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P291 Non-invasive detection of fast ripples in low-noise EEG recordings

Boran, Ece ; Ramantani, Georgia ; Märzendorfer, Pamela ; Albert, Tabea ; Curio, Gabriel ; Hilfiker, Peter ; Grunwald, Thomas ; Sarnthein, Johannes ; Fedele, Tommaso

Clinical Neurophysiology, September 2017, Vol.128(9), pp.e271-e271 [Peer Reviewed Journal]

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  • Title:
    P291 Non-invasive detection of fast ripples in low-noise EEG recordings
  • Author: Boran, Ece ; Ramantani, Georgia ; Märzendorfer, Pamela ; Albert, Tabea ; Curio, Gabriel ; Hilfiker, Peter ; Grunwald, Thomas ; Sarnthein, Johannes ; Fedele, Tommaso
  • Description: To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: http://dx.doi.org/10.1016/j.clinph.2017.07.299 Byline: Ece Boran (1), Georgia Ramantani (2), Pamela Marzendorfer (1), Tabea Albert (1), Gabriel Curio (3), Peter Hilfiker (2), Thomas Grunwald (2), Johannes Sarnthein (1), Tommaso Fedele (1) Keywords Epilepsy; EEG; Non-invasive; HFOs; Low-noise amplifier Purpose Ripples (80--250 Hz) and fast ripples (FR, 250--500 Hz) are characterized by poor signal-to-noise ratio, which reduces their visibility in non-invasive recordings. While ripples are observed in scalp EEG, FR detection has been restricted to invasive recordings. We tested the detectability of FR in the scalp EEG of epilepsy patients, recorded with a low-noise amplifier, and quantified their specificity for the prospective epileptogenic zone (EZ). Method Scalp EEG was recorded during one hour of slow wave sleep in six patients with focal lateralized epilepsy. We used a custom-made low-noise 8-channel amplifier (noise level 2.3 nV/[square root]Hz). Electrodes were placed symmetrically on both hemispheres, ipsilateral (EZ-h) as well as contralateral (nEZ-h) to the presumed epileptogenic area. Ripples and FR were detected by combining automated detection () and offline visual validation. Results For each patient, mean event rates were computed for EZ-h and nEZ-h. Across patients, FR rates were 0.17 [plus or minus] 0.03 event/min in EZ-h and 0.11 [plus or minus] 0.05 event/min in nEZ-h (p= 0.031). Ripple rates were 0.19 [plus or minus] 0.34 event/min in EZ-h and 0.22/min [plus or minus] 0.45 event/min in nEZ-h (n.s.). Across all channels, mean peak-to-peak amplitude FR was 1.02 [plus or minus] 0.58[mu]V on a background noise level of 0.33 [plus or minus] 0.12[mu]V while mean peak-to-peak ripple amplitude was 2.09 [plus or minus] 1.15[mu]V on a background noise level of 0.70 [plus or minus] 0.37[mu]V. Conclusion FR could be detected non-invasively on the scalp using an optimized low-noise amplifier. FR were more specific than ripples for the affected hemisphere. The opportunity to access FR non-invasively represents a substantial advance in scalp EEG recording and could contribute to therapy monitoring. Author Affiliation: (1) University Hospital of Zurich, Neurosurgery, Zurich, Switzerland (2) Swiss Epilepsy Centre, Zurich, Switzerland (3) Campus Benjamin Franklin, Charite, Neurology, Berlin, Germany
  • Is Part Of: Clinical Neurophysiology, September 2017, Vol.128(9), pp.e271-e271
  • Identifier: ISSN: 1388-2457 ; E-ISSN: 1872-8952 ; DOI: 10.1016/j.clinph.2017.07.299
  • Subjects: Epilepsy ; EEG ; Non-Invasive ; Hfos ; Low-Noise Amplifier ; Medicine
  • Language: English

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