The Use of Ultrasound-Measured Optic Nerve Sheath Diameter to Predict Ventriculoperitoneal Shunt Failure in Children

Abstract

Objective The goal of this study was to assess the accuracy of ultrasound-measured optic nerve sheath diameter (ONSD) as a screen for ventriculoperitoneal shunt failure. Methods We prospectively enrolled a convenience sample of children presenting to the ED with suspected shunt failure. The ONSD was measured by ultrasound and compared with computed tomography/magnetic resonance imaging (CT/MRI) and neurosurgical impression. We defined shunt failure on ultrasound as an ONSD greater than 4.0 mm in infants 12 months and younger or greater than 4.5 mm in children older than 12 months. A single emergency radiologist at our institution read all CTs and MRIs for categorical determination of shunt failure. We defined shunt failure based on neurosurgical impression as a decision to admit and perform shunt revision. We report test characteristics and 95% confidence intervals of ONSD as a predictor for shunt failure. Results We enrolled 32 subjects. The sensitivities of ONSD compared with CT/MRI and neurosurgical impression, 60.0% and 75.0%, respectively, were low. However, the negative predictive values of ONSD compared with CT/MRI and neurosurgical impression were 90.0% and 95.0%, respectively. Conclusions Optic nerve sonography may be a useful tool to identify children presenting with suspected ventriculoperitoneal shunt failure who do not require further imaging. This would reduce the use of CT scan and exposure to ionizing radiation in children with suspected shunt malfunction who do not require neurosurgical intervention. Consideration of additional risk factors and a larger sample size may yield stronger results.

Imaging Strategies for Suspected Acute Cranial Shunt Failure: A Cost-Effectiveness Analysis

“…In our model, we assigned values (or utilities) to health outcomes using a standard Health Utilities Index scale ranging from 0 (death) to 1 (baseline health, assumed as perfect health for this hypothetical population). The Health Utilities Index is a 15-item questionnaire designed to ask the minimum number of questions required to classify a subject's 10%-50% Sensitivity of CT 32 -37 66% 53%-88% Specificity of CT 32 -37 87% 76%-96% Sensitivity of fsMRI 32,36,38 58% 51%-78% Specificity of fsMRI 32,36,38 93% 89%-98% Sensitivity of ONSD 16 -19 75% 61%-83% Specificity of ONSD 16 -19 32% 22%-38% Sensitivity of SS 33 -35, 37 19% 4%-30% Specificity of SS 33 -35, 37 95% 91%-98% Probability of death and/or missed diagnosis a 0.1% (1:1000) 0.01%-0.2% Probability of radiation-induced malignancy 9,11,21,31,39 0.22% 0.07%-0.6%…”

“…16,17,21 Although the overall sensitivity of ONSD in detecting elevated ICP is modest, the high negative predictive value of this noninvasive point of care test supports its use as a screening tool, which may help identify patients with suspected shunt malfunction for whom an advanced imaging test like CT or MRI is not warranted. 20,21 With respect to the time course of development and resolution of changes in ONSD, a study of isolated human optic nerves has shown ONSD changes within minutes of pressure changes induced by intrathecal infusion, making its measurement a potentially accurate real time reflection of ICP. 22 Two case reports have also described a rapid reduction in ONSD after a therapeutic lumbar puncture for idiopathic intracranial hypertension.…”

Optic nerve ultrasound and cardiopulmonary bypass

“…Various investigators have demonstrated a clinically useful correlation between ONSD and ICP in children. [ 22 23 24 25 26 ] Beare et al . [ 23 ] compared the findings of optic ultrasound (ONSD) in children with acute neurological diseases, comparing those with and without clinical signs of increased ICP.…”

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

“…Studies of POCUS of ONSD in children undergoing evaluations for increased ICP are limited to small prospective and retrospective case series [ 15 , 17 , 18 , 21 , [23] , [24] , [25] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] ]. These studies have compared POCUS of ONSD with clinical signs of increased ICP on CT imaging or direct ICP measurements by lumbar puncture or invasive intracranial monitoring devices.…”