title: Single-trial detection for intraoperative somatosensory evoked potentials monitoring.
abstract: Abnormalities of somatosensory evoked potentials (SEPs) provide effective evidence for impairment of the somatosensory system, so that SEPs have been widely used in both clinical diagnosis and intraoperative neurophysiological monitoring. However, due to their low signal-to-noise ratio (SNR), SEPs are generally measured using ensemble averaging across hundreds of trials, thus unavoidably producing a tardiness of SEPs to the potential damages caused by surgical maneuvers and a loss of dynamical information of cortical processing related to somatosensory inputs. Here, we aimed to enhance the SNR of single-trial SEPs using Kalman filtering and time-frequency multiple linear regression (TF-MLR) and measure their single-trial parameters, both in the time domain and in the time-frequency domain. We first showed that, Kalman filtering and TF-MLR can effectively capture the single-trial SEP responses and provide accurate estimates of single-trial SEP parameters in the time domain and time-frequency domain, respectively. Furthermore, we identified significant correlations between the stimulus intensity and a set of indicative single-trial SEP parameters, including the correlation coefficient (between each single-trial SEPs and their average), P37 amplitude, N45 amplitude, P37-N45 amplitude, and phase value (at the zero-crossing points between P37 and N45). Finally, based on each indicative single-trial SEP parameter, we investigated the minimum number of trials required on a single-trial basis to suggest the existence of SEP responses, thus providing important information for fast SEP extraction in intraoperative monitoring.
authors.affiliation: Key Laboratory of Cognition and Personality (Ministry of Education), Faculty of Psychology, Southwest University, Chongqing, China.
authors.forename: L
authors.identifier: 0000-0001-7003-2903
authors.initials: L
authors.lastname: Hu
authors.affiliation: School of Chemical and Biomedical Engineering and School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore.
authors.forename: Z G
authors.initials: ZG
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Duchess of Kent Children's Hospital, 12 Sandy Bay Road, Hong Kong, China.
authors.forename: H T
authors.initials: HT
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Duchess of Kent Children's Hospital, 12 Sandy Bay Road, Hong Kong, China.
authors.forename: K D K
authors.initials: KD
authors.lastname: Luk
authors.affiliation: Department of Orthopaedics and Traumatology, The University of Hong Kong, Duchess of Kent Children's Hospital, 12 Sandy Bay Road, Hong Kong, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
keywords: Intraoperative monitoring; Kalman filtering; Single-trial analysis; Somatosensory evoked potentials (SEPs); Somatosensory system; Time–frequency multiple linear regression (TF-MLR)