Objective Neurophysiologic Markers of Cognition After Pediatric Brain Injury

Abstract

Objective:Following brain injury, clinical assessments of residual and emerging cognitive function are difficult and fraught with errors. In adults, recent AAN practice guidelines recommend objective neuroimaging and neurophysiological measures to support diagnosis. Equivalent measures are lacking in pediatrics—an especially great challenge due to the combined heterogeneity of both brain injury and pediatric development. Therefore, we aim to establish quantitative, clinically practicable measures of cognitive function following pediatric brain injury.Methods:Participants with and without brain injury were aged 8–18, clinically classified according to cognitive recovery state: N=8 in disorders of consciousness (DoC), N=7 in confusional state (CS); N=19 cognitively impaired (CI); N=13 typically-developing (TD) uninjured controls. We prospectively measured electroencephalographic markers of sensory processing and attention in an auditory “oddball'' paradigm, and of covert movement attempts in a command-following paradigm.Results:In three DoC participants, EEG markers of active attempted command-following revealed cognitive function that clinical assessment had failed to detect. These same three individuals could also be distinguished from the rest of their group by two event-related potentials (ERPs) that correlate with sensory processing and orienting attention in the oddball paradigm. Considered across the whole subject group, magnitudes of these two ERP markers significantly increased as cognitive recovery progressed (ANOVA: each p<0.001); viewed jointly, the two ERP markers cleanly delineated the four cognitive states.Conclusion:Despite heterogeneity of brain injuries and brain development, our objective EEG markers reflected cognitive recovery independent of motor function. Two of these markers required no active participation. Together, they allowed us to identify, for the first time in pediatrics, three individuals who meet the criteria for cognitive motor dissociation. To diagnose, prognose and track cognitive recovery accurately, such markers should be employed in pediatrics.

Towards electroencephalography-based consciousness assessment and cognitive function profiling in prolonged disorders of consciousness

“…While overall, the ratio of significant runs across all paradigms was not significantly different for LIS patients compared to AB participants (p > .05). Patients with PDoC who have demonstrated ability to consistently follow motor-imagery commands, have also demonstrated responses to auditory stimuli similar to that of patients who had emerged from PDoC 68,69 . As the assessment phase is the participants first introduction to the technology and for many, the first time MI has been introduced as a task where the user must purposefully modulate their brain rhythmsgiven that UWS and MCS patients have lower levels of awareness, it may take longer to learn how to follow commands to perform motor-imagery.…”

“…Additionally, given the acceptance that existing assessment protocols require patients' responses, including motor responses, to be overtly identified, to categorise awarenessthere may be patients in the UWS group who have MCS, thus, limiting the differences between the UWS and MCS groups in the current sample, when assessed using a this MI-BCI movement independent protocol. In order to determine the full capability of this multistage MI-BCI system, a larger sample size will be required for a thorough evaluation and, ideally, an up to date clinical diagnosis performed focusing on refined consciousness assessment taking into consideration a diagnosis of MCS + (capable of intentional communication), and emergence from MCS (EMCS; recovered capacity for functional communication and/or use of objects) 80 , with the latter characterised by the CRS-R as confusional state (CS) 69 . These patient groups are particularly challenging and conducting multiple sessions in patient homes, care homes and hospitals pose a range of challenges for consistency in intersession durations between subjects and intrasession conduct.…”

Cognitive-Motor Dissociation Following Pediatric Brain Injury

“…15 To assess processing of auditory stimuli, we measured auditory evoked potentials (AEP) and P300 ERPs during an oddball stimulus paradigm. 13 To assess semantic comprehension, we measured N400 ERPs elicited by recordings of previously published spoken sentences, 16 as previously applied to healthy populations (age [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] and brain-injured populations.…”

“…This EEG paradigm, frequently used in both adults 20 and pediatrics, 13 consists of frequent standard tones with randomly interspersed but infrequent deviant tones and other auditory stimuli. It requires no participation from the participant beyond passive listening.…”

“…Analysis of command-following EEG data is as described in a previous study 13 and is included in the eMaterial (links.lww. com/CPJ/A333).…”