Diagnostic evaluation of optic nerve sheath diameter in predicting elevated intracranial pressure among neurocritically ill patients: A prospective observational study.

BACKGROUND

Optic nerve sheath diameter (ONSD) is used as a surrogate for intracranial pressure (ICP) with a marked variation in its optimal cutoff in various subgroups of neurocritical illnesses. Real-world data on ultrasound (US)-ONSD performance among a diverse population and its trend corresponding with clinical deterioration are scarce. We aim to determine the diagnostic performance of ONSD compared to computed tomography (CT) in predicting elevated ICP in a mixed population of neurocritical patients.

METHODS

Baseline ONSD measurements (T1) using B-mode US were recorded among eligible patients. Follow-up ONSD (T2) was recorded during clinical deterioration defined by ≥2 drops in Glasgow Coma Scale/Full Outline of UnResponsiveness (GCS/FOUR) scores. Its diagnostic performance in predicting elevated ICP was assessed by comparing it with the concurrently taken CT findings as a reference standard. The difference between the two ONSD measurements was termed delta ONSD.

RESULTS

In the final analysis, 129 participants were included. The population comprised traumatic brain injury, stroke (hemorrhagic and ischemic), intracranial space-occupying lesions, and other medical conditions. The optimal ONSD (T2) cutoff of 5.23 mm had a diagnostic accuracy of 80.73% to predict elevated ICP (sensitivity: 82%; specificity: 78%; area under the curve: 0.88; and 95% confidence interval [CI]: 0.819-0.941). Each unit increase in delta ONSD was associated with increased odds of need for surgical intervention (odds ratio [OR]: 3.91; 95% CI: 1.31-12.6, = 0.017) and death at intensive care unit discharge (OR: 8.24; 95% CI: 1.78-41.15, = 0.007).

CONCLUSIONS

ONSD cutoff of 5.23 mm has a good diagnostic accuracy in predicting elevated ICP compared to CT during clinical deterioration. ONSD measurements correlate well with corresponding GCS/FOUR scores.