Detection of visual pursuit in patients in minimally conscious state: A matter of stimuli and visual plane?

Abstract

The findings confirm the importance of using a mirror to assess visual pursuit in patients in MCS and of initiating testing using the horizontal plane, specifically in patients in MCS- and those in chronic setting. Assessment should then be done on the vertical plane if visual pursuit is not detected on the horizontal plane.

A new computer vision-based system to help clinicians objectively assess visual pursuit with the moving mirror stimulus for the diagnosis of minimally conscious state

“…a moving person, with which some MCS patients showed no pursuit at all even though they were actually able to follow a moving mirror [16]. This result was also confirmed in [13], with additional insight being given on the influence of the mirror trajectories chosen during the clinical assessment procedure.…”

“…An earlier study -the closest to our workused off-the-shelf eye tracking technology and visual stimuli displayed on a computer monitor to quantitatively assess visual pursuit by on-and off-target fixation statistics [14,15]. In comparison to our system, this earlier system exhibits two weaknesses: (1) it does not -and cannot as it stands -conform to the recommended practice of using a mirror, and uses suboptimal stimuli instead [16,13]; (2) it necessitates extra subject participation by requiring patients to be seated in order to face the monitor displaying the stimuli, a collaborative behavior which is often unfeasible in clinical practice and necessarily leads to the exclusion of some patients from such assessment.…”

Diagnostic, pronostic et traitements des troubles de la conscience

“…Ainsi, chez plus de 80 % des patients en ECM, la sous-échelle visuelle détecte un signe de conscience [19,20]. Cette sous-échelle contient entre autres la poursuite visuelle, qui est observée chez 55 à 70 % des patients en ECM et qui est un des premiers signes de conscience à être récupéré [21,22]. De plus, l'implémentation de cette échelle doit se faire avec des outils appropriés.…”

“…De plus, l'implémentation de cette échelle doit se faire avec des outils appropriés. Par exemple, la poursuite visuelle sera significativement plus souvent observée si elle est testée avec un miroir et le patient localisera davantage un son s'il est appelé par son prénom [21][22][23][24]. Une récente étude a également montré que certains items étaient plus fréquemment observés chez les patients en ECM : la réponse à la commande, la poursuite visuelle, la fixation, les comportements moteurs automatiques et la localisation à la douleur.…”

Detection of Consciousness in the Severely Injured Brain

“…As fluctuations of consciousness are common in MCS, the CRS-R assessment should ideally be conducted serially over several days, with the best outcome determining the diagnosis. Still, the physiological significance of several signs is contentious -visual fixation for example, may be reflexive [15], and consistent visual pursuit may depend on the specific object used, and its path across the visual field [16]. In addition, the existence of paralyzed, but fully conscious pa-tients, such as those with the 'locked-in' syndrome, demonstrates that unresponsive patients may also be aware.…”