A Prospective Comparative Study of Optic Nerve Sheath Diameter Measurement by Ultrasonography vs Computed Tomography Scan for the Detection of Elevated Intracranial Pressure in Patients with Acute Neurological Emergencies.

Background and aim: Intracranial pressure (ICP) monitoring is essential to manage patients with acute neurological emergencies to improve outcomes. Non-invasive modes of monitoring are preferred over invasive as they are associated with fewer complications. Our study aimed to compare optic nerve sheath diameter (ONSD) measurement using ultrasonography (USG) and computed tomography (CT) in patients with raised ICP. Patients and methods: After ethical committee approval and applying inclusion criteria, 140 patients were included in the study. Optic nerve sheath diameter was measured using ultrasound by the physician on admission into the critical care unit before initiation of anti-edema measures in whom ICP rise was suspected. It was compared with ONSD measurement obtained via CT using electronic calipers by a neuroradiologist. Evidence of ICP rise was identified using CT scan findings. Optic nerve sheath diameter measurements were taken twice in both the right and left eye each using ultrasound and CT scan to overcome inter-observer variability. Results: A total of 150 patients were screened and 10 were excluded as they met exclusion criteria. The mean age (years) of the participants was 55.27 ± 14.90. The mean (SD) of ONSD (mm) (USG) was 4.97 (0.74). The mean (SD) of ONSD (mm) (CT) was 5.07 (0.71). Based on CT findings, 65.7% of the participants had evidence of raised ICP. At a cut-off of ONSD (mm) (CT) ≥5, it predicts raised ICP with a sensitivity of 56% and a specificity of 73%. At a cut-off of ONSD (mm) (USG) ≥4.825, it predicts raised ICP with a sensitivity of 74% and a specificity of 56%. There was no significant difference in the diagnostic performance of ONSD (mm) (CT) and ONSD (mm) (USG) in the receiver operator curve. Conclusion: Ultrasonography-guided ONSD measurement is comparable with CT-guided ONSD measurement in patients with raised ICP in patients with acute neurological emergencies. Non-invasive intracranial pressure monitoring can be reliably utilized to manage acute neurological emergencies. How to cite this article: Parameswaran P, Venkatachalam B, Selvi T, Selvaraj N, Ravi S. A Prospective Comparative Study of Optic Nerve Sheath Diameter Measurement by Ultrasonography vs Computed Tomography Scan for the Detection of Elevated Intracranial Pressure in Patients with Acute Neurological Emergencies. Indian J Crit Care Med 2026;30(1):50-55.