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

Changes in optic nerve sheath diameter and its correlation with degree of consciousness, pupil diameter, and light reflex in children with central nervous system infection after osmotherapy

Background

High intracranial pressure (ICP) is one of the most common complications of central nervous system (CNS) infection. Failure to control high intracranial pressure results in brain herniation and death. One of the treatments for high ICP involves the administration of osmotherapy in the form of 3% NaCl or 20% mannitol with observation during administration. Observation of ICP during administration of osmotherapy is possible through measurement of optic nerve sheath diameter (ONSD), which could be correlated with degree of consciousness, pupil diameter, and light reflex. Previous studies have not correlated ONSD with degree of consciousness, pupil diameter, and light reflex during the administration of osmotherapy.

Purpose

To provide insights of incorporating ONSD measurement as a form of non-invasive bedside method for ICP monitoring by correlating it with degree of consciousness, pupil diameter, and light reflex at several time points.

Methods

This study is a prospective cohort study, performed at Dr. Hasan Sadikin General Central Hospital Bandung, Cibabat General Regional Hospital, and General Regional Hospital Bandung Kiwari on children aged 2-18 years with decreased consciousness and CNS infection, from June 2023. Inter-rater reliability was performed with a correlation coefficient of 0.90. Measurement of ONSD, degree of consciousness, pupil diameter, and light reflex simultaneously up to 48 h after initiation of osmotherapy to 30 patients. Correlational analyses were performed using Spearman's rank.

Results

Observation for 48 h after administration of osmotherapy showed changes in ONSD. A significant positive correlation was found between ONSD and degree of consciousness (r = 0.621 for the right eye and r = 0.602 for the left eye, p < 0.001). A significant positive correlation was found between ONSD and light reflex (r = 0.801 for the right eye and r = 0.812 for the left eye, p < 0.001). No significant correlation was found with changes of pupil diameter (r = -0.136 for the right eye and r = -0.141 for the left eye, p > 0.05).

Conclusion

A significant correlation was found between ONSD and degree of consciousness and light reflex in children aged 2-18 years with CNS infection during administration of osmotherapy.

The Use of POCUS-Obtained Optic Nerve Sheath Diameter in Intracerebral Hemorrhage

Background: Intracerebral hemorrhage (ICH) is associated with high morbidity and mortality. ICH causes increased intracranial pressure (ICP), leading to brain herniation as the disease progresses. Neurological physical exam and monitoring of the disease progression can be challenging due to the impaired consciousness and routine clinical management in this patient population. Given the continuity of the intracranial cavity with the optic nerve subarachnoid space, an increased ICH leads to distension of the optic nerve sheath. We herein examined the correlation between the ICH volume and the optic nerve sheath diameter (ONSD) measured by point of care ultrasound (POCUS). Methods: Patients with ICH diagnosed with a head computed tomography (CT) scan were prospectively enrolled in this study. A portable ultrasound was used to measure the (ONSD); the volume of ICH hematoma, the Acute Physiology And Chronic Health Evaluation IV score, and the Intracerebral Hemorrhage score were collected. A Spearman rank correlation coefficient test was used to assess the relationship between continuous variables. A Wilcoxon rank sum test was used to assess differences in continuous variables between two groups. A p-value less than 0.05 was deemed as statistically significant. Results: A total of 28 subjects were enrolled. A moderate positive correlation was detected between hemorrhage volume and the average ONSD (correlation = 0.4214, p = 0.0255). A weak positive correlation was detected between average ONSD and APACHE IV (correlation = 0.2347, p = 0.2294). A weak moderate positive correlation was detected between average ONSD and ICH score (correlation = 0.1160, p = 0.5566). Conclusions: In this study we demonstrate that ONSD is moderately correlated with hematoma size. A potential application may include serial measurements of the ONSD with ultrasound. This may offer a quick, non-invasive technique that can be used in an intracerebral hemorrhage to monitor the stability or expansion of a hematoma indirectly, and potentially catch a catastrophic event like cerebral herniation.

Effect of paediatric caudal injection volume on optic nerve sheath diameter and regional cerebral oximetry: A randomised trial

BACKGROUND

Caudal injections commonly used for neuraxial anaesthesia in children can displace cerebrospinal fluid cranially causing safety concerns in terms of raised intracranial pressure. Optic nerve sheath diameter (ONSD) is a noninvasive surrogate for the measurement of intracranial pressure. Regional cerebral oximetry (CrSO 2 ) can monitor brain oxygenation, which may decrease by a reduction in cerebral flow due to increased intracranial pressure.

OBJECTIVES

Comparing how caudal injection volumes of 0.8 and 1.25 ml kg -1 influence ONSD and CrSO 2 within the first 30 min after injection.

DESIGN

Prospective, randomised and parallel group trial.

SETTING

Operating room.

PATIENTS

Fifty-eight elective paediatric surgical patients between ages 1 and 7 years old, ASA class I or II, without previous intracranial or ocular pathology and surgery appropriate for single - shot caudal anaesthesia.

INTERVENTION

Single-shot caudal anaesthesia with 0.8 ml kg -1 (group L, n  = 29) and 1.25 ml kg -1 (group H, n  = 29) of 2 mg kg -1 bupivacaine solution.

MAIN OUTCOME MEASURES

Optic nerve sheath diameter measured with ultrasonography and regional cerebral oximetry measured by near - infrared spectroscopy before (NIRS), immediately after, 10, 20 and 30 min after the block.

RESULTS

Mean ONSD values increased from a baseline of 4.4 ± 0.2 mm to a maximum of 4.5 ± 0.2 mm 20 min after injection in group L and from a baseline of 4.5 ± 0.3 mm to a maximum of 4.8 ± 0.3 mm 10 min after injection in group H. Eight of 29 patients in group H and none in group L had an ONSD increase by more than 10%. Both groups had a reduction of less than 2.5% in CrSO 2 .

CONCLUSION

Caudal injection with 1.25 ml kg -1 increased ONSD, an indirect measurement of ICP, more than 0.8 ml kg -1 and neither volume caused a clinically important reduction in CrSO 2 .

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04491032.

Intracranial pressure monitoring in neurosurgery: the present situation and prospects

Intracranial pressure (ICP) is one of the most important indexes in neurosurgery. It is essential for doctors to determine the numeric value and changes of ICP, whether before or after an operation. Although external ventricular drainage (EVD) is the gold standard for monitoring ICP, more and more novel monitoring methods are being applied clinically.Invasive wired ICP monitoring is still the most commonly used in practice. Meanwhile, with the rise and development of various novel technologies, non-invasive types and invasive wireless types are gradually being used clinically or in the testing phase, as a complimentary approach of ICP management. By choosing appropriate monitoring methods, clinical neurosurgeons are able to obtain ICP values safely and effectively under particular conditions.This article introduces diverse monitoring methods and compares the advantages and disadvantages of different monitoring methods. Moreover, this review may enable clinical neurosurgeons to have a broader view of ICP monitoring.

Diagnostic Accuracy of Ocular Ultrasonography in Identifying Raised Intracranial Pressure among Pediatric Population

INTRODUCTION

Role of CT scan, MRI, ophthalmoscopy, direct monitoring by a transducer probe in identifying raised intracranial pressure (ICP) in emergency department is limited. There are few studies correlating elevated optic nerve sheath diameter (ONSD) measured by point of care ultrasound (POCUS) with raised ICP in pediatrics emergencies. We studied the diagnostic accuracy of ONSD, crescent sign, and optic disc elevation in identifying increased ICP in pediatrics.

METHODS

Prospective observational study was done between April 2018 and August 2019 after ethics approval. Out of 125 subjects, 40 patients without clinical features of raised ICP were recruited as external controls and 85 with clinical features of raised ICP as study subjects. Their demographic profile, clinical examination, and ocular ultrasound findings were noted. This was followed by CT scan. Out of 85 patients, 43 had raised ICP (cases) and 42 had normal ICP (disease controls). Diagnostic accuracy of ONSD in identifying raised ICP was evaluated using STATA.

RESULTS

The mean ONSD in case group was 5.5 ± 0.6 mm, 4.9 ± 0.5 mm in disease control group and external control group was 4.8 ± 0.3 mm. Cut-off of ONSD for raised ICP at ≥4.5 mm had a sensitivity and specificity of 97.67% and 10.98%, while ≥5.0 mm showed a sensitivity and specificity of 86.05% and 71.95%. Crescent sign and optic disc elevation had good correlation with increased ICP.

CONCLUSION

ONSD ≥5 mm by POCUS identified raised ICP in pediatric population. Crescent sign and optic disc elevation may function as additional POCUS signs in identifying raised ICP.

Recognizing and managing hydrocephalus in children

ABSTRACT

Hydrocephalus is one of the most common indications for pediatric neurosurgical intervention and is associated with the need for lifelong monitoring. All clinicians should be familiar with the complications that may arise throughout life in these patients so that they can provide timely intervention. This article focuses on the assessment of hydrocephalus, the appropriate diagnostic workup and differential diagnoses, and evidence-based surgical treatments and associated outcomes.

Non-Invasive Intracranial Pressure Monitoring

(1) Background: Intracranial pressure (ICP) monitoring plays a key role in the treatment of patients in intensive care units, as well as during long-term surgeries and interventions. The gold standard is invasive measurement and monitoring via ventricular drainage or a parenchymal probe. In recent decades, numerous methods for non-invasive measurement have been evaluated but none have become established in routine clinical practice. The aim of this study was to reflect on the current state of research and shed light on relevant techniques for future clinical application. (2) Methods: We performed a PubMed search for “non-invasive AND ICP AND (measurement OR monitoring)” and identified 306 results. On the basis of these search results, we conducted an in-depth source analysis to identify additional methods. Studies were analyzed for design, patient type (e.g., infants, adults, and shunt patients), statistical evaluation (correlation, accuracy, and reliability), number of included measurements, and statistical assessment of accuracy and reliability. (3) Results: MRI-ICP and two-depth Doppler showed the most potential (and were the most complex methods). Tympanic membrane temperature, diffuse correlation spectroscopy, natural resonance frequency, and retinal vein approaches were also promising. (4) Conclusions: To date, no convincing evidence supports the use of a particular method for non-invasive intracranial pressure measurement. However, many new approaches are under development.

A Narrative Review of Point of Care Ultrasound Assessment of the Optic Nerve in Emergency Medicine

Point of care ultrasound (POCUS) of the optic nerve is easy to learn and has great diagnostic potential. Within emergency medicine, research has primarily focused on its use for the assessment of increased intracranial pressure, but many other applications exist, though the literature is heterogeneous and largely observational. This narrative review describes the principles of POCUS of the optic nerve including anatomy and scanning technique, as well as a summary of its best studied clinical applications of relevance in emergency medicine: increased intracranial pressure, idiopathic intracranial hypertension, optic neuritis, acute mountain sickness, and pediatric intracranial pressure assessment. In many of these applications, sonographic optic nerve sheath diameter (ONSD) has moderately high sensitivity and specificity, but the supporting studies are heterogeneous. Further studies should focus on standardization of the measurement of ONSD, establishment of consistent diagnostic thresholds for elevated intracranial pressure, and automation of ONSD measurement.

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.

Wearable Sensing System for NonInvasive Monitoring of Intracranial BioFluid Shifts in Aerospace Applications

The alteration of the hydrostatic pressure gradient in the human body has been associated with changes in human physiology, including abnormal blood flow, syncope, and visual impairment. The focus of this study was to evaluate changes in the resonant frequency of a wearable electromagnetic resonant skin patch sensor during simulated physiological changes observed in aerospace applications. Simulated microgravity was induced in eight healthy human participants (n = 8), and the implementation of lower body negative pressure (LBNP) countermeasures was induced in four healthy human participants (n = 4). The average shift in resonant frequency was -13.76 ± 6.49 MHz for simulated microgravity with a shift in intracranial pressure (ICP) of 9.53 ± 1.32 mmHg, and a shift of 8.80 ± 5.2097 MHz for LBNP with a shift in ICP of approximately -5.83 ± 2.76 mmHg. The constructed regression model to explain the variance in shifts in ICP using the shifts in resonant frequency (R² = 0.97) resulted in a root mean square error of 1.24. This work demonstrates a strong correlation between sensor signal response and shifts in ICP. Furthermore, this study establishes a foundation for future work integrating wearable sensors with alert systems and countermeasure recommendations for pilots and astronauts.

Time to FOCUS - 'Palliative Medicine Point-of-Care Ultrasound'

Point-of-care diagnosis has become the need of the hour and along with its guided interventions, ultrasound could be utilised bedside in a palliative care patient. Point-of-care ultrasound (POCUS) in palliative care medicine is fast emerging and has varied applications ranging from performing bedside diagnostic evaluation to the performance of interventional paracentesis, thoracocentesis and chronic pain interventions. Handheld ultrasound devices have transformed the application of POCUS and should revolutionise the future of home-based palliative care. Palliative care physicians should be enabled to carry out bedside ultrasounds at home care and hospice setting for achieving rapid symptom relief. The aim of POCUS in palliative care medicine should be adequate training of palliative care physicians, transforming the applicability of this technology to OPD as well as community driven to achieve home outreach. The goal is towards empowering technology by reaching out to the community rather than the terminally ill patient transported for the hospital admission. Palliative care physicians should receive mandatory training in POCUS to enable diagnostic proficiency and early triaging. The inclusion of ultrasound machine in an outpatient palliative care clinic brings about value addition in rapid diagnosis. Limiting POCUS application to certain selected sub-specialities such as emergency medicine, internal medicine and critical care medicine should be overcome. This would need acquiring higher training as well as improvised skill sets to perform bedside interventions. Ultrasonography competency among palliative care providers proposed as palliative medicine point-of-care ultrasound (PM-POCUS) could be achieved by imparting dedicated POCUS training within the core curriculum.

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.

Technology-Dependent Children

There are a growing number of medically complex children with implanted devices. Emergency physicians with a basic knowledge of these devices can troubleshoot and fix many of the issues that may arise. Recognition of malfunction of these devices can reduce morbidity and mortality among this special population. In this article, we review common issues that may arise in children with gastrostomy tubes, central nervous system shunts, cochlear implants, and vagal nerve stimulators.

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.

Protecting the blossoming brain - Neurocritical care in children

This special issue of the Biomedical Journal is entirely dedicated to the latest updates regarding the medical efforts to preserve the fragile young brain after injury. Thereby, we learn about symptoms and diseases such as different forms of epilepsy, acute encephalopathy, increased intracranial pressure, and posthaemorrhagic hydrocephalus, as well as about their origins, such as infection, autoimmune diseases, preterm birth, or abusive head trauma. Moreover, diagnosis and surveillance techniques are discussed, including ultrasound of the optic nerve sheath diameter and multimodal monitoring. Finally, we discover various established and emerging therapeutic approaches, comprising target temperature management, ketogenic diet, and immunomodulation.

Multimodal neurocritical monitoring

Neurocritical monitoring is important in caring for patients in the neurological intensive care unit. Although clinical neurologic examination is standard for neurocritical monitoring, changes found during the examination are often late signs and insufficient to detect and prevent secondary brain injury. Therefore, various neuromonitoring tools have been developed to monitor different physiologic parameters, such as cerebral oxygenation, cerebral blood flow, cerebral pressure, cerebral autoregulation, cerebral electric activity, and cerebral metabolism. In this review, we have discussed current commonly used neurocritical monitoring tools. No single monitor is sufficient and perfect for neurocritical monitoring. Multimodal neurocritical monitoring is the current trend. However, the lack of common formatting standards and uncertainty of improvement in patients' outcomes warrant further studies of multimodal neurocritical monitoring. Nevertheless, multimodal neurocritical monitoring considers individual pathophysiological variations in patients or their injuries and allows clinicians to tailor individualized management decisions.