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Hssain-Khalladi S, Giron A, Huneau C, Gitton C, Schwartz D, George N, Le Van Quyen M, Marrelec G, Marchand-Pauvert V. Further characterisation of late somatosensory evoked potentials using electroencephalogram and magnetoencephalogram source imaging. Eur J Neurosci 2024; 60:3772-3794. [PMID: 38726801 DOI: 10.1111/ejn.16379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 09/27/2023] [Accepted: 04/18/2024] [Indexed: 07/06/2024]
Abstract
Beside the well-documented involvement of secondary somatosensory area, the cortical network underlying late somatosensory evoked potentials (P60/N60 and P100/N100) is still unknown. Electroencephalogram and magnetoencephalogram source imaging were performed to further investigate the origin of the brain cortical areas involved in late somatosensory evoked potentials, using sensory inputs of different strengths and by testing the correlation between cortical sources. Simultaneous high-density electroencephalograms and magnetoencephalograms were performed in 19 participants, and electrical stimulation was applied to the median nerve (wrist level) at intensity between 1.5 and 9 times the perceptual threshold. Source imaging was undertaken to map the stimulus-induced brain cortical activity according to each individual brain magnetic resonance imaging, during three windows of analysis covering early and late somatosensory evoked potentials. Results for P60/N60 and P100/N100 were compared with those for P20/N20 (early response). According to literature, maximal activity during P20/N20 was found in central sulcus contralateral to stimulation site. During P60/N60 and P100/N100, activity was observed in contralateral primary sensorimotor area, secondary somatosensory area (on both hemispheres) and premotor and multisensory associative cortices. Late responses exhibited similar characteristics but different from P20/N20, and no significant correlation was found between early and late generated activities. Specific clusters of cortical activities were activated with specific input/output relationships underlying early and late somatosensory evoked potentials. Cortical networks, partly common to and distinct from early somatosensory responses, contribute to late responses, all participating in the complex somatosensory brain processing.
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Affiliation(s)
- Sahar Hssain-Khalladi
- Sorbonne Université, Inserm, CNRS, Laboratoire d'Imagerie Biomédicale, LIB, Paris, France
- Sorbonne Université, Laboratoire d'Excellence SMART, Paris, France
| | - Alain Giron
- Sorbonne Université, Inserm, CNRS, Laboratoire d'Imagerie Biomédicale, LIB, Paris, France
| | - Clément Huneau
- Université de Nantes, CNRS, Laboratoire des Sciences du Numérique de Nantes, LS2N, Nantes, France
| | - Christophe Gitton
- Sorbonne Université, Inserm, CNRS, Institut du Cerveau, ICM, Paris, France
| | - Denis Schwartz
- Sorbonne Université, Inserm, CNRS, Institut du Cerveau, ICM, Paris, France
| | - Nathalie George
- Sorbonne Université, Inserm, CNRS, Institut du Cerveau, ICM, Paris, France
| | - Michel Le Van Quyen
- Sorbonne Université, Inserm, CNRS, Laboratoire d'Imagerie Biomédicale, LIB, Paris, France
| | - Guillaume Marrelec
- Sorbonne Université, Inserm, CNRS, Laboratoire d'Imagerie Biomédicale, LIB, Paris, France
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Dimakopoulos V, Neidert MC, Sarnthein J. Low impedance electrodes improve detection of high frequency oscillations in the intracranial EEG. Clin Neurophysiol 2023; 153:133-140. [PMID: 37487419 DOI: 10.1016/j.clinph.2023.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/03/2023] [Indexed: 07/26/2023]
Abstract
OBJECTIVE Epileptic fast ripple oscillations (FR, 250-500 Hz) indicate epileptogenic tissue with high specificity. However, their low amplitude makes detection demanding against noise. Since thermal noise is reduced by low impedance electrodes (LoZ), we investigate here whether this noise reduction is relevant in the FR frequency range. METHODS We analyzed intracranial electrocorticography during neurosurgery of 10 patients where a low impedance electrode was compared to a standard electrode (HiZ) with equal surface area during stimulation of the somatosensory evoked potential, which evokes a robust response in the FR frequency range. To estimate the noise level, we computed the difference between sweep 2n and sweep 2n + 1 for all sweeps. RESULTS The power spectral density of the noise spectrum improved for the LoZ over all frequencies. In the FR range, the median noise level improved from HiZ (0.153 µV) to LoZ (0.089 µV). For evoked FR, the detection rate improved (91% for HiZ vs. 100% for LoZ). CONCLUSIONS Low impedance electrodes for intracranial EEG reduce noise in the FR frequency range and may thereby improve FR detection. SIGNIFICANCE Improving the measurement chain may enhance the diagnostic value of FR as biomarkers for epileptogenic tissue.
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Affiliation(s)
| | - Marian C Neidert
- Klinik für Neurochirurgie, Universitätsspital Zürich, Universität Zürich, Switzerland; Klinik für Neurochirurgie, Kantonsspital St. Gallen, Switzerland
| | - Johannes Sarnthein
- Klinik für Neurochirurgie, Universitätsspital Zürich, Universität Zürich, Switzerland; Klinisches Neurozentrum, Universitätsspital Zürich, Switzerland.
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Maudrich T, Hähner S, Kenville R, Ragert P. Somatosensory-Evoked Potentials as a Marker of Functional Neuroplasticity in Athletes: A Systematic Review. Front Physiol 2022; 12:821605. [PMID: 35111081 PMCID: PMC8801701 DOI: 10.3389/fphys.2021.821605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/23/2021] [Indexed: 11/13/2022] Open
Abstract
Background Somatosensory-evoked potentials (SEP) represent a non-invasive tool to assess neural responses elicited by somatosensory stimuli acquired via electrophysiological recordings. To date, there is no comprehensive evaluation of SEPs for the diagnostic investigation of exercise-induced functional neuroplasticity. This systematic review aims at highlighting the potential of SEP measurements as a diagnostic tool to investigate exercise-induced functional neuroplasticity of the sensorimotor system by reviewing studies comparing SEP parameters between athletes and healthy controls who are not involved in organized sports as well as between athlete cohorts of different sport disciplines. Methods A systematic literature search was conducted across three electronic databases (PubMed, Web of Science, and SPORTDiscus) by two independent researchers. Three hundred and ninety-seven records were identified, of which 10 cross-sectional studies were considered eligible. Results Differences in SEP amplitudes and latencies between athletes and healthy controls or between athletes of different cohorts as well as associations between SEP parameters and demographic/behavioral variables (years of training, hours of training per week & reaction time) were observed in seven out of 10 included studies. In particular, several studies highlight differences in short- and long-latency SEP parameters, as well as high-frequency oscillations (HFO) when comparing athletes and healthy controls. Neuroplastic differences in athletes appear to be modality-specific as well as dependent on training regimens and sport-specific requirements. This is exemplified by differences in SEP parameters of various athlete populations after stimulation of their primarily trained limb. Conclusion Taken together, the existing literature suggests that athletes show specific functional neuroplasticity in the somatosensory system. Therefore, this systematic review highlights the potential of SEP measurements as an easy-to-use and inexpensive diagnostic tool to investigate functional neuroplasticity in the sensorimotor system of athletes. However, there are limitations regarding the small sample sizes and inconsistent methodology of SEP measurements in the studies reviewed. Therefore, future intervention studies are needed to verify and extend the conclusions drawn here.
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Affiliation(s)
- Tom Maudrich
- Department of Movement Neuroscience, Faculty of Sport Science, Leipzig University, Leipzig, Germany
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- *Correspondence: Tom Maudrich
| | - Susanne Hähner
- Department of Movement Neuroscience, Faculty of Sport Science, Leipzig University, Leipzig, Germany
| | - Rouven Kenville
- Department of Movement Neuroscience, Faculty of Sport Science, Leipzig University, Leipzig, Germany
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Patrick Ragert
- Department of Movement Neuroscience, Faculty of Sport Science, Leipzig University, Leipzig, Germany
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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Nardone R, Sebastianelli L, Versace V, Orioli A, Saltuari L, Trinka E, Höller Y. Involvement of central sensory pathways in subjects with restless legs syndrome: A neurophysiological study. Brain Res 2021; 1772:147673. [PMID: 34597651 DOI: 10.1016/j.brainres.2021.147673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 09/14/2021] [Accepted: 09/26/2021] [Indexed: 11/26/2022]
Abstract
In patients with restless legs syndrome (RLS) a motor cortical disinhibition has been reported in transcranial magnetic stimulation (TMS) studies, but the neuronal excitability in other cortical areas has been poorly explored. The aim of this study was the functional evaluation of thalamo-cortical circuits and inhibitory cortical responses in the sensory cortex in RLS. We assessed the high-frequency somatosensory evoked potentials (HF-SEP) in sixteen subjects suffering from RLS of different degrees of severity. In patients with severe or very severe RLS we found a significant desynchronization with amplitude reduction of both pre- and post-synaptic HF-SEP bursts, which suggest an impairment in the thalamo-cortical projections and in the cortical inhibitory interneurons activity, respectively. The assessment of the central sensory pathways by means of HF-SEP may shed light on the pathophysiological mechanisms of RLS.
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Affiliation(s)
- Raffaele Nardone
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano-Meran, Italy; Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Spinal Cord Injury and Tissue Regeneration Center, Salzburg, Austria; Karl Landsteiner Institut für Neurorehabilitation und Raumfahrtneurologie, Salzburg, Austria.
| | - Luca Sebastianelli
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy, and Research Department for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Viviana Versace
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy, and Research Department for Neurorehabilitation South Tyrol, Bolzano, Italy
| | - Andrea Orioli
- Department of Neurology, Hospital of Merano (SABES-ASDAA), Merano-Meran, Italy
| | - Leopold Saltuari
- Department of Neurorehabilitation, Hospital of Vipiteno (SABES-ASDAA), Vipiteno-Sterzing, Italy, and Research Department for Neurorehabilitation South Tyrol, Bolzano, Italy; Department of Neurology, Hochzirl Hospital, Zirl, Austria
| | - Eugen Trinka
- Department of Neurology, Christian Doppler Klinik, Paracelsus Medical University, Salzburg, Austria; Centre for Cognitive Neuroscience, Salzburg, Austria; University for Medical Informatics and Health Technology, UMIT, Hall in Tirol, Austria
| | - Yvonne Höller
- Faculty of Psychology, University of Akureyri, Iceland
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Lanzone J, Boscarino M, Ricci L, Insola A, Tombini M, Di Lazzaro V, Assenza G. The effects of antiepileptic drugs on high-frequency oscillations in somatosensory evoked potentials. Clin Neurophysiol 2020; 131:1917-1924. [PMID: 32599275 DOI: 10.1016/j.clinph.2020.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/25/2020] [Accepted: 05/28/2020] [Indexed: 01/11/2023]
Abstract
OBJECTIVES High frequency oscillations (HFOs) of Somatosensory evoked potentials (SEPs) reflect the activity of thalamo-cortical and cortical neurons from the sensory pathway. Antiepileptic-drugs (AEDs) reduce seizures acting on the balance between excitation and inhibition. We aimed to study the effect of AED mono and polytherapy on SEP-HFO's components. METHODS Twenty-five patients with focal epilepsy were enrolled for the purpose of this study. Patients were divided in 3 groups according to the number of AEDs (1, 2 or 3 AEDs). Patients in group 1 underwent SEP-HFOs recording in drug naïve condition and at 1 month after AED titration. HFOs were compared in duration, amplitude and latency among the three groups. RESULTS The amplitude and duration of late HFOs of the affected hemisphere (AH) are different between groups and inversely correlated with the number of AEDs. In naïve patients monotherapy reverts the asymmetry in totHFOs (total HFOs) duration. CONCLUSION Our results demonstrate that SEP-HFOs are sensitive to the action of AEDs on cortical excitability. This effect seems to affect mainly the cortical component of HFOs in the AH and it is related to the number of AEDs taken. SIGNIFICANCE SEP-HFOs might be a viable tool to probe cortical excitability changes induced by AEDs.
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Affiliation(s)
- Jacopo Lanzone
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.
| | - Marilisa Boscarino
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Lorenzo Ricci
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | | | - Mario Tombini
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Vincenzo Di Lazzaro
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Giovanni Assenza
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
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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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Nardone R, Golaszewski S, Thomschewski A, Sebastianelli L, Versace V, Brigo F, Orioli A, Saltuari L, Höller Y, Trinka E. Disinhibition of sensory cortex in patients with amyotrophic lateral sclerosis. Neurosci Lett 2020; 722:134860. [DOI: 10.1016/j.neulet.2020.134860] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/05/2020] [Accepted: 02/21/2020] [Indexed: 12/11/2022]
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Assenza G, Lanzone J, Insola A, Amatori G, Ricci L, Tombini M, Di Lazzaro V. Thalamo-cortical network dysfunction in temporal lobe epilepsy. Clin Neurophysiol 2019; 131:548-554. [PMID: 31818685 DOI: 10.1016/j.clinph.2019.10.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 10/02/2019] [Accepted: 10/25/2019] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Imaging and neurophysiological data shows that the cortical disfunction caused by focal epilepsy is not limited to the epileptic focus, thus raising the modern vision of focal epilepsy as a network disorder. The involvement of deep thalamo-cortical projections in temporal lobe epilepsy is a clear example. We aimed at demonstrating the interictal functional impairment of thalamo-cortical network in drug-naïve TLE patients through the study of high frequency oscillations of somatosensory evoked potentials (HF-SEP). METHODS Twelve healthy controls (HC; 8 females, 52.2 ± 17.3 years-old) and 12 drug-naïve TLE patients (8 females, 55.5 ± 21.5 years-old) underwent bilateral median HF-SEP, recorded by scalp electrodes. Cp3'-Fz and Cp4'-Fz traces were filtered (400-800 Hz) to evidence HF-SEP. RESULTS HF-SEP duration in the affected hemisphere was significantly longer when compared to that of both the unaffected hemisphere and HC hemispheres. No significant inter-hemispheric differences were found in areas, powers and latencies of HF-SEP wavelets. CONCLUSION Our results demonstrate that TLE induces early interictal functional impairments of the thalamo-cortical network. SIGNIFICANCE Our data strongly corroborates the vision of focal epilepsy as a network disorder and offers a new neurophysiological tool to test pharmacological, surgical and neuromodulatory therapies.
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Affiliation(s)
- Giovanni Assenza
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.
| | - Jacopo Lanzone
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | | | - Giulia Amatori
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Lorenzo Ricci
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Mario Tombini
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Vincenzo Di Lazzaro
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
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Insola A, Di Lazzaro V, Assenza G. Cortical inhibitory dysfunction in epilepsia partialis continua: A high frequency oscillation somatosensory evoked potential study. Clin Neurophysiol 2019; 130:439-444. [PMID: 30769270 DOI: 10.1016/j.clinph.2019.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The pathophysiology of epilepsia partialis continua (EPC) is still unclear, a thalamo-cortical circuit dysfunction has been hypothesized. The aim of present study is the functional evaluation of the thalamo-cortical network in EPC by means of the study of low- and high-frequency somatosensory evoked potentials (LF-SEP and HF-SEP). METHODS Median LF-SEP and HF-SEP were recorded in 3 patients with EPC and in 2 patients with rolandic lesions without EPC (non-EPC). Recording electrodes were placed on P3, C3, F3 and P4, C4, F4 of scalp regions. HF-SEP were obtained by an offline 400-800 Hz filtering of P3-F3 and P4-F4 traces. RESULTS In EPC patients, we found a significant suppression of post-synaptic HF-SEP burst and an amplitude reduction of the P24 wave of the LF-SEPs. Both these components are related to cortical inhibitory interneuron activity. HF-SEP and LF-SEP were normal in non-EPC patients. CONCLUSION The different results obtained in patients with a rolandic lesion with and without EPC supports the hypothesis that EPC might be correlated to a dysfunction of gabaergic interneurons of a cortical sensory-motor network. SIGNIFICANCE Our results might contribute to the understanding of the physiological basis of the cortical dysfunction causing epilepsia partialis continua.
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Affiliation(s)
| | - Vincenzo Di Lazzaro
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Giovanni Assenza
- Neurology, Neurophysiology and Neurobiology Unit, Department of Medicine, Università Campus Bio-Medico di Roma, Rome, Italy.
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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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Fedele T, Schönenberger C, Curio G, Serra C, Krayenbühl N, Sarnthein J. Intraoperative subdural low-noise EEG recording of the high frequency oscillation in the somatosensory evoked potential. Clin Neurophysiol 2017; 128:1851-1857. [PMID: 28826015 DOI: 10.1016/j.clinph.2017.07.400] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 06/30/2017] [Accepted: 07/10/2017] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The detectability of high frequency oscillations (HFO, >200Hz) in the intraoperative ECoG is restricted by their low signal-to-noise ratio (SNR). Using the somatosensory evoked HFO, we quantify how HFO detectability can benefit from a custom-made low-noise amplifier (LNA). METHODS In 9 patients undergoing tumor surgery in the central region, subdural strip electrodes were placed for intraoperative neurophysiological monitoring. We recorded the somatosensory evoked potential (SEP) simultaneously by custom-made LNA and by a commercial device (CD). We varied the stimulation rate between 1.3 and 12.7Hz to tune the SNR of the N20 component and the evoked HFO and quantified HFO detectability at the single trial level. In three patients we compared Propofol® and Sevoflurane® anesthesia. RESULTS In the average, amplitude decreased in both in N20 and evoked HFO amplitude with increasing stimulation rate (p<0.05). We detected a higher percentage of single trial evoked HFO with the LNA (p<0.001) for recordings with low impedance (<5kΩ). Average amplitudes were indistinguishable between anesthesia compounds. CONCLUSION Low-noise amplification improves the detection of the evoked HFO in recordings with subdural electrodes with low impedance. SIGNIFICANCE Low-noise EEG might critically improve the detectability of interictal spontaneous HFO in subdural and possibly in scalp recordings.
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Affiliation(s)
- Tommaso Fedele
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland.
| | | | - Gabriel Curio
- Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Charité, Berlin, Germany
| | - Carlo Serra
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland
| | - Niklaus Krayenbühl
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland
| | - Johannes Sarnthein
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Neuroscience Center Zurich, Zurich, Switzerland
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Burnos S, Fedele T, Schmid O, Krayenbühl N, Sarnthein J. Detectability of the somatosensory evoked high frequency oscillation (HFO) co-recorded by scalp EEG and ECoG under propofol. NEUROIMAGE-CLINICAL 2015; 10:318-25. [PMID: 26900572 PMCID: PMC4723731 DOI: 10.1016/j.nicl.2015.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 11/25/2015] [Accepted: 11/26/2015] [Indexed: 11/17/2022]
Abstract
Objective The somatosensory evoked potential (SEP) elicited by median nerve stimulation consists of the N20 peak together with the concurrent high frequency oscillation (HFO, > 500 Hz). We describe the conditions for HFO detection in ECoG and scalp EEG in intraoperative recordings. Methods During neurosurgical interventions in six patients under propofol anesthesia, the SEP was recorded from subdural electrode strips (15 recordings) and from scalp electrodes (10/15 recordings). We quantified the spatial attenuation of the Signal-to-Noise Ratio (SNR) of N20 and HFO along the contacts of the electrode strip. We then compared the SNR of ECoG and simultaneous scalp EEG in a biophysical framework. Results HFO detection under propofol anesthesia was demonstrated. Visual inspection of strip cortical recordings revealed phase reversal for N20 in 14/15 recordings and for HFO in 10/15 recordings. N20 had higher maximal SNR (median 33.5 dB) than HFO (median 23 dB). The SNR of N20 attenuated with a larger spatial extent (median 7.2 dB/cm) than the SNR of HFO (median 12.3 dB/cm). We found significant correlations between the maximum SNR (rho = 0.58, p = 0.025) and the spatial attenuation (rho = 0.86, p < 0.001) of N20 and HFO. In 3/10 recordings we found HFO in scalp EEG. Based on the spatial attenuation and SNR in the ECoG, we estimated the scalp EEG amplitude ratio N20/HFO and found significant correlation with recorded values (rho = 0.65, p = 0.049). Conclusions We proved possible the intraoperative SEP HFO detection under propofol anesthesia. The spatial attenuation along ECoG contacts represents a good estimator of the area contributing to scalp EEG. The SNR and the spatial attenuation in ECoG recordings provide further insights for the prediction of HFO detectability in scalp EEG. The results obtained in this context may not be limited to SEP HFO, but could be generalized to biological signatures lying in the same SNR and frequency range. Somatosensory evoked HFOs can be recorded in ECoG and scalp EEG intraoperatively under propofol anesthesia. The HFO amplitude in ECoG attenuated to noise level over a smaller spatial scale than the N20 amplitude. The spatial attenuation of the cortical SNR directly relates to the noise level and to the scalp EEG amplitude. Parameters extracted from ECoG allowed estimating the ratio of N20/HFO amplitude in scalp EEG.
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Affiliation(s)
- Sergey Burnos
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland; Neuroscience Center Zurich, ETH Zurich, Zurich, Switzerland
| | - Tommaso Fedele
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland
| | - Olivier Schmid
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland
| | - Niklaus Krayenbühl
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland
| | - Johannes Sarnthein
- Neurosurgery Department, University Hospital Zurich, Zurich, Switzerland; University of Zurich, Zurich, Switzerland; Neuroscience Center Zurich, ETH Zurich, Zurich, Switzerland
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Leiken K, Xiang J, Zhang F, Shi J, Tang L, Liu H, Wang X. Magnetoencephalography detection of high-frequency oscillations in the developing brain. Front Hum Neurosci 2014; 8:969. [PMID: 25566015 PMCID: PMC4264504 DOI: 10.3389/fnhum.2014.00969] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/13/2014] [Indexed: 11/13/2022] Open
Abstract
Increasing evidence from invasive intracranial recordings suggests that the matured brain generates both physiological and pathological high-frequency signals. The present study was designed to detect high-frequency brain signals in the developing brain using newly developed magnetoencephalography (MEG) methods. Twenty healthy children were studied with a high-sampling rate MEG system. Functional high-frequency brain signals were evoked by electrical stimulation applied to the index fingers. To determine if the high-frequency neuromagnetic signals are true brain responses in high-frequency range, we analyzed the MEG data using the conventional averaging as well as newly developed time-frequency analysis along with beamforming. The data of healthy children showed that very high-frequency brain signals (>1000 Hz) in the somatosensory cortex in the developing brain could be detected and localized using MEG. The amplitude of very high-frequency brain signals was significantly weaker than that of the low-frequency brain signals. Very high-frequency brain signals showed a much earlier latency than those of a low-frequency. Magnetic source imaging (MSI) revealed that a portion of the high-frequency signals was from the somatosensory cortex, another portion of the high-frequency signals was probably from the thalamus. Our results provide evidence that the developing brain generates high-frequency signals that can be detected with the non-invasive technique of MEG. MEG detection of high-frequency brain signals may open a new window for the study of developing brain function.
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Affiliation(s)
- Kimberly Leiken
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA
| | - Jing Xiang
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA
| | - Fawen Zhang
- Department of Communication Sciences and Disorders, University of Cincinnati , Cincinnati, OH , USA
| | - Jingping Shi
- Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Lu Tang
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Hongxing Liu
- Department of Pediatrics, Magnetoencephalography (MEG) Center, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Cincinnati Children's Hospital Medical Center , Cincinnati, OH , USA ; Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
| | - Xiaoshan Wang
- Department of Neurology, Nanjing Brain Hospital, Nanjing Medical University , Jiangsu , China
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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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15
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Using Objective Response Detection techniques for detecting the tibial somatosensory evoked response with different stimulation rates. J Neurosci Methods 2011; 195:255-60. [DOI: 10.1016/j.jneumeth.2010.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Revised: 12/01/2010] [Accepted: 12/02/2010] [Indexed: 10/18/2022]
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Robinson LR, Micklesen PJ. Does stimulus rate matter when performing somatosensory evoked potentials for coma patients? Neurocrit Care 2009; 12:69-73. [PMID: 19225910 DOI: 10.1007/s12028-009-9191-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 01/15/2009] [Indexed: 10/21/2022]
Abstract
INTRODUCTION It is unclear whether the rate of stimulation for somatosensory evoked potentials (SEPs) can influence the presence or absence of cortical responses to median nerve stimulation in comatose patients. If so, this could affect how SEPs are performed and interpreted for prognostication in coma. Our objective was to determine how frequently our comatose patients had absent median nerve SEP responses at 3 Hz stimulation, but present responses at 1 Hz stimulation, and to report outcomes of these patients. METHODS We reviewed SEP recordings in 639 comatose patients over a 9-year period. All had stimulation at 3 Hz and 1 Hz. This is a retrospective review. RESULTS There were seven patients who had absent median nerve SEP responses at 3 Hz stimulation bilaterally, but had present responses at 1 Hz on one or both sides. Six of the seven died. One 16-year-old patient with traumatic brain injury awoke, but had moderate disability. CONCLUSIONS Stimulation rate is an important determinant of presence or absence of cortical responses in about 1% of comatose patients. It is unclear whether such patients have a different outcome that those with absent responses at both rates of stimulation.
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Affiliation(s)
- Lawrence R Robinson
- Department of Rehabilitation Medicine, University of Washington School of Medicine, P.O. Box 356380, Seattle, WA 98195, USA.
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Ritter P, Freyer F, Curio G, Villringer A. High-frequency (600 Hz) population spikes in human EEG delineate thalamic and cortical fMRI activation sites. Neuroimage 2008; 42:483-90. [PMID: 18586526 DOI: 10.1016/j.neuroimage.2008.05.026] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Revised: 04/30/2008] [Accepted: 05/17/2008] [Indexed: 10/22/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) measures neural activity indirectly via its slow vascular/metabolic consequences. At a temporal resolution on the order of seconds, fMRI does not reveal the real 'language of neurons', spelt out by fast electrical discharges ('spikes') which occur on a time scale of milliseconds. In animal studies, these limitations have been addressed by adding invasive electrode measurements to fMRI. Here, we propose to circumvent this 'inverse problem of fMRI' by deriving a noninvasive spike measure from recordings of ultrafast electroencephalography (EEG) signals during fMRI. We demonstrate how in response to median nerve stimulation 600 Hz oscillatory EEG signals can be measured reliably during fMRI. These high-frequency bursts (HFBs) are supposed to reflect population spikes in the thalamus and the somatosensory cortex, respectively. We show that distinct fMRI activations in these two generator structures can be attributed to spontaneous HFB fluctuations. Thus, our approach allowed the noninvasive identification of neural processes along the thalamocortical pathway unfolding at a millisecond time scale.
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Affiliation(s)
- Petra Ritter
- Berlin Neuroimaging Center and Department of Neurology, Charité Universitaetsmedizin Berlin, Germany.
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Urasaki E, Genmoto T, Yokota A, Maeda R, Akamatsu N. Effects of General Anesthesia on High-Frequency Oscillations in Somatosensory Evoked Potentials. J Clin Neurophysiol 2006; 23:426-30. [PMID: 17016153 DOI: 10.1097/01.wnp.0000186217.15904.99] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
To determine the characteristics of high-frequency oscillations (HFOs) of cortical somatosensory evoked potentials (SEPs), the effect of general anesthesia on HFOs and low-frequency primary cortical responses was studied. The authors recorded SEPs elicited by median nerve stimulation directly from human brains of seven patients who underwent implantation of subdural electrodes before surgical treatment of intractable epilepsy. Recordings were made before and during general anesthesia. Changes in the number of HFOs and amplitude ratios of HFOs/primary cortical responses were analyzed. Under general anesthesia, the number of HFO peaks and the amplitude ratios were significantly decreased. General anesthesia induced remarkably decreased HFO activities when compared to low-frequency SEPs, suggesting that each of those originated from different generators. Possible relations between gamma-amino-butyric acid (GABA)ergic inhibitory interneurons and HFOs are discussed.
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Affiliation(s)
- Eiichirou Urasaki
- Department of Neurosurgery, School of Medicine, University of Occupational and Environmental Health, Kitakyushu City, Japan.
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Urasaki E, Maeda R, Akamatsu N, Yokota A. Origins and characteristics of high-frequency (>500 hz) SEP components directly recorded from the cervical cord, thalamus, and cerebral cortex. ACTA ACUST UNITED AC 2006; 59:159-65. [PMID: 16893107 DOI: 10.1016/s1567-424x(09)70026-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Affiliation(s)
- Eiichirou Urasaki
- Department of Neurosurgery, University of Occupational and Environmental Health, School of Medicine, 1-1 Iseigaoka,Yahatanishi-ku, Kitakyushu City, Fukuoka 807-8555, Japan.
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Abstract
The recent revival of interest in high-frequency oscillation (HFO) is triggered by getting an opportunity to noninvasively monitor the timing of highly synchronized and rapidly repeating population spikes generated in the human somatosensory system. HFOs could be recorded from brainstem, cuneothalamic relay neurons, thalamus, thalamocortical radiation, thalamocortical terminals and cortex with deep brain or surface electrodes, or with magnetoencephalography. Here we briefly review the HFOs at each level of somatosensory pathways. HFOs recorded at brainstem might be produced by volume conduction from oscillations of the medial lemniscus. Thalamic HFOs at around 1000 Hz frequency would be generated within the somatosensory thalamus. Cortical HFOs would be generated by at least a few different mechanisms, thalamo-cortical projection terminals, interneurons and pyramidal cells of the primary sensory cortex. HFOs have been studied in several ways: their modulation by arousal changes, movements or drugs, their recovery function, effects of transcranial magnetic stimulation on them and also their changes in patients with various neurological diseases.
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Affiliation(s)
- Hitoshi Mochizuki
- Third Department of Internal Medicine, National Defense Medical College, Tokorozawa, Saitama, Japan
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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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Inoue K, Hashimoto I, Shirai T, Kawakami H, Miyachi T, Mimori Y, Matsumoto M. Disinhibition of the somatosensory cortex in cervical dystonia—decreased amplitudes of high-frequency oscillations. Clin Neurophysiol 2004; 115:1624-30. [PMID: 15203063 DOI: 10.1016/j.clinph.2004.02.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To determine whether patients with cervical dystonia have electrophysiological signs of disinhibition in the somatosensory cortex by recording high-frequency oscillations (HFOs) in somatosensory evoked potentials (SEPs). METHODS HFOs were recorded in 13 patients and 10 age-matched control subjects, and the data were analyzed statistically by paired comparison and by Pearson's correlation. RESULTS In patients with cervical dystonia, the early part of HFOs showed a significant decrease in amplitude, and the amplitude ratios of both early and late parts of HFOs/N20 potential were also significantly decreased. The amplitudes of HFOs and N20 potential were linearly correlated in the control subjects but not in dystonia patients. CONCLUSIONS Patients with cervical dystonia may suffer from a disturbance of inhibition in the sensory cortex. This disturbance is reflected by decreased HFO amplitude, representing decreased activities of inhibitory interneurons in area 3b.
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Affiliation(s)
- Ken Inoue
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Sciences, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
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