Background
Pupillary assessment is an important index to evaluate changes in the conditions of patients with traumatic brain injury (TBI). This study assessed the utility of M-mode ultrasound as a non-invasive bedside assessment to evaluate pupillary light reflex (PLR) sensitivity in patients with TBI.
Methods
This is a prospective observational study of patients with TBI. Patients were divided into brisk, sluggish, or absent groups based on their PLR sensitivity. M-mode ultrasound was performed according to standard operation guidelines using a standardized light stimulus.Pupillary diameter (PD) and PLR sensitivity were recorded. At the same time, the pupil was examined by M-mode ultrasound, and the diameter and pupillary contraction time (PCT) were measured at rest, ipsilateral opposite PLR, and contralateral opposite PLR.
Results
A total of 150 participants were included. In the briskgroup, during the ipsilaterallight reflex, the left and right PCTs were 0.09 ± 0.02s and 0.10 ± 0.09s, respectively, and the pupillary diameter variation rates (PDVRs) were 0.36 ± 0.10 and 0.35 ± 0.09. In the sluggish group, during the ipsilateral light reflex, the left and right PCTs were 0.20 ± 0.05s and 0.19 ±0.03s, respectively. PDVRs were 0.18 ± 0.07 and 0.19 ± 0.11, respectively. In the brisk group, the cut-off value of PDVR of ipsilateral PLR was 0.205, AUC value was 0.957, and sensitivity and specificity were 95.3% and 90.8%, the cut-off value of PDVR of contralateral PLR was 0.146, AUC value was 0.962, and sensitivity and specificity were 95.3% and 86.2%.
Conclusions
This study demonstrated the usefulness of M-mode ultrasound for quantitative evaluation of pupillary changes. It is a simple, rapid, and objective method that can accurately monitor PD and sensitivity to light reflex, especially in patients with eyelid edema or TBI, where pupils cannot be examined visually.