Optic nerve sheath ultrasonography identifies increased intracranial pressure in a diverse pediatric population: A comparative study

Abstract

Purpose : Identification of increased intracranial pressure (ICP) in the pediatric population, especially infants, can be challenging. This retrospective, observational clinical study tests the hypothesis that optic nerve sheath (ONS) ultrasonography can be reliably used to help identify such cases. We seek to characterize trends in optic nerve sheath diameter (ONSD) by age, race, and sex, and to establish reference values.

Methods : A retrospective chart review was conducted on patients age 0 to 18 years (n=1,112 eyes) at a single institution who underwent B-scan ultrasonography of the ONS. These patients were referred to the ophthalmology clinic by pediatricians and neurologists for a variety of reasons, most commonly headache. If a lumbar puncture was performed, opening pressures (OP) were also recorded. Student’s t test, ANOVA, and regression modeling was used for statistical analysis. A receiver operating characteristic (ROC) curve was generated.

Results : In the multiple regression model, age was the most predictive factor of ONSD. The ONSD for normal children measured 5.44 ± 0.04 mm, versus 5.81 ± 0.72 mm in patients clinically diagnosed with increased ICP (P<0.0001). In patients with a high OP >20 cm H₂O, the OSND was 6.34 ± 0.70 mm. Males had an ONSD of 5.54 ± 0.77 mm, larger than that of females (5.35 ± 0.63 mm, P=0.006). Whites had a .18 mm larger ONSD than blacks (5.52 ± 0.68 mm vs 5.34 ± 0.74 mm, P=0.016). There was no difference between right and left ONSD (P=0.85). The fastest growth in ONSD occurred in the first six months of life (R=.65, R²=.42, P=0.0008), and the strongest differences, determined by Tukey’s method, were between the 0-18 month and post 18 month age groups. For patients less than 18 months of age, an ONSD of 5.0 mm had a sensitivity of 100% for idiopathic increased ICP, and a specificity of 74% (AUC=0.90, P=0.0027). In patients older than 18 months, a cut-off value of 5.5 mm had a sensitivity of 79% and specificity of 51% (AUC=0.70, P<0.0001).

Conclusions : ONSD ultrasonography is a cost effective, atraumatic means of screening for elevated ICP in pediatric patients in an office setting. Age appropriate ONSD cut-off values can be applied to monitor suspected cases of increased ICP, and to determine whether further invasive diagnostic procedures such as MRI or lumbar puncture are warranted.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.