Abstract
Background
Many studies have suggested that the optic nerve sheath diameter (ONSD) measured by transorbital ultrasound could reflect the increased intracranial pressure (ICP). However, whether the optic nerve subarachnoid space width (ONSASW) could evaluate the increased ICP, and whether it has better diagnostic value for the increased ICP than ONSD are lack of knowledges.
Methods
Patients with brain injury undergoing ICP monitoring after external ventricular drainage surgery were enrolled. Within 48 hours post-surgery, ONSDI/ONSDE (ONSD including/excluding the dura mater) and OND (optic nerve diameter) were measured via transorbital ultrasound at 3mm behind the retina. The ONSASW was defined as the difference between ONSDI/ONSDE and OND (i.e., ONSDI-OND/ONSDE-OND). Patients were categorized into increased ICP and normal ICP groups based on invasive ICP measurements. The differences of the ONSASW between the two groups were compared, and ROC curve analysis was used to assess its diagnostic value for increased ICP.
Results
A total of 70 patients (including 17 patients with increased ICP and 53 patients with normal ICP) were ultimately included in the study. Significant differences were observed in ONSDI, ONSDI-OND, and ONSDE-OND between the increased and normal ICP groups (all p < 0.05). Additionally, it was determined that ONSDI, ONSDI-OND, and ONSDE-OND exhibited diagnostic value for increased ICP (all p < 0.001), with ONSDI-OND demonstrating superior performance with an area under the curve (AUC) of 0.806.
Conclusions
The ONSASW (especially defined as ONSDI-OND) is not only associated with increased ICP, but also possesses superior diagnostic value for increased ICP in brain-injured patients compared to ONSD.