A Proposal for a New Protocol for Sonographic Assessment of the Optic Nerve Sheath Diameter: The CLOSED Protocol
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Measuring and monitoring of intracranial pressure is considered standard of care in patients with suspected intracranial hypertension. Sonographic assessment of the optic nerve sheath diameter (ONSD) has been promising and potentially useful for noninvasive intracranial hypertension screening. ONSD measurements are easy to perform, repeatable at bedside, fast, low cost, and radiation-free. However, they are still burdened by inter-rater variability, lack of ultrasound (US) setting standardization (e.g., US frequency, focus depth, etc.), and possible artifacts. To overcome this problem, we propose the CLOSED protocol associated with equipment specifications, as a guide to minimize the occurrence of such artifacts enabling a more reliable and accurate measurement. We suggest that color Doppler could be used as a new standard evaluation for the ONSD.
KeywordsCLOSED protocol Optic nerve sheath diameter Ultrasound color Doppler Central retinal artery Point-of-care ultrasound
As low as reasonably achievable
Central retinal artery
Central retinal vein
Intensive care unit
Idiopathic intracranial hypertension
Idiopathic normal pressure hydrocephalus
Spatial-peak temporal-average intensity
Optic nerve sheath diameter
Pulse repetition frequency
Thermal index cranium
Soft tissue thermal index at surface
We thank Dr. Monica Ferri for color Doppler learning skills, Dr. Veronica Salvatore for assistance with US settings support, and Dr. Franziska Lohmeyer for the revision of our manuscript.
Aspide, Bertolini was involved in conception and design. Aspide, Bertolini, Albini was involved in acquisition of data. Aspide, Bertolini, Biasucci contributed in drafting the article. All authors critically revised the article and reviewed the submitted version of manuscript. Albini was also involved in Technical/material support. Mazzatenta, Palandri, and Biasucci contributed in study supervision.
Source of support
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Conflicts of Interest
The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The local Institutional Review Board approved the present study. CLOSED protocol adhered to ethical standards and Helsinki Declaration.
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