# Correlation of Optic Nerve Sheath Diameter With Severity and Outcome in Head Injury: Ultrasonographic and CT Evaluation

## TL;DR

This study shows that measuring the optic nerve sheath diameter with ultrasound can help assess the severity and outcomes of head injuries.

## Contribution

The study demonstrates that ultrasound-based optic nerve sheath diameter is a reliable, non-invasive indicator of traumatic brain injury severity and intracranial pressure.

## Key findings

- Optic nerve sheath diameter measured by ultrasound correlates with traumatic brain injury severity as assessed by the Glasgow Coma Scale.
- Higher optic nerve sheath diameter values are significantly associated with elevated intracranial pressure indicators on CT scans.
- Larger optic nerve sheath diameter values correlate with poorer clinical outcomes, including increased mortality and delayed neurological recovery.

## Abstract

Objective

This study aimed to determine the extent to which ultrasonographic and computed tomographic (CT) measurements of the optic nerve sheath diameter (ONSD) correlate with the prognosis and severity of traumatic brain injury (TBI).

Methodology

A prospective cohort study was conducted among 200 adult patients admitted to a Level 1 trauma center over one year. All patients were between 18 and 70 years of age and had sustained mild to severe TBI. Based on the Glasgow Coma Scale (GCS), patients were stratified into three categories of injury severity: mild, moderate, and severe. The ONSD was measured using both bedside ultrasonography and CT imaging. CT scans served as the reference standard for identifying intracranial pathologies. The primary objective was to evaluate whether ONSD measurement could help identify patients with intracranial hypertension (elevated intracranial pressure, ICP). CT findings, mortality, and long-term neurological outcomes were analyzed to assess the association between ONSD values and clinical prognosis.

Results

A moderate to strong positive correlation was found between the ONSD measured by ultrasonography and the severity of TBI, as assessed by the GCS. Increasing injury severity was associated with larger ONSD values. A significant association was also observed between ONSD measurements and CT indicators of elevated ICP, including midline shift, basal cistern effacement, and brain herniation. Moreover, higher ONSD values were significantly associated with poorer clinical outcomes, including increased mortality and delayed neurological recovery. The relationship between ONSD and these outcome measures appeared strong and consistent.

Conclusion

Ultrasound-based measurement of ONSD proved to be a reliable, non-invasive indicator of TBI severity and intracranial pressure. It demonstrated significant correlation not only with the degree of brain injury but also with patients’ clinical outcomes. Overall, these findings support the use of ONSD as a practical and effective surrogate tool for assessing raised ICP, particularly in situations where direct measurement is not feasible.