Quantitative Assessments of Pupillary Light Reflexes in Hospital-Onset Unconsciousness

Abstract BackgroundPatients who develop hospital-onset unconsciousness should be promptly managed in order to avoid clinical deterioration. Pupillary examination through pupillary light reflex is the mainstay method in the initial evaluation of unconscious patients, but the current method of light shedding and subjective description often shows poor reliability. The objective of this study is to explore whether a quantitative measurement of pupillary light reflexes is useful in detecting brain herniation syndrome and predicting neurological outcomes in non-neurological patients who developed hospital-onset unconsciousness.MethodsThis was a registry-based observational study on patients who activated the neurological rapid response team at Asan Medical Center (Seoul, Korea). Hospital-onset unconsciousness was defined as a newly developed stupor or comatose state during admission. Demographics, comorbidities, pupillometry parameters including Neurological Pupil index, brain herniation syndrome, in-hospital mortality, and modified Rankin Scale at 3-months were analyzed.ResultsIn 214 consecutive patients with hospital-onset unconsciousness, 37 (17%) had brain herniation syndrome. The optimal cut-off value of Neurological Pupil index for detecting brain herniation syndrome was < 1.6 (specificity, 91% [95% confidence interval (CI) = 86−95]; sensitivity, 49% [95% CI = 32−66]). The in-hospital mortality rate was 28% (59/214); the Neurological Pupil index was negatively associated with in-hospital mortality after adjustments for the presence of brain herniation syndrome (adjusted odds ratio = 0.77, 95% CI = 0.62–0.96). Poor neurological outcomes (modified Rankin Scale ≥ 4) at 3 months was observed in 76% (152/201) of the patients; the Neurological Pupil index was negatively associated with poor neurological outcomes after adjustments for clinical variables (adjusted odds ratio = 0.67, 95% CI = 0.49–0.90). ConclusionsQuantitative measurements of pupillary light reflexes may be useful for early detection of potentially life-threatening neurological conditions in patients with hospital-onset unconsciousness.