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The Pupillary Light-Off Reflex in Acute Disorders of Consciousness
Pardis Zarifkar1, Marwan H Othman1, Karen Irgens Tanderup Hansen1
1Department of Neurology, Rigshospitalet, Copenhagen University Hospital, Inge Lehmanns Vej 8, 2100, Copenhagen, Denmark.
Neurocritical Care
|September 25, 2024
Summary
The pupillary light-off reflex, a novel measure of brain function, shows a strong correlation with consciousness levels in intensive care patients. This reflex may offer improved neuromonitoring and prognostication after acute brain injury.
Area of Science:
- Neuroscience
- Ophthalmology
- Critical Care Medicine
Background:
- The pupillary light reflex assesses parasympathetic function in intensive care patients with disorders of consciousness.
- The pupillary light-off reflex, reflecting combined parasympathetic and sympathetic function, has not been systematically studied in these patients.
- This study investigates the pupillary light-off reflex's correlation with consciousness levels post-acute brain injury.
Purpose of the Study:
- To investigate the pupillary light-off reflex in patients with disorders of consciousness.
- To determine if the pupillary light-off reflex correlates with consciousness levels after acute brain injury.
- To compare the sensitivity of the pupillary light-off reflex versus the pupillary light reflex in assessing consciousness.
Main Methods:
- 100 participants were enrolled: 50 unresponsive or low-responsive patients and 50 healthy controls.
- Automated pupillometry was used to measure pupillary light-off and light reflexes under scotopic conditions.
- Exclusion criteria included active or chronic eye disease.
Main Results:
- The pupillary light-off reflex strongly correlated with consciousness levels (r = 0.62, p < 0.001).
- Pupil dilation was smallest in unresponsive patients (20% ± 21%), intermediate in low-responsive patients (47% ± 26%), and largest in controls (67% ± 17%).
- Unresponsive patients were less likely to have a preserved pupillary light-off reflex (28%) compared to the pupillary light reflex (84%), with 71% of those with preserved light-off reflexes regaining awareness.
Conclusions:
- The pupillary light-off reflex may be a more sensitive indicator of consciousness levels than the pupillary light reflex.
- Further research is warranted to explore the clinical utility of the pupillary light-off reflex for neuromonitoring and prognostication in brain injury.
- This reflex holds potential for improved patient assessment in intensive care settings.
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