Optic Nerve Sheath Diameter Assessment In Traumatic Head Injury And Its Correlation With Serial CT Evaluation As A Measure To Assess ICP

Abstract

Background: Raised intracranial pressure (ICP) is a critical determinant of morbidity and mortality in traumatic brain injury (TBI). Non-invasive measurement of optic nerve sheath diameter (ONSD) offers a potential surrogate for ICP monitoring.

Objectives: To assess the correlation between ONSD measurements on ultrasound and serial computed tomography (CT) with ICP in TBI patients and evaluate their role in guiding clinical decisions.

Methods: A prospective observational study was conducted on 50 adult TBI patients with CT features of raised ICP at a tertiary care hospital. ONSD was measured bilaterally 3 mm posterior to the globe on ultrasound at admission (T1) and before follow-up CT (T2). ICP values, Glasgow Coma Scale (GCS) scores, and CT findings were recorded. Statistical tests included paired t-tests, independent t-tests, and Pearson’s correlation.

Results: The mean age was 36.2 ± 12.8 years; 75.5% were male. Mean ONSD decreased from 5.50 mm (right) and 5.32 mm (left) at T1 to 4.90 mm and 4.91 mm at T2. Mean ICP fell from 13.8 ± 4.31 mmHg to 10.7 ± 3.50 mmHg (p < 0.001). ONSD strongly correlated with ICP at T1 (r = 0.895 right; r = 0.856 left) and T2 (r > 0.95 for both; p < 0.001). No significant differences in ONSD or ICP reduction were observed between surgical and conservative groups.

Conclusion: ONSD is a reliable, non-invasive marker of raised ICP and may serve as a valuable monitoring tool in TBI, particularly in settings where invasive monitoring is unavailable.