Diagnostic Developments in Differentiating Unresponsive Wakefulness Syndrome and the Minimally Conscious State.

Camillo Porcaro,Paolo Tonin,Zahra Mansour,Idan Efim Nemirovsky,Andrea Soddu,Francesco Riganello,Antonio Cerasa,Bobby Stojanoski

doi:10.3389/fneur.2021.778951

Abstract

When treating patients with a disorder of consciousness (DOC), it is essential to obtain an accurate diagnosis as soon as possible to generate individualized treatment programs. However, accurately diagnosing patients with DOCs is challenging and prone to errors when differentiating patients in a Vegetative State/Unresponsive Wakefulness Syndrome (VS/UWS) from those in a Minimally Conscious State (MCS). Upwards of ~40% of patients with a DOC can be misdiagnosed when specifically designed behavioral scales are not employed or improperly administered. To improve diagnostic accuracy for these patients, several important neuroimaging and electrophysiological technologies have been proposed. These include Positron Emission Tomography (PET), functional Magnetic Resonance Imaging (fMRI), Electroencephalography (EEG), and Transcranial Magnetic Stimulation (TMS). Here, we review the different ways in which these techniques can improve diagnostic differentiation between VS/UWS and MCS patients. We do so by referring to studies that were conducted within the last 10 years, which were extracted from the PubMed database. In total, 55 studies met our criteria (clinical diagnoses of VS/UWS from MCS as made by PET, fMRI, EEG and TMS- EEG tools) and were included in this review. By summarizing the promising results achieved in understanding and diagnosing these conditions, we aim to emphasize the need for more such tools to be incorporated in standard clinical practice, as well as the importance of data sharing to incentivize the community to meet these goals.

Highlights

Consciousness remains one of the most challenging phenomena to understand, and, not surprisingly, an objective and generally agreed-upon definition of consciousness remains elusive [1]
Resting-State functional Magnetic Resonance Imaging (fMRI) In addition to using eventrelated fMRI (er-fMRI), resting-state fMRI has been extensively used to assess neural mechanisms in patients diagnosed with disorder of consciousness (DOC)
We provided a comprehensive overview of the research devoted to better understand and diagnose the vegetative and minimally conscious states

Summary

Introduction

Consciousness remains one of the most challenging phenomena to understand, and, not surprisingly, an objective and generally agreed-upon definition of consciousness remains elusive [1]. Consciousness is described based on observations of wakefulness (i.e., the presence of spontaneous periods of eye-opening) and awareness (i.e., the ability for a subject to respond to internal/external stimuli coherently). Clinical research employing advanced neuroimaging tools continues to underscore the intricate aspects of this concept, and it is well-established that consciousness cannot be described with external observations of behavior alone. One essential area of research on consciousness involves a group of pathologies known as disorders of consciousness (DOC). In recent years, neuroimaging studies on DOC individuals challenged previous assumptions about their conditions. Further terminology has been adopted to describe conditions related to DOC, including cognitive motor dissociation (CMD) and higher-order cortex motor dissociation (HMD), which stress the presence of cortical function despite the absence of behavioral capacity [5, 6]

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