Ing. Kateřina Macková

Objectives: We comprehensively characterised a large paediatric cohort with focal cortical dysplasia (FCD) type 1 to expand phenotypic spectrum and to identify predictors of postsurgical outcomes. Methods: We included paediatric patients with histopathological diagnosis of isolated FCD type 1 and at least one year of postsurgical follow-up. We systematically re-analysed clinical, electrophysiological, and radiological features. The results of this re-analysis served as independent variables for subsequent statistical analyses of outcome predictors. Results: All children (N=31) had drug-resistant epilepsy with varying impacts on neurodevelopment and cognition (presurgical intelligence quotient (IQ)/developmental quotient scores: 32–106). Low presurgical IQ was associated with abnormal slow background EEG activity and disrupted sleep architecture. Scalp EEG showed predominantly multiregional and often bilateral epileptiform activity. Advanced epilepsy MRI protocols identified FCD-specific features in 74.2% of patients (23/31), 17 of whom were initially evaluated as MRI-negative. In six out of eight MRI-negative cases, fluorodeoxyglucose-PET and subtraction ictal single-photon emission computed tomography co-registered to MRI (SISCOM) helped localise the dysplastic cortex. Sixteen patients (51.6%) underwent invasive EEG. By the last follow-up (median 5 years, interquartile range 3.3–9 years), seizure freedom was achieved in 71% of patients (22/31), including 7 out of 8 MRI-negative patients. Anti-seizure medications were reduced in 21 patients, with complete withdrawal in six. Seizure outcome was predicted by a combination of the following descriptors: age at epilepsy onset, epilepsy duration, long-term invasive EEG, and specific MRI, and PET findings. Significance: This study highlights the broad phenotypic spectrum of FCD type 1, which spans far beyond the narrow descriptions of previous studies. The applied multi-layered presurgical approach helped localise the epileptogenic zone in many previously non-lesional cases, resulting in improved postsurgical seizure outcomes, which are more favourable than previously reported for FCD type 1 patients.

Objective: Epilepsy surgery in the operculo-insular cortex is challenging due to the difficult delineation of the epileptogenic zone and the high risk of post-operative deficits following resections in this region. Methods: Pre- and post-surgical data from 30 pediatric patients who underwent opercular-insular cortex surgery at Motol Epilepsy Center Prague from 2010 to 2022 were analyzed. Results: Focal cortical dysplasia (FCD, n = 15, 50%) was the predominant cause of epilepsy in the patients studied, followed by epilepsy-associated tumors (n = 5, 17%) and tuberous sclerosis complex (n = 2, 7%). In eight patients where FCD was the most likely etiology, histology was negative. Seven patients (23%) displayed normal MRI results. Seizures exhibited diverse semiology and propagation patterns (i.e., frontal, perisylvian, and temporal). Ictal and interictal EEG findings observed during video EEG were mostly extensive. Multimodal imaging and advanced post-processing were frequently utilized. Stereoelectroencephalography (SEEG) monitoring was used for localizing the epileptogenic zone and eloquent cortex in 23 patients (77%). Oblique electrodes were used as guides for better orientation of neurosurgeons during resection. The epileptogenic zone was in the dominant hemisphere in 16 patients. At the two-year follow-up, 22 patients (73%) were completely seizure-free, and eight (27%) experienced a seizure frequency reduction of > 50% (ILAE 3 and 4). Fourteen patients (47%) underwent anti-seizure medication tapering; treatment was completely withdrawn in two patients (7%). Nineteen patients (63%) remained seizure-free following the definitive outcome assessment (median: 6 years and 5 months, range: 2 years to 13 years and 5 months post-surgery). Six patients (20 %) experienced corona radiata or basal ganglia ischemia; four (13%) improved to mild hemiparesis, and one (3%) to moderate hemiparesis with ongoing rehabilitation. Two patients (7 %) operated on in the anterior insula, along with fronto-temporal resection experienced major complications - pontine ischemia and post-operative brain edema. Significance: Epilepsy surgery in the opercular-insular cortex can lead to excellent patient outcomes. A comprehensive diagnostic approach is crucial for surgical success. There is a great chance for significant recovery of postoperative deficits with the use of rehabilitation.

Introduction: The quality of fluorodeoxyglucose positron emission tomography (FDG-PET) images is limited by low effective resolution, which leads to blurring. The resolution can be additionally improved by partial volume correction (PVC) algorithms. The key input parameter influencing PVC performance is the correct specification of full width at half maximum (FWHM) of the scanner point spread function (PSF). The FWHM is standardly measured using a point source phantom under the standard protocol defined by the National Electrical Manufacturers Association (NEMA). However, the PSF varies in real conditions of human/animal neuroimaging and must be estimated individually. Therefore, a new method for fully automatic estimation of FWHM from FDG-PET images of the brain was proposed without the need for information on the scanner and protocol used. Methods: The method was based on estimating the parameters of edge spread function at the border of the gray matter from the FDG-PET image intensity function. The FWHM estimation algorithm was applied to FDG-PET brain images of 31 candidates for surgical epilepsy treatment in Motol University Hospital. The estimates were compared with FWHM measured according to NEMA standard on the same PET-CT scanners (Siemens Biograph mCT: 16 patients, Siemens Biograph Vision: 15 patients). Results: The median (interquartile range) value of estimated FWHM was 4 (3.9 - 4.1) mm, which was 11% lower than measured 4.5 mm for Siemens Biograph mCT scanner in transversal direction, and 6% lower 3.4 (3.3 -3.6) mm vs. measured 3.2 mm for Biograph Vision scanner. In the axial direction, estimated value 4.7 (4.5 - 5.2) mm was the same as the measured 4.7 mm for the Siemens Biograph mCT scanner, and 6% higher 3.6 (3.4 -3.8) mm vs. measured 3.4 mm for the Siemens Biograph Vision scanner. Conclusion: The proposed method can fully automatically estimate FWHM of PET scanner PSF only based on FDG-PET image. The estimates agreed with FWHM measured according to NEMA standard. FWHM estimation improves the performance of PVC algorithms that increase the resolution of FDG-PET images for the glucose metabolism assessment.

Objective: Focal cortical dysplasia (FCD) is the most common malformation causing refractory focal epilepsy. Surgical removal of the entire dysplastic cortex is crucial for achieving a seizure-free outcome. Precise presurgical distinctions between FCD types by neuroimaging are difficult, mainly in patients with normal magnetic resonance imaging findings. However, the FCD type is important for planning the extent of surgical approach and counselling. Methods: This study included patients with focal drug-resistant epilepsy and definite histopathological FCD type I or II diagnoses who underwent intracranial electroencephalography (iEEG). We detected interictal epileptiform discharges (IEDs) and their recruitment into repetitive discharges (RDs) to compare electrophysiological patterns characterizing FCD types. Results: Patients with FCD type II had a significantly higher IED rate (p<0.005), a shorter inter-discharge interval within RD episodes (p<0.003), sleep influence on decreased RD periodicity (p<0.036), and longer RD episode duration (p<0.003) than patients with type I. A Bayesian classifier stratified FCD types with 82% accuracy. Conclusion: Temporal characteristics of IEDs and RDs reflect the histological findings of FCD subtypes and can differentiate FCD types I and II. Significance: Presurgical prediction of FCD type can help to plan a more tailored surgical approach in patients with normal magnetic resonance findings.