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Intraoperative subdural low-noise EEG recording of the high frequency oscillation in the somatosensory evoked potential


Fedele, Tommaso; Schönenberger, Claudio; Curio, Gabriel; Serra, Carlo; Krayenbühl, Niklaus; Sarnthein, Johannes (2017). Intraoperative subdural low-noise EEG recording of the high frequency oscillation in the somatosensory evoked potential. Clinical Neurophysiology, 128(10):1851-1857.

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.

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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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurosurgery
Dewey Decimal Classification:610 Medicine & health
Uncontrolled Keywords:High frequency oscillations, Low-noise EEG, Somatosensory evoked potential, Intraoperative corticogram
Language:English
Date:27 July 2017
Deposited On:22 Feb 2018 17:23
Last Modified:14 Mar 2018 17:50
Publisher:Elsevier
ISSN:1388-2457
OA Status:Closed
Publisher DOI:https://doi.org/10.1016/j.clinph.2017.07.400
PubMed ID:28826015

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