title: Visual pursuit: within-day variability in the severe disorder of consciousness.
abstract: Visual pursuit marks substantial recuperation from a vegetative state and evolution into a minimally-conscious state, but its incidence in different studies suggests some unreliability in contrast with its established prognostic relevance. Subjects in vegetative (n=9) or minimally-conscious (n=13) states were tested for visual pursuit 6 times/day (9:30, 10:30, and 11:30 am, and 2:00, 3:00, and 4.00 pm, for a total of 132 determinations). Visual pursuit was observed at all testing times in 8 minimally-conscious patients, and never in 5 subjects in a vegetative state. Its incidence per subject ranged from 50-100% of testing times in the minimally-conscious state (83±23%), and 0-33% in a vegetative state (7%±12), with spontaneous fluctuations during the day and maximal levels at 10.30 am and 3.00 pm, and was never observed at the post-prandial time point (2:00 pm). The overall chance of observing visual tracking at least once during the day was ∼33% in the vegetative state, whereas that of not observing it in the minimally-conscious state was ∼38%. These percentages are congruent with the reported misdiagnosis rate between the two conditions, and document spontaneous variability possibly related to circadian rhythms.
authors.affiliation: S. Anna Institute and Research in Advanced Neurorehabilitation (RAN), Crotone, University of Calabria, Cosenza, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Candelieri
authors.forename: Maria Daniela
authors.initials: MD
authors.lastname: Cortese
authors.forename: Giuliano
authors.initials: G
authors.lastname: Dolce
authors.forename: Francesco
authors.initials: F
authors.lastname: Riganello
authors.forename: Walter G
authors.initials: WG
authors.lastname: Sannita
mesh_terms: D000328:Adult; D000368:Aged; D003244:Consciousness Disorders / Q000523:psychology*; D004185:Disability Evaluation; D005260:Female; D023261:Glasgow Outcome Scale; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D018458:Persistent Vegetative State / Q000523:psychology; D011597:Psychomotor Performance / Q000502:physiology*; D011698:Pursuit, Smooth / Q000502:physiology*