Point-of-care ultrasound of optic nerve sheath diameter to detect intracranial pressure in neurocritically ill children - A narrative review

Abstract

The rapid diagnosis of increased intracranial pressure is urgently needed for therapeutic reasons in neurocritically ill children, however this can rarely be achieved without invasive procedures. Point-of-care ultrasound of the optic nerve sheath diameter has been proposed as a non-invasive and reliable means to detect increased intracranial pressure in adults. Accordingly, clinicians may be able to use this technique to initiate early treatment and monitor the effectiveness of treatment in conjunction with other clinical examination and diagnostic modalities. Two meta-analyses and a systematic review have been published on this topic in adults. However, data on the correlation between optic nerve sheath diameter and intracranial pressure in neurocritically ill children are scarce. The aim of this review was to briefly describe what is being measured with point-of-care ultrasound of the optic nerve sheath diameter, summarize the most recent findings from adult literature, and provide an update of current work in children.

Multimodal neurocritical monitoring

“…Elevation in ICP can transmit through the CSF in the subarachnoid space, leading dilatation of the optic nerve sheath, which can be detected using transocular ultrasonography [ 13 ]. ONSD measurements may be a useful screening tool for ICP in settings where invasive monitoring is not promptly available [ 13 , 16 ]. A normal or low ICP produces an outward displacement (positive values) of the tympanic membrane while intracranial hypertension causes the tympanic membrane to move inward (negative values) [ 15 ].…”

Is Ocular Sonography a Reliable Method for the Assessment of Elevated Intracranial Pressure in Children?

“…On images, the optic nerve sheath is visualized to have a vertical, linear and dark pattern. 21 The ONSD is measured on the images which are saved on the machine. The ONSD measurement is performed by positioning the lens centrally.…”

Protecting the blossoming brain – Neurocritical care in children

“…With the aim of attracting attention to the urgent need for trustworthy, straightforward non-invasive ICP monitoring techniques, which allow additionally for real-time follow-up, Lin et al. have compiled the available relevant literature for adult patients, and some preliminary conclusions relating to their use in children [ 13 ]. The review focuses on the potential of point-of-care ultrasounds (POCUS) of the optic nerve sheath diameter (ONSD), as this strategy combines good results in adults, feasibility, and the possibility for continuous monitoring [ 14 ].…”

“…sum up all the components of multimodal neurocritical monitoring that are currently in use - from checklist-based global neurologic status assessment, via the specific measurements of blood flow and oxygenation, to the well-known electroencephalography and the intracranial pressure (ICP) monitoring, as discussed by Lin et al. in this issue [ 13 ].…”