title: Do you see me? The role of visual fixation in chronic disorders of consciousness differential diagnosis.
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.
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Antonino
authors: A
authors: Naro
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Antonino
authors: A
authors: Leo
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Antonio
authors: A
authors: Buda
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Alfredo
authors: A
authors: Manuli
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Alessia
authors: A
authors: Bramanti
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy.
authors: Placido
authors: P
authors: Bramanti
authors: IRCCS Centro Neurolesi "Bonino-Pulejo" Messina, Italy. Electronic address: salbro77@tiscali.it.
authors: Rocco Salvatore
authors: RS
authors: Calabrò
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000503:physiopathology*; D010775:Photic Stimulation; D011782:Quadriplegia / Q000175:diagnosis / Q000503:physiopathology; D050781:Transcranial Magnetic Stimulation; D014796:Visual Perception / Q000502:physiology*
keywords: Functional Locked-in Syndrome; Functional connectivity; Minimally Conscious State; Unresponsive Wakefulness Syndrome; Vegetative State; Visuomotor integration