present the first series of patients with avascular trajectory planning of SEEG based on magnetic resonance angiography (MRA). METHODS: Thirty-six SEEG explorations for drug-resistant focal epilepsy were performed from January 2013 to December 2015. A retrospective analysis of this consecutive surgical series was then performed. Magnetic resonance imaging included MRA with a modified contrast-enhanced magnetic resonance venography (MRV) protocol with a short acquisition delay, which allowed simultaneous arterial and venous visualization. Our criteria for satisfactory MRA were the visualization of at least first-order branches of the angular artery, paracentral and calcarine artery, and third-order tributaries of the superficial Sylvian vein, vein of Labbe, and vein of Trolard. RESULTS: Thirty-four patients underwent 36 SEEG explorations with 369 electrodes carrying 4321 contacts. Contrast-enhanced MRA using the MRV protocol was judged satisfactory for SEEG planning in all explorations. Postoperative complications were not observed in our series of 36 SEEG explorations, which included 50 transopercular insular trajectories. CONCLUSION: MRA using an MRV protocol may be applied for avascular trajectory planning during SEEG procedures. This technique provides a simultaneous visualization of cortical arteries and veins without the need for additional radiation exposure or intra-arterial catheter placement.