Automated pupillometry and the FOUR score - what is the diagnostic benefit in neurointensive care?

Introduction: The Glasgow Coma Scale (GCS) and visual inspection of pupillary function are routine measures to monitor patients with impaired consciousness and predict their outcome in the neurointensive care unit (neuro-ICU). Our aim was to compare more recent measures, i.e. FOUR score and automated pupillometry, to standard monitoring with the GCS and visual inspection of pupils.

Methods: Supervised trained nursing staff examined a consecutive sample of patients admitted to the neuro-ICU of a tertiary referral centre using GCS and FOUR score and assessing pupillary function first by visual inspection and then by automated pupillometry. Clinical outcome was evaluated 6 months after admission using the Glasgow Outcome Scale-Extended.

Results: Fifty-six consecutive patients (median age 63 years) were assessed a total of 234 times. Of the 36 patients with at least one GCS score of 3, 13 had a favourable outcome. All seven patients with at least one FOUR score of ≤ 3 had an unfavourable outcome, which was best predicted by a low "brainstem" sub-score. Compared to automated pupillometry, visual assessment underestimated pupillary diameters (median difference, 0.4 mm; P = 0.006). Automated pupillometry detected a preserved pupillary light reflex in 10 patients, in whom visual inspection had missed pupillary constriction.

Discussion: Training of nursing staff to implement frequent monitoring of patients in the neuro-ICU with FOUR score and automated pupillometry is feasible. Both measures provide additional clinical information compared to the GCS and visual assessment of pupillary function, most importantly a more granular classification of patients with low levels of consciousness by the FOUR score.