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Visual fixation in the vegetative state: an observational case series PET study
Marie-Aurélie Bruno1, Audrey Vanhaudenhuyse, Caroline Schnakers
1Coma Science Group and Cyclotron Research Centre, University of Liège, Liège, Belgium.
BMC Neurology
|May 28, 2010
Summary
Visual fixation in patients with disorders of consciousness does not necessarily indicate higher brain function. This study found similar brain metabolism and connectivity in patients with and without fixation, suggesting it may not reflect consciousness.
Area of Science:
- Neuroscience
- Clinical Neurology
- Cognitive Science
Background:
- Visual fixation is a common clinical assessment for disorders of consciousness.
- International guidelines differ on whether fixation indicates subcortical processing or higher cortical function.
Purpose of the Study:
- To investigate cerebral metabolism and functional connectivity in patients with disorders of consciousness and visual fixation.
- To determine if visual fixation correlates with higher-order cortical processing.
Main Methods:
- Studied cerebral metabolism in 10 patients with chronic post-anoxic encephalopathy and 39 controls.
- Assessed 5 patients in a vegetative state without fixation and 5 with fixation but otherwise vegetative criteria.
- Used Coma Recovery Scale-Revised (CRS-R) for assessment over at least 1 year.
Main Results:
- Patients without fixation showed widespread fronto-parietal metabolic dysfunction, similar to those with fixation.
- No difference in cortico-cortical functional connectivity with the visual cortex between patient groups.
- No difference in recovery rates between patients with or without visual fixation.
Conclusions:
- Sustained visual fixation in disorders of consciousness may not reflect consciousness or higher-order cortical function.
- Findings challenge the interpretation of visual fixation as a sole indicator of conscious awareness.
