Change in Optic Nerve Sheath Diameter and Cerebral Ventricular Shunt Failure in Children

Abstract

Importance: Ocular point-of-care ultrasonography (POCUS) may be a clinically useful method to evaluate shunt dysfunction for children with hydrocephalus presenting to the emergency department (ED).

Objective: To evaluate whether a change in the optic nerve sheath diameter (ONSD) from prior asymptomatic baseline was associated with shunt failure.

Design, setting, and participants: Participants in this prospective single-center observational cohort study at a tertiary care children's hospital were enrolled from January 5, 2018, to March 2, 2022. Children 18 years or younger with cerebrospinal fluid (CSF) shunts were consecutively recruited during routine asymptomatic visits in the outpatient neurosurgery clinic. The institution sees approximately 1000 children with shunts. Children with comorbid eye pathologic conditions known to increase the ONSD were excluded, as were those with shunt interventions between baseline and symptomatic ocular POCUS. Data analysis was completed in May 2024.

Exposures: Baseline ocular POCUS was performed on asymptomatic children with CSF shunts recruited in the outpatient neurosurgery clinic; a second ocular POCUS was performed if the patient subsequently presented to the ED with symptoms of shunt failure. Change in ONSD from prior asymptomatic baseline to symptomatic presentation was the main study exposure.

Main outcomes and measures: Shunt failure was defined as intraoperative confirmation of inadequate CSF flow through the shunt system associated with identifiable shunt complications, including catheter or valve obstruction, shunt tubing fracture or disconnection, or proximal catheter migration out of the ventricle within 96 hours from presentation to the ED.

Results: Seventy-six pairs of baseline and symptomatic ultrasonograms from 58 patients (mean [SD] age, 6.6 [4.7] years; 36 of 58 boys [62%]) were included. Twenty patients (35%) had 2 or more prior shunt revisions, and 29 (50%) had communicating hydrocephalus. The primary outcome of intraoperatively confirmed shunt failure was observed in 14 of 76 ED patient presentations (18%). The mean (SD) change in ONSD among patients with shunt failure was 0.89 (0.66) mm vs 0.16 (0.40) mm among patients without shunt failure (mean difference, 0.73 mm [95% CI, 0.47-0.99 mm]; P < .001). The odds of full shunt failure were 1.4 times higher (95% CI, 1.21-1.78; P < .001) for every 0.1-mm increase in ONSD. The area under the receiver operating characteristic curve was 0.86, with an optimal cutoff of 0.4 mm or more, yielding a sensitivity of 0.93, specificity of 0.73, positive predictive value of 0.43, and negative predictive value of 0.98, for a disease prevalence of 15%, with a positive likelihood ratio of 3.39 and negative likelihood ratio of 0.10.

Conclusions and relevance: In this single-center, prospective cohort study of symptomatic children with CSF shunts, a change in ONSD measured by ocular POCUS was associated with shunt failure. A change in ONSD from prior asymptomatic baseline to symptomatic presentation of less than 0.4 mm identified a population at low risk of true shunt failure. Further research is warranted to validate these findings, the presented change in ONSD threshold, and to risk stratify low-risk patients for cross-sectional neuroimaging.

Figure 1.. Flow Diagram of Included Participants

ED indicates emergency department.

Figure 2.. Differences in Change in Optic Nerve Sheath Diameter (ONSD) and Change in Optic Disc Elevation (ODE) Among Patients With or Without Shunt Failure

Box plots depicting differences between full shunt failure and no failure and ocular ultrasonographic measures (ODE and ONSD) with corresponding 95% CIs. Mean measures averaged the change in ONSD and change in ODE of the left and right eyes. Highest measures took the highest change in ONSD or change in ODE of the right and left eyes. Vertical lines indicate 95% CIs. The middle line inside the box indicates the median. The top of the box and the bottom of the box indicate the upper and lower quartiles, respectively, and the dots indicate outliers.

Figure 3.. Receiver Operating Characteristic Curve: Change in Optic Nerve Sheath Diameter (ONSD) and Shunt Failure

Receiver operating characteristic curve depicting test properties of the highest change measure in ONSD from either eye using the outcome of full shunt failure (A) and intermittent or full shunt failure (B). Additionally, the threshold value maximizing the difference between true-positive rate and false-positive rate (arrowhead) is presented. AUROC indicates area under the receiver operating characteristic curve.