Entropy Metrics Correlating with Higher Residual Functioning in Patients with Chronic Disorders of Consciousness.

Elisa Visani,Davide Rossi Sebastiano,Davide Sattin,Ferruccio Panzica,Gianvittorio Luria,Matilde Leonardi,Stefania Ferraro,Silvana Franceschetti

doi:10.3390/brainsci12030332

Abstract

To test the ability of different entropy measures to classify patients with different conditions of chronic disorder of consciousness, we applied the Lempel–Ziv complexity, the amplitude coalition entropy (ACE), and the synchrony coalition entropy (SCE) to the EEG signals recorded in 32 patients, clinically evaluated using the coma recovery scale revised (CRS-R). All the entropy measures indicated that differences found in the theta and alpha bands can distinguish patients in a minimal consciousness state (MCS) with respect to those in a vegetative state/unresponsive wakefulness state (VS/UWS). These differences were significant comparing the entropy measure performed on the anterior region of the left hemisphere and midline region. The values of theta-alpha entropy positively correlated with those of the CRS-R scores. Among the entropy measures, ACE most often highlighted significant differences. The higher values found in MCS were for the less impaired patients, according to their CRS-R, suggest that the preservation of signal entropy on the anterior region of the dominant hemisphere correlates with better preservation of consciousness, even in chronic conditions.

Highlights

The evaluation of EEG activity in resting conditions is an important and widely applied tool in evaluating patients with disorders of consciousness (DoCs) in acute or chronic conditions
We evaluated the contribution of different neurophysiological tests in assessing the degree of impairment in a large case series of chronic DoC patients [10]
We aimed to validate the significance of different entropy indexes, including the Lempel–Ziv complexity, Amplitude Coalition Entropy (ACE), and Synchrony Coalition Entropy (SCE) [11] in a group of chronic DoC patients, to understand if these measures can be considered as a useful tool for obtaining information in this complex pathological condition

Summary

Introduction

The evaluation of EEG activity in resting conditions is an important and widely applied tool in evaluating patients with disorders of consciousness (DoCs) in acute or chronic conditions (see [1] for a review). With uneven complexity, of EEG signal post-processing and elaboration, have been applied, including the analysis of power spectrum, complexity, entropy, or functional/effective connectivity. All these measures have the aim of suitably defining the degree of the dysfunction associated with the impaired consciousness or predicting the outcome (see recent reviews of [2–6]). We aimed to validate the significance of different entropy indexes, including the Lempel–Ziv complexity, Amplitude Coalition Entropy (ACE), and Synchrony Coalition Entropy (SCE) [11] in a group of chronic DoC patients, to understand if these measures can be considered as a useful tool for obtaining information in this complex pathological condition

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Conclusion