Normal brain functioning emerges from a complex interplay among regions forming networks. In epilepsy, these networks are disrupted causing seizures. Highly connected nodes in these networks are ...epilepsy surgery targets. Here, we assess whether functional connectivity (FC) using intracranial electroencephalography can quantify brain regions epileptogenicity and predict surgical outcome in children with drug resistant epilepsy (DRE). We computed FC between electrodes on different states (i.e. interictal without spikes, interictal with spikes, pre-ictal, ictal, and post-ictal) and frequency bands. We then estimated the electrodes' nodal strength. We compared nodal strength between states, inside and outside resection for good- (n = 22, Engel I) and poor-outcome (n = 9, Engel II-IV) patients, respectively, and tested their utility to predict the epileptogenic zone and outcome. We observed a hierarchical epileptogenic organization among states for nodal strength: lower FC during interictal and pre-ictal states followed by higher FC during ictal and post-ictal states (p < 0.05). We further observed higher FC inside resection (p < 0.05) for good-outcome patients on different states and bands, and no differences for poor-outcome patients. Resection of nodes with high FC was predictive of outcome (positive and negative predictive values: 47-100%). Our findings suggest that FC can discriminate epileptogenic states and predict outcome in patients with DRE.
Deep brain stimulation (DBS) is an established therapeutic modality for the treatment of movement disorders and an emerging therapeutic approach for the treatment of disorders of mood and thought. ...For example, recently we have shown that DBS of the fornix may ameliorate cognitive decline associated with dementia. However, like other applications of DBS, the mechanisms mediating these clinical effects are unknown. As DBS modulates neurophysiological activity in targeted brain regions, DBS might influence cognitive function via activity-dependent regulation of hippocampal neurogenesis. Using stimulation parameters analogous to clinical high-frequency DBS, here we addressed this question in mice. We found that acute stimulation of the entorhinal cortex (EC) transiently promoted proliferation in the dentate gyrus (DG). Cells generated as a consequence of stimulation differentiated into neurons, survived for at least several weeks, and acquired normal dentate granule cell (DGC) morphology. Importantly, stimulation-induced promotion of neurogenesis was limited to the DG and not associated with changes in apoptotic cell death. Using immunohistochemical approaches, we found that, once sufficiently mature, these stimulation-induced neurons integrated into hippocampal circuits supporting water-maze memory. Finally, formation of water-maze memory was facilitated 6 weeks (but not 1 week) after bilateral stimulation of the EC. The delay-dependent nature of these effects matches the maturation-dependent integration of adult-generated DGCs into dentate circuits supporting water-maze memory. Furthermore, because the beneficial effects of EC stimulation were prevented by blocking neurogenesis, this suggests a causal relationship between stimulation-induced promotion of adult neurogenesis and enhanced spatial memory.
Combined endoscopic third ventriculostomy with choroid plexus cauterization (ETV/CPC) enhances the likelihood of shunt freedom over ETV alone, and thus avoidance of shunt-related morbidity, in ...hydrocephalic infants. To date, virtually all published reports describe experiences in Africa, thus hampering generalization to other parts of the world. Here, the authors report the first North American prospective series of this combined approach to treat hydrocephalus of various etiologies in infants.
A prospective series of 50 boys and 41 girls (mean and median ages 4.7 and 3.2 months, respectively) with hydrocephalus underwent ETV/CPC performed by the senior author at Boston Children's Hospital from August 2009 through March 2014. Success data were analyzed using the Kaplan-Meier method and Cox proportional hazards model.
The 91 patients treated included those with aqueductal stenosis (23), myelomeningocele (23), posthemorrhagic hydrocephalus (25), Dandy-Walker complex (6), post-infectious hydrocephalus (6), and other conditions (8). Using Kaplan-Meier survival analysis, 57% of patients required no further hydrocephalus treatment at 1 year. Moreover, 65% remained shunt free to the limit of available follow-up (maximum roughly 4 years). A Cox proportional hazards model identified the following independent predictors of ETV/CPC failure: post-infectious etiology, age at treatment younger than 6 months, prepontine cistern scarring, and prior CSF diversion. Of patients with at least 6 months of follow-up, the overall ETV/CPC success at 6 months (59%) exceeded that predicted by the ETV Success Score (45%). Complications included 1 CSF leak and 1 transient syndrome of inappropriate antidiuretic hormone secretion, and there were no deaths.
ETV/CPC is an effective, safe, and durable treatment for infant hydrocephalus in a North American population, with 1-year success rates similar to those reported in Africa and equivalent to those for primary shunt placement in North America. These findings underscore the need for prospective multicenter studies of the outcomes, quality of life, and economic impact of the procedure compared with primary shunt insertion.
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline. Deep brain stimulation (DBS) has been used to treat a variety of brain disorders and shows ...promise in alleviating cognitive symptoms in some AD patients (Laxton et al, 2010). We previously showed that DBS of the entorhinal cortex (EC) enhances spatial memory formation in normal (wild-type) mice (Stone et al, 2011). Here we tested the effects of EC-DBS on the progressive cognitive deficits in a genetically-based mouse model of AD. TgCRND8 (Tg) transgenic mice express human amyloid precursor protein harboring the Swedish and Indiana familial AD mutations. These mice exhibit age-related increases in Aβ production, plaque deposition, as well as contextual fear and spatial memory impairments. Here, we found EC stimulation in young mice (6 weeks old) rescued the early contextual fear and spatial memory deficits and decreased subsequent plaque load in Tg mice. Moreover, stimulation in older mice (6 months old) was also sufficient to rescue the memory deficits in Tg mice. The memory enhancement induced by DBS emerged gradually (over the course of weeks) and was both persistent and specific to hippocampal-based memories. These results provide further support for the development of novel therapeutics aimed to resolve the cognitive decline and memory impairment in AD using DBS of hippocampal afferents.
Background
Spinal administration of medications is challenging in patients with complete posterior spinal fusion. We describe percutaneous image-guided intrathecal port placement for administration ...of the antisense oligonucleotide nusinersen for children and young adults with spinal muscular atrophy.
Objective
To describe and present our initial experience with a new technique for administering nusinersen in patients with spinal muscular atrophy and posterior spinal fusion.
Materials and methods
We reviewed medical records of 13 patients who received intrathecal ports using DynaCT, biplane fluoroscopy and iGuide from April 2018 through June 2019, and we describe the clinical course over 1 year.
Results
Image-guided catheter and port implantation was successful in all cases. Two ports were subsequently removed, one for persistent cerebrospinal fluid leak and one for superficial infection. The other 11 have functioned successfully for a minimum of 23 months.
Conclusion
We report our experience with image-guided intrathecal port placement in children with complete posterior spine fusion. The implanted port permits dosing in an outpatient setting and avoids the need for multiple future radiologic procedures, and it reduces discomfort, procedural costs and potential risks and sequelae of multiple anesthetics and radiation exposures. Further studies are needed to define the relative risks and benefits of intrathecal ports compared to other approaches such as repeated transforaminal lumbar punctures.
Abstract
Epilepsy is increasingly considered a disorder of brain networks. Studying these networks with functional connectivity can help identify hubs that facilitate the spread of epileptiform ...activity. Surgical resection of these hubs may lead patients who suffer from drug-resistant epilepsy to seizure freedom. Here, we aim to map non-invasively epileptogenic networks, through the virtual implantation of sensors estimated with electric and magnetic source imaging, in patients with drug-resistant epilepsy. We hypothesize that highly connected hubs identified non-invasively with source imaging can predict the epileptogenic zone and the surgical outcome better than spikes localized with conventional source localization methods (dipoles). We retrospectively analysed simultaneous high-density electroencephalography (EEG) and magnetoencephalography data recorded from 37 children and young adults with drug-resistant epilepsy who underwent neurosurgery. Using source imaging, we estimated virtual sensors at locations where intracranial EEG contacts were placed. On data with and without spikes, we computed undirected functional connectivity between sensors/contacts using amplitude envelope correlation and phase locking value for physiologically relevant frequency bands. From each functional connectivity matrix, we generated an undirected network containing the strongest connections within sensors/contacts using the minimum spanning tree. For each sensor/contact, we computed graph centrality measures. We compared functional connectivity and their derived graph centrality of sensors/contacts inside resection for good (n = 22, ILAE I) and poor (n = 15, ILAE II–VI) outcome patients, tested their ability to predict the epileptogenic zone in good-outcome patients, examined the association between highly connected hubs removal and surgical outcome and performed leave-one-out cross-validation to support their prognostic value. We also compared the predictive values of functional connectivity with those of dipoles. Finally, we tested the reliability of virtual sensor measures via Spearman’s correlation with intracranial EEG at population- and patient-level. We observed higher functional connectivity inside than outside resection (P < 0.05, Wilcoxon signed-rank test) for good-outcome patients, on data with and without spikes across different bands for intracranial EEG and electric/magnetic source imaging and few differences for poor-outcome patients. These functional connectivity measures were predictive of both the epileptogenic zone and outcome (positive and negative predictive values ≥55%, validated using leave-one-out cross-validation) outperforming dipoles on spikes. Significant correlations were found between source imaging and intracranial EEG measures (0.4 ≤ rho ≤ 0.9, P < 0.05). Our findings suggest that virtual implantation of sensors through source imaging can non-invasively identify highly connected hubs in patients with drug-resistant epilepsy, even in the absence of frank epileptiform activity. Surgical resection of these hubs predicts outcome better than dipoles.
Corona et al. propose the use of functional connectivity measures derived from MEG and EEG as a noninvasive epilepsy biomarker to map brain networks responsible for generating seizures. Such a biomarker could improve outcomes in patients with drug-resistant epilepsy, particularly those who were previously ineligible for surgery.
Abstract
Neurosurgical intervention is the best available treatment for selected patients with drug resistant epilepsy. For these patients, surgical planning requires biomarkers that delineate the ...epileptogenic zone, the brain area that is indispensable for the generation of seizures. Interictal spikes recorded with electrophysiological techniques are considered key biomarkers of epilepsy. Yet, they lack specificity, mostly because they propagate across brain areas forming networks. Understanding the relationship between interictal spike propagation and functional connections among the involved brain areas may help develop novel biomarkers that can delineate the epileptogenic zone with high precision. Here, we reveal the relationship between spike propagation and effective connectivity among onset and areas of spread and assess the prognostic value of resecting these areas.
We analysed intracranial EEG data from 43 children with drug resistant epilepsy who underwent invasive monitoring for neurosurgical planning. Using electric source imaging, we mapped spike propagation in the source domain and identified three zones: onset, early-spread and late-spread. For each zone, we calculated the overlap and distance from surgical resection. We then estimated a virtual sensor for each zone and the direction of information flow among them via Granger causality. Finally, we compared the prognostic value of resecting these zones, the clinically-defined seizure onset zone and the spike onset on intracranial EEG channels by estimating their overlap with resection.
We observed a spike propagation in source space for 37 patients with a median duration of 95 ms (interquartile range: 34–206), a spatial displacement of 14 cm (7.5–22 cm) and a velocity of 0.5 m/s (0.3–0.8 m/s). In patients with good surgical outcome (25 patients, Engel I), the onset had higher overlap with resection 96% (40–100%) than early-spread 86% (34–100%), P = 0.01 and late-spread 59% (12–100%), P = 0.002, and it was also closer to resection than late-spread 5 mm versus 9 mm, P = 0.007. We found an information flow from onset to early-spread in 66% of patients with good outcomes, and from early-spread to onset in 50% of patients with poor outcome. Finally, resection of spike onset, but not area of spike spread or the seizure onset zone, predicted outcome with positive predictive value of 79% and negative predictive value of 56% (P = 0.04).
Spatiotemporal mapping of spike propagation reveals information flow from onset to areas of spread in epilepsy brain. Surgical resection of the spike onset disrupts the epileptogenic network and may render patients with drug resistant epilepsy seizure-free without having to wait for a seizure to occur during intracranial monitoring.
Matarrese et al. provide insights into the pathophysiology of epilepsy by linking spike propagation and effective connectivity. They highlight the clinical value of spike onset as a biomarker that may improve presurgical evaluation and outcome prediction in patients with drug-resistant epilepsy.
Introduction
Literature lacks studies investigating the cortical generation of sleep spindles in drug-resistant epilepsy (DRE) and how they evolve after resection of the epileptogenic zone (EZ). ...Here, we examined sleep EEGs of children with focal DRE who became seizure-free after focal epilepsy surgery, and aimed to investigate the changes in the spindle generation before and after the surgery using low-density scalp EEG and electrical source imaging (ESI).
Methods
We analyzed N2-sleep EEGs from 19 children with DRE before and after surgery. We identified
slow
(8–12 Hz) and
fast
spindles (13–16 Hz), computed their spectral features and cortical generators through ESI and computed their distance from the EZ and irritative zone (IZ). We performed two-way ANOVA testing the effect of spindle type (
slow
vs.
fast)
and surgical phase (
pre-surgery
vs.
post-surgery
) on each feature.
Results
Power, frequency and cortical activation of slow spindles increased after surgery (p < 0.005), while this was not seen for fast spindles. Before surgery, the cortical generators of slow spindles were closer to the EZ (57.3 vs. 66.2 mm, p = 0.007) and IZ (41.3 vs. 55.5 mm, p = 0.02) than fast spindle generators.
Conclusions
Our data indicate alterations in the EEG slow spindles after resective epilepsy surgery. Fast spindle generation on the contrary did not change after surgery. Although the study is limited by its retrospective nature, lack of healthy controls, and reduced cortical spatial sampling, our findings suggest a spatial relationship between the slow spindles and the epileptogenic generators.
Corpus callosotomy (CC) is a palliative treatment for drop seizures in patients with drug-resistant nonlocalizable epilepsy. We compared drop seizure outcomes between patients undergoing anterior CC ...versus complete CC and examined factors impacting outcomes for drop seizures including age at CC and duration of epilepsy. A retrospective review of patients who underwent CC between 2003 and 2022 with a minimum of 6 months postsurgical follow-up was included. Outcome measure for drop seizures included seizure reduction ≥50% from baseline as well as elimination of drop seizures. Thirty-eight patients were included. Overall, ≥50% reduction in drop seizures occurred in nearly 70% (23 out of 33) patients with complete elimination in 58% (19 out of 33). Compared with anterior CC (n = 13), patients undergoing complete CC (n = 25) had increased likelihood of ≥50% reduction (p = 0.006) or elimination (p = 0.024) of drop seizures. Regression analysis showed that complete CC was the primary predictor for improved drop seizure outcomes (elimination, p = 0.014 or ≥50% reduction, p = 0.006), while age at CC and duration of epilepsy did not impact the outcomes. Compared to anterior CC, complete CC was significantly more likely to lead to improvement/freedom from drop seizures. Age at CC or duration of epilepsy did not influence drop seizure outcomes.
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