Scalp HFO rates are higher for larger lesions

High frequency oscillations (HFO) in scalp EEG are a new and promising non-invasive epilepsy biomarker, providing added prognostic value, particularly in pediatric lesional epilepsy. However, it is unclear if lesion characteristics, such as lesion volume, depth, type, and localization, impact scalp HFO rates. We analyzed scalp EEG from 13 children and adolescents with focal epilepsy associated with focal cortical dysplasia (FCD), low-grade tumors, or hippocampal sclerosis. We applied a validated automated detector to determine HFO rates in bipolar channels. We identified the lesion characteristics in MRI. Larger lesions defined by MRI volumetric analysis corresponded to higher cumulative scalp HFO rates (p=0.01) that were detectable in a higher number of channels (p=0.05). Both superficial and deep lesions generated HFO detectable in the scalp EEG. Lesion type (FCD vs. tumor) and lobar localization (temporal vs. extratemporal) did not affect scalp HFO rates in our study. Our observations support that all lesions may generate HFO detectable in scalp EEG, irrespective of their characteristics, whereas larger epileptogenic lesions generate higher scalp HFO rates over larger areas that are thus more accessible to detection. Our study provides crucial insight into scalp HFO detectability in pediatric lesional epilepsy, facilitating their implementation as an epilepsy biomarker in a clinical setting

Scalp High Frequency Oscillations Rates Decrease After Successful Epilepsy Surgery and are not Impacted by the Skull Defect Resulting from Craniotomy

Einleitung: Durch einen epilepsiechirurgischen Eingriff kann bei gewissen pädiatrischen Patient:innen Anfallsfreiheit erreicht werden. Es fehlen jedoch zuverlässige Prädiktoren für die Anfallsfreiheit nach der Operation. Hochfrequenzoszillationen (HFO; high frequency oscillations) im Oberflächen-EEG sind ein neuer und vielversprechender Biomarker für das Therapieansprechen. Es ist jedoch unklar, ob der durch die Kraniotomie entstandene Schädeldefekt die Erkennung von HFO in postoperativen EEG-Aufzeichnungen beeinträchtigt. Methoden: Wir untersuchten 14 Kinder und Jugendliche mit fokaler läsioneller Epilepsie, die sich einer präoperativen Oberflächen-EEG Untersuchung, einem epilepsiechirurgischen Eingriff, und einer postoperativen Oberflächen-EEG Untersuchung unterzogen, und eine postoperative Nachbeobachtung von mindestens 1 Jahr aufwiesen. Die dem Schädeldefekt nächstgelegenen EEG-Elektroden haben wir in den postoperativen MRT-Aufnahmen identifiziert. Um die HFO-Raten im präoperativen und postoperativen EEG zu bestimmen, haben wir einen zuvor validierten automatischen HFO-Detektor verwendet. Resultate: Insgesamt zeigten die HFO-Raten eine positive Korrelation mit der Anfallsfrequenz (p<0.001). Die HFO-Raten in den Kanälen über dem HFO-Bereich nahmen nach erfolgreicher Epilepsiechirurgie ab, unabhängig von ihrer Nähe zum Schädeldefekt (p=0.005). Die HFO-Raten in Kanälen ausserhalb des HFO-Bereichs, aber in der Nähe des Schädeldefekts, zeigten postoperativ keinen Anstieg (p=0.091) und unterschieden sich nicht von den kontralateralen Kanälen (p=0.726). Schlussfolgerung: Unsere Beobachtungen zeigen, dass der Schädeldefekt die postoperative HFO-Erkennung nicht beeinträchtigt. Dies stützt die Annahme, dass die HFO-Raten im Oberflächen-EEG die postoperative Anfallsfreiheit vorhersagen und somit das Therapiemanagement bei fokalen läsionellen Epilepsien steuern können

Scalp HFO rates decrease after successful epilepsy surgery and are not impacted by the skull defect resulting from craniotomy

Epilepsy surgery can achieve seizure freedom in selected pediatric candidates, but reliable postsurgical predictors of seizure freedom are missing. High frequency oscillations (HFO) in scalp EEG are a new and promising biomarker of treatment response. However, it is unclear if the skull defect resulting from craniotomy interferes with HFO detection in postsurgical recordings. We considered 14 children with focal lesional epilepsy who underwent presurgical evaluation, epilepsy surgery, and postsurgical follow-up of ≥ 1 year. We identified the nearest EEG electrodes to the skull defect in the postsurgical MRI. We applied a previously validated automated HFO detector to determine HFO rates in presurgical and postsurgical EEG. Overall, HFO rates showed a positive correlation with seizure frequency (p < 0.001). HFO rates in channels over the HFO area decreased following successful epilepsy surgery, irrespective of their proximity to the skull defect (p = 0.005). HFO rates in channels outside the HFO area but near the skull defect showed no increase following surgery (p = 0.091) and did not differ from their contralateral channels (p = 0.726). Our observations show that the skull defect does not interfere with postsurgical HFO detection. This supports the notion that scalp HFO can predict postsurgical seizure freedom and thus guide therapy management in focal lesional epilepsy

PSD Neutron Discrimination for Dose Monitoring Applications in Particle Therapy

This work presents an analytical and experimental study aiming to validate two implementations of neutron rejection in medical imaging applications, with particular focus on dose monitoring in hadrontherapy. This topic is of particular interest for carbon ion beam therapy, where the neutron background fluctuations challenge the prompt gammas profile identification associated to the Bragg peak. The first solution facilitates pulse shape discrimination: leveraging an ASIC, a dense waveform sampling is avoided, allowing the embedding of PSD analysis in a simple microcontroller. Preliminary experimental results demonstrate the possibility to perform PSD with our integrated circuit solution. An analytical model was also developed, that describes the sources of noise connected to the PSD calculation; the analytical model is in good agreement with our experimental measurements. The second solution, based on a integrated circuit, leverages the typical temporal structures of beams delivered by cyclotrones. Rejection of interaction generating the scintillation light outside a short gate correlated with prompt gamma photons time of arrival might allow to reduce the neutron background

Recovery and compensation after robotic assisted gait training in chronic stroke survivors

Background: Gait re-education is a primary rehabilitation goal after stroke. In the last decades, robots with different mechanical structures have been extensively used in the clinical practice for gait training of stroke survivors. However, the effectiveness of robotic training is still controversial, especially for chronic subjects. In this study, we investigated the short-term effects of gait training assisted by an endpoint robot in a population of chronic stroke survivors. Methods: Subjects were evaluated before and after training with clinical scales and instrumented gait analysis. Our primary outcome indicator was the walking speed. Next, we investigated the changes in kinetic and kinematic gait patterns as well as the intersegmental coordination at the level of the lower limbs. Results: Most subjects improved their speed in over-ground walking, by modifying the temporal more than the spatial gait parameters. These changes led to an improvement in the ankle power for both sides and to a slight reduction of the inclination of the pelvis during the swing phase, mainly due to a decreased knee flexion and an increased hip extension on the unimpaired leg. Conclusions: These results indicate that the proposed training induced mainly a functional change rather than an improvement of the quality of gait.Implication for RehabilitationGait re-education is a primary goal in stroke rehabilitation.Nowadays several robotic devices for gait rehabilitation are used in the clinical practice, but their effectiveness is controversial, especially for chronic survivors.After a 20-session training with an endpoint robot the chronic stroke survivors showed an improvement in overground gait speed.The increased gait speed was mainly due to functional changes of the temporal parameters and of the kinetic variables at the level of both ankle joints, as well as to a reduction of compensatory strategies observable in the unimpaired side