Correlation between Optic Nerve Sheath Diameter Measured by Computed Tomography and Elevated Intracranial Pressure in Patients with Traumatic Brain Injury

Abstract

Purpose: The optic nerve sheath diameter (ONSD) measured by ultrasonography is among the indicators of intracranial pressure (ICP) elevation. However, whether ONSD measurement is useful for initial treatment remains controversial. Thus, this study aimed to investigate the relationship between ONSD measured by computed tomography (CT) and ICP in patients with traumatic brain injury (TBI). Methods: A total of 246 patients with severe trauma from January 1, 2015 until Decem ber 31, 2015 were included in the study. A total of 179 patients with brain damage with potential for ICP elevation were included in the TBI group. The remaining 67 patients comprised the non-TBI group. A comparison was made between the two groups. Re ceiver operating characteristic (ROC) curve analysis was performed to determine the accuracy of ONSD when used as a screening test for the TBI group including those with TBI with midline shift (with elevated ICP). Results: The mean injury severity score (ISS) and glasgow coma scale (GCS) of all pa tients were 24.2±6.1 and 5.4±0.8, respectively. The mean ONSD of the TBI group (5.5±1.0 mm) was higher than that of the non-TBI group (4.7±0.6 mm). Some significant differ ences in age (55.3±18.1 vs. 49.0±14.8, p<0.001), GCS (11.7±4.1 versus 13.3±3.0, p<0.001), and ONSD (5.5±1.0 vs. 4.7±0.6, p< 0.001) were observed between the TBI and the non-TBI group. An ROC analysis was used to assess the correlation between TBI and ONSD. Re sults showed an area under the ROC curve (AUC) value of 0.752. The same analysis was used in the TBI with midline shift group, which showed an AUC of 0.912. Conclusions: An ONSD of >5.5 mm, measured on CT, is a good indicator of ICP eleva tion. However, since an ONSD is not sensitive enough to detect an increased ICP, it should only be used as one of the parameters in detecting ICP along with other screening tests.