Estimation of optic nerve sheath diameter on an initial brain computed tomography scan can contribute prognostic information in traumatic brain injury patients

Abstract

Introduction: The aim of this study was to evaluate the prognostic value of optic nerve sheath diameter (ONSD) measured on the initial brain computed tomography (CT) scan for intensive care unit (ICU) mortality in severe traumatic brain injury (TBI) patients.

Methods: A prospective observational study of all severe TBI patients admitted to a neurosurgical ICU (over a 10-month period). Demographic and clinical data and brain CT scan results were recorded. ONSD for each eye was measured on the initial CT scan. The group of ICU survivors was compared to non-survivors. Glasgow Outcome Scale (GOS) was evaluated six months after ICU discharge.

Results: Seventy-seven patients were included (age: 43±18; 81% males; mean Injury Severity Score: 35±15; ICU mortality: 28.5% (n=22)). Mean ONSD on the initial brain CT scan was 7.8±0.1 mm in non-survivors vs. 6.8±0.1 mm in survivors (P<0.001). The operative value of ONSD was a good predictor of mortality (area under the curve: 0.805). An ONSD cutoff≥7.3 had a sensitivity of 86.4% and a specificity of 74.6% and was independently associated with mortality in this population (adjusted odds ratio 95% confidence interval: 22.7 (3.2 to 159.6), P=0.002). There was a relationship between initial ONSD values and six-month GOS (P=0.03).

Conclusions: ONSD measured on the initial brain CT scan is independently associated with ICU mortality rate (when ≥7.3 mm) in severe TBI patients.See related commentary by Masquère et al.,http://ccforum.com/content/17/3/151.

Figure 1

Optic nerve sheath diameter measurement on the initial brain computed tomography scan (using DxMM™ software).

Figure 2

Box plot of optic nerve sheath diameter (mm) comparing survivors and non-survivors among severe traumatic brain injury patients.

Figure 3

Receiver-operator characteristic curves of the performance of optical nerve sheath diameter to predict mortality. Dotted lines represent 95% confidence intervals (95% CI) of each point. AUC, area under the curve.

Figure 4

Box plot of optic nerve sheath diameter (mm) according to the Glasgow Outcome Scale (GOS) determined six months after discharge from ICU for 55 survivors (P = 0.03).