Observer variation in the sonographic measurement of optic nerve sheath diameter in normal adults

Optic nerve sheath diameter and eyeball transverse diameter in severe head injury and its correlation with intracranial pressure

BACKGROUND

Gold standard for determining intracranial pressure (ICP), intraventricular catheter, is invasive with associated risks. Non-invasive investigations like magnetic resonance imaging and ultrasonography have demonstrated correlation between optic nerve sheath diameter (ONSD) and raised ICP. However, computed tomography (CT) is accessible and less operator-dependent. Literature shows variable results regarding correlations between ICP and ONSD on CT. The study aimed to investigate correlations between raised ICP and ONSD, eyeball transverse diameter (ETD), and ONSD/ETD ratios on CT scan(s) of severe head injuries.

METHODS

A retrospective review of a three-year prospectively-maintained database of severe traumatic head injuries in patients who had ICP measurements and CT scans was conducted. Glasgow Coma Score (GCS), ICP, ONSD 3 mm and 9 mm behind the globe, ETD, ONSD/ETD ratios, CT Marshall Grade, and Glasgow Outcome Score (GOS) were recorded. Statistical analysis assessed correlations between ICP and CT measurements.

RESULTS

Seventy-four patients were assessed; mortality rate: 36.5 %. Assault (48.6 %) and pedestrian-vehicle collisions (21.6 %) were the most common mechanisms. CT Marshall Grade correlated significantly with 3 mm and 9 mm ONSD, ONSD/ETD ratios, GCS, and GCS motor score, which correlated significantly with GOS. No significant correlation was found between ICP and ONSD, ETD or ONSD/ETD ratios. Marshall Grade was not significantly associated with ICP measurements but correlated with injury severity.

CONCLUSIONS

Unlike previous studies, our study not only investigated the correlation between ICP and single variables (ONSD and ETD) but also the ONSD/ETD ratios. No correlations were observed between raised ICP and ONSD, ETD or ONSD/ETD ratio on CT in neurotrauma patients.

A Narrative Review on Financial Challenges and Health Care Costs Associated with Traumatic Brain Injury in the United States

BACKGROUND

Traumatic brain injury (TBI) is a highly prevalent and potentially severe medical condition. Challenges regarding TBI management are related to accurate diagnostics, defining its severity, and establishing prompt interventions to affect outcomes. Among the health care components in the TBI handling strategy is intracranial pressure (ICP) monitoring, which is fundamental to therapy decisions. However, ICP monitoring is an Achilles tendon, imposing a significant financial burden on health care systems, particularly in middle and low-income communities. This article arises from the understanding from the authors that there is insufficient scientific evidence about the potential economic impacts from the use of noninvasive technologies in the monitoring of TBI. Based on personal experience, as well as from reading other, clinically focused studies, the thesis is that the use of such technologies could greatly affect the health care system and this article seeks to address this lack of literature, show ways in which such systems could be evaluated, and show estimations of possible results from these investigations.

OBJECTIVE

This review primarily investigates the economic burden of TBI and whether new technologies are suitable to reduce its health care costs without compromising the quality of care, according to the levels of evidence available. The objective is to stimulate more research and attention in the area.

METHODS

For this narrative review, a PubMed search was conducted for articles discussing TBI health care costs, as well as monitoring technologies (tomography, magnetic resonance imaging, optic nerve sheath diameter, transcranial Doppler, pupillometry, and noninvasive ICP waveform) and their application in managing TBI. Strategies were first evaluated from a medical noninferiority perspective before calculating the average savings of each selected strategy. All applicable studies were analyzed for quality using the Consolidated Health Economic Evaluation Reporting Standards 2022 Statement117 and this article was written to conform as much as possible with it.

RESULTS

The review included 109 references and showed a consistent potential in noninvasive technologies to reduce costs and maintain or improve the quality of care.

CONCLUSIONS

TBI prevalence has increased with a disproportionate health care burden in the last decades. Noninvasive monitoring techniques seem to be effective in reducing TBI health care costs, with few limitations, especially the need for more supporting scientific evidence. The undeniable clinical and financial potential of these techniques is compelling to further investigate their role in TBI management, as well as the creation of more comprehensive monitoring models to the understanding of complex phenomena occurring in the injured brain.

Prediction of Intracranial Pressure in Patients with an Aneurysmal Subarachnoid Hemorrhage Using Optic Nerve Sheath Diameter via Explainable Predictive Modeling

Background: The objective of this investigation was to formulate a model for predicting intracranial pressure (ICP) by utilizing optic nerve sheath diameter (ONSD) during endovascular treatment for an aneurysmal subarachnoid hemorrhage (aSAH), incorporating explainable predictive modeling. Methods: ONSD measurements were conducted using a handheld ultrasonography device during the course of endovascular treatment (n = 126, mean age 58.82 ± 14.86 years, and female ratio 67.46%). The optimal ONSD threshold associated with an increased ICP was determined. Additionally, the association between ONSD and ICP was validated through the application of a linear regression machine learning model. The correlation between ICP and various factors was explored through the modeling. Results: With an ICP threshold set at 20 cmH2O, 82 patients manifested an increased ICP, with a corresponding ONSD of 0.545 ± 0.08 cm. Similarly, with an ICP threshold set at 25 cmH2O, 44 patients demonstrated an increased ICP, with a cutoff ONSD of 0.553 cm. Conclusions: We revealed a robust correlation between ICP and ONSD. ONSD exhibited a significant association and demonstrated potential as a predictor of ICP in patients with an ICP ≥ 25 cmH2O. The findings suggest its potential as a valuable index in clinical practice, proposing a reference value of ONSD for increased ICP in the institution.

Optical coherence tomography and shear wave elastography findings in Graves ophthalmopathy

PURPOSE

The main feature of Graves ophthalmopathy (GO) is revealed by determining the activity and severity of the disease. We aimed to evaluate the use of imaging methods can also provide additional information about the severity of this disease.

METHODS

Optical coherence tomography (OCT) and shear wave elastography (SWE) findings were compared in 32 patients with mild GO group and in the healthy control group. Measuring for TSH receptor antibody (TRAb) serum level is used third-generation assay.

RESULTS

In Graves group, optic nerve sheath diameter (ONSD) values were increased in both eyes (p < 0.001, p < 0.001). SWE measurements showed a significant increase both eye optic nerve (ON) and right eye soft tissue elasticity values in GO group (p < 0.001, p < 0.001, p < 0.001, respectively). There was a significant thinning in left temporal retinal nerve fiber layer (RNFL) thickness and left RNFL peripapillary thickness in GO group (p < 0.001, p < 0.025, respectively). There was a correlation between left eye OCT and SWE findings. Also, there was a significant difference between the median left eye ON and soft tissue elasticity results in the TRAb-positive GO group (p = 0.049, p = 0.048, respectively).

CONCLUSION

SWE measurements showed a significant increase both eyes ONSD, ON and right eye soft tissue elasticity values in GO group. GO group was significant thinning in some left eye regions in OCT measurements. There was a correlation between left eye OCT and SWE findings. In addition to clinical activity score and TRAb, SWE and OCT can be used to monitor in patients with GO.

A Novel Method for Prediction of Raised Intracranial Pressure Through Automated ONSD and ETD Ratio Measurement From Ocular Ultrasound

The paper presents a novel framework for the prediction of the raised Intracranial Pressure (ICP) from ocular ultrasound images of traumatic patients through automated measurement of Optic Nerve Sheath Diameter (ONSD) and Eyeball Transverse Diameter (ETD). The measurement of ONSD using an ocular ultrasound scan is non-invasive and correlates with the raised ICP. However, the existing studies suggested that the ONSD value alone is insufficient to indicate the ICP condition. Since the ONSD and ETD values may vary among patients belonging to different ethnicity/origins, there is a need for developing an independent global biomarker for predicting raised ICP condition. The proposed work develops an automated framework for the prediction of raised ICP by developing algorithms for the automated measurement of ONSD and ETD values. It is established that the ONSD and ETD ratio (OER) is a potential biomarker for ICP prediction independent of ethnicity and origin. The OER threshold value is determined by performing statistical analysis on the data of 57 trauma patients obtained from the AIIMS, New Delhi. The automated OER is computed and compared with the conventionally measured ICP by determining suitable correlation coefficients. It is found that there is a significant correlation of OER with ICP (r = .81, p ≤ .01), whereas the correlation of ONSD alone with ICP is relatively less (r = .69, p = .004). These correlation values indicate that OER is a better parameter for the prediction of ICP. Further, the threshold value of OER is found to be 0.21 for predicting raised ICP conditions in this study. Scatter plot and Heat map analysis of OER and corresponding ICP reveal that patients with OER ≥ 0.21, have ICP in the range of 17 to 35 mm Hg. In the data available for this research work, OER ranges from 0.17 to 0.35.

Automation of ultrasonographic optic nerve sheath diameter measurement using convolutional neural networks

BACKGROUND AND PURPOSE

Ultrasonographic optic nerve sheath (ONS) diameter is a noninvasive intracranial pressure (ICP) surrogate. ICP is monitored invasively in specialized intensive care units. Noninvasive ICP monitoring is important in less specialized settings. However, noninvasive ICP monitoring using ONS diameter (ONSD) is limited by the need for experts to obtain and perform measurements. We aim to automate ONSD measurements using a deep convolutional neural network (CNN) with a novel masking technique.

METHODS

We trained a CNN to reproduce masks that mark the ONS. The edges of the mask are defined by an expert. Eight models were trained with 1000 epochs per model. The Dice-similarity-coefficient-weighted averaged outputs of the eight models yielded the final predicted mask. Eight hundred and seventy-three images were obtained from 52 transorbital cine-ultrasonography sessions, performed on 46 patients with brain injuries. Eight hundred and fourteen images from 48 scanning sessions were used for training and validation and 59 images from four sessions for testing. Bland-Altman and Pearson linear correlation analyses were used to evaluate the agreement between CNN and expert measurements.

RESULTS

Expert ONSD measurements and CNN-derived ONSD estimates had strong agreement (r = 0.7, p < .0001). The expert mean ONSD (standard deviation) is 5.27 mm (0.43) compared to CNN mean estimate of 5.46 mm (0.37). Mean difference (95% confidence interval, p value) is 0.19 mm (0.10-0.27 mm, p = .0011), and root mean square error is 0.27 mm.

CONCLUSION

A CNN can learn ONSD measurement using masking without image segmentation or landmark detection.

Effects of Supraglottic Airway Devices on Hemodynamic Response and Optic Nerve Sheath Diameter: Proseal LMA, LMA Supreme, and I-gel LMA

Background and Objectives: Supraglottic airway devices (SADs) are known to be useful in eliminating the drawbacks of laryngoscopy and tracheal intubation, especially ocular pressure and stress responses. The ultrasonographic measurement of optic nerve sheath diameter (ONSD) reflects increases in intracranial pressure (ICP). In our study, we aimed to compare the effects of SADs on hemodynamic response and ONSD. Materials and Methods: Our prospective study included 90 ASA I-II patients over the age of 18 who did not have a history of difficult intubation or ophthalmic pathology. The patients were randomly divided into three groups based on the laryngeal mask airway (LMA) devices used: ProSeal LMA (pLMA, n = 30), LMA Supreme (sLMA, n = 30), and I-gel (n = 30). The bilateral ONSD measurements and hemodynamic data of the patients who underwent standard anesthesia induction and monitoring were recorded before induction (T0) and 1 min (T1), 5 min (T5), and 10 min (T10) after SAD placement. Results: At all measurement times, the hemodynamic responses and ONSD values of the groups were similar. In all three groups, intergroup hemodynamic changes at T0 and T1 were similar and higher than those at other times of measurement (p < 0.001). The ONSD values of all groups increased at T1, and they tended to return to baseline values afterward (p < 0.001). Conclusions: We concluded that all three SADs could be used safely because they preserved both hemodynamic stability and ONSD changes in their placement processes, and they did not cause elevations in ONSD to an extent that would lead to increased ICP.

Evaluation of transorbital sonography measures of optic nerve diameter in the context of global and regional brain volume in multiple sclerosis

Transorbital sonography (TOS) could be a swift and convenient method to detect the atrophy of the optic nerve, possibly providing a marker that might reflect other quantitative structural markers of multiple sclerosis (MS). Here we evaluate the utility of TOS as a complementary tool for assessing optic nerve atrophy, and investigate how TOS-derived measures correspond to volumetric brain markers in MS. We recruited 25 healthy controls (HC) and 45 patients with relapsing-remitting MS and performed B-mode ultrasonographic examination of the optic nerve. Patients additionally underwent MRI scans to obtain T1-weighted, FLAIR and STIR images. Optic nerve diameters (OND) were compared between HC, MS patients with and without history of optic neuritis (non-ON) using a mixed-effects ANOVA model. The relationship between within-subject-average OND and global and regional brain volumetric measures was investigated using FSL SIENAX, voxel-based morphometry and FSL FIRST. OND was significantly different between HC-MS (HC = 3.2 ± 0.4 mm, MS = 3 ± 0.4 mm; p < 0.019) and we found significant correlation between average OND and normalised whole brain (β = 0.42, p < 0.005), grey matter (β = 0.33, p < 0.035), white matter (β = 0.38, p < 0.012) and ventricular cerebrospinal fluid volume (β = - 0.36, p < 0.021) in the MS group. History of ON had no impact on the association between OND and volumetric data. In conclusion, OND is a promising surrogate marker in MS, that can be simply and reliably measured using TOS, and its derived measures correspond to brain volumetric measures. It should be further explored in larger and longitudinal studies.

Noninvasive intracranial pressure assessment by optic nerve sheath diameter: Automated measurements as an alternative to clinician-performed measurements

Introduction

Optic nerve sheath diameter (ONSD) has shown promise as a noninvasive parameter for estimating intracranial pressure (ICP). In this study, we evaluated a novel automated method of measuring the ONSD in transorbital ultrasound imaging.

Methods

From adult traumatic brain injury (TBI) patients with invasive ICP monitoring, bedside manual ONSD measurements and ultrasound videos of the optic nerve sheath complex were simultaneously acquired. Automatic ONSD measurements were obtained by the processing of the ultrasound videos by a novel software based on a machine learning approach for segmentation of the optic nerve sheath. Agreement between manual and automated measurements, as well as their correlation to invasive ICP, was evaluated. Furthermore, the ability to distinguish dichotomized ICP for manual and automatic measurements of ONSD was compared, both for ICP dichotomized at ≥20 mmHg and at the 50th percentile (≥14 mmHg). Finally, we performed an exploratory subgroup analysis based on the software's judgment of optic nerve axis alignment to elucidate the reasons for variation in the agreement between automatic and manual measurements.

Results

A total of 43 ultrasound examinations were performed on 25 adult patients with TBI, resulting in 86 image sequences covering the right and left eyes. The median pairwise difference between automatically and manually measured ONSD was 0.06 mm (IQR -0.44 to 0.38 mm; p = 0.80). The manually measured ONSD showed a positive correlation with ICP, while automatically measured ONSD showed a trend toward, but not a statistically significant correlation with ICP. When examining the ability to distinguish dichotomized ICP, manual and automatic measurements performed with similar accuracy both for an ICP cutoff at 20 mmHg (manual: AUC 0.74, 95% CI 0.58-0.88; automatic: AUC 0.83, 95% CI 0.66-0.93) and for an ICP cutoff at 14 mmHg (manual: AUC 0.70, 95% CI 0.52-0.85; automatic: AUC 0.68, 95% CI 0.48-0.83). In the exploratory subgroup analysis, we found that the agreement between measurements was higher in the subgroup where the automatic software evaluated the optic nerve axis alignment as good as compared to intermediate/poor.

Conclusion

The novel automated method of measuring the ONSD on the ultrasound videos using segmentation of the optic nerve sheath showed a reasonable agreement with manual measurements and performed equally well in distinguishing high and low ICP.

Ultrasound measurement of optic nerve sheath diameter in a healthy adult Colombian population

BACKGROUND

Measurement of the optic nerve sheath diameter (ONSD) provides a rapid, safe, and easy method for detecting increased intracranial pressure (ICP). However, the normal mean and upper limit values may vary according to sex, age, ethnicity, and ultrasound technique.

AIM

We aimed to obtain the mean ONSD in a healthy Colombian adult population and to correlate it with demographic and anthropometric measures.

METHODS

In a prospective study using a 10-13 MHz linear ultrasound probe, eye transverse diameter (ETD) and ONSD in the transverse (ONSD-TP) and sagittal planes (ONSD-SP) were measured in healthy adult volunteers in Bogota, Colombia.

RESULTS

A total of 100 healthy subjects were included, with a mean age of 26,7 ± 8,3 years and 62 women. The mean ETD, ONSD-TP and ONSD-SP was 23.11 mm (95% confidence interval (CI): 22.90 mm-23.32 mm), 3.96 mm (95% CI: 3.85 mm-4.07 mm) and 4.0 mm (95% CI: 3.90 mm-4.11 mm), respectively. The ONSD in both planes ranged from 2.35 mm to 5.20 mm. There was a significant correlation between ONSD-SP and ONSD-TP (p < 0.0001) but no correlation between the ocular measures and demographic or anthropometric variables (p > 0.05). The intraclass correlation between the eyes was statistically significant.

CONCLUSION

Our study shows that ultrasound-measured ONSD in healthy adults in Colombia is similar to that found worldwide. An ONSD of 5.5 mm may be considered the upper limit for healthy adults in Colombia. ONSD can be measured in either plane; there is a good correlation between the two eyes; and ONSD is not modified by demographic or anthropometric characteristics.

The Association Between Hyponatremia and Optic Nerve Sheath Diameter: A Prospective Study

Background Hyponatremia is a common electrolyte balance disorder. It may result in brain edema and increased intracranial pressure (ICP). Optic nerve sheath diameter (ONSD) measurement remains an increasingly sought-after method in many situations associated with ICP elevations. The aim of our study was to investigate the relationship between the change of ONSD before and after hypertonic saline (3% sodium chloride) treatment and the clinical improvement with increased sodium levels in patients with symptomatic hyponatremia who presented to the emergency department. Methodology This study was conducted in the emergency department of a tertiary hospital, according to the design of a prospective, self-controlled, non-randomized trial study. Determined by power analysis, 60 patients were included in the study. The statistical analysis of the continuous data was performed using the means, standard deviations, and minimum and maximum values of the feature values. The frequency and percentage values were used to define categorical variables. The mean difference comparison of pre-and post-treatment measurements was evaluated by paired t-test. P<0.05 was considered to be significant. Results The measurement parameters' differences before and after hypertonic saline treatment were evaluated. While the mean of the right eye ONSD was 5.27±0.22 mm before treatment, it declined substantially to 4.52±0.24 mm after treatment (p<0.001). It was also found that the left eye ONSD was 5.26±0.23 mm before the treatment and declined to 4.53±0.24 mm after the treatment (p<0.001). In addition, the mean of the overall ONSD was 5.26±0.23 mm before treatment and 4.52±0.24 mm after treatment (p<0.001). Conclusions Ultrasonic measurement of ONSD can be used to monitor the clinical improvement of patients receiving hypertonic saline therapy for symptomatic hyponatremia.

Effects of pneumoperitoneum and patient position on intracranial pressure in obese patients undergoing laparoscopic cholecystectomy

Background/Aim: Optic nerve sheath diameter (ONSD) measurement is one of the non-invasive techniques used for intracranial pressure (ICP) measurement. ICP changes have been evaluated based on ONSD measurements during many laparoscopic surgeries. However, such analyses in the obese patient populations are limited. This study aimed at investigating the effects of pneumoperitoneum and reverse Trendelenburg and head-up position on ICP based on ONSD measurements in obese patients undergoing laparoscopic cholecystectomy. Methods: This observational study included 60 female patients who were scheduled for laparoscopic cholecystectomy. Obese patients with a body mass index (BMI) of 30 and above were assigned to Group 1, while BMI < 30 patients were assigned to Group 2. The first ONSD measurement was performed just before insufflation (T1). The second measurement was taken 5 min after insufflation (T2), the third measurement 5 min after placing patients in the reverse Trendelenburg and head-up position (T3), and the last measurement 5 min after the deflation while the reverse Trendelenburg and head-up position was maintained (T4). Results: ONSD measurements at the T2 and T3 time points in Group 1 patients were higher than in Group 2 patients (P = 0.012 versus P = 0.020). Both measurement values were higher in obese patients. In Group 1 patients, T2 and T3 measurements were significantly higher than T1 and T4 measurements (T2 > T1; P < 0.001, T2 > T4; P < 0.001, T3 > T1; P < 0.001, and T3 > T4; P < 0.001). No significant difference between T2 and T3 and between T1 and T4 measurements were found. In Group 2 patients, T2 measurements were significantly higher than the T1, T3, and T4 measurements, while T3 measurements were significantly higher than T1 and T4 measurements (T2 > T1; P < 0.001, T2 > T3; P = 0.022, T2 > T4; P < 0.001, T3 > T1; P < 0.001, and T3 > T4; P = 0.048). No significant difference between T1 and T4 measurements was noted. Conclusion: Laparoscopic cholecystectomy does not cause an increase in ICP of obese patients with limited pneumoperitoneum pressure, reverse Trendelenburg and head-up position, and controlled anesthesia.

Does MARPE therapy have effects on intracranial pressure? a clinical study

Background

We aimed to evaluate possible intracranial pressure (ICP) changes caused by screw activations during active microimplant-assisted rapid palatal expansion (MARPE) therapy of post-pubertal individuals by measuring the optic nerve sheath diameter (ONSD) under ultrasonography (US) guidance.

Methods

This study’s participants comprised 15 patients (7 males, 8 females) with posterior crossbite and a mean age of 16.7 years (14.25–20.08 years). The Maxillary Skeletal Expander (MSE) appliance was used to perform MARPE in all patients. Their vital signs (heart rate, mean arterial pressure (MAP), and peripheral oxygen saturation (SpO₂)) were recorded. The ONSD was measured by US immediately before the first screw activation (T0), and the measurements were repeated 1 min (T1) and 10 min (T2) after the first activation. In the last session of active MARPE therapy, the same measurement protocol was performed as in the first activation session (T3, T4, and T5). The patients’ perceptions of pain during the screw activation were also noted at T1 and T4 using a four-category verbal rating scale (VRS-4). The significant differences among different time intervals performed with the Friedman test (for all tested variables; SpO2, MAP, Heart Rate, VRS-4 and ONSD). Spearman correlation test was used for VRS-4 and ONSD comparisons. The statistical significance level was accepted as p < 0.05.

Results

The ONSD values ​​(T1 and T4) relatively increased within 1 min after screw activation but did not reach a statistically significant level (p > 0.05). There was also no significant difference between the initial (T0) and the final (T5) ONSD values ​​during the active MARPE therapy (p > 0.05).

Conclusion

There is no changes or alterations in intracranial pressure in late adolescents during active MARPE therapy.

Supplementary information

The online version contains supplementary material available at 10.1186/s12903-022-02482-x.

Observer Variability as a Determinant of Measurement Error of Ultrasonographic Measurements of the Optic Nerve Sheath Diameter: A Systematic Review

BACKGROUND

Ultrasonographic measurements of the diameter of the sheath of the optic nerve can be used to assess intracranial pressure indirectly. These measurements come with measurement error.

OBJECTIVE

Our aim was to estimate observer's measurement error as a determinant of ultrasonographic measurement variability of the optic nerve sheath diameter.

METHODS

A systematic search of the literature was conducted in Embase, Medline, Web of Science, the Cochrane Central Register of Trials, and the first 200 articles of Google Scholar up to April 19, 2021. Inclusion criteria were the following: healthy adults, B-mode ultrasonography, and measurements 3 mm behind the retina. Studies were excluded if standard error of measurement could not be calculated. Nine studies featuring 389 participants (median 40; range 15-100) and 22 observers (median 2; range 1-4) were included. Standard error of measurement and minimal detectable differences were calculated to quantify observer variability. Quality and risk of bias were assessed with the Guidelines for Reporting Reliability and Agreement Studies.

RESULTS

The standard error of measurement of the intra- and interobserver variability had a range of 0.10-0.41 mm and 0.14-0.42 mm, respectively. Minimal detectable difference of a single observer was 0.28-1.1 mm. Minimal detectable difference of multiple observers (range 2-4) was 0.40-1.1 mm. Quality assessment showed room for methodological improvement of included studies.

CONCLUSIONS

The standard errors of measurement and minimal detectable differences of ultrasonographic measurements of the optic nerve sheath diameter found in this review with healthy participants indicate caution should be urged when interpreting results acquired with this measurement method in clinical context.

Reliability and feasibility of optic nerve point-of-care ultrasound in pediatric patients with ventricular shunts

PURPOSE

To determine the interrater reliability of optic nerve sheath diameter (ONSD) and optic disc elevation (ODE) via ocular ultrasound by emergency and neurosurgery providers in children with ventricular shunts, and to explore the feasibility of acquiring and measuring images.

METHODS

Two novices who underwent focused training and one expert in ocular ultrasound independently acquired images and measured ONSD and ODE on the same children, 0-18 years with ventricular shunts, blinded to each other's images and measurements. Patient tolerance, image quality, and time-to-complete exams were recorded. Images meeting a priori defined quality metrics were included. Mixed models and bootstrap analysis were used to obtain inter-rater reliability and 95% confidence intervals.

RESULTS

Eighty-one children were enrolled from August 2016 to July 2017, with mean age 9.6 years (SD 5.25, range 5 months-17.7 years). High-quality images (≥ 4 on 7-point quality Likert scale) were obtained in 83% of ONSD assessments and 95% of ODE assessments. The ICC_ONSD was 0.82 (95% CI 0.76-0.91) for right eyes and 0.73 (95% CI 0.69-0.85) for left, while ICC_ODE was 0.81 (95% CI 0.75-0.89) for right eyes and 0.85 (95% CI 0.79-0.91) for left. Mean study duration (both eyes) was 2:52 min (SD 54 s).

CONCLUSION

Clinicians generated high-quality ocular ultrasound images with excellent interrater reliability when acquiring and measuring images of ONSD and ODE in children with ventricular shunts.

Quality assessment of optic nerve sheath diameter ultrasonography: Scoping literature review and Delphi protocol

BACKGROUND AND PURPOSE

The optic nerve is surrounded by the extension of meningeal coverings of the brain. When the pressure in the cerebrospinal fluid increases, it causes a distention of the optic nerve sheath diameter (ONSD), which allows the use of this measurement by ultrasonography (US) as a noninvasive surrogate of elevated intracranial pressure. However, ONSD measurements in the literature have exhibited significant heterogeneity, suggesting a need for consensus on ONSD image acquisition and measurement. We aim to establish a consensus for an ONSD US Quality Criteria Checklist (ONSD US QCC).

METHODS

A scoping systematic review of published ultrasound ONSD imaging and measurement criteria was performed to guide the development of a preliminary ONSD US QCC that will undergo a modified Delphi study to reach expert consensus on ONSD quality criteria. The protocol of this modified Delphi study is presented in this manuscript.

RESULTS

A total of 357 ultrasound studies were included in the review. Quality criteria were evaluated under five categories: probe selection, safety, positioning, image acquisition, and measurement.

CONCLUSIONS

This review and Delphi protocol aim to establish ONSD US QCC. A broad consensus from this process may reduce the variability of ONSD measurements in future studies, which would ultimately translate into improved ONSD clinical applications. This protocol was reviewed and endorsed by the German Society of Ultrasound in Medicine.

Measuring optic nerve sheath diameter using ultrasonography in patients with idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is primarily a disorder of obese young women characterized by symptoms associated with raised intracranial pressure in the absence of a space-occupying lesion.

OBJECTIVE

To compare the mean optic nerve sheath diameter (ONSD) measured using ultrasonography (USG) in patients with idiopathic intracranial hypertension (IIH) and normal healthy individuals.

METHODS

A prospective study. Ninety-seven participants aged 18-80 years were divided into two groups as patients with IIH (n=47) and the control group (n=50). The ONSD was measured using ultrasound with a 10-MHz probe. ONSD was measured 3 mm behind the optic disc. Receiver operating characteristic (ROC) curve analysis was performed to determine patients with IIH using ONSD.

RESULTS

Body mass index was higher in the IIH group compared with the control group (p=0.001). The mean ONSD was statistically significantly thicker in the IIH group (6.4 mm) than in the control group (4.90 mm). The cut-off value of ONSD in patients with IIH was measured as 5.70 mm. There was a significant negative correlation between ONSD and age (r:-0.416 and p<0.001). There was a positive correlation between BMI and ONSD (r: 0.437 and p<0.001).

CONCLUSIONS

Ultrasound can be a reliable, non-invasive and rapid tool to measure ONSD in monitoring patients with IIH. After the first diagnosis of IIH, based on neuroimaging and measuring intracranial pressure using invasive methods, ONSD can be used in treatment and follow-up.

Accuracy of Optic Nerve Sheath Diameter Measurements in Pocket-Sized Ultrasound Devices in a Simulation Model

Introduction

Transorbital sonographic measurement of optic nerve sheath diameter (ONSD) is an emerging non-invasive technique for the identification and monitoring of intracranial hypertension. In recent years, new pocket ultrasound devices have become available, and it is uncertain if they have the resolution to measure such small structures appropriately as compared to their predecessors. In this study, we measure the performance of three ultrasound units on a simulation model to establish their precision and accuracy.

Methods

ONSD was measured by three expert point-of-care sonographers using ultrasound machines three times on each of seven discrete ONS model sizes ranging from 3.5 to 7.9 mm. Two pocket ultrasounds (IVIZ, Sonosite, and Lumify, Philips) and one standard-sized portable ultrasound (M-Turbo, Sonosite) were used. Measurements were analyzed for mean error and variance and tested for significance using blocked covariance matrix regression analyses.

Results

The devices differed in their variances (Lumify: 0.19 mm², M-Turbo: 0.26 mm², IVIZ: 0.34 mm²) and their mean error (Lumify: -0.05 mm, M-Turbo: 0.10 mm, IVIZ: -0.10 mm). The difference in mean error between users is not significant (p = 0.45), but there is a significant difference in mean error between devices (p = 0.02).

Conclusions

Accurate ONSD measurement is possible utilizing pocket-sized ultrasound, and in some cases, may be more accurate than larger portable ultrasound units. While the differences in these devices were statistically significant, all three were highly accurate, with one pocket device (Lumify) outperforming the rest. Further study in human subjects should be conducted prior to using pocket ultrasound devices for in vivo diagnosis of intracranial hypertension.

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.

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.

Ultrasound of Optic Nerve Sheath Diameter and Stroke Outcomes

Supplemental Digital Content is available in the text.

We aimed at utilizing ocular ultrasound to determine its utility in predicting outcomes among stroke patients.

High-resolution MRI assessment of optic nerve sheath diameter in adults: optic nerve sheath variation and a new diagnostic tool for intracranial hypertension

BACKGROUND

Assessment of optic nerve sheath diameter (ONSD) is a non-invasive measure of intracranial pressure (ICP). However, it is not clear whether healthy individuals exhibit ONSD variation or whether factors other than ICP affect the ONSD.

PURPOSE

To investigate whether ONSD was correlated with age, sex, height, weight, eyeball transverse diameter (ETD), or body mass index (BMI), and to develop a new diagnostic model to increase the diagnostic accuracy of intracranial hypertension (IH).

MATERIAL AND METHODS

A total of 145 relatively healthy adults and 40 patients with acute IH who underwent high-resolution magnetic resonance imaging (MRI) were enrolled in this study. Linear regression analyses were used to determine the relationship between ONSD and these variables. If correlations were identified, an index ONSD_Δ removing variables effects was calculated. ROC analysis was used to assess the IH predictive value of ONSD_Δ in terms of sensitivity and specificity.

RESULTS

In relatively healthy adults, there was a correlation between ONSD and BMI (P = 0.002), which can be presented as an index ONSD_Δ. The ONSD_Δ model better predicted IH than the ONSD model (P = 0.035), with a sensitivity of 70.00%, a specificity of 71.72%, and an AUC of 0.755.

CONCLUSION

A correlation between ONSD and body mass index (BMI) was found using high-resolution MRI. This result indicates that the effects of BMI should be considered along with the ONSD during ICP monitoring. Meanwhile, the index ONSD_Δ was better than the ONSD in predicting IH and could be used to obtain a more precise estimation of ICP.

Is Increased Intracranial Pressure a Factor in Persistent Headache After Coronavirus Disease 2019?

ABSTRACT

This study aimed to determine pain characteristics in patients with persistent headache after COVID-19 and to investigate the role of increased intracranial pressure (ICP) in the pathogenesis of this headache. This is a case-control study comparing the parameters and measurements indicating increased ICP based on magnetic resonance imaging between COVID-19-diagnosed patients with persistent headache and a control group. Optic nerve sheath diameter (ONSD) and eyeball transverse diameter (ETD) were performed on the left eye of each participant. Seventeen of the patients (53.12%) met the diagnostic criteria for new daily persistent headache. Seven patients (21.87%) had migraine, and eight (25%) had tension headache characteristics. No significant difference was observed between the patient and control groups in terms of the ONSD and ETD values. It is possible that the etiopathogenesis is multifactorial. We consider that future studies that will evaluate ICP measurements in large patient groups can present a different perspective for this subject.

Comparison of Three Point-of-Care Ultrasound Views and MRI Measurements for Optic Nerve Sheath Diameter: A Prospective Validity Study

INTRODUCTION

Point-of-care ultrasound of the optic nerve sheath diameter (ONSD) to diagnose increased intracranial pressure (ICP) is of great interest in various clinical scenarios. Yet, the lack of examination standardization has made clinical utility difficult. We compare three ultrasound ocular plane views (inferior, sagittal, and transverse), which are currently used in the literature to evaluate their consistency. Comparisons for each view to magnetic resonance imaging (MRI) measurements were also made.

METHODS

Fifty-one patients with recent MRI of the brain, but without clinical or radiological signs of elevated ICP, were selected to undergo ocular sonography via three ultrasound planes (inferior, sagittal, and transverse). Optic nerve sheath was measured in each ultrasound view as well with MRI. Image quality scores were assigned for the ultrasound views in different orientations. The three ocular plane views were analyzed for correlation. In addition, correlation of the three ocular ultrasound views with MRI was also performed.

RESULTS

Correlation analysis showed a wide variability in the correlation between different ultrasound views with magnitude range of 0.1 to 0.8 and directions being both positive and negative. There was a difference in image quality scores between the ultrasound views. The inferior and transverse orientations were superior to the sagittal orientation in achieving high image quality. Comparison to MRI measurements did not demonstrate a significant correlation.

CONCLUSION

Our findings suggest that absolute measurements should not be compared across different ultrasound orientations given the wide variability in the correlation between the ultrasound views used to assess the optic nerve sheath. The inferior and transverse ultrasound views are the most likely to yield high-quality images, although the specific view, for the best image, in an individual patient can vary. We would caution against absolute values of ONSD to indicate increased ICP, as it may be view dependent.

The role of optic nerve sheath diameter ultrasound in brain infection

Brain infections cause significant morbidity and mortality worldwide, especially in resource-limited settings with high HIV co-infection rates. Raised intracranial pressure [ICP] may complicate brain infection and worsen neurological injury, yet invasive ICP monitoring is often unavailable. Optic nerve sheath diameter [ONSD] ultrasound may allow detection of raised ICP at the bedside; however, pathology in brain infection is different to traumatic brain injury, in which most studies have been performed. The use of ONSD ultrasound has been described in tuberculous meningitis, cryptococcal meningitis and cerebral malaria; however correlation with invasive ICP measurement has not been performed. Normal optic nerve sheath values are not yet established for most populations, and thresholds for clinical intervention cannot be assumed to match those used in non-infective brain pathology. ONSD ultrasound may be suitable for use in resource-limited settings by clinicians with limited ultrasound training. Standardisation of scanning technique, consensus on normal ONSD values, and action on abnormal results, are areas for future research. This scoping review examines the role of ONSD ultrasound in brain infection. We discuss pathophysiology, and describe the rationale, practicalities, and challenges of utilising ONSD ultrasound for brain infection monitoring and management. We discuss the existing evidence base for this technique, and identify knowledge gaps and future research priorities.

Evaluation of transpalpebral ultrasonographic measurement of optic nerve sheath diameter for indirect assessment of intracranial pressure in anesthetized and standing healthy adult horses

OBJECTIVE

To determine whether an association exists between direct intracranial pressure (ICP) measurement and ultrasonographic measurement of optic nerve sheath diameter (ONSD) in anesthetized and standing horses.

DESIGN

Cross-sectional study performed on a convenience sample of healthy adult horses.

SETTING

University teaching hospital.

ANIMALS

Eight adult horses donated to the University. Enrolled horses were free of abnormalities on physical examination, CBC, neurological evaluation, and ophthalmological examination.

MEASUREMENTS AND MAIN RESULTS

Horses were anesthetized in lateral recumbency for placement of an ICP transducer. Three head positions (neutral, elevated, and lowered) were used to alter ICP. ICP and ONSD in 2 directions (D1 and D2) were recorded at 5 and 10 minutes after position change to elevated and lowered. ICP and ONSD measurements were repeated in standing sedated horses 24-36 hours after recovery from anesthesia. Linear regressions were performed with ICP as the dependent variable and ONSD as the independent variable by head position and times. Linear regressions were also performed for change from neutral under anesthesia, with ONSD as the independent variable and ICP as the dependent variable, by head position and times. Significance was set at P < 0.05. There was a moderate association between ICP and ONSD in horses with head lowered at 5 and 10 minutes (R² values = 63%-78%) and weak association in head elevated at 10 minutes (R² values = 56%-63%). There was a weak association between change from neutral ICP and change from neutral ONSD in the elevated anesthetized position at 10 minutes for summed D1 + D2 (R²  = 33%).

CONCLUSIONS

Consistent associations between direct ICP and ONSD in anesthetized or standing horses were not observed. This inconsistency limits the clinically utility of transpalpebral ultrasonographic ONSD measurement for ICP monitoring in horses.

Blunt and Penetrating Severe Traumatic Brain Injury

Severe traumatic brain injury is a common problem. Current practices focus on the importance of early resuscitation, transfer to high-volume centers, and provider expertise across multiple specialties. In the emergency department, patients should receive urgent intracranial imaging and consideration for tranexamic acid. Close observation in the intensive care unit environment helps identify problems, such as seizure, intracranial pressure crisis, and injury progression. In addition to traditional neurologic examination, patients benefit from use of intracranial monitors. Monitors gather physiologic data on intracranial and cerebral perfusion pressures to help guide therapy. Brain tissue oxygenation monitoring and cerebromicrodialysis show promise in studies.

Neuromonitoring After Cardiac Arrest: Can Twenty-First Century Medicine Personalize Post Cardiac Arrest Care?

Cardiac arrest survivors comprise a heterogeneous population, in which the etiology of arrest, systemic and neurologic comorbidities, and sequelae of post-cardiac arrest syndrome influence the severity of secondary brain injury. The degree of secondary neurologic injury can be modifiable and is influenced by factors that alter cerebral physiology. Neuromonitoring techniques provide tools for evaluating the evolution of physiologic variables over time. This article reviews the pathophysiology of hypoxic-ischemic brain injury, provides an overview of the neuromonitoring tools available to identify risk profiles for secondary brain injury, and highlights the importance of an individualized approach to post cardiac arrest care.

An Automated Algorithm for Optic Nerve Sheath Diameter Assessment from B-mode Ultrasound Images

BACKGROUND AND PURPOSE

The optic nerve sheath diameter (ONSD) is a promising surrogate marker for the detection of raised intracranial pressure (ICP). However, inconsistencies in manual ONSD assessment are thought to affect ONSD and the corresponding ONSD cutoff values for the diagnosis of elevated ICP, hereby hampering the full potential of ONSD. In this study, we developed an image intensity-invariant algorithm to automatically estimate ONSD from B-mode ultrasound images at multiple depths.

METHODS

The outcomes of the algorithm were validated against manual ONSD measurements by two human experts. Each expert analyzed the images twice (M1 and M2) in unknown order.

RESULTS

The algorithm proved capable of segmenting the ONSD in 39 of 42 images, hereby showing mean differences of -.08 ± .45 and -.05 ± .41 mm compared to averaged ONSD values (M1 + M2/2) of Operator 1 and Operator 2, respectively, whereas the mean difference between the two experts was .03 ± .26 mm. Moreover, differences between algorithm-derived and expert-derived ONSD values were found to be much smaller than the 1 mm difference that is expected between patients with normal and elevated ICP, making it likely that our algorithm can distinguish between these patient groups.

CONCLUSIONS

Our algorithm has the potential to improve the accuracy of ONSD as a surrogate marker for elevated ICP because it has no intrinsic variability. However, future research should be performed to validate if the algorithm does indeed result in more accurate noninvasive ICP predictions.

Comparison of ultrasonography and computed tomography for measuring optic nerve sheath diameter for the detection of elevated intracranial pressure

OBJECTIVE

The main aim of this study was to compare optic nerve sheath diameter (ONSD) measured using ultrasonography (USG) and computed tomography (CT) almost simultaneously in the same patients with suspected elevated intracranial pressure. The other aim of this study was to evaluate the diagnostic ability for detecting elevated intracranial pressure using ONSD measured by USG (USG-ONSD) and by CT (CT-ONSD).

PATIENTS AND METHODS

This prospective, observational study was undertaken from June to October 2020 in the emergency department (ED) of a tertiary medical center in Seoul. ONSD was measured by USG and CT at 3 mm behind the posterior aspect of the globe.

RESULT

A total of 199 patients were enrolled. The median USG-ONSD and CT-ONSD were significantly higher in patients with elevated intracranial pressure than in patients with normal intracranial pressure. The interclass correlation coefficient between USG-ONSD and CT-ONSD was 0.785 (95% CI 0.715-0.837). A Bland-Altman plot showed significant agreement between USG and CT measurements. The optimal cutoff for detecting elevated intracranial pressure was >5.3 mm (sensitivity of 75.4% and specificity of 90.8%) for USG and >5.0 mm (sensitivity of 68.4% and specificity of 85.2%) for CT.

CONCLUSION

The ONSD measured using USG and CT were increased in patients with elevated intracranial pressure. Measurement of ONSD by USG and CT showed very high agreement.

The Diagnostic Accuracy of Noninvasive Methods to Measure the Intracranial Pressure: A Systematic Review and Meta-analysis

BACKGROUND

Although invasive monitoring is the standard method for intracranial pressure (ICP) measurement, it is not without potential for serious complications. Noninvasive methods have been proposed as alternatives to invasive ICP monitoring. The study aimed to investigate the diagnostic accuracy of the currently available noninvasive methods for intracranial hypertension (ICH) monitoring.

METHODS

We searched 5 databases for articles evaluating the diagnostic accuracy of noninvasive methods in diagnosing ICH in PubMed, Institute of Science Index, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), and Embase. The quantitative analysis was conducted if there were at least 2 studies evaluating a specific method. The accuracy measures included the sensitivity, specificity, likelihood ratios, and diagnostic odds ratio.

RESULTS

We included 134 articles. Ultrasonographic optic nerve sheath diameter (US ONSD) had high diagnostic accuracy (estimated sensitivity of 90%; 95% confidence interval [CI], 87-92, estimated specificity of 88%; 95% CI, 84-91) while the magnetic resonance imaging (MRI) ONSD had estimated sensitivity of 77%; 95% CI, 64-87 and estimated specificity of 89%; 95% CI, 84-93, and computed tomography (CT) ONSD had estimated sensitivity of 93%; 95% CI, 90-96 and estimated specificity of 79%; 95% CI, 56-92. All MRI signs had a very high estimated specificity ranging from 90% to 99% but a low estimated sensitivity except for sinus stenosis which had high estimated sensitivity as well as specificity (90%; 95% CI, 75-96 and 96%; 95% CI, 91-99, respectively). Among the physical examination signs, pupillary dilation had a high estimated specificity (86%; 95% CI, 76-93). Other diagnostic tests to be considered included pulsatility index, papilledema, transcranial Doppler, compression or absence of basal cisterns, and ≥10 mm midline shift. Setting the cutoff value of ICH to ≥20 mm Hg instead of values <20 mm Hg was associated with higher sensitivity. Moreover, if the delay between invasive and noninvasive methods was within 1 hour, the MRI ONSD and papilledema had a significantly higher diagnostic accuracy compared to the >1 hour subgroup.

CONCLUSIONS

Our study showed several promising tools for diagnosing ICH. Moreover, we demonstrated that using multiple, readily available, noninvasive methods is better than depending on a single sign such as physical examination or CT alone.

Using Oculomotor Features to Predict Changes in Optic Nerve Sheath Diameter and ImPACT Scores From Contact-Sport Athletes

There is mounting evidence linking the cumulative effects of repetitive head impacts to neuro-degenerative conditions. Robust clinical assessment tools to identify mild traumatic brain injuries are needed to assist with timely diagnosis for return-to-field decisions and appropriately guide rehabilitation. The focus of the present study is to investigate the potential for oculomotor features to complement existing diagnostic tools, such as measurements of Optic Nerve Sheath Diameter (ONSD) and Immediate Post-concussion Assessment and Cognitive Testing (ImPACT). Thirty-one high school American football and soccer athletes were tracked through the course of a sports season. Given the high risk of repetitive head impacts associated with both soccer and football, our hypotheses were that (1) ONSD and ImPACT scores would worsen through the season and (2) oculomotor features would effectively capture both neurophysiological changes reflected by ONSD and neuro-functional status assessed via ImPACT. Oculomotor features were used as input to Linear Mixed-Effects Regression models to predict ONSD and ImPACT scores as outcomes. Prediction accuracy was evaluated to identify explicit relationships between eye movements, ONSD, and ImPACT scores. Significant Pearson correlations were observed between predicted and actual outcomes for ONSD (Raw = 0.70; Normalized = 0.45) and for ImPACT (Raw = 0.86; Normalized = 0.71), demonstrating the capability of oculomotor features to capture neurological changes detected by both ONSD and ImPACT. The most predictive features were found to relate to motor control and visual-motor processing. In future work, oculomotor models, linking neural structures to oculomotor function, can be built to gain extended mechanistic insights into neurophysiological changes observed through seasons of participation in contact sports.

Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

BACKGROUND

Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels.

METHODS

An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter.

RESULTS

All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: -80.5 + 238.2 × AON.

CONCLUSION

In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.

Usefulness of the optic nerve sheath ultrasound in patients with cessation of cerebral flow

Optic nerve sheath diameter (ONSD) ultrasound has proven to be a useful tool for the detection of intracranial hypertension (IH). The ONSD values, in patients with cessation of cerebral blood flow (CCBF), has not been clarified yet.

OBJECTIVE

Establish an association between ONSD and CCBF in neurocritical patients admitted to an ICU.

PATIENTS AND METHODS

Cross-sectional study of patients admitted in a third level ICU, between April 2017 and April 2018, with neurological pathology. ONSD ultrasound was performed in the first 24 hours and as the patient was diagnosed of CCBF. The ONSD values of patients with and without diagnosis of CCBF were compared.

RESULTS

99 patients were included, 29 of whom showed CCBF in transcranial Doppler. The ONSD measurement did not demonstrate significant differences between both groups, 6,59 ± 0,75 in the group with CCBF and 6,39 ± 0,56 in the group without CCBF p=0.141.

CONCLUSION

In our study, ONSD values capable of recognizing CCBF were not identified.

Review: Optikussonografie – ein update 2020

Die Optikus-Sonografie bildet Papille, Sehnerv sowie dessen perineuralenLiquorraum ab und eröffnet damit u. a. einen diagnostischen Zugang zumintrakraniellen Liquorsystem und dessen Druck(ICP). Auf diese Weise lässt sich eine relevante ICP-Erhöhung über 20 mmHg nicht-invasiv und bettseitig belegen. Mit Einzelmessungen und Verlaufskontrollen hilft die Methode u. a. vor und nach der Etablierung eines invasiven ICP-Monitorings in der Intensiv- und Notfallmedizin sowie bei der Beurteilung chronischer Dysregulationen des ICP.

Optic nerve sheath diameter sonography during the acute stage of intracerebral hemorrhage: a potential role in monitoring neurocritical patients

BACKGROUND

Optic nerve sheath diameter (ONSD) sonography has been proposed as a reliable bedside tool for the detection of increased intracranial pressure (ICP). ONSD reacts almost simultaneously to oscillations in ICP. The aim of this study was to investigate the ONSD dynamics in the acute stage of intracerebral hemorrhage (ICH) and to compare ONSD dynamics to the clinical outcome.

METHODS

We enrolled 35 acute ICH patients and 20 healthy volunteers in this prospective study. At the admission, all patients underwent brain CT scan and ONSD sonography. We repeated the ONSD on the second and the third day in all patients while CT scan was repeated if a patient condition deteriorated. The changes in serial ONSD measurements were termed as stable or unstable ONSD trend. ONSD trend was considered as unstable if variations of average ONSD were above 5%. The outcome of the patient was assessed with the Modified Rankin Scale (mRS) and Glasgow Outcome Scale (GOS).

RESULTS

In healthy volunteers serial ONSD recordings for 3 days revealed a stable trend in 100%. However, in the study group, 23 patients had unstable and 12 had stable ONSD trend during the acute stage of ICH. The patients with unstable ONSD trend were more likely to have worse outcomes (p value 0.003).

CONCLUSION

In patients with ICH, the acute-phase ONSD dynamics can help in predicting the clinical outcome.

Ultrasonographic measurement of the optic nerve sheath in the differential diagnosis and follow-up of migraine with and without aura: A pilot study

OBJECTIVE

Headache continues to be a common cause of emergency admissions. At first glance, primary headaches may not be distinguished from secondary headaches. This study aimed to evaluate the use of ultrasonic measurement of optic nerve sheath diameter (ONSD) in the clinical diagnosis of migraine patients during attack and during periods without attacks.

PATIENTS AND METHODS

This prospective study was conducted at the emergency department and neurology outpatient clinic of a tertiary hospital between October 2019 and January 2020. Patients diagnosed with episodic migraine and between ages 18-60 were included in the study. Migraine diagnosis and classification were based on criteria from the 2018 International Classification of Headache Disorders. ONSD measurement was performed with ultrasonography. ONSD measurements of the same migraine patients during attack and attack-free periods were compared with measurements of healthy volunteers.

RESULTS

A total of 82 participants consisting of 42 migraine patients and 40 control subjects were evaluated. In the control group, mean ONSD of the right eye was 4.88 ± 0.31 mm and mean ONSD of the left eye was 4.86 ± 0.31 mm. Mean ONSD measurement of the left eye was 4.80 ± 0.36 mm and mean ONSD of the right eye was 4.82 ± 0.37 during the attack period of the migraine patients. There was no significant difference between the migraine patients and the control group according to right and left eye ONSD measurements (attack-free period: p = 0.200, p = 0.448; attack period: p = 0.338, p = 0.660, respectively). There was no significant difference between ONSD measurements during the attack period and attack-free period in migraine patients (right eye p = 0.32; left eye p = 0.532).

CONCLUSION

The results of our study indicate that ONSD measurements may provide clinical insight into differential diagnosis preceding neuroimaging in migraine patients. On the other hand, since our study is the first on this topic, it should be noted that further studies are needed to come to a conclusion.

Optic Nerve Sheath Diameter Measured by Point-of-Care Ultrasound and MRI

BACKGROUND AND PURPOSE

Ultrasound (US) measurement of the optic nerve sheath diameter (ONSD) and optic nerve diameter (OND) is a method frequently used to screen for an increased intracranial pressure. The aim of this study was to assess the accuracy of US measurements of ONSD and OND, when compared to magnetic resonance imaging (MRI) measurements as the criterion standard.

METHODS

In this prospective, single-institution study, orbital US was performed for those patients requiring an emergent brain MRI. ONSD and OND of both eyes were measured in the axial and coronal planes in straight gaze by US. ONSD and OND from brain and orbital MRI were measured by two neuroradiologists. Correlation and agreement between readings were assessed using Pearson's correlations.

RESULTS

Eighty-two patients met inclusion criteria. The mean axial and coronal ONSD in the MRI examinations was 5.6 and 5.7 mm at 3-5.9 mm behind the globe, respectively. The mean ONSD from the US measurements was 6.22 and 5.52 mm in the axial and coronal planes, respectively. The mean OND in US examinations was 4.31 mm (axial) and 3.68 mm (coronal). Axial versus coronal measurements of ONSD had a modest correlation in US assessment with an r² of .385 (P < .001) but there were no correlations between any of the US and MRI measurements.

CONCLUSIONS

In measuring ONSD and OND, US measurements showed a modest correlation between axial and coronal measurements, but no concordance was found between US and MRI in our setting.

The effect of laryngoscope types on hemodynamic response and optic nerve sheath diameter. McCoy, Macintosh, and C-MAC video-laryngoscope

OBJECTIVES

This study aims to investigate the effect of McCoy, Macintosh laryngoscope, and C-MAC video-laryngoscopes on optic nerve sheath diameter (ONSD) and hemodynamic responses to laryngoscopy and intubation.

METHODS

This prospective randomized study was conducted in Zonguldak Bülent Ecevit University Hospital, Zonguldak, Turkey, between July 2019 and January 2020. Informed written consent was obtained from all patients. Patients with previous intracranial/ocular surgery or glaucoma were excluded from the study. The patients were randomized to use McCoy, Macintosh, and C-MAC (30 per group). Intubations were performed by the same person. Mean arterial pressure, heart rate (HR), and ONSD were recorded before the induction and repeated in 1, 3, 5, and 10 minutes after the intubation.

RESULTS

The effects of laryngoscopy and intubation on hemodynamic responses and ONSD were similar between groups (p greater than 0.05). While the comparison within groups showed ONSD increase in McCoy group and HR and ONSD increase in the Macintosh group compared to baseline 1 min after the intubation, no change was observed in hemodynamic responses and ONSD measurements in the C-MAC® group (p greater than 0.05).

CONCLUSIONS

In this study, there was no significant difference between the groups in terms of ONSD and hemodynamic responses to laryngoscopy and intubation. It was observed that there were no significant changes in ONSD values just in C-MAC® video-laryngoscope group. Therefore, intubations with C-MAC® video-laryngoscope are thought to be more appropriate for patients with an increase in intracranial pressure.

Effects of Age and Sex on Optic Nerve Sheath Diameter in Healthy Volunteers and Patients With Traumatic Brain Injury

The measurement of optic nerve sheath diameter (ONSD) has been reported as a non-invasive marker for intracranial pressure (ICP). Nevertheless, it is uncertain whether possible ONSD differences occur with age and sex in healthy and brain-injured populations. The aim of this study was to investigate the effects of sex and age on ONSD in healthy volunteers and patients with traumatic brain injury. We prospectively included 122 healthy adult volunteers (Galliera Hospital, Genova, Italy), and compared age/sex dependence of ONSD to 95 adult patients (Addenbrooke's Hospital, Cambridge, UK) with severe traumatic brain injury (TBI) requiring intubation and invasive ICP monitoring. The two groups were stratified for sex and age. Age was divided into 3 subgroups: (1) young adults: 18–44 years; (2) middle-aged adults: 45–64 years; (3) old adults: >65 years. In healthy volunteers, ONSD was significantly different between males and females [median (interquartile range): 4.2 (3.9–4.6) mm vs. 4.1 (3.6–4.2) mm (p = 0.01), respectively] and was correlated with age (R = 0.50, p < 0.0001). ONSD was significantly increased in group 3 compared to groups 2 and 1, indicating that ONSD values are higher in elderly subjects. In TBI patients, no differences in ONSD were found for sex and the correlation between ONSD and age was non-significant (R = 0.13, p = 0.20). ONSD increases with age and is significantly larger for males in healthy volunteers but not in TBI patients. Different ONSD cut-off values need not be age- or sex-adjusted for the assessment of increased ICP in TBI patients.

Comparative and retrospective evaluation of the predictive performance of optic nerve sheath thickness and optic nerve sheath diameter for traumatic brain injury using facial computed tomography

OBJECTIVE

To evaluate the predictive performance of optic nerve sheath thickness (ONST) on the outcomes of traumatic brain injury (TBI) and to compare the inter-observer agreement To evaluate the predictive performance of optic nerve sheath thickness (ONST) for traumatic brain injury (TBI) and to compare the predictive performance and inter-observer agreement between ONST and optic nerve sheath diameter (ONSD) on facial computed tomography (CT).

METHODS

We retrospectively enrolled patients with a history of facial trauma and who underwent both facial CT and brain CT. Two reviewers independently measured ONST and ONSD of each patient using facial CT images. Final brain CT with clinical outcome was used as the reference standard for TBI. Multivariate logistic regression analyses, receiver operating characteristic (ROC) curves, and intraclass correlation coefficients were used for statistical analyses.

RESULTS

Both ONST (P=0.002) and ONSD (P=0.001) on facial CT were significantly independent factors to distinguish between TBI and healthy brains; an increase in ONST and ONSD values corresponded with an increase in the risk of TBI by 8.9- and 7.6-fold, respectively. The predictive performances of the ONST (sensitivity, 96.2%; specificity, 94.3%; area under the ROC curve, 0.968) and ONSD (sensitivity, 92.6%; specificity, 90.2%; area under the ROC curve, 0.955) were excellent and exhibited similar sensitivity, specificity, and area under the curve (P=0.18-0.99). Interobserver and intraobserver intraclass correlation coefficients for ONST were significantly higher than those for ONSD (all P<0.001).

CONCLUSION

ONST on facial CT is a feasible predictor of TBI and demonstrates similar performance and superior observer agreement than ONSD. We recommend using ONST measurements to assess the need for additional brain CT scans in TBI-suspected cases.

Evaluation of the medial rectus muscle and optic nerve using strain and shear wave elastography in Graves' patients

PURPOSE

The purpose of this study was to describe the elastic properties of the medial rectus muscle and optic nerve in Graves' patients without clinically apparent ophthalmopathy using strain elastography (SE) and shear wave elastography (SWE) and to determine whether these elastic properties could be used to aid in the diagnosis of the medial rectus muscle or optic nerve involvement.

MATERIALS AND METHODS

Thirty participants diagnosed with Graves' disease without ophthalmopathy and 30 healthy volunteers (control group) were prospectively examined between November 2018 and August 2019. SE and SWE findings in both groups were compared using the χ² test and the independent samples t test.

RESULTS

A statistically significant softening of the medial rectus muscle was observed in the SE patterns of the Graves' patients (p = 0.009). A statistically appreciable distinction was observed between the medial rectus muscle (7.64 ± 2.1 and 9.20 ± 1.7 kPa, p = 0.000) and the optic nerve (8.35 ± 2.8 and 9.37 ± 1.5 kPa, p = 0.019) in the SWE modulus of the Graves' patients and healthy volunteers.

CONCLUSION

SE and SWE can be used to identify structural alterations to the medial rectus muscle and optic nerve before clinically apparent Graves' ophthalmopathy has developed.

Automatic Optic Nerve Measurement: A New Tool to Standardize Optic Nerve Assessment in Ultrasound B-Mode Images

Transorbital sonography provides reliable information about the estimation of intra-cranial pressure by measuring the optic nerve sheath diameter (ONSD), whereas the optic nerve (ON) diameter (OND) may reveal ON atrophy in patients with multiple sclerosis. Here, an AUTomatic Optic Nerve MeAsurement (AUTONoMA) system for OND and ONSD assessment in ultrasound B-mode images based on deformable models is presented. The automated measurements were compared with manual ones obtained by two operators, with no significant differences. AUTONoMA correctly segmented the ON and its sheath in 71 out of 75 images. The mean error compared with the expert operator was 0.06 ± 0.52 mm and 0.06 ± 0.35 mm for the ONSD and OND, respectively. The agreement between operators and AUTONoMA was good and a positive correlation was found between the readers and the algorithm with errors comparable with the inter-operator variability. The AUTONoMA system may allow for standardization of OND and ONSD measurements, reducing manual evaluation variability.

Bedside Ultrasonographic Assessment of Optic Nerve Sheath Diameter As a Means of Detecting Raised Intracranial Pressure in Neuro-Trauma Patients: A Cross-Sectional Study

Background:

Optic nerve sheath diameter (ONSD) measurement is emerging as a noninvasive method to estimate raised ICP. It is helpful in situations where imaging of brain or direct ICP monitoring is not available or feasible. Use of ONSD is still limited, so this study was planned to determine whether the bedside sonographic measurement of ONSD can reliably predict elevated ICP in neuro-trauma patients.

Methodology:

After approval from Hospital Ethics Committee, this cross-sectional study was conducted in hundred traumatic brain injury (TBI) patients with suspected elevated ICP, admitted to neurosurgical ICU. The severity of brain injury was assessed according to Glasgow coma scale (GCS), initial CT scan findings, and revised trauma score (RTS). All patients underwent ONSD sonography of the eye and CT scan subsequently. ONSD of ≥5.0 mm was considered as a benchmark of raised ICP.

Results:

Mean ONSD of the study group with ONSD ≥5.0 mm was 5.6 ± 0.3 mm. ONSD was raised in 46% of patients, more so in patients with low GCS (3-6). The relationship of ONSD with GCS, CT scan findings, and RTS was highly significant. The sensitivity of the bedside sonographic measurement ONSD to detect raised ICP was 93.2% and specificity was 91.1% when compared with CT scan. Positive Predictive Value of the ONSD measurement was 89.1% and the negative predictive value was 94.4%.

Conclusion:

Ultrasonographic assessment of ONSD is a reliable modality to detect raised ICP in neurotrauma patients. It can be helpful in the early initiation of treatment of elevated ICP, thus preventing secondary brain damage.

Ultrasound measurement of optic nerve sheath diameter pre- and post-lumbar puncture

BACKGROUND

To test the hypothesis that optic nerve sheath diameter (ONSD) correlates with real-time changes in intracranial pressure, we performed ultrasound measurements of the ONSD in ambulatory patients undergoing elective lumbar puncture (LP). We conducted a prospective cohort study, including adult patients undergoing LP in a non-emergent setting. We measured ONSD perpendicular to the optic nerve at 3 mm behind the globe in both eyes in the traverse and sagittal planes, with the patient supine. The primary outcome was change in ONSD from pre-LP to post-LP. We calculated association of opening and closing LP pressures with changes in the pre- and post-LP ONSD measurements.

RESULTS

The mean patient age was 49.0 years (SD = 37-61, range 19-67) with 21 females (72.4%) and 26 (89.7%) white American (not Hispanic or Latino). The average opening pressure and closing pressures were 20.4 cm and 13.5 cm with a difference of 6.9 cm, (95% CI 3.9-10.0 cm). Pressures between the participants with baseline ONSD measurement > 5 mm (average opening pressure = 21.3 cm) to those < 5 mm (20.2 cm) differed by 1.1 cm (95% CI - 5.7 to 8.0). Linear regression revealed no association between the sagittal, transverse, average, and change in ONSD measurements with the observed LP opening pressure, change in LP pressure, or volume of cerebral spinal fluid (CSF) drained.

CONCLUSIONS

In this study of ambulatory patients undergoing rapid decreases in ICP via elective LP, we detected no acute changes in ultrasonographic measurement of the ONSD.