Do you see me? The role of visual fixation in chronic disorders of consciousness differential diagnosis

Antonino Naro, Antonino Leo, Antonio Buda, Alfredo Manuli, Alessia Bramanti, Placido Bramanti, Rocco Salvatore Calabrò

Research output: Contribution to journalArticle

Abstract

Visual fixation (VF) of a target is a possible, although atypical, feature of the Unresponsive Wakefulness Syndrome (UWS). Whether VF may indicate residual awareness in these patients is debatable, since it may simply subtend a series of reflex processes. Objective tools should therefore be used to identify aware VF, which depends on the integrity of visuomotor networks encompassing frontal-parietal-occipital areas. The aim of our study was to detect residual visuomotor network functionality potentially sustaining aware VF. To this end, we evaluated the visuomotor integration (VMI) and visual P300 patterns in a chronic Disorder of Consciousness (DOC) sample and a control group of healthy individuals (HC), using an associative stimulation protocol combining transcranial magnetic stimulation (TMS) with visual stimulation through transorbital alternating current stimulation. The Minimally Conscious State (MCS) patients showed preserved patterns of VMI and P300, whereas nearly all the UWS patients showed no significant VMI. Notably, the electrophysiological findings were correlated with the visual domain of the Coma Recovery Scale-Revised. Nonetheless, two fixating UWS individuals had a VMI similar to MCS patients. Our data suggest that some UWS patients showing VF could be aware, but unable to manifest it clearly, probably because of a severe motor output impairment, which is a condition compatible with the Functional Locked-In Syndrome.

Original languageEnglish
Pages (from-to)59-66
Number of pages8
JournalBrain Research
Volume1653
DOIs
Publication statusPublished - Dec 15 2016

Keywords

  • Functional connectivity
  • Functional Locked-in Syndrome
  • Minimally Conscious State
  • Unresponsive Wakefulness Syndrome
  • Vegetative State
  • Visuomotor integration

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Developmental Biology
  • Clinical Neurology

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