Optic nerve sheath diameter based on preoperative brain computed tomography and intracranial pressure are positively correlated in adults with hydrocephalus

Objective: The usefulness of optic nerve sheath diameter (ONSD) in predicting increased intracranial pressure (ICP) is not well established in adults with hydrocephalus. In this retrospective study, we evaluated the correlation between ONSD measured on brain computed tomography (CT) and ICP in adults with hydrocephalus. Patients and Methods: ONSDs were measured on preoperative brain CT images from 64 adult patients with hydrocephalus who underwent extracranial ventricular drainage or a ventriculoperitoneal shunt in 2016. ICP was defined as ventricular fluid pressure. Results: The ONSD measured on preoperative CT was greater in patients (n = 8) with a higher ICP ( > 20 mmHg, 5.8vs. 4.9 mm, P = 0.001). The ONSD was linearly correlated with ICP (r = 0.543, P < 0.001) and was predictive of increased ICP with an area under the receiver operating characteristic curve of 0.834. The optimal cutoff value of 5.3 mm ONSD yielded 88% sensitivity and 79% specificity. The inter-class coefficient of ONSD on preoperative CT was 0.882. The correlation between ONSD on preoperative CT and ICP was detected only in patients with communicating and non-communicating hydrocephalus (r = 0.437 and r = 0.585, P = 0.037 and P = 0.002, respectively). Conclusion: ONSD measured on preoperative brain CT was linearly correlated with ICP in adult patients with communicating and non-communicating hydrocephalus, and it was a predictor of increased ICP with good discrimination and high inter-observer reliability. These results suggest that preoperative ONSD measurement on brain CT can be helpful to safely manage such patients by providing information about ICP.