Diagnostic accuracy test of quantitative pupillary light reflex as an indicator of increased intracranial pressure in traumatic brain injury patients: a cross-sectional study

Abstract

Introduction: The gold standard of intracranial pressure (ICP) measurement is an invasive procedure of inserting ICP monitor and one of the limitations of its surrogate, ultrasonography-based (US) optic nerve sheath diameter (ONSD) measurement is operator-dependent. Quantitative pupillary light reflex (PLR) measurement provides objective data promisingly able to predict ICP elevation. The aim of this study was to evaluate diagnostic accuracy of PLR as an indicator of ICP elevation in traumatic brain injury (TBI) patients compared to US-ONSD measurement. Methods: This was a cross-sectional study involving moderate and severe TBI patients aged 18-65 years without any eye lesion, nor medication and illness that may influence PLR. Healthy volunteers were recruited as control group. ONSD and quantitative PLR measurements (baseline diameter, maximum constriction, constriction velocity, latency and amplitude) were assessed to both groups. The Student t-test or Mann-Whitney U-test was used to compare the ONSD and PLR between case and control group. Further analyses were done to determine the sensitivity, specificity and cut-off value of PLR compared to ONSD in case group. Result: ONSD measurements or parameters were significantly different between case and control group (p<0.001), while all PLR parameters were significantly different (p<0.005) except for right eye constriction latency. The baseline diameter of the right eye had the highest accuracy with cut-off value of >3.9 mm (specificity of 100%, sensitivity of 50%). Other PLR components had variable in accuracy. Conclusion: The baseline diameter of the right eye was the most accurate PLR component as an indicator of ICP elevation, represented by ONSD.