Functional Evaluation of Awareness in Vegetative and Minimally Conscious State

Silvia Marino,Nicola De Stefano,Antonio Giorgio,Silvia Guerrera,Rosa Morabito,Lilla Bonanno,Carmela Rifici,Rosella Ciurleo,Placido Bramanti,Annalisa Baglieri

doi:10.2174/1874440001711010017

Abstract

Objective:The aim of this study was to assess differences in brain activation in a large sample of Vegetative State (VS) and Minimally Conscious State (MCS) patients, using functional magnetic resonance imaging (fMRI).Methods:We studied 50 patients four to seven months after brain injury. By using international clinical criteria and validated behavioural scales such as the Glasgow Coma Scale and the Clinical Unawareness Assessment Scale, the patients were grouped into VS (n=23) and MCS (n=27). All patients underwent to fMRI examination. After 6 months, the patients were reassessed using Glasgow Outcome Scale and Revised Coma Recovery Scale.Results:fMRI showed significant (p<0.01, cluster-corrected) brain activation in the primary auditory cortex bilaterally during the acoustic stimuli in patients with both VS and MCS. However, ten patients clinically classified as VS, showed a pattern of brain activation very similar to that of MCS patients. Six months later, these ten VS patients had significant clinical improvement, evolving into MCS, whereas the other VS patients and patients with MCS remained clinically stable.Conclusion:Brain activity could help in discerning whether the status of wakefulness in VS is also accompanied by partial awareness, as occurs in MCS. This may have very important prognostic implications.

Highlights

Functional neuroimaging is increasingly used in the clinical domain of Vegetative State (VS) and Minimally Conscious State (MCS) patients [1 - 4]
Using simple noxious somatosensory and auditory stimulation, positron emission tomography (PET) studies have showed in VS patients preserved activation in lower-level primary sensory cortices but not in higher-order associative cortices, secondary somatosensory, insular, posterior parietal, and anterior cingulate cortices, which were otherwise activated in healthy subjects [4, 7 - 9]
These findings have not been confirmed by fMRI studies on MCS and VS patients converted to MCS [11 14], where activation of higher-order associative cortices was found

Summary

Methods

We studied 50 patients four to seven months after brain injury. After 6 months, the patients were reassessed using Glasgow Outcome Scale and Revised Coma Recovery Scale. Results: fMRI showed significant (p

Conclusion

INTRODUCTION

MATERIALS AND METHODS

RESULTS