Ultrasonographic measurement of the optic nerve sheath diameter and its association with eyeball transverse diameter in 585 healthy volunteers

The crescent sign on ocular ultrasound and correlation with elevated intracranial pressure: A prospective cohort study

OBJECTIVES

While lumbar puncture (LP) remains gold standard for assessing intracranial pressure (ICP), LP can be difficult to perform and lead to complications. Noninvasive correlations for elevated ICP via ocular ultrasound (OUS) have shown mixed results. The primary objective of this study is to identify the frequency and test characteristics of the crescent sign on OUS for elevated ICP. Secondary objectives include comparison of test characteristics to optic nerve sheath diameter (ONSD) and optic disc elevation (ODE).

DESIGN

Single center, prospective, observational cohort study enrolling adults (age ≥ 18 years) who presented to an outpatient Neurology LP clinic. An OUS protocol was performed prior to scheduled LP, with measurement of the opening pressure (OP) by manometry. Patients were excluded if LP was unable to be completed (for any reason) or if completed in the sitting position. Elevated OP was defined as ≥25cmH2O.

RESULTS

In total, 68 patients were enrolled; seven were excluded due to no OP measured, leaving 61 patients for analysis. Forty-six patients had normal OP, while 15 had elevated OP. The crescent sign was observed in 19 patients (31 %). Overall sensitivity, specificity, and accuracy of the crescent sign was 67 %, 80 %, and 74 %, respectively. Comparison of accuracy between the six other OUS findings demonstrated no significant differences between test characteristics (p > 0.10 for each).

CONCLUSIONS

The crescent sign was observed in 31 % of patients, with moderate sensitivity, specificity, and accuracy for elevated ICP. This study has several limitations and evaluations in the acute care setting are needed.

Optic nerve sheath diameter/eyeball transverse diameter ratio by ultrasound in prediction of increased intracranial pressure in children with viral encephalitis

Introduction

Increased intracranial pressure (ICP) is common with viral encephalitis in children which is associated with complications and prognosis. The optic nerve sheath diameter (ONSD) is a new indicator for the assessment of intracranial pressure using ultrasound, CT scan and MRI imaging. Given the influence of physical development on ONSD size in children, we expect more accurate assessment of intracranial pressure with ONSD/ETD (eyeball transverse diameter) ratio by ultrasound. The aim of the study is to determine the performance of the ONSD/ETD ratio measurement to predict ICP occurring in children with viral encephalitis and evaluate the therapeutic effect.

Methods

Children with viral encephalitis from May 2022 to June 2024 were recruited in this study. The initial ONSD/ETD ratio measurement by ultrasound were completed before lumbar puncture. Children were divided into the increased ICP group and the normal ICP group based on whether the ICP was over 200 mmH2O measured by lumbar puncture. The ultrasound was repeated on the 3rd and 7th day of treatment.

Results

The ONSD/ETD ratios measured in the two groups before treatment were 0.231 ± 0.019 and 0.182 ± 0.012, respectively (p < 0.01). The ONSD/ETD ratio on the 3rd day of treatment in the increased ICP group was significantly lower than the data before treatment (p < 0.01). The data on the 7th day of treatment in increased ICP group was significantly lower than the data before treatment (p < 0.01), but not statistically significant compared to the data on the 3rd day of treatment (p = 0.650). The ROC curve demonstrated an AUC for ONSD/ETD ratio in predicting the occurrence of increased ICP in children with viral encephalitis was 0.974 [95% confidence interval (CI): 0.939-1.000, p < 0.01], with a sensitivity of 95.1% and specificity of 93.3% at a cut-off value of 0.198.

Conclusion

Our study shows that ONSD/ETD can be used as an easy reference tool for evaluating ICP in children with viral encephalitis which can reflect the therapeutic effect.

Super-resolution multi-contrast unbiased eye atlases with deep probabilistic refinement

Purpose

Eye morphology varies significantly across the population, especially for the orbit and optic nerve. These variations limit the feasibility and robustness of generalizing population-wise features of eye organs to an unbiased spatial reference.

Approach

To tackle these limitations, we propose a process for creating high-resolution unbiased eye atlases. First, to restore spatial details from scans with a low through-plane resolution compared with a high in-plane resolution, we apply a deep learning-based super-resolution algorithm. Then, we generate an initial unbiased reference with an iterative metric-based registration using a small portion of subject scans. We register the remaining scans to this template and refine the template using an unsupervised deep probabilistic approach that generates a more expansive deformation field to enhance the organ boundary alignment. We demonstrate this framework using magnetic resonance images across four different tissue contrasts, generating four atlases in separate spatial alignments.

Results

When refining the template with sufficient subjects, we find a significant improvement using the Wilcoxon signed-rank test in the average Dice score across four labeled regions compared with a standard registration framework consisting of rigid, affine, and deformable transformations. These results highlight the effective alignment of eye organs and boundaries using our proposed process.

Conclusions

By combining super-resolution preprocessing and deep probabilistic models, we address the challenge of generating an eye atlas to serve as a standardized reference across a largely variable population.

Evaluation of the effect of fluid management on intracranial pressure in patients undergoing laparoscopic gynaecological surgery based on the ratio of the optic nerve sheath diameter to the eyeball transverse diameter as measured by ultrasound: a randomised controlled trial

BACKGROUND

During gynecological laparoscopic surgery, pneumoperitoneum and the Trendelenburg position (TP) can lead to increased intracranial pressure (ICP). However, it remains unclear whether perioperative fluid therapy impacts ICP. The purpose of this research was to evaluate the impact of restrictive fluid (RF) therapy versus conventional fluid (CF) therapy on ICP in gynecological laparoscopic surgery patients by measuring the ratio of the optic nerve sheath diameter (ONSD) to the eyeball transverse diameter (ETD) using ultrasound.

METHODS

Sixty-four patients who were scheduled for laparoscopic gynecological surgery were randomly assigned to the CF group or the RF group. The main outcomes were differences in the ONSD/ETD ratios between the groups at predetermined time points. The secondary outcomes were intraoperative circulatory parameters (including mean arterial pressure, heart rate, and urine volume changes) and postoperative recovery indicators (including extubation time, length of post-anaesthesia care unit stay, postoperative complications, and length of hospital stay).

RESULTS

There were no statistically significant differences in the ONSD/ETD ratio and the ONSD over time between the two groups (all p > 0.05). From T2 to T4, the ONSD/ETD ratio and the ONSD in both groups were higher than T1 (all p < 0.001). From T1 to T2, the ONSD/ETD ratio in both groups increased by 14.3%. However, the extubation time in the RF group was shorter than in the CF group [median difference (95% CI) -11(-21 to -2) min, p = 0.027]. There were no differences in the other secondary outcomes.

CONCLUSION

In patients undergoing laparoscopic gynecological surgery, RF did not significantly lower the ONSD/ETD ratio but did shorten the tracheal extubation time, when compared to CF.

TRIAL REGISTRATION

ChiCTR2300079284. Registered on December 29, 2023.

Effect of systemic lidocaine infusion on optic nerve sheath diameter during laparoscopic hysterectomy: a randomized controlled study

BACKGROUND

During laparoscopic hysterectomy (LH), the elevation of intra-abdominal and intra-thoracic pressures due to pneumoperitoneum (PP) results in an increase in intracranial pressure (ICP). The Trendelenburg position (TP) is an accentuating factor. This trial aimed to assess the effect of intravenous (IV) lidocaine infusion on optic nerve sheath diameter (ONSD), a widely accepted surrogate measure for ICP, during PP and TP.

METHODS

A randomized, placebo-controlled study was conducted on 66 patients scheduled for LH, equally divided into a lidocaine group and a saline group. ONSD, the primary outcome, was recorded before induction (T1), before PP initiation in the supine position (T2), five minutes (T3), 30 minutes (T4), and 60 minutes (T5) after PP and TP, and five minutes after termination of PP in the supine position (T6). Secondary outcomes included numerical rating scale (NRS) scores at arrival to the post-anesthesia care unit (PACU), 6, 12, and 24 hours after surgery, and postoperative adverse effects.

RESULTS

ONSD at T4 and T5 was significantly lower in the lidocaine group than in the saline group (T4: 4.94±0.43 mm vs. 5.27±0.37 mm; P =0.003, T5: 5.08±0.46 vs. 5.41±0.38 mm; P =0.004). The lidocaine group had significantly lower NRS values than the saline group only at PACU arrival (median [Q1-Q3]: 5 [4-6] vs. 6 [5-6.25]; P =0.016). Fewer patients in the lidocaine group experienced postoperative headache (P =0.029).

CONCLUSIONS

IV lidocaine during LH can attenuate the ONSD distension, decrease pain scores at PACU arrival, and reduce the incidence of postoperative headache.

Computed Tomography Optic Nerve Sheath Diameter-to-Eyeball Transverse Diameter Ratio as a Novel Noninvasive Parameter for Prognostication in Traumatic Brain Injury

Background Traumatic brain injury (TBI) remains a foremost cause of death and disability globally, with elevated intracranial pressure (ICP) being a crucial factor in patient outcomes. While invasive monitoring is the gold standard for assessing ICP, it carries risks and is not always feasible. This study proposes a novel noninvasive parameter using computed tomography (CT) imaging. Aims and objectives The study aims to determine the efficacy of the optic nerve sheath diameter (ONSD)-to-eyeball transverse diameter (ETD) ratio from CT scans in predicting TBI patients' prognosis. The primary objective is to study the ONSD/ETD ratio's efficacy in assessing TBI's severity. The secondary objective is to correlate the ONSD/ETD ratio with the Glasgow Coma Scale (GCS) and Rotterdam computed tomography scoring (RCTS) and assess its clinical benefit. Materials and methods This combined retrospective and prospective analytical study included 308 consecutive patients who underwent CT imaging for TBI at a tertiary care center with a dedicated trauma and neurosurgical unit. We evaluated bilateral ONSD and ETD using axial CT scans. The ONSD/ETD ratio correlated with the GCS, RCTS, and clinical outcomes. Results The cut-off values for elevated ICP were ONSD of >5.17 mm, ETD of <22.2 mm, and ONSD/ETD ratio of >0.21. Variables between GCS (<12 and >12) and the ONSD/ETD ratio (<0.21 and >0.21) were statistically significant (chi-square {χ2} = 18.52, p = 0.000). The ONSD shows a strong positive correlation with RCTS (r = 0.82, p = 0.01), ETD shows a moderate negative correlation with RCTS (r = -0.50), and the ONSD/ETD ratio shows a strong negative correlation with GCS (r = -0.783, p = 0.01). The area under the curve for the ONSD/ETD ratio (0.920) was higher than that for ONSD (0.932) and ETD (0.490). The ONSD/ETD ratio's sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 95.6%, 72.0%, and 100%, respectively, demonstrating that it is an excellent predictor of raised ICP. Conclusion The CT-ONSD/ETD ratio correlates with the severity of TBI as assessed by GCS and RCTS. It could serve as a noninvasive parameter for monitoring ICP and guiding the need for sequential CT in TBI patients, potentially aiding in prognostication and clinical management.

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.

Characterization of Ocular Sonography Findings and their Relationship to Clinical Features from a South Indian Cohort of Idiopathic Intracranial Hypertension

Background

Idiopathic intracranial hypertension (IIH) typically manifests with headache, accompanied by papilledema and visual loss, and has a higher prevalence in females. In recent years, ocular sonography, particularly, measurement of optic nerve sheath diameter (ONSD), is being investigated for diagnosis of IIH.

Methods

A total of 35 patients over the age of 18 years, fulfilling the modified Dandy's criteria for diagnosis of IIH were included. Patients underwent assessment with magnetic resonance imaging, lumbar puncture, and ocular sonography to measure ONSD and ocular arterial indices.

Results

The mean ONSD values (in centimeters) in the right eye of patients with IIH was 0.57 ± 0.13, while it was 0.48 ± 0.03 in controls. In the left eye, the mean ONSD value (cm) was 0.59 ± 0.13 in patients with IIH and 0.48 ± 0.03 in controls. ONSD was significantly higher in cases compared to controls (P < 0.001, Welch test). Pulsatility index of the central retinal artery was significantly higher in cases compared to controls (P < 0.001, Welch test). Resistance index of the ophthalmic artery was statistically significant (P < 0.005, Welch test). Receiver operating characteristic curve analysis revealed a cutoff value of 5.1 mm on the right side and 5 mm on the left side had a sensitivity and specificity of more than 80% for IIH diagnosis.

Conclusion

Our study provides insights into the utility of optic nerve sheath measurements and arterial indices in the diagnosis of IIH in a South Indian cohort. Further research is needed to fully understand the longitudinal relationship of these parameters and treatment outcomes in IIH.

Association between optic nerve sheath diameter/eyeball transverse diameter ratio and neurological outcomes in patients with aneurysmal subarachnoid hemorrhage

OBJECTIVE

The optic nerve sheath diameter (ONSD)/eyeball transverse diameter (ETD) ratio is a more reliable marker of intracranial pressure than the ONSD alone. We aimed to investigate the predictive value of the ONSD/ETD ratio (OER) for neurological outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

Adult patients with aSAH who visited the emergency department of a tertiary hospital connected to a South Korean university between January 2015 and December 2021 were included. Data on patient characteristics and brain computed tomography scan findings, including the ONSD and ETD, were collected using a predefined protocol. According to the neurological outcome at hospital discharge, the patients were divided into the unfavorable neurological outcome (UNO; cerebral performance category [CPC] score 3-5) and the favorable neurological outcome (FNO; CPC score 1-2) groups. The primary outcome was the association between the OER and neurological outcomes in patients with aSAH.

RESULTS

A total of 171 patients were included in the study, of whom 118 patients (69%) had UNO. Neither the ONSD (p=0.075) nor ETD (p=0.403) showed significant differences between the two groups. However, the OER was significantly higher in the UNO group in the univariate analysis (p=0.045). The area under the receiver operating characteristic curve of the OER for predicting UNO was 0.603 (p=0.031). There was no independent relationship between the OER and UNO in the multivariate logistic regression analysis (adjusted odds ratio, 0.010; p=0.576).

CONCLUSION

The OER was significantly higher in patients with UNO than in those with FNO, and the OER was more reliable than the ONSD alone. However, the OER had limited utility in predicting UNO in patients with aSAH.

Brain injury mobile diagnostic system: Applications in civilian medical service and on the battlefield-General concept and medical aspects

To present the concept of a portable ultrasound tomography device for diagnosing traumatic and vascular brain lesions. The device consisting of multiple transcranial ultrasound probes placed on the surface of the head, specifically but not exclusively in natural acoustic windows. An integral part of the mobile diagnostic system (MDS) is a decision support system based on artificial intelligence algorithms utilizing information from: head images, laboratory data, and assessment of the patient's clinical condition. The MDS can significantly reduce the time from stroke onset to rtPA therapy in civilian medical services and support therapeutic and evacuation strategies in instances of brain and skull trauma on the battlefield.

Optic Nerve Sheath Diameter: A Cross-Sectional Study of Ultrasonographic Measurement in Healthy Black South African Adults

Ultrasonographic optic nerve sheath diameter (ONSD) measurement is an accurate, portable, and non-invasive method of detecting raised intracranial pressure that can also reflect dynamic, real-time changes in intracranial pressure fluctuations. Various studies have shown the mean range of ONSD to vary greatly across different population groups. This study aimed to determine the mean ONSD in healthy Black South African adults. In this cross-sectional study, healthy black South African adult participants underwent optic nerve sheath ultrasound of the right eye, with the diameter being measured at 3 mm behind the retina in two different planes. The average of the two measurements was used to find the mean optic nerve sheath diameter. This measurement was compared to that found in a Canadian adult population, and the effect of age, gender, and co-morbidities on ONSD was assessed. A total of 99 participants were included in this study, of which 39 were male and 60 were female. The mean ONSD was found to be 5.1 mm (SD ± 0.33). This value was significantly higher than the mean ONSD observed in the Canadian population (p < 0.001). There was no significant difference found between the mean ONSD in males and females (p = 0.652), and both age and presence of co-morbidities were not found to significantly correlate with ONSD. (p = 0.693 and p = 0.974, respectively).

Pediatric optic nerve and globe measurements on magnetic resonance imaging: establishing norms for children

BACKGROUND

Normal optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) may be beneficial for describing optic nerve pathway abnormality reflecting increased intracranial pressure. Nonetheless, magnetic resonance imaging (MRI) measurement of the normal ONSD range and its associations with clinical factors and eyeball transverse diameter (ETD) are not well established in children.

PURPOSE

To establish normal OND, ONSD, ETD, and OND/ONSD and ONSD/ETD measurements in children and their associations with age and sex.

MATERIAL AND METHODS

We evaluated and analyzed 336 brain MRI studies of children aged 0.5 months to 18 years. We measured a total of 672 optic nerves. The OND and ONSD were measured 1 cm anterior to the optic foramina and 3 mm behind the optic disc on an axial T2 sequence.

RESULTS

The mean OND 3 mm and 1 cm, ONSD 3 mm and 1 cm, and ETD were 0.23 ± 0.05 mm and 0.16 ± 0.04 mm, 0.53 ± 0.08 mm and 0.38 ± 0.06 mm, and 2.3 ± 0.13, respectively. Only ONSD 1 cm was independent of age (P = 0.247). ONSD 3 mm and ETD were significantly wider in boys compared to girls and significantly influenced by age (both P < 0.001). Age at scan and ETD were significantly correlated (P < 0.001).

CONCLUSION

We established MRI-based OND, ONSD, ETD, and ONSD/ETD and OND/ONSD ratio normative values in children, which can be helpful in pediatric populations with disease.

Extracorporeal Circulation and Optic Nerve Ultrasound: A Pilot Study

Background and Objectives: Cardiopulmonary bypass (CPB) is an extracorporeal circuit that provides surgical access to an immobile and bloodless area, allowing for technical and procedural advances in cardiothoracic surgery. CBP can alter the integrity of the blood–brain barrier and cause changes in intracranial pressure (ICP) postoperatively. Optical nerve sheath diameter (ONSD) measurement is among the alternative non-invasive methods for ICP monitoring. In this study, we aimed to evaluate the optic nerve sheath diameter measurements under the guidance of ultrasonography for ICP changes during the extracorporeal circulation process. Materials and Methods: The study population included 21 patients over 18 years of age who required extracorporeal circulation. Demographic data of the patients, such as age, gender, comorbidity, American Society of Anesthesiologists (ASA) classification and reason for operation (coronary artery disease or mitral or aortic valve disease) were recorded. The ONSD was measured and evaluated before the extracorporeal circulation (first time) and at the 30th minute (second time), 60th minute (third time) and 90th minute (fourth time) of the extracorporeal circulation. Non-invasive ICP (ICP ONSD) values were calculated based on the ONSD values found. Results: The mean ONSD values measured before the extracorporeal circulation of the patients were found to be 4.13 mm (3.8–4.6) for the right eye and 4.36 mm (4.1–4.7) for the left eye. Calculated nICPONSD values of 11.0 mm Hg (1.0–21.0) for the right eye and 10.89 mm Hg (1.0–21.0) for the left eye were found. It was observed that there was a significant increase in the ONSD and nlCPONSD values recorded during the extracorporeal circulation of all patients compared to the baseline values (p < 0.005). Conclusions: During extracorporeal circulation, ultrasound-guided ONSD measurement is an easy, inexpensive and low-complication method that can be performed at the bedside during the operation to monitor ICP changes.

The Role of Ultrasound in Pediatric Skull Fractures: Determination of Fracture and Optic Nerve Sheath Diameter Measurements

BACKGROUND

The aim of the present study was to determine the accuracy of point-of-care ultrasound (POCUS) for detecting skull fractures and to evaluate sonographic measurements of optic nerve sheath diameter (ONSD) and ONSD/eyeball vertical diameter (EVD) ratios in children with head trauma.

METHODS

Children who presented with local signs of head trauma and underwent cranial computed tomography (CT) were enrolled. The suspected area was examined by POCUS to identify a skull fracture, and then the ONSD at 3 mm posterior to the globe and the EVD were measured. Ratios of ONSD measurement at 3 mm/EVD were reported. All ONSD measurements and ratios were calculated from cranial CT images.

RESULTS

There were 112 children enrolled in the study. The sensitivity and specificity of POCUS for skull fractures was 93.7% (95% confidence interval [CI], 82.8-98.6) and 96.8% (95% CI, 89.1-99.6), whereas the positive predictive value was 95.7% (95% CI, 85.1-98.8), and the negative predictive value was 95.3% (95% CI, 87.3-98.4). There was high agreement between POCUS and CT for identifying skull fractures (κ, 0.90 [±0.04]). In the group without elevated intracranial pressure findings on CT, patients with space-occupying lesions (SOLs) had higher sonographic ONSD measurements and ratios (P < 0.001) compared with cases without SOLs.

CONCLUSIONS

When used with clinical decision rules to minimize the risk for clinically important traumatic brain injury, POCUS seems to be a promising tool to detect skull fractures and calculate ONSD measurements and rates to predict the risk for SOLs and perform further risk stratification of children with minor head trauma.

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.

Optic nerve sheath diameter in intracranial hypertension: Measurement external or internal of the dura mater?

BACKGROUND AND PURPOSE

Optic nerve sheath diameter (ONSD) is a promising metric to estimate intracranial pressure (ICP). There is no consensus whether ONSD should be measured external (ONSDext) or internal (ONSDint) of the dura mater. Expert opinion favors ONSDint, though without clear evidence to support this. Adjustments of ONSD for eye diameter (ED) and optic nerve diameter (OND) have been suggested to improve precision. We examined the diagnostic accuracy of ONSDext and ONSDint for estimating ICP, unadjusted as well as adjusted for ED and OND.

METHODS

We performed an observational cohort study, measuring ONSDext and ONSDint in patients with invasive ICP monitoring at Karolinska University Hospital in Stockholm, Sweden. We used ONSDext and ONSDint unadjusted as well as adjusted for ED and for OND. We compared the area under the receiver operator characteristics curve (AUROC) for these methods. Thresholds for elevated ICP were set at ≥20 and ≥22 mmHg, respectively.

RESULTS

We included 220 measurements from 100 patients. Median ONSDext and ONSDint were significantly different at 6.7 and 5.2 mm (p = .00). There was no significant difference in AUROC for predicting elevated ICP between ONSDext and ONSDint (.67 vs. .64, p = .31). Adjustment for ED yielded better diagnostic accuracy (AUROC, cutoff, sensitivity, specificity) for ONSDext/ED (.76, .29, .81, .62) and ONSDint/ED (.71, .24, .5, .89).

CONCLUSIONS

ONSDext and ONSDint differ significantly and are not interchangeable. However, there were no significant differences in diagnostic accuracy between ONSDext and ONSDint. Adjustment for ED may improve diagnostic accuracy of ONSD.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prognostic values of optic nerve sheath diameter for comatose patients with acute stroke: An observational study

BACKGROUND

Optic nerve sheath diameter (ONSD) measurement is one of the non-invasive methods recommended for increased intracranial pressure (ICP) monitoring.

AIM

This study aimed to evaluate the roles of optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse diameter (ETD) ratio in predicting prognosis of death in comatose patients with acute stroke during their hospitalization.

METHODS

A total of 67 comatose patients with acute stroke were retrospectively recruited. The ONSD and ETD were measured by cranial computed tomography (CT) scan. All patients underwent cranial CT scan within 24 h after coma onset. Patients were divided into death group and survival group according to their survival status at discharge. The differences of the ONSD and ONSD/ETD ratio between the two groups and their prognostic values were compared.

RESULTS

The ONSD and ONSD/ETD ratio were 6.07 ± 0.72 mm and 0.27 ± 0.03 in the comatose patients, respectively. The ONSD was significantly greater in the death group than that in the survival group (6.32 ± 0.67 mm vs 5.65 ± 0.62 mm, t = 4.078, P < 0.0001). The ONSD/ETD ratio was significantly higher in the death group than that in the survival group (0.28 ± 0.03 vs 0.25 ± 0.02, t = 4.625, P < 0.0001). The area under the receiver operating characteristic curve was 0.760 (95%CI: 0.637-0.882, P < 0.0001) for the ONSD and 0.808 (95%CI: 0.696-0.920, P < 0.0001) for the ONSD/ETD ratio.

CONCLUSION

The mortality increased in comatose patients with acute stroke when the ONSD was > 5.7 mm or the ONSD/ETD ratio was > 0.25. Both indexes could be used as prognostic tools for comatose patients with acute stroke. The ONSD/ETD ratio was more stable than the ONSD alone, which would be preferred in clinical practice.

Optic nerve sheath diameter at high altitude: standardized measures in healthy volunteers

Background

Increases in the diameter of the optic nerve sheath (ONSD) on ultrasound are associated with high intracranial pressure (hICP). The normal value varies with altitude and the population studied. The objective of this study is to describe the normal values of the ONSD in a healthy adult population of the city of Bogotá, Colombia, at 2640 meters above sea level (masl).

Patients and methods

A prospective observational study was conducted on a total of 247 healthy individuals recruited from May 2021 to May 2022 who were subjected to the color, low power, optic disk, safety, elevated frequency, dual (CLOSED) protocol for measuring the bilateral ONSD adjusted to the eyeball transverse diameter (ETD).

Results

A total of 230 individuals were analyzed; the average ONSD of the right eye (RE) was 0.449 cm (range 0.288–0.7) and that of the left eye (LE) was 0.454 cm (range 0.285–0.698); the correlation between RE and LE was 0.93 (p < 0.005), and the correlation of the ONSD/ETD ratios for the RE and LE was lower (r² = 0.79, p < 0.005). A total of 10.8% of the studied population had values greater than 0.55 cm.

Conclusions

The median ONSD and ONSD/ETD ratio in the city of Bogotá are similar to those described in other populations; however, approximately 10.8% of the healthy population may present higher values, which would limit the use of ONSD on its own for clinical decision-making, only repeated measurements with significant changes in the ONSD and ONSD/ETD or asymmetries between the measurements of both eyes linked to clinical findings would allow the diagnosis of hICP.

Optic nerve sheath diameter is associated with outcome in severe Covid-19

Neurological symptoms are common in Covid-19 and cerebral edema has been shown post-mortem. The mechanism behind this is unclear. Elevated intracranial pressure (ICP) has not been extensively studied in Covid-19. ICP can be estimated noninvasively with measurements of the optic nerve sheath diameter (ONSD). We performed a cohort study with ONSD ultrasound measurements in severe cases of Covid-19 at an intensive care unit (ICU). We measured ONSD with ultrasound in adults with severe Covid-19 in the ICU at Karolinska University Hospital in Sweden. Patients were classified as either having normal or elevated ONSD. We compared ICU length of stay (ICU-LOS) and 90 day mortality between the groups. 54 patients were included. 11 of these (20.4%) had elevated ONSD. Patients with elevated ONSD had 12 days longer ICU-LOS (95% CI 2 to 23 p = 0.03) and a risk ratio of 2.3 for ICU-LOS ≥ 30 days. There were no significant differences in baseline data or 90 day mortality between the groups. Elevated ONSD is common in severe Covid-19 and is associated with adverse outcome. This may be caused by elevated ICP. This is a clinically important finding that needs to be considered when deciding upon various treatment strategies.

Optic nerve sheath diameter and optic nerve sheath diameter/eyeball transverse diameter ratio in prediction of malignant progression in ischemic stroke

Background

The optic nerve sheath diameter (ONSD)/eyeball transverse diameter (ETD) ratio has been suggested in the evaluation of intracranial pressure (ICP). The aim of this study was to evaluate the predictive value of ONSD and ONSD/ETD in relation to risk for secondary malignant middle cerebral artery infarction (MMI).

Methods

A total of 91 patients with MCA occlusion were included in this study. Data were divided into two groups based on development of MMI or not. ONSD and ETD were measured by unenhanced computed tomography (CT). The differences in ONSD and the ONSD/ETD ratios between the MMI and non-MMI groups were compared. Receiver operating characteristic curve analyses were used to test the diagnostic value of ONSD and ONSD/ETD independently, to predict MMI.

Results

The ONSD in the MMI group and non-MMI group were 5.744 ± 0.140 mm and 5.443 ± 0.315 mm, respectively (P = 0.001). In addition, the ONSD/ETD ratios in the MMI group and non-MMI group were 0.258 ± 0.008 and 0.245 ± 0.006, respectively (P = 0.001). The receiver operating characteristic (ROC) curve demonstrated an area under the curve (AUC) for ONSD of 0.812 [95% confidence interval (CI): 0.718–0.906, P = 0.001], with a sensitivity of 97.4% and a specificity of 66.0% at the cut-off value of 5.520 mm. The AUC for ONSD/ETD ratio in predicting occurrence of MMI was 0.895 (95% CI: 0.823–0.968, P = 0.001), with a sensitivity of 84.2% and a specificity of 92.5% at a cut-off value of 0.250.

Conclusion

In acute stroke patients with massive cerebral infarction, an increased ONSD or ONSD/ETD ratio increases the odds of malignant progression and may be used as an indicator for emergent therapeutic interventions. In addition, the ONSD/ETD ratio may be more valuable than ONSD in predicting the malignant progression of acute stroke patients.

The Prognostic Value of Optic Nerve Sheath Diameter/Eyeball Transverse Diameter Ratio in the Neurological Outcomes of Out-of-Hospital Cardiac Arrest Patients

Background and objectives: The optic nerve sheath diameter (ONSD) is indicative of elevated intracranial pressure. However, the usefulness of the ONSD for predicting neurologic outcomes in cardiac arrest survivals has been debatable. Reportedly, the ONSD/eyeball transverse diameter (ETD) ratio is a more reliable marker for identifying intracranial pressure than sole use of ONSD. Materials and Methods: This retrospective study aimed to investigate the prognostic value of the ONSD/ETD ratio in out-of-hospital cardiac arrest (OHCA) patients. We studied the brain computed tomography scans of adult OHCA patients with return of spontaneous circulation, who visited a single hospital connected with a Korean university between January 2015 and September 2020. We collected baseline characteristics and patient information from electronic medical records and ONSD and ETD were measured by two physicians with a pre-defined protocol. According to their neurologic outcome upon hospital discharge, patients were divided into good neurologic outcome (GNO; cerebral performance category [CPC] 1–2) and poor neurologic outcome (PNO; CPC 3–5) groups. We evaluated the ONSD/ETD ratio between the GNO and PNO groups to establish its prognostic value for neurologic outcomes. Results: Of the 100 included patients, 28 had GNO. Both the ONSD and ETD were not significantly different between the two groups (ONSD, 5.48 mm vs. 5.66 mm, p = 0.054; ETD, 22.98 mm vs. 22.61 mm, p = 0.204). However, the ONSD/ETD ratio was significantly higher in the PNO group in the univariate analysis (0.239 vs. 0.255, p = 0.014). The area under the receiver operating characteristic curve of ONSD/ETD ratio for predicting PNO was 0.66 (95% confidence interval, 0.56–0.75; p = 0.006). There was no independent relationship between the ONSD/ETD ratio and PNO in multivariate analysis (aOR = 0.000; p = 0.173). Conclusions: The ONSD/ETD ratio was more reliable than sole use of ONSD and might be used to predict neurologic outcomes in OHCA survivors.

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.

Optic Nerve Sheath Diameter for Predicting Outcomes in Post-Cardiac Arrest Syndrome: An Updated Systematic Review and Meta-Analysis

We aimed to identify the efficacy of optic nerve sheath diameter (ONSD) in predicting mortality and poor neurological outcomes (PNO) in post-cardiac arrest syndrome (PCAS) by the measurement time of outcomes. We conducted an extensive literature search in EMBASE, MEDLINE, and Cochrane Library, which included studies on the prognostic accuracy of ONSD in predicting PNO and mortality in PCAS by the measured time of outcomes. A total of 791 patients from nine studies were included. Increased ONSD was weakly associated with PNO by a high heterogeneity (standardized mean difference with 95% confidence interval = 0.74 (0.22, 1.27); I² = 87%). The analysis by the measurement time of PNO and mortality for ONSD had no significant difference due to insufficient articles or high heterogeneities. The prognostic accuracy of ONSD was 23.97 (pooled diagnostic odds ratio, I² = 0%) and 0.94 (area under the curve) for short-term PNO. The pooled results showed low or very low quality and very low quality of evidence for PNO and mortality, respectively. ONSD measurement might be an effective predictor for short-term PNO in PCAS. An analysis by measurement time of outcomes showed no significant evidence for ONSD measurement effectiveness in predicting mortality and PNO.

Optic Nerve Ultrasound Evaluation in Animals and Normal Subjects

In recent years, ultrasonographic measurement of the optic nerve sheath diameter (ONSD) has been widely used to identify the presence of increased intracranial pressure (ICP). Intracranial hypertension is a life-threatening condition that can be caused by various neurological and non-neurological disorders, and it is associated to poor clinical results. Ultrasonography could be used to qualitatively and efficiently detect ICP increases, but to reach this purpose, clear cut-off values are mandatory. The aim of this review is to provide a wide overview of the most important scientific publications on optic nerve ultrasound normal values assessment published in the last 30 years. A total of 42 articles selected from PubMed medical database was included in this review. Our analysis showed that ocular ultrasonography is considered to be a valuable diagnostic tool, especially when intracranial hypertension is suspected, but unfortunately this research provided conflicting results that could be due to the different ultrasound protocols. This is mainly caused by the use of B scan alone, which presents several limitations. The use of B-scan coupled with the standardized A-scan approach could give more accurate, and reliable ultrasound evaluation, assuring higher data objectivity.

Relationship between the ratio of optic nerve sheath diameter to eyeball transverse diameter and morphological characteristics of dogs

OBJECTIVE

To assess the feasibility of ocular ultrasonography for measurement of the ratio of optic nerve sheath diameter (ONSD) to eyeball transverse diameter (ETD) in dogs with various morphologies and to evaluate the interobserver reliability of the ONSD/ETD ratio and its correlation with various morphological variables.

ANIMALS

45 healthy dogs of various breeds.

PROCEDURES

Height, head circumference, body weight, body condition score, intraocular pressure, and blood pressure were recorded for each dog. Unsedated dogs underwent bilateral ocular ultrasonography once. A veterinarian and board-certified ophthalmologist who were unaware of subject signalment independently reviewed the ultrasonographic videos and selected 1 image for each eye on which the ETD and ONSD were measured. The ONSD/ETD ratio was calculated and compared between the 2 observers. Correlations between the ONSD/ETD ratio and various physiologic and morphological variables were assessed.

RESULTS

172 ONSD/ETD ratios were recorded. The ONSD/ETD ratio was calculated for at least 1 eye for 44 of the 45 (98%) dogs. Mean ± SD time required to complete the ultrasonographic examination was 90 ± 30 seconds (range, 15 seconds to 3 minutes). The mean ± SD ONSD/ETD ratio was 0.17 ± 0.01 (range, 0.15 to 0.20). The ONSD/ETD ratio did not differ significantly between the left and right eyes or the 2 observers and was not correlated with any of the variables assessed.

CONCLUSIONS AND CLINICAL RELEVANCE

Ocular ultrasonography was a rapid, noninvasive, and reliable method for measurement of the ONSD/ETD ratio. The ONSD/ETD ratio did not appear to be influenced by dog morphology.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The clinical and prognostic values of optic nerve sheath diameter and optic nerve sheath diameter/eyeball transverse diameter ratio in comatose patients with supratentorial lesions

Background

The optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse diameter (ETD) ratio have been proven to be correlated with intracranial pressure. This study aimed to evaluate the prognostic roles of ONSD and the ONSD/ETD ratio in comatose patients with supratentorial lesions and to determine the relationship of these two indices with the prognosis of such patients.

Methods

A total of 54 comatose patients with supratentorial lesions and 50 healthy controls were retrospectively included in this study. ONSD and ETD were measured by unenhanced computed tomography (CT). The differences in ONSD and the ONSD/ETD ratio between the two groups were compared. The prognosis of comatose patients was scored using the Glasgow Outcome Scale (GOS) at the 3-month follow-up, and these patients were classified into good (GOS score ≥ 3) and poor (GOS score < 3) prognosis groups. The differences in ONSD and the ONSD/ETD ratio were compared between comatose patients with good prognoses and those with poor prognoses.

Results

The ONSD and ONSD/ETD ratios in the comatose patients were 6.30 ± 0.60 mm and 0.27 ± 0.03, respectively, and both were significantly greater than those in the healthy controls (5.10 ± 0.47 mm, t = 11.426, P < 0.0001; 0.22 ± 0.02, t = 11.468, P < 0.0001; respectively). ONSD in patients with poor prognosis was significantly greater than that in patients with good prognosis (6.40 ± 0.56 vs. 6.03 ± 0.61 mm, t = 2.197, P = 0.032). The ONSD/ETD ratio in patients with poor prognosis was significantly greater than that in patients with good prognosis (0.28 ± 0.02 vs. 0.26 ± 0.03, t = 2.622, P = 0.011). The area under the receiver operating characteristic (ROC) curve, used to predict the prognosis of comatose patients, was 0.650 (95% confidence interval (CI): 0.486–0.815, P = 0.078) for ONSD and 0.711 (95% CI: 0.548–0.874, P = 0.014) for the ONSD/ETD ratio.

Conclusions

The ONSD and ONSD/ETD ratios were elevated in comatose patients. The ONSD/ETD ratio might be more valuable than ONSD in predicting the prognoses of comatose patients with supratentorial lesions.

Predictive Utility of Changes in Optic Nerve Sheath Diameter after Cardiac Arrest for Neurologic Outcomes

The optic nerve sheath diameter (ONSD) can help predict the neurologic outcomes of patients with post-cardiac arrest (CA) return of spontaneous circulation (ROSC). We aimed to investigate the effect of ONSD changes before and after CA on neurologic outcomes in patients with ROSC after CA using brain computed tomography (CT). The study included patients hospitalized after CA, who had undergone pre- and post-CA brain CT between January 2001 and September 2020. The patients were divided into good and poor neurologic outcome (GNO and PNO, respectively) groups based on their neurologic outcome at hospital discharge. We performed between-group comparisons of the amount and rate of ONSD changes in brain CT and calculated the area under the curve (AUC) to determine their predictive value for neurologic outcomes. Among the 96 enrolled patients, 25 had GNO. Compared with the GNO group, the PNO group showed a significantly higher amount (0.30 vs. 0.63 mm; p = 0.030) and rate (5.26 vs. 12.29%; p = 0.041) of change. The AUC for predicting PNO was 0.64 (95% confidence interval = 0.53–0.73; p = 0.04), and patients with a rate of ONSD change >27.2% had PNO with 100% specificity and positive predictive value. Hence, ONSD changes may predict neurologic outcomes in patients with post-CA ROSC.

Bedside sonographic measurements of optic nerve sheath diameter in children with diabetic ketoacidosis

BACKGROUND

Bedside sonographic assessment of the optic nerve sheath has gained popularity for evaluating intracranial pressure in recent years.

OBJECTIVE

To investigate the bedside sonographic measurements of optic nerve sheath diameter (ONSD) and ONSD/eyeball diameter ratios, which are related with cerebral edema (CE), in children with diabetic ketoacidosis (DKA) before and after treatment.

METHODS

Children aged 12 months to 18 years, who were diagnosed with DKA were included. The ONSD was measured at 3 mm posterior to the globe in the anterior axial transbulbar view. The eyeball transverse diameter (ETD) and eyeball vertical diameter (EVD) were measured and ratios of ONSD/ETD and ONSD/EVD were calculated. Bedside ultrasound (US) examinations were performed at the beginning and at the end of fluid therapy.

RESULTS

About 43 patients were enrolled. About 12 (27.9%) patients had mild, 14 (32.6%) moderate, and 17 (39.5%) severe DKA. At baseline, the ONSD measurements and ratios were significantly higher in severe DKA group than in those with mild or moderate DKA group. All ONSD measurements, ONSD/ETD, and ONSD/EVD ratios at the end of therapy were significantly lower compared with baseline measurements. At the end of therapy, ONSD measurements and ratios were similar among DKA severity groups.

CONCLUSION

The ONSD measurements and ratios decreased from the beginning of DKA treatment, which could be considered as an indicator of an increase in intracranial pressure at the time of admission. Ocular US may serve as a promising tool to perform further risk stratification of children with DKA and to identify DKA-related CE.

Increase in optic nerve sheath diameter predicts early cerebral involvement in fat embolism syndrome

Early diagnosis of cerebral fat embolism in a patient with contradiction to MRI is challenging. Here we report an interesting case, where the raised optic nerve sheath diameter helped us to predict the early cerebral involvement with fat emboli in a left femoral shaft fracture patient. MRI scan could not be performed due to the presence of a metallic implant in the patient from a previous surgery. He was later diagnosed as an atypical presentation of fat embolism syndrome. Optic nerve sheath monitoring also helped us to guide further management of the patient.

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.

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.

Real-time change of optic nerve sheath diameter after rebleeding of ruptured intracranial dissecting aneurysm

Ultrasonographic measurement of optic nerve sheath diameter (ONSD) has been validated to detect and monitor the increased intracranial pressure (IICP) in neurosurgical field. Especially, the ONSD has been known to reflect well the ICP in case of intracranial hemorrhage (ICH) occurring in the anterior circulation of intracranial vascular system, however it has not been well elucidated the role of ONSD in the posterior circulating vascular problems. A 43-year-old man presented with a subarachnoid hemorrhage with intraventricular hemorrhage due to rupture of dissecting aneurysm at right vertebral artery, and immediately performed the stent-assisted coil embolization. Two day after coil embolization, he became nearly alert without definite neurologic deficits. The ONSD was reduced from 5.8 mm to 5.5 mm. The 10^th postoperative days, the patient suddenly changed into stuporous mentality due to rebleeding of aneurysm. The ONSD was enlarged to 6.7 mm. We report a case of intimate relationship between ONSD and IICP after rupture of dissecting aneurysm located in posterior circulation.

Variability of the Optic Nerve Sheath Diameter on the Basis of Sex and Age in a Cohort of Healthy Volunteers

Many studies have demonstrated that the optic nerve sheath diameter (ONSD) is a good indicator of intracranial pressure (ICP). There are uncertainties regarding the optimal ONSD threshold, considering age and sex differences in the healthy population, and these differences could lead to uncertainties in evaluation of ONSD in pathological conditions.The aim of this prospective observational study was to investigate if age and sex could influence ONSD in a cohort of healthy Italian volunteers recruited during preanesthetic assessment for low-risk surgical procedures.The population was stratified for sex (males versus females) and for age (18-44 years, 45-64 years, and ≥65 years). The axial and longitudinal ONSD diameters were measured by two trained investigators.A significant difference in ONSD between males and females was found (median 4.2 (interquartile range 3.9-4.6) versus 4.1 (interquartile range 3.6-4.2) mm, P = 0.01), and a positive correlation between ONSD and age was found (R = 0.50, P < 0.0001).It was concluded that ONSD increases with age and is significantly larger in the healthy male population. These discrepancies should be taken into consideration when ONSD measurement is performed.

Prognostic Role of Optic Nerve Sheath Diameter for Neurological Outcomes in Post-Cardiac Arrest Patients: A Systematic Review and Meta-Analysis

Objective

The present study investigated whether optic nerve sheath diameter (ONSD) could be used to predict neurological outcomes in post-cardiac arrest (CA) patients.

Methods

We performed a comprehensive literature search in the Cochrane Library, ScienceDirect, PubMed, and Web of Science from inception to June 2020 for eligible articles. Stata 14.0 software was used to calculate the pooled odds ratios (ORs) and 95% confidence intervals (95% CIs), sensitivity, specificity, summary receiver operating characteristic (SROC) curve, subgroup analysis, sensitivity analysis, and publication bias.

Results

Eight studies involving 473 patients were considered eligible for this meta-analysis. The pooled result using a random-effects model showed that broadened ONSD is associated with poor neurological outcomes in post-CA patients (OR = 15.62, 95% CI: 5.50-44.34, P < 0.001; I ² = 58.4%, P = 0.018), with a sensibility of 0.60 (95% CI: 0.45-0.73) and specificity of 0.94 (95% CI: 0.83-0.98). The area under the curve of the SROC curve for ONSD was 0.87 (95% CI: 0.84-0.90). Subgroup analysis revealed that sample size and time of ONSD measurement may be the source of heterogeneity. Sensitivity analysis demonstrated the stability of the results of this meta-analysis. No publication bias using Deeks' funnel plot was noted across the studies (P = 0.23).

Conclusion

This meta-analysis confirmed that ONSD can be used to predict neurological outcomes in post-CA patients.

Emergency Ocular Ultrasound - Common Traumatic and Non-Traumatic Emergencies Diagnosed with Bedside Ultrasound

Point-of-care ocular ultrasound (POCOUS) in the ambulatory and critical care setting has become an invaluable diagnostic tool for patients presenting with traumatic or atraumatic vision and ocular complaints. Sonographic bedside evaluation is intuitive and easy to perform and can accurately diagnose a variety of pathologies. These include detachment or hemorrhage of the retina or vitreous, lens dislocation, retrobulbar hematoma or air, as well as ocular foreign bodies, infections, tumors, and increased optic nerve sheath diameter that can be assessed in the setting of suspected increased intracranial pressure. The ocular anatomy is easy to visualize with sonography, as the eye is a superficial structure filled with fluid. Over the last two decades, a large number of scientific publications have documented that POCOUS in emergent or critical care settings is an accurate diagnostic tool and expands and improves emergency diagnosis and management. This article will review POCOUS exam techniques as well as normal sonographic findings and common pathologies.

Neurological Complications and Noninvasive Multimodal Neuromonitoring in Critically Ill Mechanically Ventilated COVID-19 Patients

Purpose: The incidence and the clinical presentation of neurological manifestations of coronavirus disease-2019 (COVID-19) remain unclear. No data regarding the use of neuromonitoring tools in this group of patients are available. Methods: This is a retrospective study of prospectively collected data. The primary aim was to assess the incidence and the type of neurological complications in critically ill COVID-19 patients and their effect on survival as well as on hospital and intensive care unit (ICU) length of stay. The secondary aim was to describe cerebral hemodynamic changes detected by noninvasive neuromonitoring modalities such as transcranial Doppler, optic nerve sheath diameter (ONSD), and automated pupillometry. Results: Ninety-four patients with COVID-19 admitted to an ICU from February 28 to June 30, 2020, were included in this study. Fifty-three patients underwent noninvasive neuromonitoring. Neurological complications were detected in 50% of patients, with delirium as the most common manifestation. Patients with neurological complications, compared to those without, had longer hospital (36.8 ± 25.1 vs. 19.4 ± 16.9 days, p < 0.001) and ICU (31.5 ± 22.6 vs. 11.5±10.1 days, p < 0.001) stay. The duration of mechanical ventilation was independently associated with the risk of developing neurological complications (odds ratio 1.100, 95% CI 1.046-1.175, p = 0.001). Patients with increased intracranial pressure measured by ONSD (19% of the overall population) had longer ICU stay. Conclusions: Neurological complications are common in critically ill patients with COVID-19 receiving invasive mechanical ventilation and are associated with prolonged ICU length of stay. Multimodal noninvasive neuromonitoring systems are useful tools for the early detection of variations in cerebrovascular parameters in COVID-19.

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.

Ultrasonic Assessment of Optic Nerve Sheath Diameter in Patients at Risk of Sepsis-Associated Brain Dysfunction: A Preliminary Report

Sepsis-associated brain dysfunction (SABD) with increased intracranial pressure (ICP) is a complex pathology that can lead to unfavorable outcome. Ultrasonographic measurement of optic nerve sheath diameter (ONSD) is used for non-invasive assessment of ICP. We aimed to assess the role of ONSD as a SABD screening tool. This prospective preliminary study covered 10 septic shock patients (5 men; aged 65, IQR 50-78 years). ONSD was measured bilaterally from day 1 to 10 (n = 1), until discharge (n = 3) or death (n = 6). The upper limit for ONSD was set at 5.7 mm. Sequential organ failure assessment score was calculated on a daily basis as a surrogate formulti-organ failure due to sepsis in the study population. On day 1, the medians of right and left ONSD were 5.56 (IQR 5.35-6.30) mm and 5.68 (IQR 5.50-6.10) mm, respectively, and four subjects had bilaterally elevated ONSD. Forty-nine out of 80 total measurements performed (61%) exceeded 5.7 mm during the study period. We found no correlations between ONSD and sequential organ failure assessment (SOFA) during the study period (right: R = -0.13-0.63; left R = -0.24-0.63). ONSD measurement should be applied for screening of SABD cautiously. Further research is needed to investigate the exact role of this non-invasive method in the assessment of brain dysfunction in these patients.

The prognostic value of optic nerve sheath diameter in patients with subarachnoid hemorrhage

BACKGROUND

We evaluated the role of optic nerve sheath diameter (ONSD) using brain computed tomography (CT) in predicting neurological outcomes of patients with subarachnoid hemorrhage (SAH).

METHODS

This was a retrospective, multicenter, observational study of adult patients with SAH admitted between January 2012 and June 2017. Initial brain CT was performed within 12 h from onset of SAH, and follow-up brain CT was performed within 24 h from treatment of a ruptured aneurysm. Primary outcome was neurological status at 6-month follow-up assessed with the Glasgow Outcome Scale (GOS, 1 to 5).

RESULTS

Among 223 SAH patients, 202 (90.6%) survived until discharge. Of these survivors, 186 (83.4%) manifested favorable neurological outcomes (GOS of 3, 4, or 5). In this study, the ONSDs in the group of patients with poor neurological outcome were significantly greater than those in the favorable neurological outcome group (all p < 0.01). Intracranial pressure (ICP) was monitored in 21 (9.4%) patients during the follow-up CT. A linear correlation existed between the average ONSD and ICP in simple correlation analysis (r = 0.525, p = 0.036). Analysis of the receiver  operating characteristic curve for prediction of poor neurological outcome showed that ONSD had considerable predictive value (C-statistics, 0.735 to 0.812). In addition, the performance of a composite of Hunt and Hess grade and ONSD was increasingly associated with poor neurological outcomes than the use of each marker alone.

CONCLUSIONS

ONSD measured with CT may be used in combination with clinical grading scales to improve prognostic accuracy in SAH patients.

A study to evaluate effect of PEEP and end-tidal carbon dioxide on optic nerve sheath diameter

Background and Aims:

PEEP is commonly used to improve postoperative respiratory outcomes in surgical and ICU patients. It is thought to increase ICP by impending CSF outflow and cerebral venous drainage. Hyperventilation is used to decrease ICP in patients having intracranial hypertension. We investigated the effect of various levels of PEEP and EtCO₂ on ONSD as an indirect predictor of ICP in patients undergoing surgery under GA.

Methods:

After induction, different levels of PEEP and EtCO₂ were applied to 50 patients. Sonographic ONSD was measured 5 minutes after stabilization of each new setting. Haemodynamic parameters like pulse, SpO₂, BP were also recorded. Quantitative variables were expressed as Mean ± SD and compared across between follow-ups using paired t-test. Qualitative variables were expressed in number and percentage.

Results:

Baseline ONSD was 0.44 ± 0.06 cm. It increased significantly to 0.45 ± 0.07 cm, 0.47 ± 0.07 cm and 0.49 ± 0.07 cm after applying PEEP of 8, 12 and 15 cm H₂O PEEP, respectively. It significantly decreased to 0.42 ± 0.06 cm, 0.41 ± 0.06 cm and 0.40 ± 0.06 cm after hyperventilation, EtCO₂ range 35–37, 32–34 and 29–31 mm Hg. Results were statistically significant but clinically not significant.

Conclusion:

We conclude that there are acute and dynamic alterations in ONSD in response to hyperventilation and presence of PEEP in anaesthetised patients. Ocular sonography may be used as a reliable indicator of acute variations in ICP.

New directions in point-of-care ultrasound at the crossroads of paediatric emergency and critical care

PURPOSE OF REVIEW

The diagnostic capability, efficiency and versatility of point-of-care ultrasound (POCUS) have enabled its use in paediatric emergency medicine (PEM) and paediatric critical care (PICU). This review highlights the current applications of POCUS for the critically ill child across PEM and PICU to identify areas of progress and standardized practice and to elucidate areas for future research.

RECENT FINDINGS

POCUS technology continues to evolve and advance bedside clinical care for critically ill children, with ongoing research extending its use for an array of clinical scenarios, including respiratory distress, trauma and dehydration. Rapidly evolving and upcoming applications include diagnosis of pneumonia and acute chest syndrome, identification of intra-abdominal injury via contrast-enhancement, guidance of resuscitation, monitoring of increased intracranial pressure and procedural guidance.

SUMMARY

POCUS is an effective and burgeoning method for both rapid diagnostics and guidance for interventions and procedures. It has clinical application for a variety of conditions that span PEM and PICU settings. Formal POCUS training is needed to standardize and expand use of this valuable technology by PICU and PEM providers alike.

Measurement of the Optic Nerve Sheath Diameter with Magnetic Resonance Imaging and Its Association with Eyeball Diameter in Healthy Adults

BACKGROUND AND PURPOSE

The optic nerve sheath diameter (ONSD) is an indirect marker of the intracranial pressure, but the normal range of ONSD as measured using magnetic resonance imaging (MRI) and its associations with clinical parameters and the eyeball transverse diameter (ETD) remain unclear.

METHODS

We included 314 healthy adults who underwent brain MRI examinations for health screening between June 2014 and September 2017. The ONSD and ETD of each eye were calculated using time-of-flight magnetic resonance angiography. Linear regression analyses were performed to assess the relationships between ONSD and variables including age, sex, height, weight, body mass index (BMI), mean arterial blood pressure (MABP), intraocular pressure (IOP), and ETD. We further investigated a normative value for the ONSD/ETD ratio and its associated factors.

RESULTS

The mean ONSD and ETD were 4.71 mm [95% confidence interval (CI), 4.66-4.75 mm] and 21.24 mm (95% CI, 21.13-21.35 mm), respectively. Multiple linear regression analysis showed that ONSD was only associated with ETD (p<0.001), with it being independent of age, sex, height, weight, BMI, MABP, and IOP. The ONSD/ETD ratio had a mean value of 0.22 (95% CI, 0.22-0.22), and was not correlated with age, sex, height, weight, BMI, MABP, or IOP.

CONCLUSIONS

This study determined the normative value of MRI-based ONSD in healthy Korean adults. There was a strong correlation between the ETD and ONSD, which can be presented as the ONSD/ETD ratio. This parameter needs to be investigated further in disease populations.