Measurement of optic nerve sheath diameter by ultrasound in healthy term neonates

Influence of sex and disease etiology on the development of papilledema and optic nerve sheath extension in the setting of intracranial pressure elevation in children

Introduction

Dilatation of the optic nerve sheath diameter and swelling of the optic disc are known phenomena associated with intracranial pressure elevation.

Research question

Do sex and disease etiology have an impact on the development of optic disc elevation and optic nerve sheath extension in children in the setting of ICP elevation? Fundoscopic papilledema and point-of-care-ultrasound techniques-optic nerve sheath diameter (US-ONSD) and optic disc elevation (US-ODE) - were compared in this regard.

Material and methods

72 children were included in this prospective study; 50 with proven pathology (e.g. pseudotumor cerebri, tumor), 22 with pathology excluded. Bilateral US-ONSD and US-ODE were quantified by US using a 12-MHz-linear-array-transducer. This was compared with fundoscopic optic disc findings and in 28 patients with invasive ICP values, stratified for sex and etiology.

Results

In patients with proven disease, significant more girls (69%) had fundoscopic papilledema compared with boys (37%, p < 0.05). Girls had also larger US-ODE values (0.86 ± 0.36 mm vs. 0.65 ± 0.40 mm in boys). 80% of tumor patients had initial papilledema (100% girls, 79% boys), compared with 50% in pseudotumor cerebri (PTC) (83% girls, 30% boys). US-ONSD had no sex- and no etiology-specificity.

Discussion and conclusion

Presence of papilledema appears to be influenced by sex and etiology, whereas US-ONSD is not. Girls seem more likely to develop papilledema under similar conditions. Male sex and PTC appear as risk factors for being undetected by fundoscopic findings. US-ONSD and US-ODE seem useful tools to identify pathologies with potentially increased ICP requiring treatment in children regardless of sex and etiology.

Optic Nerve Ultrasound Evaluation in Children: A Review

Managing patients with neurocritical illness requires monitoring and treating elevated intracranial pressure (ICP), especially in cases in children. In terms of precise and real-time measurements, invasive ICP measurements are presently the gold standard for the initial diagnosis and follow-up ICP assessments. As a rapid and non-invasive way to detect elevated ICP, point-of-care ultrasonography (POCUS) of optic nerve sheath diameter (ONSD) has been proposed. The utility of bedside POCUS of ONSD to detect elevated ICP with excellent diagnostic test accuracy in adults has already been demonstrated. Nonetheless, data on the relationship between POCUS of ONSD and ICP in children are scarce. Therefore, the purpose of this review is to point out the most recent findings from the pediatric published literature and briefly discuss what was assessed with ONSD ultrasound examination, and also to describe and discuss the diagnostic procedures available for optic nerve ultrasound appraisal. A search of the medical databases PubMed and Scopus was carried out. The terms such as "ocular ultrasonography", "ICP assessment", "children", "point-of-care ultrasound", and "POCUS" were searched. In conclusion, the use of the standardized A-scan technique coupled with the B-scan technique should be suggested to provide data that are as accurate, precise, repeatable, and objective as possible.

Evaluation of the correlation of the new Ballard scoring with the ultrasonographic optical nerve sheath diameter and brain volume of preterm infants

BACKGROUND

Optic nerve sheath diameter (ONSD) measurements with magnetic resonance imaging and ultrasonography in preterm infants are similar.

AIM

We measured ultrasonographic ONSD and calculated the brain volumes of preterm infants using two-dimensional cranial ultrasonography and explored the relationships thereof with gestational age, birth weight, head circumference, and new Ballard score.

METHOD

This prospective study included preterm infants admitted to the neonatal intensive care unit without intracranial pathology. Two images per eye were obtained from a linear array ultrasound transducer placed on the patient's superior eyelid. The ONSD was measured 3 mm behind the globe. The brain was considered an ellipsoid, and estimated absolute brain volumes were calculated by subtracting the volumes of the two lateral ventricles from the total brain volumes.

RESULTS

A total of 143 preterm infants (male 74, female 69) included in the study. The mean gestational age of the study population was 29.7 weeks (23-36), and the mean birth weight was 1390 g (500-2850). There was a significant difference in ONSD between the male and female gender. A significant, strong, and positive correlation was found between ONSD measurements and gestational age (r 0.901, p < 0.001), new Ballard score (r 0.946, p < 0.001), birth weight, head circumference, and brain volumes.

CONCLUSION

Our results suggested that ONSD measurements are highly correlated with anthropometry, and it could be a promising bedside, non-invasive objective tool for the determination of exact gestational age postnatally along with the new Ballard score.