Estimation of Intracranial Pressure in Patients with Traumatic Brain Injury by Optic Nerve Sheath Diameter Ultrasonography

BACKGROUND AND OBJECTIVES: Intracranial pressure (ICP) is the cornerstone for physiological neuromonitoring after traumatic brain injuries (TBIs). Optic nerve sheath diameter (ONSD) ultrasonography serves as a noninvasive alternative for the gold standard invasive ICP monitoring devices. We aimed to evaluate the use of ultrasound ONSD as a tool for early detection and follow-up of increasing ICP in TBI in a low socioeconomic developing country where invasive devices are not always available. METHODS: A prospective observational study was conducted on 50 polytrauma patients with TBI, who were older than 18 years with and Glasgow Coma Scale above 5, and a computed tomography (CT) brain in trauma survey showing signs of increasing ICP. All patients were recruited from the emergency department and intensive care unit at Cairo and October 6 University hospitals from January to May 2022. Clinical assessment, CT brain, and ONSD ultrasonography were performed on admission, after 12 hours, and after 48 hours. ONSD 5.0 mm was correlated with raised ICP in this study. RESULTS: ONSD ranged from 4.6 to 7.1 mm with mean ± SD of 5.93 ± 0.55 on admission. On the second follow-up, the range regressed to 4.5 to 6.0 mm with mean ± SD of 4.8 ± 0.48, suggesting a decrease in the measurements of ONSD after receiving treatment either medical or surgical. The correlation between the measurement of ONSD and the CT findings indicating raised or decreased ICP was found in 94%, 82%, and 90% of patients on admission, first follow-up, and second follow-up, respectively. The specificity of ONSD measurement was 100% on admission and second follow-up, and its accuracy was 94% and 90 % for both occasions, respectively. CONCLUSION: Bedside ONSD measurements are highly correlated with CT brain findings and dynamic changes in ICP in response to head trauma management protocols. Hence, ultrasonic ONSD can replace invasive monitoring in following the ICP of patients with TBI.