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

Measurement of Optic Nerve Sheath Diameter by Computed Tomography in the Pediatric Population: Normal Values

PURPOSE

To determine the normal values of optic nerve sheath diameter (ONSD) by computed tomography (CT) in the pediatric population.

METHODS

The CT scans of pediatric patients aged 1 to 16 years who underwent brain CT for different reasons, who did not have intracranial pathology or increased intracranial pressure, and who had no pathology on CT were included in the study. Four age groups were defined with the following ranges: 1 to 2, 3 to 6, 7 to 10, and 11 to 16 years. ONSD was measured from axial CT images, 3 and 10 mm behind the optic globe.

RESULTS

The normative values of ONSD measured on CT imaging in children aged 1 to 16 years were reported. The change in ONSD according to age was investigated. ONSD was found to increase with age at both levels measured. The difference was statistically significant.

CONCLUSIONS

Normal values should be known to detect pathologies that may cause an increase in optic nerve diameter. The values reported in this study can serve as a reference for normal optic nerve sheath diameter in the pediatric age group. [J Pediatr Ophthalmol Strabismus. 2024;61(1):38-43.].

The role of sonographic optic nerve sheath diameter measurements in pediatric head trauma

PURPOSE

To determine the accuracy of bedside sonographic measurements of optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse (ETD) diameter ratios to predict space-occupying lesions (SOLs) or elevated intracranial pressure (ICP) in pediatric head trauma.

METHODS

Children who presented to the emergency department with head trauma and underwent cranial computed tomography (CT) were enrolled and examined by ocular ultrasonography (US), and the ONSD was measured at 3 mm posterior to the globe and ETD were measured. Ratios of ONSD at 3 mm/ETD were calculated. All ONSD measurements and ratios were calculated from cranial CT images.

RESULTS

Subjects with elevated ICP had increased ONSD measurements and ratios. To predict elevated ICP, the AUC for ONSD at 3 mm was 0.956 (95% CI 0.896-1). At a cut-off level of 5.1 mm, the sensitivity and specificity of ONSD 3 mm values for elevated ICP were 92.9% and 94.0%. For the ONSD 3 mm/ETD ratio, it was 0.980 (95% CI 0.959-1). At a cut-off level of 0.22, the sensitivity and specificity were 100% sensitivity and 88.0%. All sonographic ONSD measurements and ratios were significantly correlated with readings calculated from cranial CT images.

CONCLUSION

Sonographic ONSD measurements and ratios were found to be quite sensitive to detect elevated ICP on cranial CT images. Additionally, there was a significant correlation between measurements calculated by ocular US and cranial CT scans. Bedside ocular US seems to be a promising and useful tool to determine ICP in children with head trauma.

Ultrasound measurement of the optic nerve sheath diameter in traumatic brain injury: a narrative review

Background : Raised intracranial pressure (ICP) needs to be investigated in various situations, especially in traumatic brain injury (TBI). Ultra-sonographic (US) measurement of the optic nerve sheath diameter (ONSD) is a promising noninvasive tool for assessing elevated ICP. Objectives : This narrative review aimed to explain the history of and indications forUS measurement of ONSD. We focused on the detection of elevated ICP after TBI and discussed the possible improvements in detection methods. Conclusions : US measurement of ONSD in TBI cases provides a qualitative but no quantitative assessment of ICP. Current studies usually calculate their own optimum cutoff value for detecting raised ICP based on the balance between sensitivity and specificity of the method when compared with invasive methods. There is no universally accepted threshold. We did not find any paper focusing on the prognosis of patients benefiting from it when compared with usual care. Another limitation is the lack of standardization. US measurement of ONSD cannot be used as the sole technique to detect elevated ICP and monitor its evolution, but it can be a useful tool in a multimodal protocol and it might help to determine the prognosis of patients in various situations.

Determination of ventriculoperitoneal shunt dysfunction using optic nerve sheath diameter measurement on CT scan in pediatric patients with hydrocephalus

PURPOSE

We aimed to evaluate whether optic nerve sheath diameter (ONSD) measurement by computed tomography (CT) can be a diagnostic criteria for the detection of ventriculoperitoneal shunt dysfunction among children whose fontanels are still open.

METHODS

Patients with a ventriculoperitoneal shunt who were currently showing clinical and radiological signs of acute hydrocephalus depending on the shunt dysfunction were included in this study. The study was designed to compare the preoperative and postoperative ONSDs of three groups of patients divided according to their ages: group 1, patients aged < 4 months; group 2, patients aged 4-18 months; and group 3, patients aged > 18 months.

RESULTS

We included 138 patients (mean age, 35.18 ± 51.01 months). Among the patients, 46.4% were females and 53.6% were males. ONSD measurements in the preoperative period were < 2.86 ± 0.59 in group 1, 3.93 ± 0.82 in group 2, and 5.40 ± 0.81 in group 3 and those in the postoperative period were 2.02 ± 0.38 in group 1, 2.72 ± 0.62 in group 2, and 3.64 ± 0.81 in group 3. Right, left, and mean ONSDs increased significantly in the three groups and were found to be statistically significant.

CONCLUSION

ONSD measurement in CT has been evaluated as an appropriate finding that can be used especially in acute hydrocephalus, when clinical and radiological findings are not diagnostic.

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

Point-of-care ultrasound has been widely used by clinicians at the bedside in recent years. Various types of point-of-care ultrasound practices are employed, especially in pediatric emergency rooms and intensive care units. Pediatric intensive care specialists perform point-of-care ultrasound virtually as a part of physical examination since it provides just-in-time vital clinical information, which could assist in acute management strategies in critically ill patients. Measurement of optic nerve sheath diameter using point-of-care ultrasound is a noninvasive and radiation-free technique to determine raised intracranial pressure. Ophthalmic artery and central retinal artery Doppler indices can be used as transcranial Doppler to assess raised intracranial pressure. The aim of this review was to provide detailed information on ultrasonographic measurements of optic nerve sheath diameter and central retinal artery Doppler indices as techniques of interest for predicting increased intracranial pressure in pediatric patients in view of the literature.

Diagnostic modalities to determine ventriculoperitoneal shunt malfunction: A systematic review and meta-analysis

BACKGROUND

Ventriculoperitoneal (VP) shunt malfunction is an emergency. Timely diagnosis can be challenging because shunt malfunction often presents with symptoms mimicking other common pediatric conditions.

METHODS

We performed a systematic review and meta-analysis to determine which commonly used imaging modalities; Magnetic resonance imaging (MRI), Computed Tomography (CT), X-ray Shunt series or Optic Nerve Sheath Diameter (ONSD) ultrasound, are superior in evaluating shunt malfunction.

INCLUSION CRITERIA

patients less than 21 years old with symptoms of shunt malfunction. We calculated the pooled sensitivity, specificity, Likelihood Ratios (LR+, LR-) using a random-effects model.

RESULTS

Eight studies were included encompassing 1906 patients with a prevalence of VP shunt malfunction of (29.3%). Shunt series: sensitivity (14%-53%), specificity (99%), LR+ (23.2), and LR- (0.47-0.87). CT scan: sensitivity (53%-100%), specificity (27%-98%), LR+ (1.34-22.87), LR- (0.37). MRI: sensitivity (57%), specificity (93%), LR+ (7.66), and LR- (0.49). ONSD: sensitivity (64%), specificity (22%-68%), LR+ (4.4-8.7), LR- (0.93). A positive shunt series, CT scan, MRI, or ONSD has a post-test probability of (23%-84%). A normal shunt series, CT scan, MRI, or ONSD results in a post-test probability of (7%-31%). A positive shunt series results in a post-test probability of 80%, which is equivalent to the post-test probability of CT scan (23-84%) and MRI (83%).

CONCLUSION

Despite the low sensitivity, a positive shunt series obviates the need for further imaging studies. Prompt referral for neurosurgical intervention is recommended. A negative shunt series or any result (positive or negative) from CT, MRI, or ONSD will still require an emergent neurosurgical referral.

Determination of normal values of optic nerve sheath diameter in newborns with bedside ultrasonography

OBJECTIVES

Bedside sonographic opthalmic ultrasound measurement of optic nerve sheath diameter (ONSD) is an easy, portabl, noninvasive and a radiation free technique to determine increased intracranial pressure. This prospective, multicenter study was aimed to establish the range of normal values for ONSD in preterm and term newborns with a large study population.

METHODS

Newborns without intracranial pathology in the Newborn Intensive Care Units and in Obstetrics and Gynecology Departments were enrolled in the study. ONSD was measured at 3 mm distance behind of the right optic nerve head. As 3 mm distance was beyond the optic nerve head in some of the premature newborns, we had also measurements at 2 and 2.5 mm.

RESULTS

ONSD was measured in 554 newborns. Mean ONSD of preterm babies at 2, 2.5 and 3 mm distances were 3.2 ± 0.3 mm (range 2.0-4.2 mm), 3.3 ± 0.3 mm (range 2.2-4.5 mm) and 3.6 ± 0.2 mm (range 2.9-4.5 mm), (p_{2.0-2.5 mm} < 0.001, p _2.5-3.0mm < 0.001, p_{2.0-3.0 mm} < 0.001) respectively. Mean ONSD of term babies at 3 mm was higher than the mean ONSD of preterm babies in 33 weeks 0 day- 37 weeks 0 days group (p < 0.001). In correlation analysis, a significant, strong and positive correlation was found between ONSD measurements and gestational age, weight, height and head circumference at 2, 2.5 and 3 mm distances.

CONCLUSION

The normal values reported by the present study may be used for evaluating the ONSD of newborns with different conditions with increased incracranial pressure.

Effects of prone positioning with neck extension on intracranial pressure according to optic nerve sheath diameter measured using ultrasound in children

PURPOSE

Optic nerve sheath diameter has been used for measure of intracranial pressure. The aim of this study was to evaluate the effect of prone positioning with neck extension on intracranial pressure in infants undergoing craniosynostosis surgery and to determine precautions using optic nerve sheath diameter measurement.

METHODS

We enrolled 30 infants who were scheduled for correction of craniosynostosis in which planning included the prone position with neck extension. Optic nerve sheath diameter (anterior/lateral transbulbar approach) was measured 5 times in each eyeball at the following time points: 15 min after intubation in supine position as the baseline value (supine 1); 10 min after final surgical position before skin incision (prone); and 10 min after returning to supine position at the conclusion of surgery (supine 2). Hemodynamic parameters, airway peak pressure, oxygen saturation, and E_TCO₂ were monitored. Data were analyzed using repeated-measures multivariate analysis of variance to evaluate the effect of different positions under anesthesia on changes in using optic nerve sheath diameter and P < 0.05 was considered to be statistically significant.

RESULTS

There was no difference in optic nerve sheath diameter after prone position with neck extension in all the measure. After surgery, optic nerve sheath diameter was decreased compared with the preoperative baseline values (Rt anterior/lateral 5.6/5.5: 5.4/5.2; Lt anterior/lateral 5.6/5.5: 5.4/5.3, P < 0.05, respectively).

CONCLUSIONS

In conclusion, prone positioning with head extension did not further increase intracranial pressure, although the surgical procedure could reduce intracranial pressure in the immediate postoperative period in infants undergoing craniosynostosis surgery.

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

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.

Bedside Optic Nerve Ultrasonography for Diagnosing Increased Intracranial Pressure: A Systematic Review and Meta-analysis

BACKGROUND

Optic nerve ultrasonography (optic nerve sheath diameter sonography) has been proposed as a noninvasive, quick method for diagnosing increased intracranial pressure.

PURPOSE

To examine the accuracy of optic nerve ultrasonography for diagnosing increased intracranial pressure in children and adults.

DATA SOURCES

13 databases from inception through May 2019, reference lists, and meeting proceedings.

STUDY SELECTION

Prospective optic nerve ultrasonography diagnostic accuracy studies, published in any language, involving any age group or reference standard.

DATA EXTRACTION

3 reviewers independently abstracted data and performed quality assessment.

DATA SYNTHESIS

Of 71 eligible studies involving 4551 patients, 61 included adults, and 35 were rated as having low risk of bias. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of optic nerve ultrasonography in patients with traumatic brain injury were 97% (95% CI, 92% to 99%), 86% (CI, 74% to 93%), 6.93 (CI, 3.55 to 13.54), and 0.04 (CI, 0.02 to 0.10), respectively. Respective estimates in patients with nontraumatic brain injury were 92% (CI, 86% to 96%), 86% (CI, 77% to 92%), 6.39 (CI, 3.77 to 10.84), and 0.09 (CI, 0.05 to 0.17). Accuracy estimates were similar among studies stratified by patient age, operator specialty and training level, reference standard, sonographer blinding status, and cutoff value. The optimal cutoff for optic nerve sheath dilatation on ultrasonography was 5.0 mm.

LIMITATION

Small studies, imprecise summary estimates, possible publication bias, and no evaluation of effect on clinical outcomes.

CONCLUSION

Optic nerve ultrasonography can help diagnose increased intracranial pressure. A normal sheath diameter measurement has high sensitivity and a low negative likelihood ratio that may rule out increased intracranial pressure, whereas an elevated measurement, characterized by a high specificity and positive likelihood ratio, may indicate increased intracranial pressure and the need for additional confirmatory tests.

PRIMARY FUNDING SOURCE

None. (PROSPERO: CRD42017055485).

Reducing the radiation exposure from CT scanning in children with shunts: a nationwide survey and a departmental CT protocol

INTRODUCTION

Low dose ionising radiation such as from CT scans carries a low but cumulative risk of cancer and children are particularly sensitive. Children with VP Shunts often undergo multiple CT scans. We developed a CT protocol with reduced radiation for paediatric patients with shunts and compared it with the current practice in the other neurosurgical units in the UK and ROI by conducting a nationwide survey.

METHODS

An email questionnaire was send to the superintendent radiographer in every Neurosurgical unit in the UK and the ROI.

RESULTS

The response rate was 70%. Only 5 (19%) of the responding units used a dedicated CT shunt protocol with reduced radiation. Radiation was reduced by lowering the tube current. In comparison, our protocol uses a combination of less tube current and fewer slices. This reduced the radiation exposure of a CT head significantly with sufficient image quality to make a diagnosis.

CONCLUSION

Radiation from CT for paediatric shunt patients scans can and should be reduced. This can be achieved by using reduced radiation protocols. A national paediatric CT shunt protocol could lead to significant reduction in effective radiation dose.

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

OBJECTIVES

We compared cost-effectiveness of cranial computed tomography (CT), fast sequence magnetic resonance imaging (fsMRI), and ultrasonography measurement of optic nerve sheath diameter (ONSD) for suspected acute shunt failure from the perspective of a health care organization.

METHODS

We modeled 4 diagnostic imaging strategies: (1) CT scan, (2) fsMRI, (3) screening ONSD by using point of care ultrasound (POCUS) first, combined with CT, and (4) screening ONSD by using POCUS first, combined with fsMRI. All patients received an initial plain radiographic shunt series (SS). Short- and long-term costs of radiation-induced cancer were assessed with a Markov model. Effectiveness was measured as quality-adjusted life-years. Utilities and inputs for clinical variables were obtained from published literature. Sensitivity analyses were performed to evaluate the effects of parameter uncertainty.

RESULTS

At a previous probability of shunt failure of 30%, a screening POCUS in patients with a normal SS was the most cost-effective. For children with abnormal SS or ONSD measurement, fsMRI was the preferred option over CT. Performing fsMRI on all patients would cost $269 770 to gain 1 additional quality-adjusted life-year compared with POCUS. An imaging pathway that involves CT alone was dominated by ONSD and fsMRI because it was more expensive and less effective.

CONCLUSIONS

In children with low pretest probability of cranial shunt failure, an ultrasonographic measurement of ONSD is the preferred initial screening test. fsMRI is the more cost-effective, definitive imaging test when compared with cranial CT.