Category
Research
Ultrasound
Year
2026
Market
Defense
Traumatic brain injury accounted for 32.4% of casualties for U.S. servicemen in Iraq and Afghanistan; yet the tools to detect evolving intracranial hypertension in forward environments are rarely available. In those critical early hours, clinicians are often left making high-stakes neurological decisions without imaging, without specialists, and without any reliable way to monitor intracranial pressure (ICP). ONSD assessed with ultrasound is a promising portable, accurate, and radiation free diagnostic ideally suited for forward and austere military settings.
The Study at a Glance
Optic nerve sheath diameter (ONSD) ultrasound leverages a straightforward anatomical principle: the optic nerve sheath communicates directly with the subarachnoid space, meaning elevated ICP causes measurable dilation of the sheath. A bedside ultrasound probe placed over the closed eyelid can detect that dilation in seconds; no radiation, no contrast, no specialized suite required.
The diagnostic evidence is strong. Koziarz et al. (2019) reported 97% sensitivity and 86% specificity across 71 studies and 4,551 TBI patients. Robba et al. (2018) found a pooled diagnostic odds ratio of 67.5. Kim et al. (2019) reported 99% sensitivity at a 5.0 mm threshold. These findings support the clinical basis for potential adoption in military settings.
ONSD Use Cases during Military Deployment
There are multiple potential uses for ONSD in military setting: initial risk stratification after head injury, serial monitoring during Prolonged Casualty Care, and evaluation of undifferentiated altered mental status.
Conclusion
Optic nerve sheath diameter ultrasound is a plausible and evidence-supported adjunctive neurodiagnostic tool for military medicine. Its strengths align closely with the demands of forward care: portable, non-invasive, repeatable, and capable of providing a meaningful physiologic signal when CT, MRI, invasive ICP monitoring, and specialist consultation are unavailable. It is not a replacement for definitive neurodiagnostic workup. But, in an austere environment, ONSD ultrasound may be one of the most practical tools available.
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References
Figures were created specifically for this article series using original illustrations and AI-assisted graphic design tools. Clinical concepts were derived from the references cited in the accompanying text.
- Le TD, Gurney JM, Singh KP, et al. Trends in Traumatic Brain Injury Among U.S. Service Members Deployed in Iraq and Afghanistan, 2002 to 2016. Am J Prev Med. 2023;65:230-238.
- Koziarz A, Sne N, Kegel F, et al. Bedside Optic Nerve Ultrasonography for Diagnosing Increased Intracranial Pressure: A Systematic Review and Meta-analysis. Ann Intern Med. 2019;171:896-905.
- Robba C, Santori G, Czosnyka M, et al. Optic nerve sheath diameter measured sonographically as non-invasive estimator of intracranial pressure: a systematic review and meta-analysis. Intensive Care Med. 2018;44:1284-1294.
- Kim SE, Hong EP, Kim HC, Lee SI, Jeon JP. Ultrasonographic optic nerve sheath diameter to detect increased intracranial pressure in adults: a meta-analysis. Acta Radiol. 2019;60:221-229.
