Ratio of Optic Nerve Sheath Diameter to Eyeball Transverse Diameter by Ultrasound Can Predict Intracranial Hypertension in Traumatic Brain Injury Patients: A Prospective Study

Background Measuring optic nerve sheath diameter (ONSD), an indicator to predict intracranial hypertension, is noninvasive and convenient, but the reliability of ONSD needs to be improved. Instead of using ONSD alone, this study aimed to evaluate the reliability of the ratio of ONSD to eyeball transverse diameter (ONSD/ETD) in predicting intracranial hypertension in traumatic brain injury (TBI) patients. Methods We performed a prospective study on patients admitted to the Surgery Intensive Care Unit. The included 52 adults underwent craniotomy for TBI between March 2017 and September 2018. The ONSD and ETD of each eyeball were measured by ultrasound and computed tomography (CT) scan within 24 h after a fiber optic probe was placed into lateral ventricle. Intracranial pressure (ICP) > 20 mmHg was regarded as intracranial hypertension. The correlations between invasive ICP and ultrasound-ONSD/ETD ratio, ultrasound-ONSD, CT-ONSD/ETD ratio, and CT-ONSD were each analyzed separately. Results Ultrasound measurement was successfully performed in 94% ( n = 49) of cases, and ultrasound and CT measurement were performed in 48% ( n = 25) of cases. The correlation efficiencies between ultrasound-ONSD/ETD ratio, ultrasound-ONSD, CT-ONSD/ETD ratio, and ICP were 0.613, 0.498, and 0.688, respectively ( P