Abstract: Objective  To evaluate the correlation between optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods  All patients were diagnosed with aSAH and received microsurgery clipping at the Department of Critical Care Medicine, Beijing Tiantan Hospital, Capital Medical University from December 1, 2019 to June 1, 2022. The patients received head computed tomography (CT) and subdural ICP monitoring devices were kept to monitor the ICP. The ONSD were measured with CT and ICP was recorded. The agreement among the three observers was evaluated with intraclass correlation coefficient (ICC), and the regression of ONSD and ICP was evaluated with Spearman's correlation coefficient. Results  A total of 184 patients were included, with 282 data of ONSD and ICP recorded. The median ICP was 12 (9, 18) mmHg (1 mmHg=0.133 kPa)， and the median ONSD was 5.59 (5.26, 5.99) mm. The ICC of left and right ONSD measured by three observers was 0.895 (0.872-0.915, P<0.001) and 0.869 (0.841-0.894, P<0.001), respectively. There was a significant positive correlation between ONSD and ICP (r=0.273，95% CI: 0.158-0.381, P<0.001). The area under the receiver operating characteristics curve of ONSD to predict ICP>22 mmHg was 0.753 (95% CI: 0.670-0.836, P<0.001), The cutoff point was 5.61 mm, with 85.2% sensitivity and 55.3% specificity. Conclusion  Measurement of ONSD by CT is repeatable, and it significantly correlates by ICP. 

Key words: intracranial aneurysms, subarachnoid hemorrhage, optic nerve sheath diameter, intracranial pressure, neurocritical care