Focal Cortical Dysplasia Type Ⅲ Related Medically Refractory Epilepsy: MRI Findings and Potential Predictors of Surgery Outcome

This study aims to explore the relationship between neuropathologic and the post-surgical prognosis of focal cortical dysplasia (FCD) typed-Ⅲ-related medically refractory epilepsy. A total of 266 patients with FCD typed-Ⅲ-related medically refractory epilepsy were retrospectively studied. Presurgical clinical data, type of surgery, and postsurgical seizure outcome were analyzed. The minimum post-surgical follow-up was 1 year. A total of 266 patients of FCD type Ⅲ were included in this study and the median follow-up time was 30 months (range, 12~48 months). Age at onset ranged from 1.0 years to 58.0 years, with a median age of 12.5 years. The number of patients under 12 years old was 133 (50%) in patients with FCD type Ⅲ. A history of febrile seizures was present in 42 (15.8%) cases. In the entire postoperative period, 179 (67.3%) patients were seizure-free. Factors with p < 0.15 in univariate analysis, such as age of onset of epilepsy (p = 0.145), duration of epilepsy (p = 0.004), febrile seizures (p = 0.150), being MRI-negative (p = 0.056), seizure type (p = 0.145) and incomplete resection, were included in multivariate analysis. Multivariate analyses revealed that MRI-negative findings of FCD (OR 0.34, 95% CI 0.45–0.81, p = 0.015) and incomplete resection (OR 0.12, 95% CI 0.05–0.29, p < 0.001) are independent predictors of unfavorable seizure outcomes. MRI-negative finding of FCD lesions and incomplete resection were the most important predictive factors for poor seizure outcome in patients with FCD type Ⅲ.

Management of patients with medically intractable epilepsy and anterior temporal lobe encephaloceles

OBJECTIVE Temporal lobe encephaloceles (TLENs) are a significant cause of medically refractory epilepsy, but there is little consensus regarding their workup and treatment. This study characterizes these lesions and their role in seizures and aims to standardize preoperative evaluation and surgical management. METHODS Patients with TLEN who had undergone resective epilepsy surgery from December 2015 to August 2020 at a single institution were included in the study. Medical records were reviewed for each patient to collect relevant seizure workup information including demographics, radiological findings, surgical data, and neuropsychological evaluation. RESULTS For patients who presented to the authors’ program with suspected medically intractable temporal lobe epilepsy (219 patients), TLEN was considered to be the epileptogenic focus in 5.5%. Ten patients with TLEN had undergone resection and were included in this study. Concordance between ictal scalp electroencephalography (EEG) lateralization and TLEN was found in 9/10 patients (90%), and 4/10 patients (40%) had signs suggestive of idiopathic intracranial hypertension (IIH). Surgical outcome was reported in patients with at least 12 months of follow-up (9/10). Patients with scalp EEG findings concordant with the TLEN side had a good outcome (Engel class I: 7 patients, class II: 1 patient). One patient with discordant EEG findings had a bad outcome (Engel class III). No significant neuropsychological deficits were observed after the surgery. CONCLUSIONS TLENs are epileptogenic lesions that should be screened for in patients with medically refractory epilepsy who have signs of IIH and no other lesions on MRI. Restricted resection is safe and effective in patients with scalp EEG findings concordant with TLEN.

Using a Robotic-Assisted Approach for Stereotactic Laser Ablation Corpus Callosotomy: A Technical Report

<b><i>Background:</i></b> Corpus callosotomy for medically intractable epilepsy is an effective ablative procedure traditionally achieved using either standard open craniotomy or with less-invasive approaches. Advances in robotic-assisted stereotactic guidance for neurosurgery can be applied for LITT for corpus callosotomy. <b><i>Clinical Presentations:</i></b> Two patients were included in this study. One was a 25-year-old female patient with extensive bi-hemispheric malformations of cortical development and medically refractory epilepsy, and the other was an 18-year-old male with medically refractory epilepsy and atonic seizures, who underwent a complete corpus callosotomy using robotic-assisted stereotactic guidance for LITT. <b><i>Results:</i></b> Both patients underwent successful intended corpus callosotomy with volumetric analysis demonstrating a length disconnection of 74% and a volume disconnection of 55% for patient 1 and a length disconnection of 83% and a volume disconnection of 33% for patient 2. Postoperatively, both patients had clinical reductions in seizure. <b><i>Conclusion:</i></b> Our experience demonstrates that robotic guidance systems can safely and effectively be adapted for minimally invasive LITT corpus callosotomy.

Alternate Seizure Spread with Agenesis of the Corpus Callosum

Agenesis of the corpus callosum is a brain malformation that can occur in isolation or in conjunction with other congenital or developmental defects. The clinical sequelae of this condition include epilepsy, cognitive deficits, developmental delay, and various neurological and psychiatric disorders. Here we present the case of a patient with congenital complete agenesis of the corpus callosum and medically refractory epilepsy who underwent stereoelectroencephalography. This identified a left frontal ictal focus and revealed that contralateral spread occurred though the anterior commissure, a rare and interesting occurrence. Left frontal resection resulted in significant improvement. This demonstrates the role of the anterior commissure in ictal spread and the potential for novel methods of seizure spread in patients with temporal lobe epilepsy that must be considered in a surgical approach.

Navigated transcranial magnetic stimulation mapping of the motor cortex for preoperative diagnostics in pediatric epilepsy

OBJECTIVE Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy. METHODS A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses. RESULTS Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0–17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients). CONCLUSIONS Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.