Optic Nerve Sheath Diameter Estimation to Detect Increased Intracranial Pressure in Traumatic Brain Injury patients at a Level I Trauma Center in Eastern India.

Objective: To evaluate the diagnostic accuracy of optic nerve sheath diameter (ONSD) measured by ultrasound as a non-invasive marker for detecting elevated intracranial pressure (ICP) in patients with traumatic brain injury (TBI), based on clinical and radiological findings.

Methods: This diagnostic accuracy study included 180 adult patients with isolated TBI admitted to a Level I Trauma Centre in Eastern India. ONSD was measured bilaterally using a 7.5 MHz linear ultrasound probe, 3 mm posterior to the globe. Clinical and radiological parameters were recorded, and increased ICP was determined based on a predefined clinical signs and computed tomography findings. Statistical analysis included logistic regression and receiver operating characteristic (ROC) curve analysis using Jamovi software.

Results: The mean ONSD was significantly higher in patients with increased ICP (5.36±0.56 mm) compared to those without (4.13±0.34 mm, p<0.001). ROC analysis showed excellent diagnostic performance (area under the curve: 0.942), with sensitivity and specificity of 93.2% and 81.8%, respectively, at a cut-off value of 5.0 mm. The positive predictive value was 74.0%, and the negative predictive value was 99.0%. Increased ONSD was associated with TBI severity and poor Glasgow Outcome Scale scores at 3 months.

Conclusion: Ultrasound-measured ONSD is a sensitive, non-invasive bedside tool for detecting increased ICP in TBI patients, particularly useful in resource-limited settings.