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JAMA Neurology Apr 2021Focal epilepsy is characterized by the cyclical recurrence of seizures, but, to our knowledge, the prevalence and patterns of seizure cycles are unknown.
IMPORTANCE
Focal epilepsy is characterized by the cyclical recurrence of seizures, but, to our knowledge, the prevalence and patterns of seizure cycles are unknown.
OBJECTIVE
To establish the prevalence, strength, and temporal patterns of seizure cycles over timescales of hours to years.
DESIGN, SETTING, AND PARTICIPANTS
This retrospective cohort study analyzed data from continuous intracranial electroencephalography (cEEG) and seizure diaries collected between January 19, 2004, and May 18, 2018, with durations up to 10 years. A total of 222 adults with medically refractory focal epilepsy were selected from 256 total participants in a clinical trial of an implanted responsive neurostimulation device. Selection was based on availability of cEEG and/or self-reports of disabling seizures.
EXPOSURES
Antiseizure medications and responsive neurostimulation, based on clinical indications.
MAIN OUTCOMES AND MEASURES
Measures involved (1) self-reported daily seizure counts, (2) cEEG-based hourly counts of electrographic seizures, and (3) detections of interictal epileptiform activity (IEA), which fluctuates in daily (circadian) and multiday (multidien) cycles. Outcomes involved descriptive characteristics of cycles of IEA and seizures: (1) prevalence, defined as the percentage of patients with a given type of seizure cycle; (2) strength, defined as the degree of consistency with which seizures occur at certain phases of an underlying cycle, measured as the phase-locking value (PLV); and (3) seizure chronotypes, defined as patterns in seizure timing evident at the group level.
RESULTS
Of the 222 participants, 112 (50%) were male, and the median age was 35 years (range, 18-66 years). The prevalence of circannual (approximately 1 year) seizure cycles was 12% (24 of 194), the prevalence of multidien (approximately weekly to approximately monthly) seizure cycles was 60% (112 of 186), and the prevalence of circadian (approximately 24 hours) seizure cycles was 89% (76 of 85). Strengths of circadian (mean [SD] PLV, 0.34 [0.18]) and multidien (mean [SD] PLV, 0.34 [0.17]) seizure cycles were comparable, whereas circannual seizure cycles were weaker (mean [SD] PLV, 0.17 [0.10]). Across individuals, circadian seizure cycles showed 5 peaks: morning, mid-afternoon, evening, early night, and late night. Multidien cycles of IEA showed peak periodicities centered around 7, 15, 20, and 30 days. Independent of multidien period length, self-reported and electrographic seizures consistently occurred during the days-long rising phase of multidien cycles of IEA.
CONCLUSIONS AND RELEVANCE
Findings in this large cohort establish the high prevalence of plural seizure cycles and help explain the natural variability in seizure timing. The results have the potential to inform the scheduling of diagnostic studies, the delivery of time-varying therapies, and the design of clinical trials in epilepsy.
Topics: Adolescent; Adult; Aged; Circadian Rhythm; Cohort Studies; Electrocorticography; Epilepsies, Partial; Female; Humans; Implantable Neurostimulators; Male; Middle Aged; Retrospective Studies; Seizures; Young Adult
PubMed: 33555292
DOI: 10.1001/jamaneurol.2020.5370 -
Seizure Apr 2020Stereoelectroencephalography-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC) consists of coupling SEEG investigation with RF-TC stereotactic lesioning... (Review)
Review
Stereoelectroencephalography-guided radiofrequency-thermocoagulation (SEEG-guided RF-TC) consists of coupling SEEG investigation with RF-TC stereotactic lesioning directly through the recording electrodes. In this systematic review the surgical technique, indications, and outcomes are described. Maximum accuracy is reached when a frame-based procedure with a robotic assistance and a per-operative vascular X-ray imaging are performed. Monitoring of the lesioning procedure based on the impedance, a sharp modification of which indicates that the thermocoagulation has reached its maximum volume, allows the optimization of the lesion size. The first indication concerns patients in whom a SEEG is required to determine whether surgery is feasible and in whom resection is indeed possible. Even if surgery is performed owing to insufficient efficacy of SEEG-guided RF-TC, the procedure remains interesting owing to its high positive predictive value for good outcome after surgery. The second indication concerns patients in whom phase I non-invasive investigations have concluded to surgical contraindication and who may still undergo SEEG in a purely therapeutic perspective (small deep zones inaccessible to surgery and network nodes of large epileptic networks). Lastly, SEEG-guided RF-TC can be considered as a first-line treatment for periventricular nodular heterotopia (PNH). Independently of indication, the overall seizure-free rate is 23% and the responder rate is 58%. The best results are obtained for PNH (38% seizure-free and 81% responders), while the worst results have been reported for temporal lobe-epilepsy in a dedicated study. The overall complication rate is 2.5%. More evidence is needed to help determine the exact place of SEEG-guided RF-TC in the surgical management algorithm.
Topics: Drug Resistant Epilepsy; Electrocoagulation; Electrocorticography; Epilepsies, Partial; Humans; Periventricular Nodular Heterotopia; Stereotaxic Techniques
PubMed: 30711397
DOI: 10.1016/j.seizure.2019.01.021 -
Seizure Apr 2020Electrical stimulation mapping is a longstanding practice that aids in identification and delineation of eloquent cortex. Initially used to expand our understanding of... (Review)
Review
Electrical stimulation mapping is a longstanding practice that aids in identification and delineation of eloquent cortex. Initially used to expand our understanding of the typical human cortex, it now plays a significant role in mapping cortical function in individuals with atypical structural and functional tissue organization undergoing epilepsy surgery. This review discusses the unique challenges that arise in the functional testing of the immature cortex of a child and the parameters of stimulation that optimize accurate results in conventional open implantation and in stereo-electroencephalography. The prerequisite baseline evaluation and preparation recommended to increase the yield from pediatric stimulation mapping sessions is described, as are ideal approaches to the mapping of the sensory, motor, language, and visual cortices.
Topics: Brain Mapping; Cerebral Cortex; Child; Electric Stimulation; Electrocorticography; Epilepsy; Evoked Potentials; Humans; Monitoring, Intraoperative; Neurosurgical Procedures
PubMed: 31445890
DOI: 10.1016/j.seizure.2019.07.023 -
Brain Topography Jan 2022Traveling waves appear in various signals that measure neuronal activity. Some signals measured in animals have singles-cell resolution and directly point to neuronal...
Traveling waves appear in various signals that measure neuronal activity. Some signals measured in animals have singles-cell resolution and directly point to neuronal activity. In those cases, activation of distributed neurons forms a wave front, and the front propagates across the cortical surface. Other signals are variants of neuroelectric potentials, i.e. electroencephalography, electrocorticography and field potentials. Instead of having fine spatial resolution, these signals reflect the activity of neuronal populations via volume conduction (VC). Sources of traveling waves in neuroelectric potentials have not been well addressed so far. As animal studies show propagating activation of neurons that spread in measured areas, it is often considered that neuronal activations during scalp waves have similar trajectories of activation, spreading like scalp waves. However, traveling waves on the scalp differ from those found directly on the cortical surface in several dimensions: traveling velocity, traveling distance and areal size occupied by single polarity. We describe that the simplest sources can produce scalp waves with perceived spatial dimensions which are actually a magnification of neuronal activity emanating from local sources due to VC. This viewpoint is not a rigorous proof of our magnification concept. However, we suggest the possibility that the actual dimensions of neuronal activity producing traveling waves is not as large as the dimension of the traveling waves.
Topics: Animals; Electrocorticography; Electroencephalography; Humans; Neurons; Scalp
PubMed: 34086189
DOI: 10.1007/s10548-021-00853-1 -
Trends in Cognitive Sciences Apr 2018The human default network (DN) plays a critical role in internally directed cognition, behavior, and neuropsychiatric disease. Despite much progress with functional... (Review)
Review
The human default network (DN) plays a critical role in internally directed cognition, behavior, and neuropsychiatric disease. Despite much progress with functional neuroimaging, persistent questions still linger concerning the electrophysiological underpinnings, fast temporal dynamics, and causal importance of the DN. Here, we review how direct intracranial recording and stimulation of the DN provides a unique combination of high spatiotemporal resolution and causal information that speaks directly to many of these outstanding questions. Our synthesis highlights the electrophysiological basis of activation, suppression, and connectivity of the DN, each key areas of debate in the literature. Integrating these unique electrophysiological data with extant neuroimaging findings will help lay the foundation for a mechanistic account of DN function in human behavior and cognition.
Topics: Brain Waves; Cerebral Cortex; Electrocorticography; Functional Neuroimaging; Humans; Nerve Net
PubMed: 29525387
DOI: 10.1016/j.tics.2018.02.002 -
Clinical Neurophysiology : Official... Aug 2022Deep brain stimulation (DBS) offers the unique opportunity to record human neural population activity as multiunit activity and local field potentials (LFP) directly... (Review)
Review
Deep brain stimulation (DBS) offers the unique opportunity to record human neural population activity as multiunit activity and local field potentials (LFP) directly from the target area in the depth of the brain. This has led to important discoveries through characterization of pathological activity patterns and identification of motor and cognitive correlates of basal ganglia function in patients with movement disorders. These findings have been covered extensively in a large body of literature, but the technical aspects of microelectrode and LFP recordings in DBS patients are rarely reported. This review summarizes the experience from invasive neurophysiology experiments in over 500 DBS cases in the last 20 years in a single centre. It introduces the basics of intraoperative microelectrode recordings, discusses the neurophysiological and technical aspects of LFP signals and gives and outlook on current and next-generation developments - from sensing enabled implantable devices to combined electrocorticography and LFP recordings during adaptive DBS.
Topics: Basal Ganglia; Deep Brain Stimulation; Electrocorticography; Humans; Movement Disorders; Neurophysiology
PubMed: 35659821
DOI: 10.1016/j.clinph.2022.05.004 -
ENeuro Oct 2023Intracranial electroencephalography (iEEG) provides a unique opportunity to record and stimulate neuronal populations in the human brain. A key step in neuroscience...
Intracranial electroencephalography (iEEG) provides a unique opportunity to record and stimulate neuronal populations in the human brain. A key step in neuroscience inference from iEEG is localizing the electrodes relative to individual subject anatomy and identified regions in brain atlases. We describe a new software tool, Your Advanced Electrode Localizer (YAEL), that provides an integrated solution for every step of the electrode localization process. YAEL is compatible with all common data formats to provide an easy-to-use, drop-in replacement for problematic existing workflows that require users to grapple with multiple programs and interfaces. YAEL's automatic extrapolation and interpolation functions speed localization, especially important in patients with many implanted stereotactic (sEEG) electrode shafts. The graphical user interface is presented in a web browser for broad compatibility and includes an interactive 3D viewer for easier localization of nearby sEEG contacts. After localization is complete, users may enter or import data into YAEL's 3D viewer to create publication-ready visualizations of electrodes and brain anatomy, including identified brain areas from atlases; the response to experimental tasks measured with iEEG; and clinical measures such as epileptiform activity or the results of electrical stimulation mapping. YAEL is free and open source and does not depend on any commercial software. Installation instructions for Mac, Windows, and Linux are available at https://yael.wiki.
Topics: Humans; Electroencephalography; Electrocorticography; Brain; Brain Mapping; Electrodes, Implanted
PubMed: 37857509
DOI: 10.1523/ENEURO.0328-23.2023 -
NeuroImage Oct 2022Since the second-half of the twentieth century, intracranial electroencephalography (iEEG), including both electrocorticography (ECoG) and stereo-electroencephalography... (Review)
Review
Since the second-half of the twentieth century, intracranial electroencephalography (iEEG), including both electrocorticography (ECoG) and stereo-electroencephalography (sEEG), has provided an intimate view into the human brain. At the interface between fundamental research and the clinic, iEEG provides both high temporal resolution and high spatial specificity but comes with constraints, such as the individual's tailored sparsity of electrode sampling. Over the years, researchers in neuroscience developed their practices to make the most of the iEEG approach. Here we offer a critical review of iEEG research practices in a didactic framework for newcomers, as well addressing issues encountered by proficient researchers. The scope is threefold: (i) review common practices in iEEG research, (ii) suggest potential guidelines for working with iEEG data and answer frequently asked questions based on the most widespread practices, and (iii) based on current neurophysiological knowledge and methodologies, pave the way to good practice standards in iEEG research. The organization of this paper follows the steps of iEEG data processing. The first section contextualizes iEEG data collection. The second section focuses on localization of intracranial electrodes. The third section highlights the main pre-processing steps. The fourth section presents iEEG signal analysis methods. The fifth section discusses statistical approaches. The sixth section draws some unique perspectives on iEEG research. Finally, to ensure a consistent nomenclature throughout the manuscript and to align with other guidelines, e.g., Brain Imaging Data Structure (BIDS) and the OHBM Committee on Best Practices in Data Analysis and Sharing (COBIDAS), we provide a glossary to disambiguate terms related to iEEG research.
Topics: Brain; Brain Mapping; Electrocorticography; Electrodes; Electroencephalography; Humans
PubMed: 35792291
DOI: 10.1016/j.neuroimage.2022.119438 -
Stereotactic and Functional Neurosurgery 2017Cortical spreading depolarization (CSD) is an electrophysiologic phenomenon found mostly in the setting of neurologic injury resulting in the disturbance of ion... (Review)
Review
Cortical spreading depolarization (CSD) is an electrophysiologic phenomenon found mostly in the setting of neurologic injury resulting in the disturbance of ion homeostasis and leading to changes in the local vascular response. The bioelectric etiology of CSD shares similarities to those in epileptic disorders, yet the relationship between seizures and CSD is unclear, with several studies observing cortical depression before, during, and after seizure activity, thus obscuring our understanding of whether CSD activity potentiates or limits seizures and vice versa. Cortical sampling has exhibited how the redistribution of ion concentrations in the intra- and extracellular environments interplay between the excitation of seizures and the electrical depression of CSD. Modeling of both environments has suggested that CSD synchronizes the affected tissue, creating a favorable environment for seizure activity; however, other studies have demonstrated the opposite: epileptiform activity initiating waves of CSD. Further studies have underscored the role of the vascular response and subsequent ischemia in CSD that contributes to epileptogenesis. Investigations in migraine, traumatic brain injury, and other neurologic injuries suggest that several drugs may target CSD. Manipulations in the occurrence and nature of CSD can potentially alter the threshold for seizure activity, and perhaps minimize immediate and long-term sequelae associated with epilepsy.
Topics: Cerebral Cortex; Cortical Spreading Depression; Electrocorticography; Humans; Seizures
PubMed: 28088802
DOI: 10.1159/000452841 -
Clinical Neurophysiology : Official... Oct 2021We clarified the clinical and mechanistic significance of physiological modulations of high-frequency broadband cortical activity associated with spontaneous saccadic...
OBJECTIVE
We clarified the clinical and mechanistic significance of physiological modulations of high-frequency broadband cortical activity associated with spontaneous saccadic eye movements during a resting state.
METHODS
We studied 30 patients who underwent epilepsy surgery following extraoperative electrocorticography and electrooculography recordings. We determined whether high-gamma activity at 70-110 Hz preceding saccade onset would predict upcoming ocular behaviors. We assessed how accurately the model incorporating saccade-related high-gamma modulations would localize the primary visual cortex defined by electrical stimulation.
RESULTS
The dynamic atlas demonstrated transient high-gamma suppression in the striatal cortex before saccade onset and high-gamma augmentation subsequently involving the widespread posterior brain regions. More intense striatal high-gamma suppression predicted the upcoming saccade directed to the ipsilateral side and lasting longer in duration. The bagged-tree-ensemble model demonstrated that intense saccade-related high-gamma modulations localized the visual cortex with an accuracy of 95%.
CONCLUSIONS
We successfully animated the neural dynamics supporting saccadic suppression, a principal mechanism minimizing the perception of blurred vision during rapid eye movements. The primary visual cortex per se may prepare actively in advance for massive image motion expected during upcoming prolonged saccades.
SIGNIFICANCE
Measuring saccade-related electrocorticographic signals may help localize the visual cortex and avoid misperceiving physiological high-frequency activity as epileptogenic.
Topics: Adolescent; Child; Child, Preschool; Drug Resistant Epilepsy; Electrocorticography; Female; Gamma Rhythm; Humans; Male; Saccades; Visual Cortex; Young Adult
PubMed: 34454266
DOI: 10.1016/j.clinph.2021.06.020