Quantitative pupillometry as a sensitive biomarker for detecting subtle neurological impairment in mild traumatic...

Mild traumatic brain injury accounts for roughly 55 million trauma cases globally each year. However, diagnosis and management remain challenging as conventional methods like cranial CT and the Glasgow Coma Scale do not reliably detect subtle neurological impairments. Quantitative Pupillometry has shown promise in severe traumatic brain injury, but data on its use in mild traumatic brain injury is limited. This study aims to evaluate whether Quantitative Pupillometry can detect subtle neurological dysfunction in patients with mild traumatic brain injury.

We retrospectively analyzed 38 adult patients with mild traumatic brain injury admitted between December 2023 and October 2024. Quantitative Pupillometry was assessed in the emergency room using the NPi 200^® Pupillometer. Cranial CT was used to detect subarachnoid hemorrhage. Pupillary parameters (Neurological Pupil Index, constriction/dilation velocities, latency) and clinical data (GCS) were analyzed.

Mean age in our cohort was 61.8 years (SD 21.1). subarachnoid hemorrhage was present in 58% of patients (n = 22/38), with bleeding equally distributed between the hemispheres. In patients with subarachnoid hemorrhage, average pupillary dilation velocity was significantly lower compared to those without subarachnoid hemorrhage (0.7 mm/s vs. 1.1 mm/s, p = 0.043). Strong positive and significant correlations were found between pupillometric velocity parameters and GCS scores: bilateral constriction velocity (Sr = 0.9, p < 0.001) and dilation velocity (Sr = 0.8, p = 0.006). Multivariate regression analysis explained 73.8% of GCS variance, identifying increased pupillary latency and subarachnoid hemorrhage as significant predictors for worse GCS outcomes. ROC curve analysis confirmed the predictive value of subarachnoid hemorrhage presence (AUC = 0.8) and pupillary latency (AUC = 0.7).

Quantitative Pupillometry, especially pupillary reflex velocities, is a sensitive tool for detecting subtle neurological impairments in mild traumatic brain injury patients who may appear clinically normal. This pilot study supports Quantitative Pupillometry as an effective tool for early identification of neurological deterioration, potentially improving triage and patient safety. These findings lay the foundation for further validation of Quantitative Pupillometry in mild traumatic brain injury assessment.