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Jacobs J, Zijlmans M. HFO to Measure Seizure Propensity and Improve Prognostication in Patients With Epilepsy. Epilepsy Curr 2020; 20:338-347. [PMID: 33081501 PMCID: PMC7818207 DOI: 10.1177/1535759720957308] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The study of high frequency oscillations (HFO) in the electroencephalogram (EEG)
as biomarkers of epileptic activity has merely focused on their spatial location
and relationship to the epileptogenic zone. It has been suggested in several
ways that the amount of HFO at a certain point in time may reflect the disease
activity or severity. This could be clinically useful in several ways,
especially as noninvasive recording of HFO appears feasible. We grouped the
potential hypotheses into 4 categories: (1) HFO as biomarkers to predict the
development of epilepsy; (2) HFO as biomarkers to predict the occurrence of
seizures; (3) HFO as biomarkers linked to the severity of epilepsy, and (4) HFO
as biomarkers to evaluate outcome of treatment. We will review the literature
that addresses these 4 hypotheses and see to what extent HFO can be used to
measure seizure propensity and help determine prognosis of this unpredictable
disease.
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Affiliation(s)
- Julia Jacobs
- 157744Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Maeike Zijlmans
- 36512UMC Utrecht Brain Center Rudolf Magnus, Utrecht, the Netherlands
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Gerner N, Thomschewski A, Marcu A, Trinka E, Höller Y. Pitfalls in Scalp High-Frequency Oscillation Detection From Long-Term EEG Monitoring. Front Neurol 2020; 11:432. [PMID: 32582002 PMCID: PMC7280487 DOI: 10.3389/fneur.2020.00432] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 04/23/2020] [Indexed: 11/17/2022] Open
Abstract
Aims: Intracranially recorded high-frequency oscillations (>80 Hz) are considered a candidate epilepsy biomarker. Recent studies claimed their detectability on the scalp surface. We aimed to investigate the applicability of high-frequency oscillation analysis to routine surface EEG obtained at an epilepsy monitoring unit. Methods: We retrospectively analyzed surface EEGs of 18 patients with focal epilepsy and six controls, recorded during sleep under maximal medication withdrawal. As a proof of principle, the occurrence of motor task-related events during wakefulness was analyzed in a subsample of six patients with seizure- or syncope-related motor symptoms. Ripples (80-250 Hz) and fast ripples (>250 Hz) were identified by semi-automatic detection. Using semi-parametric statistics, differences in spontaneous and task-related occurrence rates were examined within subjects and between diagnostic groups considering the factors diagnosis, brain region, ripple type, and task condition. Results: We detected high-frequency oscillations in 17 out of 18 patients and in four out of six controls. Results did not show statistically significant differences in the mean rates of event occurrences, neither regarding the laterality of the epileptic focus, nor with respect to active and inactive task conditions, or the moving hand laterality. Significant differences in general spontaneous incidence [WTS(1) = 9.594; p = 0.005] that indicated higher rates of fast ripples compared to ripples, notably in patients with epilepsy compared to the control group, may be explained by variations in data quality. Conclusion: The current analysis methods are prone to biases. A common agreement on a standard operating procedure is needed to ensure reliable and economic detection of high-frequency oscillations.
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Affiliation(s)
- Nathalie Gerner
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Mathematics, Paris-Lodron University of Salzburg, Salzburg, Austria
| | - Aljoscha Thomschewski
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Mathematics, Paris-Lodron University of Salzburg, Salzburg, Austria,*Correspondence: Aljoscha Thomschewski
| | - Adrian Marcu
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria
| | - Yvonne Höller
- Department of Neurology, Christian-Doppler Medical Centre, Centre for Cognitive Neuroscience, Paracelsus Medical University, Salzburg, Austria,Department of Psychology, University of Akureyri, Akureyri, Iceland
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Höller P, Trinka E, Höller Y. High-Frequency Oscillations in the Scalp Electroencephalogram: Mission Impossible without Computational Intelligence. COMPUTATIONAL INTELLIGENCE AND NEUROSCIENCE 2018; 2018:1638097. [PMID: 30158959 PMCID: PMC6109569 DOI: 10.1155/2018/1638097] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 06/20/2018] [Accepted: 07/12/2018] [Indexed: 01/22/2023]
Abstract
High-frequency oscillations (HFOs) in the electroencephalogram (EEG) are thought to be a promising marker for epileptogenicity. A number of automated detection algorithms have been developed for reliable analysis of invasively recorded HFOs. However, invasive recordings are not widely applicable since they bear risks and costs, and the harm of the surgical intervention of implantation needs to be weighted against the informational benefits of the invasive examination. In contrast, scalp EEG is widely available at low costs and does not bear any risks. However, the detection of HFOs on the scalp represents a challenge that was taken on so far mostly via visual detection. Visual detection of HFOs is, in turn, highly time-consuming and subjective. In this review, we discuss that automated detection algorithms for detection of HFOs on the scalp are highly warranted because the available algorithms were all developed for invasively recorded EEG and do not perform satisfactorily in scalp EEG because of the low signal-to-noise ratio and numerous artefacts as well as physiological activity that obscures the tiny phenomena in the high-frequency range.
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Affiliation(s)
- Peter Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
| | - Yvonne Höller
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University, Salzburg, Austria
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Simpson AJ, Cunningham MO, Baker MR. Electrodiagnostic applications of somatosensory evoked high-frequency EEG oscillations: Technical considerations. Brain Res Bull 2018; 137:351-355. [PMID: 29366907 DOI: 10.1016/j.brainresbull.2018.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 01/02/2018] [Accepted: 01/15/2018] [Indexed: 10/18/2022]
Abstract
INTRODUCTION High frequency oscillations (HFOs) embedded within the somatosensory evoked potential (SEP) are not routinely recorded/measured as part of standard clinical SEPs. However, HFOs could provide important additional diagnostic/prognostic information in various patient groups in whom SEPs are tested routinely. One area is the management of patients with hypoxic ischaemic encephalopathy (HIE) in the intensive care unit (ICU). However, the sensitivity of standard clinical SEP recording techniques for detecting HFOs is unknown. METHODS SEPs were recorded using routine clinical methods in 17 healthy subjects (median nerve stimulation; 0.5 ms pulse width; 5 Hz; maximum 4000 stimuli) in an unshielded laboratory. Bipolar EEG recordings were acquired (gain 50 k; bandpass 3Hz-2 kHz; sampling rate 5 kHz; non-inverting electrode 2 cm anterior to C3/C4; inverting electrode 2 cm posterior to C3/C4). Data analysis was performed in MATLAB. RESULTS SEP-HFOs were detected in 65% of controls using standard clinical recording techniques. In 3 controls without significant HFOs, experiments were repeated using a linear electrode array with higher spatial sampling frequency. SEP-HFOs were observed in all 3 subjects. CONCLUSIONS Currently standard clinical methods of recording SEPs are not sufficiently sensitive to permit the inclusion of SEP-HFOs in routine clinical diagnostic/prognostic assessments. Whilst an increase in the number/density of EEG electrodes should improve the sensitivity for detecting SEP-HFOs, this requires confirmation. By improving and standardising clinical SEP recording protocols to permit the acquisition/analysis of SEP-HFOs, it should be possible to gain important insights into the pathophysiology of neurological disorders and refine the management of conditions such as HIE.
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Affiliation(s)
- A J Simpson
- Institute of Neuroscience, The Medical School, Newcastle University, NE2 4HH, UK
| | - M O Cunningham
- Institute of Neuroscience, The Medical School, Newcastle University, NE2 4HH, UK
| | - M R Baker
- Institute of Neuroscience, The Medical School, Newcastle University, NE2 4HH, UK; Department of Neurology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK; Department of Clinical Neurophysiology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP, UK.
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Koelewijn L, Hamandi K, Brindley LM, Brookes MJ, Routley BC, Muthukumaraswamy SD, Williams N, Thomas MA, Kirby A, Te Water Naudé J, Gibbon F, Singh KD. Resting-state oscillatory dynamics in sensorimotor cortex in benign epilepsy with centro-temporal spikes and typical brain development. Hum Brain Mapp 2015; 36:3935-49. [PMID: 26177579 DOI: 10.1002/hbm.22888] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 05/29/2015] [Accepted: 06/15/2015] [Indexed: 12/29/2022] Open
Abstract
Benign Epilepsy with Centro-Temporal Spikes (BECTS) is a common childhood epilepsy associated with deficits in several neurocognitive domains. Neurophysiological studies in BECTS often focus on centro-temporal spikes, but these correlate poorly with morphology and cognitive impairments. To better understand the neural profile of BECTS, we studied background brain oscillations, thought to be integrally involved in neural network communication, in sensorimotor areas. We used independent component analysis of temporally correlated sources on magnetoencephalography recordings to assess sensorimotor resting-state network activity in BECTS patients and typically developing controls. We also investigated the variability of oscillatory characteristics within focal primary motor cortex (M1), localized with a separate finger abduction task. We hypothesized that background oscillations would differ between patients and controls in the sensorimotor network but not elsewhere, especially in the beta band (13-30 Hz) because of its role in network communication and motor processing. The results support our hypothesis: in the sensorimotor network, patients had a greater variability in oscillatory amplitude compared to controls, whereas there was no difference in the visual network. Network measures did not correlate with age. The coefficient of variation of resting M1 peak frequency correlated negatively with age in the beta band only, and was greater than average for a number of patients. Our results point toward a "disorganized" functional sensorimotor network in BECTS, supporting a neurodevelopmental delay in sensorimotor cortex. Our findings further suggest that investigating the variability of oscillatory peak frequency may be a useful tool to investigate deficits of disorganization in neurodevelopmental disorders.
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Affiliation(s)
- Loes Koelewijn
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Khalid Hamandi
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Lisa M Brindley
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
| | - Matthew J Brookes
- Sir Peter Mansfield Magnetic Resonance Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom
| | - Bethany C Routley
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
| | | | - Natalie Williams
- Dyscovery Centre, University of South Wales, Newport, United Kingdom
| | - Marie A Thomas
- Dyscovery Centre, University of South Wales, Newport, United Kingdom
| | - Amanda Kirby
- Dyscovery Centre, University of South Wales, Newport, United Kingdom
| | | | - Frances Gibbon
- Child Health, University Hospital of Wales, Cardiff, United Kingdom
| | - Krish D Singh
- CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom
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Waterstraat G, Fedele T, Burghoff M, Scheer HJ, Curio G. Recording human cortical population spikes non-invasively--An EEG tutorial. J Neurosci Methods 2014; 250:74-84. [PMID: 25172805 DOI: 10.1016/j.jneumeth.2014.08.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 08/11/2014] [Accepted: 08/13/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Non-invasively recorded somatosensory high-frequency oscillations (sHFOs) evoked by electric nerve stimulation are markers of human cortical population spikes. Previously, their analysis was based on massive averaging of EEG responses. Advanced neurotechnology and optimized off-line analysis can enhance the signal-to-noise ratio of sHFOs, eventually enabling single-trial analysis. METHODS The rationale for developing dedicated low-noise EEG technology for sHFOs is unfolded. Detailed recording procedures and tailored analysis principles are explained step-by-step. Source codes in Matlab and Python are provided as supplementary material online. RESULTS Combining synergistic hardware and analysis improvements, evoked sHFOs at around 600 Hz ('σ-bursts') can be studied in single-trials. Additionally, optimized spatial filters increase the signal-to-noise ratio of components at about 1 kHz ('κ-bursts') enabling their detection in non-invasive surface EEG. CONCLUSIONS sHFOs offer a unique possibility to record evoked human cortical population spikes non-invasively. The experimental approaches and algorithms presented here enable also non-specialized EEG laboratories to combine measurements of conventional low-frequency EEG with the analysis of concomitant cortical population spike responses.
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Affiliation(s)
- Gunnar Waterstraat
- Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany.
| | - Tommaso Fedele
- Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.
| | - Martin Burghoff
- Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany.
| | - Hans-Jürgen Scheer
- Bernstein Focus: Neurotechnology Berlin, Germany; Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin, Germany
| | - Gabriel Curio
- Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charite - University Medicine Berlin, Hindenburgdamm 30, 12203 Berlin, Germany; Bernstein Focus: Neurotechnology Berlin, Germany; Bernstein Center for Computational Neuroscience Berlin, Germany.
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Exploring the physiology and function of high-frequency oscillations (HFOs) from the somatosensory cortex. Clin Neurophysiol 2011; 122:1908-23. [DOI: 10.1016/j.clinph.2011.05.023] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 05/30/2011] [Accepted: 05/31/2011] [Indexed: 01/10/2023]
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Abstract
A brief review of previous studies is presented on ultra-fast activities > 300 Hz (high frequency oscillations, HFOs) overlying the cortical response in the somatosensory evoked potential (SEP) or magnetic field (SEF). The characteristics of somatosensory HFOs are described in terms of reproducibility and origin (area 3b and 1) of the HFOs, changes during a wake-sleep cycle, effects of higher stimulus rate or tactile interference, etc. Also, several hypotheses on the neural mechanisms of the HFOs are introduced; the early HFO burst is probably generated from action potentials of thalamocortical fibers at the time when they arrive at the area 3b (and 1), since this component is resistant to higher stimulus rate > 10Hz or general anesthesia: by contrast, the late HFO burst is sensitive to higher stimulus rate, reflecting activities of a postsynaptic neural network in the somatosensory cortices, area 3b and 1. As to possible mechanisms of the late HFO burst genesis, an interneuron hypothesis, a fast inhibitory postsynaptic potential (IPSP) hypothesis of the pyramidal cell and a chattering cell hypothesis will be discussed on the basis of physiological and pathological features of the somatosensory HFOs.
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Affiliation(s)
- Isamu Ozaki
- Faculty of Health Sciences, Aomori University of Health and Welfare, Aomori, Japan.
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Abstract
Spontaneous and stimulus-induced oscillatory EEG activities range over a wide scope of frequencies from 1 Hz to 1 kHz. In the ultrafast domain, trains of 5-10 micropotentials are superimposed to primary thalamic and cortical components in somtosensory evoked potentials (SEP) as brief bursts of 1000 Hz and 600 Hz, respectively. Over the last years, hypotheses on generators and functions of this frequency-edge of population activity have been elaborated in numerous studies. Here, the relevant findings and ideas were surveyed from the body of literature. Special emphasis was paid to the anatomical and cellular origin of burst SEP, their assumed impact on somatosensory coding and perspectives for scientific as well as clinical applications.
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Affiliation(s)
- Fabian Klostermann
- Charité-Universitätsmedizin Berlin, CBF, Dept. ol Neurology, Hindenburgdamm 30, 12200 Berlin, Germany.
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