Optic nerve sheath ultrasound in the assessment of paediatric hydrocephalus

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.

Optic Nerve Sheath Diameter Ultrasound: A Non-Invasive Approach to Evaluate Increased Intracranial Pressure in Critically Ill Pediatric Patients

Early diagnosis of increased intracranial pressure (ICP) is crucial for prompt diagnosis and treatment of intracranial hypertension in critically ill pediatric patients, preventing secondary brain damage and mortality. Although the placement of an external ventricular drain coupled to an external fluid-filled transducer remains the gold standard for continuous ICP monitoring, other non-invasive approaches are constantly being improved and can provide reliable estimates. The use of point-of-care ultrasound (POCUS) for the assessment of ICP has recently become widespread in pediatric emergency and critical care settings, representing a valuable extension of the physical examination. The aim of this manuscript is to review and discuss the basic principles of ultra-sound measurement of the optic nerve sheath diameter (ONSD) and summarize current evidence on its diagnostic value in pediatric patients with ICP. There is increasing evidence that POCUS measurement of the ONSD correlates with ICP, thus appearing as a useful extension of the physical examination in pediatrics, especially in emergency medicine and critical care settings for the initial non-invasive assessment of patients with suspected raised ICP. Its role could be of value even to assess the response to therapy and in the follow-up of patients with diagnosed intracranial hypertension if invasive ICP monitoring is not available. Further studies on more homogeneous and extensive study populations should be performed to establish ONSD reference ranges in the different pediatric ages and to define cut-off values in predicting elevated ICP compared to invasive ICP measurement.

Utility of Serial Optic Nerve Sheath Diameter Measurements in Patients Undergoing Cerebral Spinal Fluid Diversion Procedures for Hydrocephalus

BACKGROUND

Functional status of cerebrospinal fluid (CSF) diversion procedure for hydrocephalus is difficult to assess on several occasions. We report the use of serial ultrasonographic measurement of optic nerve sheath diameter (ONSD) to assess the functional status of CSF diversion procedures in patients with hydrocephalus.

METHODS

In this prospective observational study, ultrasonographic ONSD measurement was performed preoperatively, on postoperative days 1, 3, and 7 (n = 51 at each time point) and at follow-up (n = 31) in patients undergoing ventriculoperitoneal shunt or endoscopic third ventriculostomy for hydrocephalus. Change in ONSD values during first week after CSF diversion procedure and at follow-up were correlated with ventriculoperitoneal shunt/ETV function.

RESULTS

ONSD ≥5.5 mm strongly correlated with clinical and imaging features of raised ICP (P < 0.001). Mean ONSD progressively decreased in the postoperative period and was the lowest on postoperative day 7 (P < 0.001) with >95% of patients having ONSD <5.5 mm at that time point. At follow-up (median, 12 months; n = 31), ONSD had further reduced in 78.6% of patients. All 3 patients with shunt dysfunction had an increase in the ONSD value compared with that on postoperative day 7.

CONCLUSIONS

ONSD measurement on postoperative day 7 after CSF diversion correlates well with early surgical outcome but decreases further in many patients at a follow-up of 12 months. Rise in postoperative day 7 ONSD at follow-up correlates with failure of the CSF diversion procedure.

Ultrasonographic Optic Nerve Sheath Diameter Measurement to Detect Intracranial Hypertension in Children With Neurological Injury: A Systematic Review

OBJECTIVES

Ultrasound measured optic nerve sheath diameter is a noninvasive, nonirradiating tool for estimating intracranial hypertension. The objective of this systematic review and meta-analysis is summarization of the current evidence for accuracy of ultrasound measured optic nerve sheath diameter in detecting intracranial hypertension in pediatric patients.

DATA SOURCES

Medical subject heading terms were used to search MEDLINE, Embase, Google Scholar, Web of Science, and the Cochrane Library for relevant citations. Publications from January 1, 2000, to June 30, 2019, were included in the search strategy.

STUDY SELECTION

Studies were included if they involved patients less than 18 years, where ultrasound measured optic nerve sheath diameter was compared to conventional, nonophthalmic tests for intracranial hypertension. Studies were excluded if there was insufficient data to compute a sensitivity/specificity table. Case reports, case series, and manuscripts not published in English were also excluded.

DATA EXTRACTION

The initial search returned 573 citations. Of these, 57 were selected for review.

DATA SYNTHESIS

Eleven citations were included in the final meta-analysis. A bivariate random-effects meta-analysis was performed, which revealed a pooled sensitivity for ultrasound measured optic nerve sheath diameter of 93% (95% CI, 74-99%), a specificity of 74% (95% CI, 52-88%), and a diagnostic odds ratio of 39.00 (95% CI, 4.16-365.32). The area under the curve of the hierarchical summary receiver operating characteristic curve was 0.90 (95% CI, 0.87-0.93). Subgroup analyses of the test's performance evaluating new-onset intracranial hypertension and in comparison to invasively measured intracranial pressure were performed. The test performance in these instances was similar to findings in the primary analysis.

CONCLUSIONS

We are unable to identify a threshold value in ultrasound measured optic nerve sheath diameter for the determination of intracranial hypertension in children. Even though the ultrasound measured optic nerve sheath diameter measurement is highly sensitive to the presence of increased intracranial pressure, the test has only moderate specificity. Therefore, other confirmatory methods and further investigation is necessary in the clinical care of children. The technique is likely not sufficiently precise for clinical use in the absence of other confirmatory methods, and further investigation is necessary to determine clinical protocols for its use in children.

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.

Effect of neck extension on ultrasonographic optic nerve sheath diameter as a surrogate for intracranial pressure in patients undergoing palatoplasty: A prospective observational study

Palatoplasty is performed with neck extension in patients with a cleft palate. The neck extension required for a better surgical view during palatoplasty can affect intracranial pressure. We evaluated the effect of neck extension on intracranial pressure by measuring the optic nerve sheath diameter using ultrasonography during palatoplasty. The optic nerve sheath diameter was measured in 30 patients at 10 min after anesthetic induction in the supine position (T1), at 10 min after neck extension before preparing for a sterile field (T2), at the end of surgery with neck extension (T3), and at 10 min after the supine position (T4). Hemodynamic and respiratory variables such as systolic blood pressure, heart rate, end-tidal carbon dioxide partial pressure, and peak airway pressure were also measured at the same time points. In comparison with the optic nerve sheath diameter measured at 10 min after anesthetic induction in the supine position (T1), the mean optic nerve sheath diameters were significantly increased at 10 min after neck extension before preparing for a sterile field (T2), at the end of surgery with neck extension (T3), and at 10 min after the supine position (T4; 4.19 ± 0.26, 5.20 ± 0.29, 4.38 ± 0.36, and 4.35 ± 0.30 mm, respectively). However, hemodynamic and respiratory variables were not significantly different at all time points. We found that the optic nerve sheath diameter, an indicator of intracranial pressure, was increased during palatoplasty with neck extension, which suggests that the position may affect the intracranial pressure of patients with a cleft palate.

Moving Beyond the Stethoscope: Diagnostic Point-of-Care Ultrasound in Pediatric Practice

Diagnostic point-of-care ultrasound (POCUS) is a growing field across all disciplines of pediatric practice. Machine accessibility and portability will only continue to grow, thus increasing exposure to this technology for both providers and patients. Individuals seeking training in POCUS should first identify their scope of practice to determine appropriate applications within their clinical setting, a few of which are discussed within this article. Efforts to build standardized POCUS infrastructure within specialties and institutions are ongoing with the goal of improving patient care and outcomes.

Determination of cerebral edema with serial measurement of optic nerve sheath diameter during treatment in children with diabetic ketoacidosis: a longitudinal study

Background Cerebral edema is a fatal complication that can occur in children with diabetic ketoacidosis (DKA). Its clinical signs are generally not explicit, and subclinical cerebral edema can occur. This study is one of the few longitudinal studies conducted to identify cerebral edema in patients with DKA by measuring the optic nerve sheath diameter (ONSD). The aim of this study was to investigate cerebral edema in children with DKA with serial measurement of ONSD, which is an early and reliable indicator of cerebral edema, and to monitor changes in ONSD during therapy. Methods The study was conducted by measuring ONSD ultrasonographically at baseline and during the course of therapy in patients with DKA. All participants were diagnosed and received therapy at our unit between May 2016 and June 2017. The study was registered with the Clinical Trials database, with a study number of NCT02937441. Measurements were obtained while the patients were in the supine position with their eyes closed, and axial transbulbar images of both eyes were obtained with a 6-15-MHz linear probe. Results The ONSD values of children with DKA changed during the treatment, reaching the highest values at 12-16 h of therapy, and the greatest ONSD was observed in children who had moderate and severe DKA. Conclusions During treatment of children with DKA, it is possible to predict cerebral edema by measuring ONSD, and this may contribute to clinical management, especially fluid treatment.

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

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.

Optic Nerve Sheath Diameter for Preterm Infants: A Pilot Study

OBJECTIVE

In preterm infants, early diagnosis and management of a raised intracranial pressure (ICP) may be important to improve neurodevelopmental outcomes. While invasive ICP monitoring is not recommended, ultrasonography of the optic nerve sheath diameter (ONSD) could provide a noninvasive alternative to evaluate ICP. The objective of this pilot study was to document ranges of ONSD in preterm infants.

METHODS

This prospective cohort pilot evaluated preterm infants who were admitted to the neonatal intensive care unit without suspected raised ICP. Three images per eye were obtained from a 20-5 MHz linear array ultrasound transducer placed on the patient's superior eyelid. The OSND was measured 3 mm behind the globe. A second ultrasonographer duplicated half of the scans. Multiple linear regression analysis was conducted for both right and left ONSD with corrected gestational age, weight, and head circumference as predictors. Lin's concordance assessed interrater reliability.

RESULTS

In 12 preterm infants 114 scans were performed on both eyes. The median age was 33 weeks (corrected gestational age) with a range of 29-36 weeks. Corrected gestational age was the strongest predictor for ONSD, and preliminary measurements at each gestational age were established. Interrater reliability demonstrated substantial agreement (Qc = 0.97).

CONCLUSION

In preterm infants, ONSD strongly correlates with corrected gestational age. These data should be validated with other imaging modalities before abnormal ranges can be considered.

Point-of-care ultrasound in pediatric anesthesiology and critical care medicine

Ultrasound has increasingly become a clinical asset in the hands of the anesthesiologist and intensivist who cares for children. Though many applications for ultrasound parallel adult modalities, children as always are not simply small adults and benefit from the application of ultrasound to their management in various ways. Body composition and size are important factors that affect ultrasound performance in the child, as are the pathologies that may uniquely afflict children and aspects of procedures unique to this patient population. Ultrasound simplifies vascular access and other procedures by visualizing structures smaller than those in adults. Maturation of the thoracic cage presents challenges for the clinician performing pulmonary ultrasound though a greater proportion of the thorax can be seen. Moreover, ultrasound may provide unique solutions to sizing the airway and assessing it for cricothyroidotomy. Though cardiac ultrasound and neurosonology have historically been performed by well-developed diagnostic imaging services, emerging literature stresses the utility of clinician ultrasound in screening for pathology and providing serial observations for monitoring clinical status. Use of ultrasound is growing in clinical areas where time and diagnostic accuracy are crucial. Implementation of ultrasound at the bedside will require institutional support of education and credentialing. It is only natural that the pediatric anesthesiologist and intensivist will lead the incorporation of ultrasound in the future practice of these specialties.

Pulsatile Dynamics of the Optic Nerve Sheath and Intracranial Pressure: An Exploratory In Vivo Investigation

BACKGROUND

Raised intracranial pressure (ICP) may lead to increased stiffness of the optic nerve sheath (ONS).

OBJECTIVE

To develop a method for analyzing ONS dynamics from transorbital ultrasound and investigate a potential difference between patients with raised ICP vs normal ICP.

METHODS

We retrospectively analyzed data from 16 patients (≤12 years old) for whom ultrasound image sequences of the ONS had been acquired from both eyes just before invasive measurement of ICP. Eight patients had an ICP ≥20 mm Hg. The transverse motion on each side of the ONS was estimated from ultrasound, and Fourier analysis was used to extract the magnitude of the displacement corresponding to the heart rate. By calculating the normalized absolute difference between the displacements on each side of the ONS, a measure of ONS deformation was obtained. This parameter was referred to as the deformability index. According to our hypothesis, because deformability is inversely related to stiffness, we expected this parameter to be lower for ICP ≥20 mm Hg compared with ICP <20 mm Hg. The one-sided Mann-Whitney U test was used for statistical comparison.

RESULTS

The deformability index was significantly lower in the group with ICP ≥20 mm Hg (median value 0.11 vs 0.24; P = .002).

CONCLUSION

We present a method for assessment of ONS pulsatile dynamics using transorbital ultrasound imaging. A significant difference was noted between the patient groups, indicating that deformability of the ONS may be relevant as a noninvasive marker of raised ICP. The clinical implications are promising and should be investigated in future clinical studies.

ABBREVIATIONS

AUC, area under curveICP, intracranial pressureONS, optic nerve sheathONSD, optic nerve sheath diameterROC, receiver operating characteristic.

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.

Precision Medicine With Point-of-Care Ultrasound: The Future of Personalized Pediatric Emergency Care

The Precision Medicine Initiative spearheaded by the National Institute of Health has pioneered a new model of health care focused on health care delivery that is tailored to an individual. Medical advances have already provided clinicians with the tools to better predict treatment outcomes based on the individual needs of each patient's disease process. Three-dimensional printing allows medical devices and implants to be custom made-to-order. Technological advances in preoperative imaging have augmented the ability for surgeons to plan a specific surgical approach for each patient. In a similar vein, point-of-care ultrasound offers the emergency care provider an opportunity to move beyond protocols and provide precise medical care tailored to the acute needs of each ill or injured emergent patient. In this article, we explore several cutting-edge applications of point-of-care ultrasound that can help providers develop a personalized approach to resuscitation and emergent procedures in pediatrics.

Optic Nerve and Cerebral Edema in the Course of Diabetic Ketoacidosis

In the recent years we have been observing an increased incidence of type 1 diabetes in children and adolescents. This leads to a more frequent acute complication of type 1 diabetes among children with hyperglycemia. The most common of these is diabetic ketoacidosis (DKA), while cerebral edema is the most dangerous. In children with DKA, cerebral edema most often presents with clinical symptoms but may also appear in the so-called "subclinical" form. That is why the search continues for new methods of assessing and monitoring cerebral edema in the course of DKA treatment. Ultrasonographic optic nerve sheath diameter (US ONSD) assessment is performed in various clinical scenarios when cerebral edema is suspected. It is most often performed in adult patients but increasingly often in children. US ONSD assessment is useful in the treatment of DKA in children with type 1 diabetes. This manuscript provides an overview of research results available in PubMed and other available databases on the course of treatment of DKA in children with type 1 diabetes.

Pediatric emergency medicine point-of-care ultrasound: summary of the evidence

The utility of point-of-care ultrasound is well supported by the medical literature. Consequently, pediatric emergency medicine providers have embraced this technology in everyday practice. Recently, the American Academy of Pediatrics published a policy statement endorsing the use of point-of-care ultrasound by pediatric emergency medicine providers.  To date, there is no standard guideline for the practice of point-of-care ultrasound for this specialty. This document serves as an initial step in the detailed "how to" and description of individual point-of-care ultrasound examinations.  Pediatric emergency medicine providers should refer to this paper as reference for published research, objectives for learners, and standardized reporting guidelines.

The relationship between transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) and invasively measured ICP in children. : Part II: age-related ONSD cut-off values and patency of the anterior fontanelle

PURPOSE

To analyse the diagnostic accuracy of age-related optic nerve sheath diameter (ONSD) cut-off values in children for detecting raised intracranial pressure (ICP) and to assess the benefit of using patency of the anterior fontanelle in describing a different set of cut-off values.

METHODS

The ONSD measurement was performed prior to invasive ICP measurement in children under general anesthesia. The diagnostic accuracy of the ONSD measurement was compared to ICP at thresholds of 20, 15, 10, and 5 mmHg. This was further analysed in children above and below the age of 1 year, with a subgroup analysis of age at 4 years, and assessment of the anterior fontanelle (AF) as a reliable physiological marker in part II of this study.

RESULTS

Data from 174 children were analysed. In children ≤1 year old, the ONSD measurement with the best diagnostic accuracy for detecting ICP ≥ 20 mmHg was 5.16 mm, compared to 5.75 mm in children >1 year old (p < 0.001). In addition, patency of the anterior fontanelle (AF) was found to be a useful clinical marker for defining different ONSD cut-off values at ICP thresholds of 20, 15, 10 and 5 mmHg.

CONCLUSION

Transorbital ultrasound measurement of the ONSD is a reliable non-invasive marker of ICP particularly at higher thresholds of 20 and 15 mmHg. Patency of the AF is a useful clinical marker for defining different ONSD cut-off values in children.

The relationship between transorbital ultrasound measurement of the optic nerve sheath diameter (ONSD) and invasively measured ICP in children : Part I: repeatability, observer variability and general analysis

PURPOSE

The aim of this study was to investigate the relationship between optic nerve sheath diameter (ONSD) measurement and invasively measured intracranial pressure (ICP) in children.

METHODS

ONSD measurement was performed prior to invasive measurement of ICP. The mean binocular ONSD measurement was compared to the ICP reading. Physiological variables including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse rate, temperature, respiratory rate and end tidal carbon dioxide (ETCO2) level were recorded at the time of ONSD measurement. Diagnostic accuracy analysis was performed at various ICP thresholds and  repeatability, intra- and inter-observer variability, correlation between measurements in different imaging planes as well the relationship over the entire patient cohort were examined in part I of this study.

RESULTS

Data from 174 patients were analysed. Repeatability and intra-observer variability were excellent (α = 0.97-0.99). Testing for inter-observer variability revealed good correlation (r = 0.89, p < 0.001). Imaging in the sagittal plane demonstrated a slightly better correlation with ICP (r = 0.66, p < 0.001). The ONSD measurement with the best diagnostic accuracy for detecting an ICP ≥ 20 mmHg over the entire patient cohort was 5.5 mm, sensitivity 93.2 %, specificity 74 % and odds ratio (OR) of 39.3.

CONCLUSION

Transorbital ultrasound measurement of the OSND is a reliable and reproducible technique, demonstrating a good relationship with ICP and high diagnostic accuracy for detecting raised ICP.

A Unique Model for ONSD Part II: Inter/Intra-operator Variability

OBJECTIVE

To evauluate our novel ultrasound model for measurement of optic nerve sheath diameter (ONSD) and determine the intra- and inter-operator variability associated with this technique.

METHODS

We conducted ten measurements of ONSD per model amongst eight different models with a single experienced operator to examine intra-operator variability. Similarly, we had seven different operators measure the OSND twice in eight different models, in order to determine inter-operator variability analyzed with a three level linear statistical model.

RESULTS

For intra-operator variability, the intra-cluster correlation coefficients for the experienced and novice operators were 0.643 and 0.453 respectively. This displayed improvement in intra-operator variability with experience. The inter-cluster correlation coefficient was 0 for the group of novice operators, indicating negligible difference amongst multiple operators in measuring any given model of ONSD. A strong, statistically significant, linear relationship between the actual model disc size and the ultrasound ONSD measures was identified, implying the reliability of the images produced by our novel model.

CONCLUSIONS

Utilizing a novel model for ONSD ultrasonography, we have determined the intraoperator reliability of ONSD measurement to be moderate, with no appreciable difference amongst multiple operators. Improvement in measurement reliability has been demonstrated between expert and novice operators with our model, indicating the potential benefit of simulation platforms for teaching the technique of ONSD ultrasound.

High resolution transbulbar sonography in children with suspicion of increased intracranial pressure

PURPOSE

To evaluate the accuracy of high resolution transbulbar sonography for the estimation of intracranial pressure (ICP) in children.

METHODS

In children and adolescents with acute neurologic symptoms of various origin, transbulbar sonography was performed. Besides measurement of the optic nerve sheath diameter (ONSD), the ultrastructure of the subarachnoid space of the optic nerve sheath was evaluated. The results of transbulbar sonography were correlated with clinical data based on cross-sectional imaging, ICP measurement, and ophthalmologic examination.

RESULTS

Eighty-one patients (age 3-17.8 years, mean 11.7 years) were included. In 25 children, cross-sectional imaging and ICP measurement revealed increased intracranial pressure. The mean ONSD was 6.85 ± 0.81 mm. Twenty patients (20/25, 80 %) had a microcystic appearance of the subarachnoid space of the optic nerve. In 56 children without evidence of increased intracranial pressure, the mean ONSD was 5.77 ± 0.48 mm. Forty-nine patients (49/56, 87.5 %) had a normal homogenous appearance of the subarachnoid space. The ONSD in children with increased intracranial pressure was significantly higher than in patients without (p < 0.001).

CONCLUSION

High resolution transbulbar sonography of the optic nerve is a useful technique for the rapid and non-invasive estimation of intracranial pressure in children. Besides measurement of the optic nerve sheath diameter, evaluation of the ultrastructure of the subarachnoid space of the optic nerve is a helpful parameter.

Sonography of the Optic Nerve Sheath Diameter for Detection of Raised Intracranial Pressure Compared to Computed Tomography: A Systematic Review and Meta-analysis

OBJECTIVES

The diagnosis of raised intracranial pressure (ICP) is important in many critically ill patients. The optic nerve sheath is contiguous with the subarachnoid space; thus, an increase in ICP results in a corresponding increase in the optic nerve sheath diameter. The objective of this study was to assess the diagnostic accuracy of sonography of the optic nerve sheath diameter compared to computed tomography (CT) for predicting raised ICP.

METHODS

We searched PubMed, EMBASE, and the Cochrane database from 1986 to August 2013 and performed hand searches. Two independent reviewers extracted data. Study quality was assessed by using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. We calculated κ agreement for study selection and evaluated clinical and quality homogeneity before the meta-analysis.

RESULTS

From 1214 studies, we selected 45 for full review. Twelve studies with 478 participants were included (κ = 0.89). Ocular sonography yielded sensitivity of 95.6% (95% confidence interval [CI], 87.7%-98.5%), specificity of 92.3% (95% CI, 77.9%-98.4%), a positive likelihood ratio of 12.5 (95% CI, 4.16-37.5), and a negative likelihood ratio of 0.05 (95% CI, 0.02-0.14). Average quality according to the QUADAS tool was 7.4 of 11. There was moderate to high heterogeneity based on the prediction ellipse area and variance logit of sensitivity (2.1754) and specificity (2.6720).

CONCLUSIONS

Ocular sonography shows good diagnostic test accuracy for detecting raised ICP compared to CT: specifically, high sensitivity for ruling out raised ICP in a low-risk group and high specificity for ruling in raised ICP in a high-risk group. This noninvasive point-of-care method could lead to rapid interventions for raised ICP, assist centers without CT, and monitor patients during transport or as part of a protocol to reduce CT use.

Ultrasonographic assessment of optic nerve sheath diameter during pediatric laparoscopy

This study investigated the extent of the raised intracranial pressure resulting from carbon dioxide (CO2) pneumoperitoneum by ultrasonographically measuring optic nerve sheath diameter (ONSD) in children undergoing laparoscopic surgery. Twenty-five children aged less than 9 y (53.1 ± 23.3 mo, mean ± standard deviation) and scheduled for an elective laparoscopic surgery participated. ONSD was assessed using ocular ultrasonography 10 min after induction of anesthesia (T0), 10 min after induction of CO2 pneumoperitoneum at 10 mm Hg intra-abdominal pressure (T1) and in an anesthetized state without CO2 pneumoperitoneum at the conclusion of the surgery (T2). During CO2 pneumoperitoneum, ONSD increased significantly compared with ONSD after anesthesia induction (T0: 4.3 ± 0.3 mm, T1: 4.6 ± 0.3 mm, p < 0.05). In all enrolled patients, any neurologic complications were not observed during the intra-operative or post-operative period. In children undergoing laparoscopic surgery, an increase in ONSD was ascertained during CO2 pneumoperitoneum, and thus the corresponding increase in intracranial pressure could be predicted.

Change in optic nerve sheath diameter as a radiological marker of outcome from endoscopic third ventriculostomy in children

PURPOSE

The purpose of this study was to investigate the value of the change in optic nerve sheath diameter (ONSD) as a radiological marker of endoscopic third ventriculostomy (ETV) outcome in children.

METHODS

Magnetic resonance imaging (MRI) scans of patients on whom ETVs were performed between the periods of January 2009 and June 2013 were reviewed. ONSD measurements on pre- and post-operative images were performed by two blinded observers, and the relationship between the change in these measurements and outcome from ETV were investigated. These findings were then also compared to conventional imaging features associated with ETV outcome.

RESULTS

MRI scans of 24 patients were adequate to measure the ONSD pre- and post-operatively. In patients with successful ETV (n = 19), the mean change in ONSD was 0.73 mm and in patients with a failed ETV (n = 5), the mean change in ONSD was 0.18 mm (p = 0.0007). A change in ONSD of 7.5 % of the initial measurement demonstrated a sensitivity of 92.9 % and a sensitivity of 85.7 % for ETV outcome (area under the receiver operating characteristic curve (AUROC) = 0.96).

CONCLUSION

Change in ONSD is a useful radiological marker of ETV outcome and may be used in combination with conventional radiological parameters to aid decision-making in this difficult group of patients.

Establishing intensivist-driven ultrasound at the PICU bedside--it's about time*

OBJECTIVE

To discuss pediatric intensivist-driven ultrasound and the exigent need for research and practice definitions pertaining to its implementation within pediatric critical care, specifically addressing issues in ultrasound-guided vascular access and intensivist-driven echocardiography.

CONCLUSIONS

Intensivist-driven ultrasound improves procedure safety and reduces time to diagnosis in clinical ultrasound applications, as demonstrated primarily in adult patients. Translating these applications to the PICU requires thoughtful integration of the technology into practice and would best be informed by dedicated ultrasound research in critically ill children.

Optic nerve sheath diameter measurements by CT scan in ventriculoperitoneal shunt obstruction

The objective of the study was to determine differences in optic nerve sheath diameter (ONSD) measurements taken from computed tomography (CT) scans of patients with ventriculoperitoneal shunt (VPS) obstruction versus controls. Inpatients 0-15 years with confirmed VPS obstruction requiring neurosurgical intervention were identified using ICD9 codes. ONSDs, orbit, cranium, and foramen magnum sizes were measured on their pre-surgical CT. Controls included cases at times when their VPS was not obstructed and age and gender matched patients with a CT scan done in the emergency room for head trauma (normal CT findings). Paired T-tests were used for both case-control comparisons. In order to compare the optic nerve sheath size more accurately, the ONSD width was divided by the width of the orbit and by the foramen magnum (antero-posterior) length. Twenty patients were identified with 25 events of VPS obstruction. The right ONSD (RON) was chosen to study. RON/orbit width and RON/foramen magnum diameter for the VPS obstruction versus self-controls, were 0.22 and 0.22, compared to 0.19 and 0.18, respectively, for the non-obstructed self-controls (P = .044 and P = .008, respectively). The same measurements for the VPS obstruction versus age and gender matched controls were 0.22 and 0.21 for the VPS obstruction cases, respectively, compared to 0.17 and 0.16, respectively for the age and gender matched controls (P < .001 and P < .001, respectively). This data confirms that the optic nerve diameter increases during a VPS obstruction. ONSD measurements by ultrasound could add to the evaluation for VPS obstruction.

Cranial computed tomography utilization for suspected ventriculoperitoneal shunt malfunction in a pediatric emergency department

BACKGROUND

Computed tomography (CT) scan, the largest medical source of ionizing radiation in the United States, is used to test for failure of ventricular peritoneal shunts.

STUDY OBJECTIVES

To quantify the exposure to cranial CT scans in pediatric patients presenting with symptoms of shunt malfunction, and to measure the association of signs and symptoms with clinical shunt malfunction and the need for neurosurgical intervention within 30 days of presentation.

METHOD

This was a quality improvement study evaluating a pathway used by providers in a tertiary care pediatric emergency department with 85,000 patient visits per year, by retrospective chart review of 223 patient visits for suspected shunt malfunction. We determined the median CT scan per patient per year and the association of signs and symptoms on the pathway with radiological signs of shunt failure and neurosurgical intervention within 30 days of scan.

RESULTS

The median exposure was 2.6 (interquartile range 1.44-4.63) scans per patient per year. Among 11 signs and symptoms, none was associated with radiologic shunt failure. Neurosurgical intervention within 30 days was positively associated with bulging fontanelle (adjusted odds ratio [AOR] 11.78; 95% confidence interval [CI] 1.67-83.0) and behavioral change (AOR 3.01; 95% CI 1.14-7.93), and negatively associated with seizure (AOR 0.13; 95% CI 0.02-0.79) and fever (AOR 0.15; 95% CI 0.04-0.55).

CONCLUSIONS

Patients with ventricular peritoneal shunts underwent many cranial CT scans each year. None of the signs or symptoms included on the clinical pathway was predictive of changes on CT scan.

Bedside optic nerve sheath diameter ultrasound for the evaluation of suspected pediatric ventriculoperitoneal shunt failure in the emergency department

OBJECTIVE

To determine the feasibility and test characteristics of optic nerve sheath diameter (ONSD) measured by ocular ultrasound as a screening tool for ventriculoperitoneal shunt (VPS) failure.

METHODS

Prospective observational study using a convenience sample of children 6 months to 18 years of age, presenting to an academic pediatric emergency department for evaluation of possible VPS failure between September 2008 and March 2009. ONSD was measured by anterior transbulbar and lateral transbulbar techniques. Mean ONSD was compared between subjects with and without shunt failure, as determined by neurosurgical decision to operate.

RESULTS

A total of 39 encounters were completed, including 20 VPS failures. The mean ONSD was 4.5 ± 0.9 and 5.0 ± 0.6 mm among encounters with and without shunt failure (p = 0.03), respectively. The mean ONSD was not statistically different when obtained by the anterior transbulbar vs. the lateral transbulbar approach (4.8 ± 1.0 vs. 4.7 ± 0.8 mm, p = 0.12). ONSD ultrasound had a sensitivity of 61.1 % (95 % CI 35.7-82.7) and specificity of 22.2 % (95 % CI 6.4-47.6 %) for detecting shunt failure in this sample.

CONCLUSIONS

ONSD ultrasound does not appear to be a useful primary screening tool in emergency department evaluation of VPS failure. There was no difference between the anterior transbulbar approach and the lateral transbulbar approach. Children with VPS in our sample have larger ONSD measurements than in previously reported studies.

Does optic nerve sheath diameter on MRI decrease with clinically improved pediatric hydrocephalus?

INTRODUCTION

Serial change in ventricular size is recognized as an imperfect indicator of ongoing hydrocephalus in children. Potentially, other radiographic features may be useful in determining the success of hydrocephalus interventions. In this study, optic nerve sheath diameter (ONSD), optic nerve tortuosity, and optic disk bulging were assessed as indicators of hydrocephalus control in children who underwent endoscopic third ventriculostomy (ETV) or posterior fossa tumor resection.

METHODS

Sixteen children underwent ETV or tumor resection for treatment of hydrocephalus. T2-weighted axial magnetic resonance images of the orbit were obtained, and the ONSD was measured posterior to the optic globe, pre- and post-intervention. Evidence of optic disk bulging and optic nerve tortuosity was also assessed. Ventricular size was estimated using the frontal and occipital horn ratio (FOR).

RESULTS

There was a significant reduction in the ONSD post-ETV (n = 9) and after tumor resection (n = 7). Average preoperative ONSD was 6.21 versus 5.71 mm postoperatively (p = 0.0017).There was also an 88% (p = 0.011) and 60% (p = 0.23) reduction in optic disk bulging and tortuosity, respectively. The FOR normalized in the tumor resection group but not the ETV group. After intervention, all patients showed improvement in signs and symptoms of hydrocephalus.

CONCLUSION

In our study population, ONSD decreased in response to measures to reduce hydrocephalus. Optic disk bulging also appears to resolve. Serial reduction in ONSD, and optic disk bulging may be indicators of improved hydrocephalus following pediatric neurosurgical interventions.

Non-invasive methods of estimating intracranial pressure

Non-invasive measurement of intracranial pressure can be invaluable in the management of critically ill patients. We performed a comprehensive review of the literature to evaluate the different methods of measuring intracranial pressure. Several methods have been employed to estimate intracranial pressure, including computed tomography, magnetic resonance imaging, transcranial Doppler sonography, near-infrared spectroscopy, and visual-evoked potentials. In addition, multiple techniques of measuring the optic nerve and the optic nerve sheath diameter have been studied. Ultrasound measurements of the optic nerve sheath diameter and Doppler flow are especially promising and may be useful in selected settings.

Ultrasonography of the optic nerve in neurocritically ill patients

The rapid diagnosis of intracranial hypertension is urgently needed for therapeutic reasons in various clinical settings. This can rarely be achieved without invasive procedures such as intracranial pressure (ICP) monitoring or neuroimaging. The optic nerve is surrounded by cerebrospinal fluid (CSF) and dura mater, which forms the optic nerve sheath (ONS). Because of the connection with the intracranial subarachnoid space, ONS diameter (ONSD) is influenced by CSF pressure variations. Bedside ultrasonographic measurement of ONSD has been proposed as a non-invasive and reliable means to detect raised ICP in neurocritically ill patients. In several studies, it proves to have a good correlation with the direct measurement of ICP and a low interobserver variability. However, no general consensus exists over the upper normal ONSD limit. We performed a review of the literature on the use of the ultrasonography of the optic nerve in the evaluation of patients with suspected intracranial hypertension. The aim of this review is to describe the technique and to assess the validity of this diagnostic method.

Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis

PURPOSE

To evaluate the diagnostic accuracy of ultrasonography of optic nerve sheath diameter (ONSD) for assessment of intracranial hypertension.

METHODS

Systematic review without language restriction based on electronic databases, with manual review of literature and conference proceedings until July 2010. Studies were eligible if they compared ultrasonography of ONSD with intracranial pressure (ICP) monitoring. Data were extracted independently by three authors. Random-effects meta-analysis and meta-regression were performed.

RESULTS

Six studies including 231 patients were reviewed. No significant heterogeneity was detected for sensitivity, specificity, positive and negative likelihood ratios or diagnostic odds ratio. For detection of raised intracranial pressure, pooled sensitivity was 0.90 [95% confidence interval (CI) 0.80-0.95; p for heterogeneity, p (het) = 0.09], pooled specificity was 0.85 (95% CI 0.73-0.93, p (het) = 0.13), and the pooled diagnostic odds ratio was 51 (95% CI 22-121). The area under the summary receiver-operating characteristic (SROC) curve was 0.94 (95% CI 0.91-0.96).

CONCLUSIONS

Ultrasonography of ONSD shows a good level of diagnostic accuracy for detecting intracranial hypertension. In clinical decision-making, this technique may help physicians decide to transfer patients to specialized centers or to place an invasive device when specific recommendations for this placement do not exist.

Morphometric analysis of the optic nerve in experimental hydrocephalus-induced rats

PURPOSE

It was the aim of this study to investigate changes caused to the optic nerve of rats submitted to experimental hydrocephalus through morphometric analysis.

METHOD

At postnatal day 7, the rats underwent injection of kaolin into the cisterna magna, were sacrificed at postnatal day 14, 21 or 28, and the right optic nerves were dissected. We analyzed the area, minor diameter, densities of oligodendrocytes and astrocytes, total and damaged fibers as well as the relationship between damaged and total fibers.

RESULTS

At postnatal day 14, there was a reduction in the density of astrocytes and damaged fibers when compared to the controls. At postnatal day 21, the area and the minor diameter were reduced compared to the controls, and the densities of oligodendrocytes and damaged fibers were increased compared to the controls. At postnatal day 28, there was a reduction in the area and the minor diameter and an increase in the densities of oligodendrocytes, astrocytes and damaged fibers when compared to controls.

CONCLUSION

The optic nerve of rats submitted to experimental hydrocephalus suffers morphometric changes.

Increased intracranial pressure in patients with cystinosis

Patients with cystinosis have risk factors known to be associated with secondary increased intracranial pressure. The authors report a series of patients with cystinosis and describe their experience in the diagnosis and management of increased intracranial pressure in this population. The ophthalmologist should be aware of this vision-threatening association.

Cerebral biometry at birth and at 4 and 8 months of age. A prospective study using US

BACKGROUND

Although longitudinal reference intervals for ventricular size are crucial for the diagnosis of dilated ventricles, such data are sparse.

OBJECTIVE

To establish references for ventricular measurements at birth, and at 4 and 8 months follow-up, and to examine the inter-observer variation of the measurements.

MATERIALS AND METHODS

This prospective, longitudinal study included 120 term newborns (boys 65, girls 55), mean age 1.5 days on initial scans, with re-examination at 4 months and 8 months of age. One examiner performed all the examinations, measuring: ventricular index, frontal horn width, third ventricle width, frontal subarachnoid space depth, optic nerve sheath diameter and resistive index.

RESULTS

One hundred eight (90%) and 90 (75%) of the infants, respectively, attended for follow-up at 4 and 8 months of age. All measures increased with age, except for the depth of the subarachnoid spaces that showed an initial rise, followed by a mild drop at 8 months, and for the resistive index that remained stable at 0.6. The increase was particularly significant for frontal horn width with an increase from 2.2 mm at birth to 6.5 mm at 4 months in boys, and 2.1-5.8 mm in girls. The agreement between two observers was fair to moderate for most of the measurements.

CONCLUSION

The increase in the width of the frontal horns between birth and 4 months of age, as well as the wide normal range found among all three age groups are noteworthy and should inform future diagnostics.