Individual patient data systematic review and meta-analysis of optic nerve sheath diameter ultrasonography for detecting raised intracranial pressure: protocol of the ONSD research group

Assessing Stress Induced by Fluid Shifts and Reduced Cerebral Clearance during Robotic-Assisted Laparoscopic Radical Prostatectomy under Trendelenburg Positioning (UroTreND Study)

In addition to general anesthesia and mechanical ventilation, robotic-assisted laparoscopic radical prostatectomy (RALP) necessitates maintaining a capnoperitoneum and placing the patient in a pronounced downward tilt (Trendelenburg position). While the effects of the resulting fluid shift on the cardiovascular system seem to be modest and well tolerated, the effects on the brain and the blood-brain barrier have not been thoroughly investigated. Previous studies indicated that select patients showed an increase in the optic nerve sheath diameter (ONSD), detected by ultrasound during RALP, which suggests an elevation in intracranial pressure. We hypothesize that the intraoperative fluid shift results in endothelial dysfunction and reduced cerebral clearance, potentially leading to transient neuronal damage. This prospective, monocentric, non-randomized, controlled clinical trial will compare RALP to conventional open radical prostatectomy (control group) in a total of 50 subjects. The primary endpoint will be the perioperative concentration of neurofilament light chain (NfL) in blood using single-molecule array (SiMoA) as a measure for neuronal damage. As secondary endpoints, various other markers for endothelial function, inflammation, and neuronal damage as well as the ONSD will be assessed. Perioperative stress will be evaluated by questionnaires and stress hormone levels in saliva samples. Furthermore, the subjects will participate in functional tests to evaluate neurocognitive function. Each subject will be followed up until discharge. Conclusion: This trial aims to expand current knowledge as well as to develop strategies for improved monitoring and higher safety of patients undergoing RALP. The trial was registered with the German Clinical Trials Register DRKS00031041 on 11 January 2023.

Non-invasive intracranial pressure estimation using ultrasonographic measurement of area of optic nerve subarachnoid space

OBJECTIVE

To verify whether the area of the ONSAS (ONSASA) obtained by transorbital ultrasonography can be used to accurately evaluate the intracranial pressure (ICP).

METHODS

The recorded indexes included the optic nerve diameter, the optic nerve sheath diameter (ONSD), the width of both sides of the ONSAS (ONSASW) at 3 mm from the optic nerve head and the entire ONSASA outlined between 3 and 7 mm. After exploring and comparing five models to describe the relationship between body mass index (BMI), mean arterial blood pressure (MABP), ONSASA and ICP, the best model was determined.

RESULTS

In all, 90 patients with neurological diseases undergoing continuous invasive ICP monitoring were included in the study. In the training group, the correlation coefficient for the association between the ICP and ONSASA (Pearson's correlation r=0.953) was higher than that for the association of the ICP with the ONSD (r=0.672; p<0.0001) and ONSASW at 3 mm behind the globe (r=0.691; p<0.0001). In the training group, the weighting function for prediction of the ICP was as follows: non-invasive ICP=2.050×ONSASA-0.051×BMI +0.036*MABP-5.837. With 20 mm Hg as the cut-off point for a high or low ICP, the sensitivity and specificity of ONSASA predicting ICP was 1.00 and 0.92. Receiver operator curve analysis revealed that the calculated cut-off value for predicting elevated ICP was 19.96 (area under curve= 0.960, 95% CI 0.865 to 1.00).

CONCLUSION

Measurement of the ONSASA using ultrasonography can serve as a practical method for rapid and non-invasive quantification for evaluating ICP through an accurate mathematical formula with the BMI and MABP considered as contributing parameters.

TRIAL REGISTRATION NUMBER

The study was registered in the Chinese Clinical Trial Registry (Study no ChiCTR2100045274).

Lateral Ventricular Volume Asymmetry and Optic Nerve Sheath Diameter Predict Intracranial Pressure in Traumatic Brain Injury Patients

Background

Various noninvasive methods of intracranial pressure (ICP) measurement have been proposed. Each has unique advantages and limitations. This study was aimed at investigating the relationships between lateral ventricular asymmetry on admission computed tomography, optic nerve sheath diameter (ONSD), and ICP in traumatic brain injury (TBI) patients.

Methods

A prospective observational study was conducted in the patients admitted to our department between October 2018 and October 2020. 20 patients with moderate-severe TBI with a Glasgow Coma Scale of 3-12 were enrolled. Lateral ventricle volume (LVV) value measurements were conducted using ITK-SNAP software. The lateral ventricular volume ratio (LVR) was quantified by dividing the larger LVV by the smaller.

Results

ONSD and LVR had a good correlation with ICP. Admission LVR of >1.735 was shown to have a sensitivity of 90.9% and a specificity of 88.9% for prediction of ICP increase (AUC = 0.879; standard error = 0.091; 95% CI = 0.701 to 1.0; significance level p < 0.004). Admission ONSD of >5.55 mm was shown to have a sensitivity of 81.8% and a specificity of 88.9% for prediction of ICP increase (AUC = 0.919; standard error = 0.062; 95% CI = 0.798 to 1.0; significance level p < 0.002). Combining the ONSD and LVR, the sensitivity could be improved to 90.9% in parallel test, and the specificity could be improved to 100% in serial test.

Conclusion

ONSD and LVR measurements can diagnose elevated ICP in traumatic brain injury patients. ONSD combining with LVR may further improve the diagnostic evaluation.

Ultrasonographic optic nerve sheath diameter as a noninvasive marker for intracranial hypotension

Background:

Invasive intracranial pressure (ICP) can result in complications, pain, or even aggravate intracranial hypotension (IH) or headache in patients with IH.

Objective:

To investigate whether ultrasonographic measurements of optic nerve sheath diameter (ONSD) could serve as a noninvasive IH marker.

Methods:

Ultrasonographic ONSD was measured prior to lumbar puncture (LP) and ONSD measurements compared to LP’s opening pressure. We analyzed correlations between ONSD and ICP and determined the optimal ONSD cut-off point for IH. According to their LP on admission, patients were divided into three groups: IH group, normal ICP group, and elevated ICP group. Correlations between ONSD and ICP were analyzed using Pearson’s correlation. A receiver operating characteristic (ROC) curve was generated to determine the optimal cut-off point for IH.

Results:

In total, 136 subjects (75 men, 55.1% men) were included, and 1088 ONSDs were measured. The ONSD of the IH group (2.96 ± 0.15 mm) was significantly lower than that of the normal (3.59 ± 0.33 mm) and elevated ICP groups (4.90 ± 0.42 mm, p < 0.001). There was a significant difference in ONSD within all groups (p < 0.001), and the differences between the two groups were also statistically significant. ONSD and ICP values were strongly correlated, with an r = 0.952 (95% confidence interval [CI]: 0.924–0.969; p < 0.001). After adjusting for age, diastolic blood pressure, systolic blood pressure, body mass index, waistline, and head circumference, ONSD was positively associated with ICP. ROC curve analysis revealed an area under the curve of 0.990 (95% CI: 0.975–1.000). The ONSD cut-off point for identifying decreased opening pressure on LP was 3.15 mm, with 98.3% sensitivity and 91.7% specificity.

Conclusions:

Ultrasonographic ONSD may be a noninvasive, valuable, and easy-to-perform bedside technology for evaluating IH.

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.

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.

Comparison of Two Techniques to Measure Optic Nerve Sheath Diameter in Patients at Risk for Increased Intracranial Pressure

OBJECTIVES

Intracranial pressure over 20 mm Hg is associated with poor neurologic prognosis, but measuring intracranial pressure directly requires an invasive procedure. Dilation of the optic nerve sheath on axial ultrasound of the eye has been correlated with elevated intracranial pressure, but optimal cutoffs have been inconsistent possibly related to the measurement technique. A coronal technique has been studied on healthy volunteers but not on patients with high intracranial pressure. We compared two measurement techniques (axial and coronal) in patients with suspected high intracranial pressure due to trauma, bleeding, tumor, or infection.

DESIGN

Prospective blinded observational study.

SETTING

Two tertiary referral center ICUs.

PATIENTS

Twenty adults admitted to the ICU at risk for increased intracranial pressure expected to receive invasive intracranial monitoring.

INTERVENTIONS

Ultrasound measurements of the optic nerve sheath in axial and coronal views either averaged between eyes or the highest in either eye.

MEASUREMENTS AND MAIN RESULTS

Coronal measurements showed less variability between each eye than axial measurements (mean difference 0.5 mm vs 1 mm; p = 0.03) and were associated with high intracranial pressure at first measurement and over 24 hours (area under the receiver operating characteristic range 0.7-0.8). Mean and highest axial measurements showed improved association with first (area under the receiver operating characteristic 0.87-0.94) and highest intracranial pressure measurement (area under the receiver operating characteristic 0.89-0.96) within 24 hours. A cutoff of highest axial measurement in either eye greater than 6.2 mm or mean axial measurement between eyes of 5.6 mm had a sensitivity of 100% in predicting high intracranial pressure over the following 24 hours.

CONCLUSIONS

The highest axial measurement of optic nerve sheath diameter in either eye is the most predictive of patients with high intracranial pressure in our population. This comparison of measurement techniques has not previously been described and should be further explored to set test cutoffs for ultrasound of the optic nerve sheath diameter.

Correlation of optic nerve and optic nerve sheath diameter with intracranial pressure in pigs

Objective

Several studies have shown an association between intracranial pressure and the diameter of the optic nerve sheath measured by transbulbar ultrasonography. To understand the pathophysiology of this phenomenon, we aimed to measure the changes of the optic nerve, optic nerve sheath and perineural space separately with increasing intracranial pressure in a porcine model.

Methods

An external ventricular drain was placed into the third ventricle through a right paramedian burrhole in eight anesthesized pigs. The diameters of the optic nerve and the optic nerve sheath were measured while the intracranial pressure (ICP) was increased in steps of 10mmHg from baseline up to 60 mmHg.

Results

The median diameters of the optic nerve (ON) increased from 0.36 cm (baseline– 95% confidence interval (CI) 0.33 cm to 0.45 cm) to 0.68 cm (95% CI 0.57 cm to 0.82 cm) at ICP of 60 mmHg (p<0.0001) and optic nerve sheath (ONS) from 0.88 cm (95% CI 0.79 cm to 0.98 cm) to 1.24 cm (95% CI 1.02 cm to 1.38 cm) (p< 0.002) while the median diameter of the perineural space (PNS) (baseline diameter 95% CI 0.40 cm to 0.59 cm to diameters at ICP 60 95% CI 0.38 cm to 0.62 cm) did not change significantly (p = 0.399). Multiple comparisons allowed differentiation between baseline and values ≥40 mmHg for ON (p = 0.017) and between baseline and values ≥ 50mmHg for ONS (p = 0.006). A linear correlation between ON (R² = 0.513, p<0.0001) and ONS (R² = 0.364, p<0.0001) with ICP was found. The median coefficient of variation for intra- and inter-investigator variability was 8% respectively 2.3%.

Conclusion

Unexpectedly, the increase in ONS diameter with increasing ICP is exclusively related to the increase of the diameter of the ON. Further studies should explore the reasons for this behaviour.

Ultrasonographic optic nerve sheath diameter monitoring of elevated intracranial pressure: two case reports

Ultrasonography assessments of optic nerve sheath diameter (ONSD) is a non-invasive method that may help identify elevated intracranial pressure (ICP). However, this technique was used to evaluate the elevated ICP caused by traumatic brain injury. The objective of this study was to examine clinical cases of the changes in ICP with venous sinus stenosis and venous sinus thrombosis found the advantage of this technique in the application. And we dynamically monitor ONSD and ICP as a lens for understanding the dynamic assessment for ICP. The first case of venous sinus stenosis with elevated ICP identified in real-time by changes in ONSD, which are correlated with ICP before and after stenting. Another case of venous sinus thrombosis with elevated ICP. And after treatment, the patient underwent an ultrasound ONSD examination and lumbar puncture (LP) at the 1st, the 2nd and 3rd month of follow-up. The previously enlarged ONSDs retracted and LP opening pressure gradually returned to normal. These cases indicate that ONSD examination may help dynamically assess ICP changes and evaluate the efficacy of ICP treatment. These results provide utile, evidence based, preliminary clinical recommendations and indicate that ONSD examination might be a useful method of evaluating ICP, especially if repeated evaluations are needed.

Optic Nerve Sheath Diameter Ultrasound: Optic Nerve Growth Curve and Its Application to Detect Intracranial Hypertension in Children

PURPOSE

First, to create an optic nerve growth curve from normal optic nerve sheath diameter (ONSD) values measured by using B-scan ultrasonography in subjects 0-18 years of age. Second, to identify age-appropriate cutoff values of ONSD to be used in the diagnosis of intracranial hypertension (IHT).

DESIGN

Prospective cross-sectional study.

METHODS

B-scan ocular ultrasonography was performed on both eyes of 215 subjects 0-18 years of age, divided into 3 groups: 165 healthy children, 29 children with IHT (all >4 years of age), and 21 children with optic disc drusen (ODD).

RESULTS

There were no statistically significant differences in between the ONSDs of healthy children and those in subjects with ODD. An optic nerve growth curve was created by using ONSDs measured in healthy subjects 0-18 years of age, using the equation: ONSD = ln [33.15] - (-0.18 × ln [children's age]). The curve showed a progressive increase of ONSD up to 10 years of age, and it remained constant until the age of 18. For this reason, 2 different cutoff values were calculated for age groups 4-10 and 11-18. Values were 4.10 mm and 4.4 mm, respectively, with a 100.0% sensitivity and a specificity ranging from 83.9% to 98.8%. A sensitivity of 28.6% was reached for the population of subjects 4-18 years of age with a threshold value of 5 mm, as used in published reports.

CONCLUSIONS

The ONSD continued to enlarge gradually until the age of 10. Therefore, 2 different cutoff values for the age groups 4-10 and 11-18 were calculated, considering the ONSDs of subjects 11-18 years of age overlapping with those of adults. No patients with IHT <4 years old were found. Further studies are needed to evaluate the correct cutoff values for these ages.

Ultrasonography Assessments of Optic Nerve Sheath Diameter as a Noninvasive and Dynamic Method of Detecting Changes in Intracranial Pressure

Importance

The crtierion standard method for monitoring intracranial pressure (ICP) can result in complications and pain. Hence, noninvasive, repeatable methods would be valuable.

Objective

To examine how ultrasonographic optic nerve sheath diameter (ONSD) correlated with noninvasive and dynamically monitored ICP changes.

Design, Setting, and Participants

The ONSD was measured before the lumbar puncture (LP) in 60 patients on admission. Patients with elevated ICP were divided into group 1 (200 < LP ≤ 300 mm H2O) and group 2 (LP > 300 mm H2O). Patients underwent follow-up ONSD and LP measurements within 1 month. We analyzed the correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP, which were the respective changes in ONSD and ICP from admission to follow-up.

Main Outcomes and Measures

The ultrasonographic ONSD and ICP were measured on admission and follow-up. The correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP were analyzed using Pearson correlation analyses.

Results

For 60 patients (Han nationality; mean [SD] age, 36.2 [12.04] years; 29 [48%] female) on admission, the ONSD and ICP values were strongly correlated, with an r of 0.798 (95% CI, 0.709-0.867; P < .001). Twenty-five patients with elevated ICP who completed the follow-up were included. The mean (SD) ONSD and ICP on admission were 4.50 (0.54) mm and 302.40 (54.26) mm H2O, respectively. The ONSD and ICP values obtained on admission were strongly correlated , with an r of 0.724 (95% CI, 0.470-0.876; P < .001). The mean (SD, range) changes in ICP and ONSD were 126.64 (52.51 mm H2O, 20-210 mm H2O) (95% CI, 106.24-146.07) and 1.00 (0.512 mm, 0.418-2.37 mm) (95% CI, 0.83-1.20), respectively. The change in ONSD was strongly correlated with the change in ICP, with an r of 0.702 (95% CI, 0.425-0.870; P < .001). The follow-up evaluations revealed that the elevated ICP and dilated ONSD had returned to normal, and no evidence of difference was found in the mean ONSDs between group 1 (3.49 mm; 95% CI, 3.34-3.62 mm) and group 2 (3.51 mm; 95% CI, 3.44-3.59 mm) (P = .778) at follow-up.

Conclusions and Relevance

The dilated ONSDs decreased along with the elevated ICP reduction. Ultrasonographic ONSD measurements may be a useful, noninvasive tool for dynamically evaluating ICP.

Ultrasonographic optic nerve sheath diameter to detect increased intracranial pressure in adults: a meta-analysis

BACKGROUND

The optimal optic nerve sheath diameter (ONSD) cut-off for identifying increased intracranial pressure (IICP) remains unclear in adult patients.

PURPOSE

To validate the diagnostic accuracy of ultrasonographic (US) ONSD > 5.0 mm as a cut-off for detecting IICP by computed tomographic (CT) through a meta-analysis.

MATERIAL AND METHODS

A systemic literature review was performed of online databases from January 1990 to September 2017. A bivariate random-effects model was used to estimate pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence intervals (CIs). A summary receiver operating characteristic (SROC) graph was used to provide summary points for sensitivity and specificity. Meta-regression tests were performed to estimate the influence of the study characteristics on DOR. Publication bias was assessed using Deeks' funnel plot asymmetry test.

RESULTS

Six studies with 352 patients were included in the meta-analysis. US ONSD > 5.0 mm revealed pooled sensitivity of 99% (95% CI = 96-100) and specificity of 73% (95% CI = 65-80) for IICP detection. DOR was 178. The area under the SROC curve was 0.981, indicating a good level of accuracy. Meta-regression studies showed no significant associations between DOR and study characteristics such as probe mode (relative DOR [RDOR] = 0.60; P = 0.78), study quality (RDOR = 0.52; P = 0.67), IICP prevalence (RDOR = 0.04; P = 0.17), or pathology at admission (RDOR = 1.30; P = 0.87).

CONCLUSION

US ONSD > 5.0 mm can be used to rapidly detect IICP in adults in emergency departments and intensive care units. Further meta-analysis based on individual patient-level databases is needed to confirm these results.

Military trainees can accurately measure optic nerve sheath diameter after a brief training session

BACKGROUND

Identification of elevated intracranial pressure is important following traumatic brain injury. We assessed the feasibility of educating military trainees on accurately obtaining optic nerve sheath diameter measurements using a brief didactic and hands-on training session. Optic nerve sheath diameter is a noninvasive surrogate marker for elevated intracranial pressure, and may be of value in remote military operations, where rapid triage decisions must be made without access to advanced medical equipment.

METHODS

Military trainees with minimal ultrasound experience were given a 5-min didactic presentation on optic nerve sheath diameter ultrasound. Trainees practiced optic nerve sheath diameter measurements guided by emergency physician ultrasound experts. Trainees then measured the optic nerve sheath diameter on normal volunteers. Following this, a trained physician measured the optic nerve sheath diameter on the same volunteer as a criterion standard. An average of three measurements was taken.

RESULTS

Twenty-three military trainees were enrolled. A mixed design ANOVA was used to compare measurements by trainees to those of physicians, with a mean difference of - 0.6 mm (P = 0.76). A Bland-Altman analysis showed that the degree of bias in optic nerve sheath diameter measures provided by trainees was very small: d = - 0.004 for the right eye and d = - 0.007 for the left eye.

CONCLUSION

This study demonstrates that optic nerve sheath diameter measurement can be accurately performed by novice ultrasonographers after a brief training session. If validated, point-of-care optic nerve sheath diameter measurement could impact the triage of injured patients in remote areas.

Quality And Feasibility of Sonographic Measurement of the Optic Nerve Sheath Diameter to Estimate the Risk of Raised Intracranial Pressure After Traumatic Brain Injury in Prehospital Setting

OBJECTIVE

In patients with traumatic brain injury (TBI), early detection and subsequent prompt treatment of elevated intracranial pressure (ICP) is a challenge in the prehospital setting, because physical examination is limited in comatose patients and invasive device placement is not possible. The aim of this study was to evaluate the quality and feasibility of optic nerve sheath diameter (ONSD) measurements obtained during the prehospital management of patients with TBI.

METHODS

This study was a prospective, observational study of 23 patients with moderate and severe TBI during prehospital medical care. The primary endpoint was the quality of ONSD measurements expressed as the percentage of ONSD validated by the experts. Secondary endpoints included the feasibility of ONSD measurements as the percentage of ONSD performed and assessment by operators of ease and duration to perform.

RESULTS

Ultrasound ONSD was performed in 19 (82%) patients and 80% of ONSD measurements were validated by the experts. The ONSD measurements were possible in 15 (79%) cases. The physicians have assessed the ease of use at 8 (interquartile range [IQR] = 2.5-8) on 10 for and the median time to obtain ONSD measurement was 4 min (IQR = 3-5). ONSD measurement was performed in 12 (63%) cases during the transport and in 7 (37%) cases on scene, with 58% (n = 7) and 71% (n = 5) validated ONSD, respectively. The success rate in the helicopter was 43% compared to 80% in the ambulance.

CONCLUSION

This study shows that it is feasible to obtain high-quality ONSD measurements in the management of patients with TBI in a prehospital setting. A randomized study evaluating the usefulness of ONSD to guide management of TBI in the prehospital phase may be of great interest.

Optic nerve sheath diameter measured sonographically as non-invasive estimator of intracranial pressure: a systematic review and meta-analysis

PURPOSE

Although invasive intracranial devices (IIDs) are the gold standard for intracranial pressure (ICP) measurement, ultrasonography of the optic nerve sheath diameter (ONSD) has been suggested as a potential non-invasive ICP estimator. We performed a meta-analysis to evaluate the diagnostic accuracy of sonographic ONSD measurement for assessment of intracranial hypertension (IH) in adult patients.

METHODS

We searched on electronic databases (MEDLINE/PubMed^®, Scopus^®, Web of Science^®, ScienceDirect^®, Cochrane Library^®) until 31 May 2018 for comparative studies that evaluated the efficacy of sonographic ONSD vs. ICP measurement with IID. Data were extracted independently by two authors. We used the QUADAS-2 tool for assessing the risk of bias (RB) of each study. A diagnostic meta-analysis following the bivariate approach and random-effects model was performed.

RESULTS

Seven prospective studies (320 patients) were evaluated for IH detection (assumed with ICP > 20 mmHg or > 25 cmH₂O). The accuracy of included studies ranged from 0.811 (95% CI 0.678‒0.847) to 0.954 (95% CI 0.853‒0.983). Three studies were at high RB. No significant heterogeneity was found for the diagnostic odds ratio (DOR), positive likelihood ratio (PLR) and negative likelihood ratio (NLR), with I² < 50% for each parameter. The pooled DOR, PLR and NLR were 67.5 (95% CI 29‒135), 5.35 (95% CI 3.76‒7.53) and 0.088 (95% CI 0.046‒0.152), respectively. The area under the hierarchical summary receiver-operating characteristic curve (AUHSROC) was 0.938. In the subset of five studies (275 patients) with IH defined for ICP > 20 mmHg, the pooled DOR, PLR and NLR were 68.10 (95% CI 26.8‒144), 5.18 (95% CI 3.59‒7.37) and 0.087 (95% CI 0.041‒0.158), respectively, while the AUHSROC was 0.932.

CONCLUSIONS

Although the wide 95% CI in our pooled DOR suggests caution, ultrasonographic ONSD may be a potentially useful approach for assessing IH when IIDs are not indicated or available (CRD42018089137, PROSPERO).

High-resolution transbulbar ultrasonography helping differentiate intracranial hypertension in bilateral optic disc oedema patients

PURPOSE

The enlargement of optic nerve sheath diameter (ONSD) has been proven to be related with raised intracranial pressure (ICP). No prospective study has been focused on utilizing retrobulbar ultrasonography in optic disc oedema patient presented to ophthalmologist.

METHODS

High-resolution transbulbar ultrasonography was performed in a cohort of patient presented with bilateral optic disc oedema. The subarachnoid space of optic nerve (SAS), ONSD and optic nerve diameter (OND) was measured prior to other ancillaries including lumbar puncture. Subjects were classified into increased intracranial pressure (IIP) and normal intracranial pressure (NIP) group according to the open cerebrospinal fluid pressure more than 200 mm H₂ 0. The SAS, ONSD and OND were compared between groups and with normal control. The sensitivity of SAS or ONSD change for predicating intracranial hypertension was assessed.

RESULTS

A total of 20 IIP, 25 NIP patients and 25 normal controls were evaluated. The mean SAS and ONSD measured in idiopathic intracranial hypertension group was significantly increased than that of NIP and controls (p < 0.001), whereas the OND showed no statistic difference between each group. The sensitivities using the SAS and ONSD for differentiating increased ICP in optic disc oedema patients were 0.99 and 0.97, respectively.

CONCLUSIONS

The enlarged SAS and ONSD measured by high-resolution transbulbar sonography are very sensitive parameters to predicate increased ICP in bilateral optic disc oedema patients.

Alterations in optic nerve sheath diameter according to cerebrovascular disease sub-groups

BACKGROUND

ONSD (optic nerve sheath diameter) is a method used for indirect measurement of the increased intracranial pressure. In previous studies, the relation between the increased intracranial pressure and ONSD was analyzed in the patients suffering from cerebrovascular diseases (CVD). In our study, the patients suffering from ischemic CVD were categorized into 4 subgroups according to Oxfordshire Community Stroke Project classification (OCSP); the relationship between each group and ONSD, and the influence on each eye were analyzed.

METHODS

The study included the patients over the age of 18 applying to the emergency department of Malatya State Hospital with the symptoms of stroke between the dates of 1/1/2015 and 1/9/2016. The patients diagnosed with stroke by means of clinical and neuroradiological imaging were examined in 4 subgroups according to Oxfordshire Community Stroke Project. The aim of the study is to predict the intracranial pressure (ICP) levels of the patients through ONSD measurement and CT images.

RESULTS

In the comparison of the right and left optic nerve sheath diameters of CVD group and control group, the obtained results were found to be statistically significant (p<0.001). When the CVD subgroups were compared with the control group in terms of right and left optic nerve sheath diameters, the highest right-left optic nerve sheath diameter was detected to be in TACI (Total Anterior Circulation Infarction) group (p<0.001).

DISCUSSION/CONCLUSION

In the early cases of CVD, mortality and morbidity can be decreased through the early diagnosis of the possible existence of ICP increase according to ONSD level.

Optic Nerve Sheath Diameter Ultrasound Evaluation in Intensive Care Unit: Possible Role and Clinical Aspects in Neurological Critical Patients' Daily Monitoring

Background. The increase of the optic nerve sheath diameter (ONSD) is a reliable, noninvasive sonographic marker of intracranial hypertension. Aim of the study was to demonstrate the efficacy of ONSD evaluation, when monitoring neurocritical patients, to early identify malignant intracranial hypertension in patients with brain death (BD). Methods. Data from ultrasound ONSD evaluation have been retrospectively analyzed in 21 sedated critical patients with neurological diseases who, during their clinical course, developed BD. 31 nonneurological controls were used for standard ONSD reference. Results. Patients with neurological diseases, before BD, showed higher ONSD values than control group (CTRL: RT 0.45 ± 0.03 cm; LT 0.45 ± 0.02 cm; pre-BD: RT 0.54 ± 0.02 cm; LT 0.55 ± 0.02 cm; p < 0.000) even without intracranial hypertension, evaluated with invasive monitoring. ONSD was further significantly markedly increased in respect to the pre-BD evaluation in neurocritical patients after BD, with mean values above 0.7 cm (RT 0.7 ± 0.02 cm; LT 0.71 ± 0.02 cm; p < 0.000), with a corresponding dramatic raise in intracranial pressure. Logistic regression analysis showed a strong correlation between ONSD and ICP (R 0,895, p < 0.001). Conclusions. ONSD is a reliable marker of intracranial hypertension, easy to be performed with a minimal training. Routine ONSD daily monitoring could be of help in Intensive Care Units when invasive intracranial pressure monitoring is not available, to early recognize intracranial hypertension and to suspect BD in neurocritical patients.

Noninvasive and quantitative intracranial pressure estimation using ultrasonographic measurement of optic nerve sheath diameter

We aimed to quantitatively assess intracranial pressure (ICP) using optic nerve sheath diameter (ONSD) measurements. We recruited 316 neurology patients in whom ultrasonographic ONSD was measured before lumbar puncture. They were randomly divided into a modeling and a test group at a ratio of 7:3. In the modeling group, we conducted univariate and multivariate analyses to assess associations between ICP and ONSD, age, sex, BMI, mean arterial blood pressure, diastolic blood pressure. We derived the mathematical function "Xing &Wang" from the modelling group to predict ICP and evaluated the function in the test group. In the modeling group, ICP was strongly correlated with ONSD (r = 0.758, p < 0.001), and this association was independent of other factors. The mathematical function was ICP = -111.92 + 77.36 × ONSD (Durbin-Watson value = 1.94). In the test group, a significant correlation was found between the observed and predicted ICP (r = 0.76, p < 0.001). Bland-Altman analysis yielded a mean difference between measurements of -0.07 ± 41.55 mmH₂O. The intraclass correlation coefficient and its 95%CIs for noninvasive ICP assessments using our prediction model was 0.86 (0.79-0.90). Ultrasonographic ONSD measurements provide a potential noninvasive method to quantify ICP that can be conducted at the bedside.

Ultrasonographic Evaluation of Optic Nerve Sheath Diameter among Healthy Chinese Adults

The aim of the work described here was to establish the range for optic nerve sheath diameter (ONSD) and potential factors influencing ONSD in healthy Chinese adults. Both ONSDs were measured twice in the sagittal and transversal planes by two observers. The final ONSD value for each participant was the average of 16 measurements of both eyes. The ONSD range (N = 3680) among 230 participants was 2.65-4.30 mm. The upper ONSD limit was lower than those in previous studies in Caucasian and African samples. Simple linear regression analyses revealed that the ONSD was correlated with sex, body mass index and waistline and head circumference. After adjustment for potential confounds between these factors, sex (coefficient = 0.225, p < 0.001) and body mass index (coefficient = 0.042, p < 0.001) were independently associated with ONSD. Underweight women had the smallest ONSD. These results suggest that racial, sex, and body mass index differences should be noted when assessing ultrasonographic criteria.

Monitoring of Intracranial Pressure by CT-Defined Optic Nerve Sheath Diameter

BACKGROUND AND PURPOSE

Intracranial pressure (ICP) can be monitored by the optic nerve sheath diameter (ONSD) technique. We hypothesized that diameter of the optic canal (OC) can be a limiting factor for this technique.

METHODS

In the prospective cohort study, we analyzed CT scans of 600 OCs of healthy adults and 54 canals of patients with ICP monitoring. The diameters were measured through its length and the narrowest one was chosen for further analysis. ONSD was measured at 3 and 10 mm from the anterior opening of the canal. The correlation analysis was performed between invasive and ONSD methods of ICP monitoring and OC diameters in pathological cases.

RESULTS

The narrowest cross-sectional area of the normal OC was 13.85±2.89 mm² and varied from 25.5 to 6.6 mm². Apparently 9.17% OCs were narrow (˂10.9 mm²). Correlations exist between the optic nerve sheath area at the 3-mm distance from the anterior opening of the canal and the area of the anterior opening itself (P = .012), and the sheath area 10 mm from the anterior opening and the narrowest part of the canal (P = .015). Cases with narrow canals provided false-negative readings via ONSD method if compared with invasive monitoring.

CONCLUSION

In its narrowest part, the average OC is 11 to 16.75 mm² wide. We suggest measuring this area simultaneously with the ONSD during ICP monitoring. If the area of the narrowest lumen of the canal is less than 10 mm², ONSD technique for ICP monitoring should not be used.

Sonographic assessment of the optic nerve sheath diameter in the diagnosis of idiopathic intracranial hypertension

OBJECTIVE

Sonographic assessment of the optic nerve sheath diameter (ONSD) is a useful technique in detecting raised intracranial pressure (ICP) in neurocritical care patients. Its utility in idiopathic intracranial hypertension (IIH) is less known. The aim of this study was to evaluate the diagnostic accuracy of ONSD for detecting IIH.

MATERIAL AND METHODS

Ultrasound measurement of ONSD was performed in 19 patients with IIH and in 11 patients with different neurological diseases without raised ICP that required undergoing a lumbar puncture. The validity of this technique for diagnosing IIH was established with cerebrospinal fluid manometry values.

RESULTS

Patients with IIH showed significantly enlarged ONSD than those without IIH. The best cut-off point for detecting raised ICP was 6.3 mms, with a sensitivity, specificity and positive likelihood ratio of 94.7%, 90.9% and 10.4, respectively. After a therapeutic lumbar puncture an 87% of cases had a partial reduction of ONSD values.

CONCLUSION

Sonographic assessment of ONSD seems to be a useful and reliable technique for detecting raised ICP. While the spinal manometry is not replaced in usual clinical settings, transorbital sonography alternatively allows a suitable and harmless screening of patients with suspected IIH. It would be desirable to perform an internal validation of the technique in each hospital in order to get the optimal cut-off point.

Coronal Axis Measurement of the Optic Nerve Sheath Diameter Using a Linear Transducer

OBJECTIVES

The true optic nerve sheath diameter cutoff value for detecting elevated intracranial pressure is variable. The variability may stem from the technique used to acquire sonographic measurements of the optic nerve sheath diameter as well as sonographic artifacts inherent to the technique. The purpose of this study was to compare the traditional visual axis technique to an infraorbital coronal axis technique for assessing the optic nerve sheath diameter using a high-frequency linear array transducer.

METHODS

We conducted a cross-sectional study at an academic medical center. Timed optic nerve sheath diameter measurements were obtained on both eyes of healthy adult volunteers with a 10-5-MHz broadband linear array transducer using both traditional visual axis and coronal axis techniques. Optic nerve sheath diameter measurements were obtained by 2 sonologists who graded the difficulty of each technique and were blinded to each other's measurements for each participant.

RESULTS

A total of 42 volunteers were enrolled, yielding 84 optic nerve sheath diameter measurements. There were no significant differences in the measurements between the techniques on either eye (P = .23 [right]; P = .99 [left]). Additionally, there was no difference in the degree of difficulty obtaining the measurements between the techniques (P = .16). There was a statistically significant difference in the time required to obtain the measurements between the traditional and coronal techniques (P < .05).

CONCLUSIONS

Infraorbital coronal axis measurements are similar to measurements obtained in the traditional visual axis. The infraorbital coronal axis technique is slightly faster to perform and is not technically challenging.

Assessment of intra-interobserver reliability of the sonographic optic nerve sheath diameter measurement

Diagnosis and measuring the level of increase in intracranial pressure (ICP) is critical, especially for the management of trauma patients in the emergency department and intensive care unit. However, measurements are operator-dependent as in all of the sonographic diagnoses. The aim of this study is to assess the operator variations in the measurement of optic nerve sheath diameter (ONSD). There were four emergency medicine specialists involved in the study. Each had at least 1 year of experience of ultrasound scans and performed at least 25 prior ocular scans examining the ONSD. Two measurements were made 1 week apart from both axial and longitudinal planes. Sixty healthy adults were involved in the study and every investigator obtained four measurements from each. Intra-interobserver reliabilities were tested. The investigators performed 60 ocular ultrasounds on individual healthy adults and obtained two measurements in axial and longitudinal planes 1 week apart. Therefore, 960 measurements were analyzed. The levels of compatibilities for most of the measurements were found at acceptable levels statistically. However, it is not possible to say that there was a perfect compatibility among the sonographers according to the previously conducted reliability studies of ultrasound measurements. According to our results, it is hard to say that sonographic measurement of the ONSD is a highly reliable method both in longitudinal and transverse planes.

Optimal optic nerve sheath diameter threshold for the identification of elevated opening pressure on lumbar puncture in a Chinese population

Ultrasonography of the optic nerve sheath diameter (ONSD) is a non-invasive and rapid method that might be helpful in the identification of increased intracranial pressure (ICP). The use of an ONSD greater than 5 mm on ultrasound as an indicator of increased ICP in a Caucasian population has been studied. However, the cut-off point of this predictor in Chinese patients has not been established. Thus, we conducted this study to identify the ONSD criterion for the detection of elevated opening pressure on lumbar puncture (LP) in a Chinese population and to investigate the influencing factors. This study was a blind cross-sectional study. Patients who presented with suspected increased ICP were included. The opening pressure on LP of each participant was confirmed. We analyzed the clinical differences between the groups of patients with abnormal and normal opening pressures on LP. A receiver operating characteristic curve was constructed to determine the ONSD cut-off point for the identification of abnormal opening pressure on LP. In total, 279 patients were recruited, and 101 patients presented with elevated opening pressure on LP. ONSD was a significant independent predictor of elevated opening pressure on LP (p<0.001). However, no statistical significance was observed regarding the factors that might have affected this relationship including gender, age, body mass index, waistline, head circumference, hypertension and pathological subtype. The ONSD cut-off point for the identification of elevated opening pressure on LP was 4.1 mm; this cut-off yielded a sensitivity of 95% and a specificity of 92%. ONSD is a strong and accurate predictor of elevated opening pressure on LP. The cut-off point of this predictor in a Chinese population was remarkably lower than that found in a Caucasian population. Thus, ethnic differences should be noted when using the ONSD as an indicator of increased ICP.

Monitoring of intracranial pressure in patients with traumatic brain injury

Since Monro published his observations on the nature of the contents of the intracranial space in 1783, there has been investigation of the unique relationship between the contents of the skull and the intracranial pressure (ICP). This is particularly true following traumatic brain injury (TBI), where it is clear that elevated ICP due to the underlying pathological processes is associated with a poorer clinical outcome. Consequently, there is considerable interest in monitoring and manipulating ICP in patients with TBI. The two techniques most commonly used in clinical practice to monitor ICP are via an intraventricular or intraparenchymal catheter with a microtransducer system. Both of these techniques are invasive and are thus associated with complications such as hemorrhage and infection. For this reason, significant research effort has been directed toward development of a non-invasive method to measure ICP. The principle aims of ICP monitoring in TBI are to allow early detection of secondary hemorrhage and to guide therapies that limit intracranial hypertension (ICH) and optimize cerebral perfusion. However, information from the ICP value and the ICP waveform can also be used to assess the intracranial volume-pressure relationship, estimate cerebrovascular pressure reactivity, and attempt to forecast future episodes of ICH.