Evaluation of Optic Nerve Sheath Diameter and Transcranial Doppler As Noninvasive Tools to Detect Raised Intracranial Pressure in Children

Optic nerve sheath diameter as a non-invasive tool to detect clinically relevant raised intracranial pressure in children: an observational analytical study

BACKGROUND

Raised intracranial pressure (ICP) contributes to approximately 20% of the admissions in the paediatric intensive care unit (PICU) in our setting. Timely identification and treatment of raised ICP is important to prevent brain herniation and death in such cases. The objective of this study was to examine the role of optic nerve sheath diameter (ONSD) in detecting clinically relevant raised ICP in children.

METHODS

A hospital-based observational analytical study in a PICU of a tertiary care institute in India on children aged 2-14 years. ONSD was measured in all children on three time points that is, day 1, day 2 and between day 4 and 7 of admission. ONSD values were compared between children with and without clinical signs of raised ICP.

RESULTS

Out of 137 paediatric patients recruited, 34 had signs of raised ICP. Mean ONSD on day 1 was higher in children with signs of raised ICP (4.99±0.57 vs 4.06±0.40; p<0.01). Mean ONSD on day 2 also was higher in raised ICP patients (4.94±0.55 vs 4.04±0.40; p<0.01). The third reading between days 4 and 7 of admission was less than the first 2 values but still higher in raised ICP patients (4.48±1.26 vs 3.99±0.57; p<0.001). The cut-off ONSD value for detecting raised ICP was 4.46 mm on the ROC curve with an area under curve 0.906 (95% CI 0.844 to 0.968), 85.3% sensitivity and 86.4% specificity. There was no difference in ONSD between the right and the left eyes at any time point irrespective of signs of raised ICP.

CONCLUSION

We found that measurement of ONSD by transorbital ultrasound was able to detect clinically relevant raised ICP with an excellent discriminatory performance at the cut-off value of 4.46 mm.

The role of optic nerve sheath ultrasonography in increased intracranial pressure: A systematic review and meta analysis

OBJECTIVES

To review the optimal diagnostic cut-off of ultrasonographic optic nerve sheath diameter (ONSD) in the diagnosis of increased intracranial pressure (IICP).

METHODS

A systematic search was conducted of available studies assessing the use of ONSD ultrasonography in patients with suspected IICP. Meta-analysis of diagnostic accuracy of ultrasonographic ONSD was performed using a bivariate model of random effects to summarize pooled sensitivity and specificity. A summary receiver operating characteristics (SROC) curve was plotted. Accuracy measures associated with ONSD cut-off and predefined covariates were investigated with meta-regression.

RESULTS

We included 38 studies, comprising a total of 2824 patients. A total of 21 studies used invasive techniques as a reference standard estimation of IICP and meta-analysis revealed a pooled sensitivity of 0.90 (95% CI 0.85-0.93) and specificity of 0.87 (95% CI 0.80-0.91). Optimal ONSD cut-off values ranged between 4.1 mm and 7.2 mm. Meta-regression analysis showed that ONSD cut-off values of 5.6 to 6.3 mm were associated with higher pooled specificity compared to cut-off values of 4.9 to 5.5 mm (0.93, 95% CI 0.85-0.97 vs. 0.78, 95% CI 0.65-0.87; p = 0.036).

CONCLUSIONS

Ultrasonography of ONSD shows a high diagnostic accuracy for IICP, with high pooled sensitivity and specificity. Additionally, larger cut-off values seem to significantly increase specificity without compromising sensitivity, which support their use as optimal ONSD cut-off. The overall high sensitivity of ultrasonographic ONSD suggests its usefulness as a screening tool for IIC, which may provide an estimate of when invasive methods are warranted.

CLINICAL RELEVANCE

ONSD ultrasonography is a fast and cost-effective method with a high diagnostic accuracy to detect IICP. The optimum ONSD cut-off hasn't been established before, but we suggest the 5.6 to 6.3 mm range as the best for the diagnosis of IICP.

Ultrasound-guided puncture into newborn rat brain

Since the brain structure of neonatal rats was not fully formed during the first 4 days, it cannot be detected using ultrasound. The objective of this study was to investigate the use of ultrasound to guide puncture in the normal coronal brain structure and determine the puncture depth of the location of the cortex, hippocampus, lateral ventricle, and striatum of newborn rats of 5-15 days. The animal was placed in a prone position. The specific positions of the cortex, hippocampus, lateral ventricle, and striatum were measured under ultrasound. Then, the rats were punctured with a stereotaxic instrument, and dye was injected. Finally, the brains of rats were taken to make frozen sections to observe the puncture results. By ultrasound, the image of the cortex, hippocampus, lateral ventricle, and striatum of the rat can be obtained and the puncture depth of the cortex (8 days: 1.02 ± 0.12, 10 days: 1.02 ± 0.08, 13 days: 1.43 ± 0.05), hippocampus (8 days: 2.63 ± 0.07, 10 days: 2.77 ± 0.14, 13 days: 2.82 ± 0.09), lateral ventricle (8 days: 2.08 ± 0.04, 10 days: 2.26 ± 0.03, 13 days: 2.40 ± 0.06), and corpus striatum (8 days: 4.57 ± 0.09, 10 days: 4.94 ± 0.31, 13 days: 5.13 ± 0.10) can be accurately measured. The rat brain structure and puncture depth changed with the age of the rats. Ultrasound technology can not only clarify the brain structure characteristics of 5-15-day-old rats but also guide the puncture and injection of the rat brain structure. The results of this study laid the foundation for the future use of ultrasound in experimental animal models of neurological diseases.

Multimodal Neuromonitoring in Pediatric Neurocritical Care: Current Perspectives

Children with neurological illness in the critical care unit are always at higher risk of developing secondary brain injury (SBI). Brain insult can lead to changes in cerebral autoregulation, intracranial pressure (ICP), cerebral oxygenation, and metabolism. This can cause a raised ICP, cerebral ischemia, hypoxia, excitotoxicity, cellular energy failure, and nonconvulsive status epilepticus. Simultaneous and continuous assessment of these parameters will help to improve patient care and neurological outcomes. Even though clinical examination and neuroimaging can help in the initial diagnosis of the neurological illness, they may not be helpful in continuous monitoring of cerebral pathophysiological changes. The ideal single neuromonitoring device to detect these real-time changes is currently unavailable. However, a range of invasive and noninvasive monitors are available to monitor these cerebral functional parameters. Invasive monitoring techniques include invasive ICP monitoring, cerebral autoregulation monitoring, brain tissue partial oxygen pressure, and cerebral microdialysis. Noninvasive-monitoring techniques include pupillometry, brain and ocular ultrasonography, near-infrared spectroscopy, and electrophysiological monitoring. Multimodal (MM) neuromonitoring involves incorporating these techniques and tools for the early identification and treatment of primary and secondary brain insults. The utility and feasibility of most of these techniques are well described in adult neurocritical care. Even though the evidence on their usage in children is primarily available in pediatric traumatic brain injury, the emerging data help to further expand their utility in pediatric nontraumatic coma. MM neuromonitoring aims to provide clinical and pathophysiological information to the intensivists to improve their understanding of the child's neurological status and to formulate patient-specific treatment approaches.

[Pediatric neurocritical care]

Pediatric neurocritical care requires multidisciplinary expertise for the care of critically ill children. Approximately 14-16% of critically ill children in pediatric intensive care suffer from a primary neurological disease, whereby cardiac arrest and severe traumatic brain injury play major roles in Europe. The short-term goal of interventions in the pediatric intensive care unit is to stabilize vital functions, whereas the overarching goal is to achieve survival without neurological damage that enables fulfillment of the individual developmental physiological potential. For this reason, evidence-based methods for brain monitoring during the acute phase and recovery are necessary, which can be performed clinically or with technical devices. This applies to critically ill children with primary neurological diseases and for all children at risk for secondary neurological insults. Patients with diseases of the peripheral nervous system are also treated in pediatric intensive care medicine. In these patients, the primary aim frequently consists of bridging the time until recovery after acute deterioration, for example during an infection. In these patients, monitoring the cerebral function can be especially challenging, because due to the underlying disease the results of the examination cannot be interpreted in the same way as for previously neurologically healthy children. This article summarizes the complexity of pediatric neurocritical care by presenting examples of diagnostic and therapeutic approaches in the context of various neurological diseases that can be routinely encountered in the pediatric intensive care unit and can only be successfully treated by multidisciplinary teams.

Noninvasive methods to monitor intracranial pressure

PURPOSE OF REVIEW

Intracranial pressure (ICP) is determined by the production of and outflow facility of cerebrospinal fluid. Since alterations in ICP are implicated in several vision-threatening and life-threatening diseases, measurement of ICP is necessary and common. All current clinical methods to measure ICP are invasive and carry the risk for significant side effects. Therefore, the development of accurate, reliable, objective, and portal noninvasive devices to measure ICP has the potential to change the practice of medicine. This review discusses recent advances and barriers to the clinical implementation of noninvasive devices to determine ICP.

RECENT FINDINGS

Many noninvasive methods to determine ICP have been developed. Although most have significant limitations limiting their clinical utility, several noninvasive methods have shown strong correlations with invasively obtained ICP and have excellent potential to be developed further to accurately quantify ICP and ICP changes.

SUMMARY

Although invasive methods remain the mainstay for ICP determination and monitoring, several noninvasive biomarkers have shown promise to quantitatively assess and monitor ICP. With further refinement and advancement of these techniques, it is highly possible that noninvasive methods will become more commonplace and may complement or even supplant invasively obtained methods to determine ICP in certain situations.

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.

Transcranial Doppler Ultrasound, a Review for the Pediatric Intensivist

The use of transcranial Doppler ultrasound (TCD) is increasing in frequency in the pediatric intensive care unit. This review highlights some of the pertinent TCD applications for the pediatric intensivist, including evaluation of cerebral hemodynamics, autoregulation, non-invasive cerebral perfusion pressure/intracranial pressure estimation, vasospasm screening, and cerebral emboli detection.

Multimodal Neurologic Monitoring in Children With Acute Brain Injury

Children with acute neurologic illness are at high risk of mortality and long-term neurologic disability. Severe traumatic brain injury, cardiac arrest, stroke, and central nervous system infection are often complicated by cerebral hypoxia, hypoperfusion, and edema, leading to secondary neurologic injury and worse outcome. Owing to the paucity of targeted neuroprotective therapies for these conditions, management emphasizes close physiologic monitoring and supportive care. In this review, we will discuss advanced neurologic monitoring strategies in pediatric acute neurologic illness, emphasizing the physiologic concepts underlying each tool. We will also highlight recent innovations including novel monitoring modalities, and the application of neurologic monitoring in critically ill patients at risk of developing neurologic sequelae.

Predictive Value of Optic Nerve Sheath Diameter for Diagnosis of Intracranial Hypertension in Children With Severe Brain Injury

BACKGROUND AND AIMS

Intracranial Hypertension (ICH) is a life-threatening complication of brain injury. The invasive measurement of intracranial pressure (ICP) remains the gold standard to diagnose ICH. Measurement of Optic Nerve Sheath Diameter (ONSD) using ultrasonography is a non-invasive method for detecting ICH. However, data on paediatric brain injury are scarce. The aim of the study was to determine the performance of the initial ONSD measurement to predict ICH occurring in children with severe brain injury and to describe the ONSD values in a control group.

METHODS

In this cross-sectional study, ONSD was measured in children aged 2 months-17 years old with invasive ICP monitoring: before placement of ICP probe and within the 60 min after, and then daily during 3 days. ONSD was also measured in a control group.

RESULTS

Ninety-nine patients were included, of whom 97 were analysed, with a median (IQR) age of 8.7 [2.3-13.6] years. The median (IQR) PIM 2 score was 6.6 [4.4-9.7] and the median (IQR) PELOD score was 21 [12-22]. Aetiologies of brain injury were trauma (n = 72), infection (n = 17) and stroke (n = 8). ICH occurred in 65 children. The median (IQR) ONSD was 5.58 mm [5.05-5.85]. ONSD performed poorly when it came to predicting ICH occurrence within the first 24 h (area under the curve, 0.58). There was no significant difference between the ONSD of children who presented with ICH within the first 24 h and the other children, with a median (IQR) of 5.6 mm [5.1-5.9] and 5.4 mm [4.9-5.8], respectively. Infants aged less than 2 years had a median (IQR) ONSD of 4.9 mm [4.5-5.2], significantly different from children aged more than 2 years, whose median ONSD was 5.6 mm [5.2-5.9]. Age, aetiology or ICP levels did not change the results. Thirty-one controls were included, with a median age of 3.7 (1.2-8.8) years. The median (IQR) of their ONSD measurement was 4.5 mm [4.1-4.8], significantly lower than the patient group.

CONCLUSION

In a paediatric severe brain injury population, ONSD measurement could not predict the 24 h occurrence of ICH. Severity of patients, timing and conditions of measurements may possibly explain these results.