Correlation between optic nerve sheath diameter measured by bedside ultrasound and intracranial pressure in neurologically ill patients in a Chinese population.

Background: We assessed the correlation between optic nerve sheath diameter (ONSD) values measured by bedside ultrasound and intracranial pressure (ICP) changes among patients under neurocritical care and evaluated the diagnostic performance of ONSD for increased ICP.

Methods: Sixty-seven neurologically critical patients who were hospitalised in the intensive care unit (ICU) of Jining No.1 People's Hospital between September 2023 and March 2024 and underwent lumbar puncture were included. The ONSD was measured and recorded using bedside ultrasound before the lumbar puncture. Patients were divided into normal and increased ICP groups on the basis of the initial lumbar puncture pressure on admission, and both groups were compared. Spearman's correlation analysis was used for evaluating the correlation between ONSD values and ICP. Receiver operating characteristic (ROC) curves were employed for evaluating the diagnostic performance of ONSD for increased ICP.

Result: At admission, the Glasgow Coma Scale scores of patients in the increased ICP group were significantly lower than those of patients in the normal ICP group (P < 0.05). The ONSD level of patients in the increased ICP group was significantly higher than that of patients in the normal ICP group (P < 0.05). Spearman's correlation analysis revealed that ONSD positively correlated with ICP among patients with severe neurological diseases (r = 0.777, P < 0.001). The area under the ROC curve when using ONSD for diagnosing lumbar puncture opening pressure ≥ 200 mmH₂O was 0.896 (95% confidence interval, 0.817-0.974). When using ONSD ≥ 4.74 mm as the threshold for diagnosing lumbar puncture opening pressure ≥ 200 mmH₂O, the sensitivity and specificity were 0.909 and 0.765, respectively.

Conclusion: In patients with critical neurological illness, ONSD measured using bedside ultrasound positively correlated with ICP. Increased ICP can be diagnosed for ONSD ≥ 4.74 mm. The ONSD value measured by bedside ultrasound can be used for evaluating ICP among patients with critical neurological illness.