Ultrasound assessment of the optic nerve sheath diameter in adult patients with suspected intracranial hypertension: A scoping review

OBJECTIVES: The aim of this study was to map how the ultrasound measurement of the optic nerve sheath diameter is performed in adults with suspected intracranial hypertension. METHODS: This scoping review was conducted in accordance with the JBI Collaboration and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping review guidelines. Two independent reviewers searched PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Latin American and Caribbean Health Sciences Literature (LILACS), Nursing Database (BDENF), Cochrane Library, Scopus, Embase, Livivo, Web of Science Core Collection, and the CAPES thesis and dissertation repository. Grey literature included Google Scholar. RESULTS: Of the 2019 records identified, 239 were included. Optic nerve sheath diameter (ONSD) ultrasonography is primarily performed in adults with suspected or at risk of intracranial hypertension, particularly critically ill, neurocritical care, emergency, and trauma patients. Across the included studies, patients were assessed in the supine position, with their eyes closed, using a high-frequency linear transducer in B-mode. The optic nerve is most consistently measured 3 mm posterior to the globe. The included studies showed variability in ONSD cut-off values suggestive of increased intracranial pressure. Lower thresholds, particularly >5.0 mm, showed high sensitivity (99%) but lower specificity (73%), whereas values between 5.6 and 6.3 mm tended to provide greater specificity. Studies assessing diagnostic performance reported favourable results for ONSD ultrasonography; however, heterogeneity in cut-off values, populations, reference standards, and measurement techniques precludes the definition of a universally accepted threshold. CONCLUSION: ONSD is a viable, noninvasive approach for assessing suspected intracranial hypertension; it most commonly employs a high-frequency linear transducer in B-mode. The optic nerve is most consistently measured 3 mm posterior to the globe. However, variability in measurement techniques and cut-off values highlights the need for greater standardisation. Furthermore, the limited number of studies addressing the role of nursing indicates a knowledge gap that must be bridged to integrate ONSD ultrasound into nursing practice. OSF REGISTRATION: https://osf.io/m4ej9/.