Cognitive Processing in Non-Communicative Patients: What Can Event-Related Potentials Tell Us?

Abstract

Event-related potentials (ERP) have been proposed to improve the differential diagnosis of non-responsive patients. We investigated the potential of the P300 as a reliable marker of conscious processing in patients with locked-in syndrome (LIS). Eleven chronic LIS patients and 10 healthy subjects (HS) listened to a complex-tone auditory oddball paradigm, first in a passive condition (listen to the sounds) and then in an active condition (counting the deviant tones). Seven out of nine HS displayed a P300 waveform in the passive condition and all in the active condition. HS showed statistically significant changes in peak and area amplitude between conditions. Three out of seven LIS patients showed the P3 waveform in the passive condition and five of seven in the active condition. No changes in peak amplitude and only a significant difference at one electrode in area amplitude were observed in this group between conditions. We conclude that, in spite of keeping full consciousness and intact or nearly intact cortical functions, compared to HS, LIS patients present less reliable results when testing with ERP, specifically in the passive condition. We thus strongly recommend applying ERP paradigms in an active condition when evaluating consciousness in non-responsive patients.

The Effect of Transcutaneous Auricular Vagal Nerve Stimulation (taVNS) on P3 Event-Related Potentials during a Bayesian Oddball Task

“…The potential clinical uses of taVNS depend on the consequences of this stimulation. The P3 is linked to attention which is demonstrated in clinical settings in studies of patients with lost consciousness [ 77 , 78 ]. This is also indicated in studies of attentional-deficit hyperactive disorder (ADHD), where P3 amplitudes are reduced in patients compared to controls [ 79 ].…”

30+ years of P300 brain–computer interfaces

“…The results from assessment with passive and (especially) active command‐following tasks could indicate conscious function, which might lead to re‐assessment of the patient's condition. P300‐based systems could also provide communication and facilitate outcome prediction (Chatelle et al, 2012; Chennu et al, 2017; Guger et al, 2017; Lugo, Quitadamo, et al, 2014; Lugo, Rodriguez, et al, 2014; Real et al, 2016; Spataro et al, 2018; Wang et al, 2017).…”

Multifactor consciousness level assessment of participants with acquired brain injuries employing human–computer interfaces

“…They also may involve using external stimuli such as auditory signals [3]. Another example of an EEG-based technique is a mismatch negativity (MMN) approach [4,5]. Over the last two decades, computed tomography (CT) and magnetic resonance imaging (MRI) scans have become standard medical practice, and they are widely used for many aspects of modern medicine, like for example detection of tumors or identification of sites of injury from impact [6][7][8].…”