Ultrasonographic optic nerve sheath diameter correlation with ICP and accuracy as a tool for noninvasive surrogate ICP measurement in patients with decompressive craniotomy

Using Optic Nerve Sheath Diameter for Intracranial Pressure (ICP) Monitoring in Traumatic Brain Injury: A Scoping Review

INTRODUCTION

Neuromonitoring represents a cornerstone in the comprehensive management of patients with traumatic brain injury (TBI), allowing for early detection of complications such as increased intracranial pressure (ICP) [1]. This has led to a search for noninvasive modalities that are reliable and deployable at bedside. Among these, ultrasonographic optic nerve sheath diameter (ONSD) measurement is a strong contender, estimating ICP by quantifying the distension of the optic nerve at higher ICP values. Thus, this scoping review seeks to describe the existing evidence for the use of ONSD in estimating ICP in adult TBI patients as compared to gold-standard invasive methods.

MATERIALS AND METHODS

This review was conducted in accordance with the Joanna Briggs Institute methodology for scoping reviews, with a main search of PubMed and EMBASE. The search was limited to studies of adult patients with TBI published in any language between 2012 and 2022. Sixteen studies were included for analysis, with all studies conducted in high-income countries.

RESULTS

All of the studies reviewed measured ONSD using the same probe frequency. In most studies, the marker position for ONSD measurement was initially 3 mm behind the globe, retina, or papilla. A few studies utilized additional parameters such as the ONSD/ETD (eyeball transverse diameter) ratio or ODE (optic disc elevation), which also exhibit high sensitivity and reliability.

CONCLUSION

Overall, ONSD exhibits great test accuracy and has a strong, almost linear correlation with invasive methods. Thus, ONSD should be considered one of the most effective noninvasive techniques for ICP estimation in TBI patients.

G, Gunasekaran A, Chandar V. Comparison of Optic Nerve Sheath Diameter (ONSD) Measurements Obtained from USG Before and After Placement of Ventriculoperitoneal Shunt in Obstructive Hydrocephalus as a Surrogate Marker for Adequacy of Shunt Function: A Prospective Observational Study

Introduction  Optic nerve sheath diameter (ONSD) measured using ultrasonography has been widely used as a surrogate marker of elevated intracranial pressure. However, literature is sparse on the correlation between ONSD and ventriculoperitoneal (VP) shunt function, especially in adults with hydrocephalus. Our study was designed to assess the correlation between ONSD measured using ultrasonography before and 12 hours after VP shunt placement and the success of VP shunt placement assessed using computed tomography (CT) of the brain. Materials and Methods  Fifty-one patients between 16 and 60 years of age, with obstructive hydrocephalus scheduled for VP shunt surgery were included in this prospective, observational study. ONSD measurements were obtained from both eyes prior to induction of anesthesia, immediately after the surgery, and at 6, 12, and 24 hours after the surgery. An average of three readings was obtained from each eye. Cerebrospinal fluid (CSF) opening pressure was noted after entry into the lateral ventricle. Noncontrast CT (NCCT) brain was obtained 12 hours after the surgery and was interpreted by the same neurosurgeon for signs of successful VP shunt placement. Results  There was a significant reduction in ONSD in the postoperative period compared to ONSD measured preoperatively. The average ONSD (mean ± standard deviation) measured prior to induction of anesthesia, immediately after the surgery, and at 6, 12, and 24 hours after the surgery was 5.71 ± 0.95, 5.20 ± 0.84, 5.06 ± 0.79, 4.90 ± 0.79, and 4.76 ± 0.75 mm, respectively. The mean CSF opening pressure was 19.6 ± 6.9 mm Hg. Postoperative NCCT brain revealed misplacement of the shunt tip in only one patient. Conclusion  ONSD measured using ultrasonography may be used as a reliable indicator of VP shunt function in adults with obstructive hydrocephalus.

Cerebral hemodynamics and optic nerve sheath diameter acquired via neurosonology in critical patients with severe coronavirus disease: experience of a national referral hospital in Peru

Aim

We aimed to describe the neurosonological findings related to cerebral hemodynamics acquired using transcranial Doppler and to determine the frequency of elevated ICP by optic nerve sheath diameter (ONSD) measurement in patients with severe coronavirus disease (COVID-19) hospitalized in the intensive care unit of a national referral hospital in Peru.

Methods

We included a retrospective cohort of adult patients hospitalized with severe COVID-19 and acute respiratory failure within the first 7 days of mechanical ventilation under deep sedoanalgesia, with or without neuromuscular blockade who underwent ocular ultrasound and transcranial Doppler. We determine the frequency of elevated ICP by measuring the diameter of the optic nerve sheath, choosing as best cut-off value a diameter equal to or >5.8 mm. We also determine the frequency of sonographic patterns obtained by transcranial Doppler. Through insonation of the middle cerebral artery. Likewise, we evaluated the associations of clinical, mechanical ventilator, and arterial blood gas variables with ONSD ≥5.8 mm and pulsatility index (PI) ≥1.1. We also evaluated the associations of hemodynamic findings and ONSD with mortality the effect size was estimated using Poisson regression models with robust variance.

Results

This study included 142 patients. The mean age was 51.39 ± 13.3 years, and 78.9% of patients were male. Vasopressors were used in 45.1% of patients, and mean arterial pressure was 81.87 ± 10.64 mmHg. The mean partial pressure of carbon dioxide (PaCO2) was elevated (54.08 ± 16.01 mmHg). Elevated intracranial pressure was seen in 83.1% of patients, as estimated based on ONSD ≥5.8 mm. A mortality rate of 16.2% was reported. In the multivariate analysis, age was associated with elevated ONSD (risk ratio [RR] = 1.07). PaCO2 was a protective factor (RR = 0.64) in the cases of PI ≥ 1.1. In the mortality analysis, the mean velocity was a risk factor for mortality (RR = 1.15).

Conclusions

A high rate of intracranial hypertension was reported, with ONSD measurement being the most reliable method for estimation. The increase in ICP measured by ONSD in patients with severe COVID-19 on mechanical ventilation is not associated to hypercapnia or elevated intrathoracic pressures derived from protective mechanical ventilation.

A Pathophysiological Approach to Spontaneous Orbital Meningoceles: Case Report and Systematic Review

BACKGROUND

Spontaneous orbital cephaloceles are a rare condition. The purpose of this study is to provide a description of a clinical case and to carry out a systematic literature review.

METHODS

A systematic review of the English literature published on the Pubmed, Scopus, and Web of Science databases was conducted, according to the PRISMA recommendations.

RESULTS

A 6-year-old patient was admitted for right otomastoiditis and thrombosis of the sigmoid and transverse sinuses, as well as the proximal portion of the internal jugular vein. Radiological examinations revealed a left orbital mass (22 × 14 mm) compatible with asymptomatic orbital meningocele (MC) herniated from the superior orbital fissure (SOF). The child underwent a right mastoidectomy. After the development of symptoms and signs of intracranial hypertension (ICH), endovascular thrombectomy and transverse sinus stenting were performed, with improvement of the clinical conditions and reduction of the orbital MC. The systematic literature review encompassed 29 publications on 43 patients with spontaneous orbital MC. In the majority of cases, surgery was the preferred treatment.

CONCLUSIONS

The present case report and systematic review highlight the importance of ICH investigation and a pathophysiological-oriented treatment approach. The experiences described in the literature are limited, making the collection of additional data paramount.

Diagnostic Value of the Combination of Ultrasonographic Optic Nerve Sheath Diameter and Width of Crural Cistern with Respect to the Intracranial Pressure in Patients Treated with Decompressive Craniotomy

BACKGROUND

The monitoring of intracranial pressure (ICP) and detection of increased ICP are crucial because such increases may cause secondary brain injury and a poor prognosis. Although numerous ultrasound parameters, including optic nerve sheath diameter (ONSD), width of the crural cistern (WCC), and the flow velocities of the central retinal artery and middle cerebral artery, can be measured in patients after hemicraniectomy, researchers have yet to determine which of these is better for evaluating ICP. This study aimed to analyze the correlation between ICP and ultrasound parameters and investigate the best noninvasive estimator of ICP.

METHODS

This observational study enrolled 50 patients with brain injury after hemicraniectomy from January 2021 to December 2021. All patients underwent invasive ICP monitoring with microsensor, transcranial, and ocular ultrasound postoperatively. We measured the ONSD including the dura mater (ONSDI), the ONSD excluding the dura mater, the optic nerve diameter (OND), the eyeball transverse diameter (ETD), the WCC, and the flow velocities in the central retinal artery and middle cerebral artery. Then, we calculated the ONSDI-OND (the difference between ONSDI and OND) and ONSDI/ETD (the ratio of ONSDI to ETD). Patients were divided into a normal ICP group (n = 35) and an increased ICP group (≥ 20 mm Hg, n = 15) according to the ICP measurements. Correlations were then assessed between the values of the ultrasound parameters and ICP.

RESULTS

The ONSDI, ONSDI-OND, and ONSDI/ETD were positively associated with ICP (r = 0.455, 0.482, 0.423 and p = 0.001, < 0.001, 0.002, respectively), whereas the WCC was negatively associated with ICP (r = - 0.586, p < 0.001). The WCC showed the highest predictive power for increased ICP (area under the receiver operating characteristic curve [AUC] = 0.904), whereas the ONSDI-OND and ONSDI also presented with acceptable predictive power among the ONSD-related parameters (AUC = 0.831, 0.803, respectively). The cutoff values for increased ICP prediction for ONSDI, ONSDI-OND, and WCC were 6.29, 3.03, and 3.68 mm, respectively. The AUC of the combination of ONSDI-OND and WCC was 0.952 (95% confidence interval 0.896-1.0, p < 0.001).

CONCLUSIONS

The ONSDI, ONSDI-OND, and WCC were correlated with ICP and had acceptable accuracy levels in estimating ICP in patients after hemicraniectomy. Furthermore, WCC showed a higher diagnostic value than ONSD-related parameters, and the combination of ONSDI-OND and WCC was a satisfactory predictor of increased ICP.

Is optic nerve sheath diameter a promising screening tool to predict neurological outcomes and the need for secondary decompressive craniectomy in moderate to severe head injury patients? A prospective monocentric observational pilot study

Background

Optic nerve sheath diameter (ONSD) has been shown to be a noninvasive and quick method to calculate intracranial pressure (ICP) and subsequent neurologic outcomes, although with variable cutoffs. ICP can be indirectly assessed by noninvasive methods such as transcranial Doppler, ONSD, tympanic membrane displacement, and fundoscopy. Knowledge regarding the diagnostic accuracy of ONSD for predicting unfavorable outcomes within 72 hours (h) of moderate and severe head injury is limited. The objective of this study was to measure ONSD measurements at 24-h intervals in moderate to severe head injury patients and to find its association with clinical outcomes in the target population.

Methods

This prospective observational study was done on moderate to severe head injury patients. ONSD was measured twice at 24-h intervals over 48 h. The clinical outcome was divided into the favorable group (patients who were in conservative treatment with a stable Glasgow Coma Scale [GCS] score and discharged following treatment) and the unfavorable group (patients who had a drop in GCS motor score of one or more, or expired or underwent surgical intervention) within 72 h following traumatic brain injury. The Kruskal-Wallis test, Mann- Whitney test, and receiver operating characteristic curves were used to establish the association between ONSD and clinical outcomes.

Results

ONSD values measured at 24-h intervals >6.1 mm (P < 0.0146) and 6.2 mm (P < 0.0001) were found to be predictors of unfavorable outcomes (expired or underwent surgery), and hence the need for a secondary decompressive craniectomy (DC).

Conclusion

ONSD is an efficient screening tool to assess neurological outcomes in severe head injury patients. It can reliably predict the need for secondary DC at an earlier stage before secondary brain damage ensues in these patients.

Novel application of the Rotterdam CT score in the prediction of intracranial hypertension following severe traumatic brain injury

OBJECTIVE

Severe traumatic brain injury (TBI) is associated with intracranial hypertension (ICHTN). The Rotterdam CT score (RS) can predict clinical outcomes following TBI, but the relationship between the RS and ICHTN is unknown. The purpose of this study was to investigate clinical and radiological factors that predict ICHTN in patients with severe TBI.

METHODS

The authors performed a single-center retrospective review of patients who, between 2018 and 2021, had an intracranial pressure (ICP) monitor placed following TBI. Radiological and clinical characteristics related to the TBI and ICP monitoring were collected. The main outcome of interest was ICHTN, which was a dichotomous outcome (yes or no) defined on a per-patient basis as an ICP > 22 mm Hg that persisted for at least 5 minutes and required an escalation of treatment. ICHTN included both elevated opening pressure on initial monitor placement and ICP elevations later during hospitalization. Multivariate logistic regression was performed to determine variables associated with ICHTN. Diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUROC).

RESULTS

Seventy patients with severe TBI and an ICP monitor were included in this study. There was a predominance of male patients (94.0%), and the mean patient age was 40 years old. Most patients (67%) had an intraparenchymal catheter placed, whereas 33% of patients had a ventriculostomy catheter placed. In the multivariate logistic regression analysis, the RS was an independent predictor of ICHTN (OR 2.0, 95% CI 1.2-3.5, p = 0.014). No instances of ICHTN were observed in patients with an RS of 2 or less and no sulcal effacement. The AUROC of the RS and sulcal effacement was higher than the AUROC of the RS alone for predicting ICHTN (0.76 vs 0.71, p = 0.003, z-test).

CONCLUSIONS

The RS was predictive of ICHTN in patients with severe TBI, and the diagnostic accuracy of the model was improved with the inclusion of sulcal effacement at the vertex on CT of the head. Patients with a low RS and no sulcal effacement are likely at low risk for the development of ICHTN.

Neuromonitoring in Critically Ill Patients

OBJECTIVES

Critically ill patients are at high risk of acute brain injury. Bedside multimodality neuromonitoring techniques can provide a direct assessment of physiologic interactions between systemic derangements and intracranial processes and offer the potential for early detection of neurologic deterioration before clinically manifest signs occur. Neuromonitoring provides measurable parameters of new or evolving brain injury that can be used as a target for investigating various therapeutic interventions, monitoring treatment responses, and testing clinical paradigms that could reduce secondary brain injury and improve clinical outcomes. Further investigations may also reveal neuromonitoring markers that can assist in neuroprognostication. We provide an up-to-date summary of clinical applications, risks, benefits, and challenges of various invasive and noninvasive neuromonitoring modalities.

DATA SOURCES

English articles were retrieved using pertinent search terms related to invasive and noninvasive neuromonitoring techniques in PubMed and CINAHL.

STUDY SELECTION

Original research, review articles, commentaries, and guidelines.

DATA EXTRACTION

Syntheses of data retrieved from relevant publications are summarized into a narrative review.

DATA SYNTHESIS

A cascade of cerebral and systemic pathophysiological processes can compound neuronal damage in critically ill patients. Numerous neuromonitoring modalities and their clinical applications have been investigated in critically ill patients that monitor a range of neurologic physiologic processes, including clinical neurologic assessments, electrophysiology tests, cerebral blood flow, substrate delivery, substrate utilization, and cellular metabolism. Most studies in neuromonitoring have focused on traumatic brain injury, with a paucity of data on other clinical types of acute brain injury. We provide a concise summary of the most commonly used invasive and noninvasive neuromonitoring techniques, their associated risks, their bedside clinical application, and the implications of common findings to guide evaluation and management of critically ill patients.

CONCLUSIONS

Neuromonitoring techniques provide an essential tool to facilitate early detection and treatment of acute brain injury in critical care. Awareness of the nuances of their use and clinical applications can empower the intensive care team with tools to potentially reduce the burden of neurologic morbidity in critically ill patients.

Optic nerve sheath diameter as a quantitative parameter associated with the outcome in patients with traumatic brain injury undergoing hematoma removal

PURPOSE

To determine the association between optic nerve sheath diameter (ONSD) and outcome in patients with traumatic brain injury (TBI) who undergo hematoma removal (HR).

METHODS

This study was a retrospective analysis of data from a single center between 2016 and 2021. Adult patients with TBI who underwent HR within 24 h after admission were included in this study. Preoperative and postoperative ONSD of the surgical side and the mean ONSD of both sides were measured for analysis. The primary outcome was mortality at 30 days. Receiver operating characteristic curve analysis was performed to calculate the area under the curve (AUC) and 95% confidence interval (CI) for 30 days mortality.

RESULTS

Sixty-one patients were enrolled in the study. Among them, 48 (78.7%) survived for 30 days after admission. The AUC and 95% CI of the postoperative mean ONSD on both sides and postoperative/preoperative mean of the ONSD ratio on both sides were 0.884 [0.734-0.955] and 0.875 [0.751-0.942], respectively. The postoperative mean of both ONSDs of 6.0 mm had high accuracy as a cut-off value with a sensitivity of 85%, specificity of 83%, positive likelihood ratio (LR) of 5.0, and negative LR- of 0.18.

CONCLUSION

This study demonstrated that postoperative ONSD and the postoperative/preoperative ONSD ratio were associated with postoperative outcome in patients with TBI who underwent HR.

Value of Optic Nerve Sheath Diameter in Diagnosis and Follow Up of Patients with Disturbed Conscious Level

Background

Ultrasonographic measurement of optic nerve sheath diameter is a simple, non-invasive, and reliable method of detecting elevated intracranial pressure (ICP) in critical patients. Optic nerve sheath communicates with the dura mater covering the brain and contains cerebrospinal fluid, allowing pressure transmission from the cranium. Therefore, changes in cerebrospinal fluid (CSF) pressure have been shown to produce changes in ONSD.

Objective

This study aimed to assess the accuracy of optic nerve sheath diameter (ONSD) in diagnosis and follow-up patients with disturbed conscious levels compared with CT brain and fundus examination.

Patients and Methods

One hundred forty-one participants were included in the study, classified into 76 cases admitted with disturbed conscious levels due to elevated ICP and 65 controls. All patients were subjected to CT brain and optic nerve US and fundus examination at the time of admission and follow-up after 48 h after proper management.

Results

The current study showed that ONSD is significant in predicting elevated ICP at the cut-off point of average ONSD of 5.19 mm with 97% sensitivity and 98% specificity, and the area under the curve (AUC) was 0.996. The present study revealed a significant inverse correlation between ONSD and GCS in patients with increased ICP.

Conclusion

Ultrasonic measurement of ONSD is a promising technique in diagnosing and following patients with disturbed conscious levels.

Optic nerve sheath diameter in severe preeclampsia with neurologic features versus controls

BACKGROUND

Optic nerve sheath diameters (ONSD) have been validated as an accurate screening tool to detect elevated intracranial pressure in hypertensive encephalopathy. The neurologic manifestations of preeclampsia and/or eclampsia mimic those of hypertensive encephalopathy. This study was performed to assess the incidence of elevated optic nerve sheath diameters of patients with severe preeclampsia and neurologic criteria compared to non-preeclamptic patients. The secondary objective was to determine baseline optic nerve sheath diameters in patients with severe preeclampsia without neurologic criteria and preeclampsia without severe features.

METHODS

Single site cohort study including 62 pregnant women 18 years or older and 20 weeks or further gestation. Patients with preeclampsia without severe features, preeclampsia with severe features by non-neurologic criteria, preeclampsia with severe features with neurologic criteria, and patients without preeclampsia were enrolled via convenience sampling. One blinded reviewer measured sheath diameters; baseline demographics and pregnancy data were collected by chart review. Statistical analysis was completed with STATA/IC 16. Categorical variables were compared by the χ2 test. Continuous variables were presented as mean ± standard deviation, and discrete variables were presented as medians and compared by Kruskal-Wallis testing. Normality was confirmed by Shapiro-Wilk testing. Linear and logistic regression were used to test the association between the preeclampsia groups and optic nerve sheath diameters. Models were presented as unadjusted and adjusted for BMI, gestation, hypertension, diabetes, parity, and gravidity.

RESULTS

The incidence of optic nerve sheath diameters > 5.8 mm was 43.8% in the severe preeclampsia with neurologic features cohort, and 42.1% in the control cohort, with a relative risk of 1.04. Patients with severe preeclampsia without neurologic features had sheath diameters of 5.75 mm ± 1.09 mm; non-severe preeclampsia patients had sheath diameters of 5.54 mm ± 1.26 mm.

CONCLUSIONS

We did not find a significant elevated optic nerve sheath diameter relative risk between severe preeclampsia patients with neurologic features and non-preeclampsia control patients. This is the first study to assess a North American population utilizing ACOG criteria for severe and non-severe preeclampsia, with severe cohorts additionally stratified by neurologic criteria.

Comparing ultrasonographic optic nerve sheath diameter to head computed tomography scan to predict intracranial pressure elevation

Introduction:

Intracranial hypertension is an emergency condition that needs to be recognized as soon as possible. Lumbar puncture, the gold standard diagnostic procedure for intracranial hypertension, is contraindicated in some conditions while brain imaging procedures may be too difficult to be performed on critically ill patients. To solve this problem, this study aims to assess an alternative method to detect intracranial hypertension by measuring optic nerve sheath diameter using ocular ultrasound and optic nerve sheath diameter difference in each etiology.

Methods:

This cross-sectional study was conducted at the Emergency Department of Dr Iskak Tulungagung General Hospital. Sixty-nine patients who visited the emergency room for the first onset of intracranial pathology were included for optic nerve sheath diameter measurement by ultrasound. Subjects were divided into elevated and non-elevated intracranial pressure groups based on head computed tomography scan findings. The optic nerve sheath diameter results were compared and analyzed.

Result:

There were 29 subjects in the elevated intracranial pressure group and 40 subjects in the non-elevated intracranial pressure group. The mean of optic nerve sheath diameter in the elevated and non-elevated intracranial pressure groups was 0.63 ± 0.06 and 0.57 ± 0.06 cm, respectively (p = 0.000). Based on receiver operating characteristics analysis, 0.58 cm was the most optimal cut-off value.

Conclusion:

Ultrasonographic optic nerve sheath diameter can be used to predict elevated intracranial pressure in suspected patients who are contraindicated to invasive intracranial pressure measurement or critically ill. There were significant differences between elevated and non-elevated intracranial pressure groups in stroke and trauma subjects.

Monitoring of optic nerve sheath diameter on computed tomography for noninvasive assessment of intracranial pressure: Case report: Optic nerve sheath and intracranial pressure

Introduction: It is important to measure intracranial pressure because traumatic brain injuries lead to intracranial hypertension and ischaemic brain lesions. The gold standard for measurement of intracranial pressure is invasive methods, but they can lead to complications and are not always available. Measurement of the optic nerve sheath diameter is a useful noninvasive way to estimate intracranial pressure and it can be done via ultrasonography, computed tomography and magnetic resonance imaging. Increased optic nerve sheath diameter on computed tomography can help to diagnose intracranial hypertension and to verify the need for urgent therapy and invasive measurements. Case report: We present 74 years old patient with traumatic brain injury and intracranial bleeding. Optic nerve sheath diameter was 6.81 mm on the left and 6.83 mm on the right side on the initial scan. In the coming days, existing haematomas were enlarged and there were newly formed haematomas, so there were changes in the optic nerve sheath diameter. After the haematoma evacuation, the sheath diameter was 6.56 mm on the left and 6.47 mm on the right side. At the time of the second neurologic deterioration, the sheath diameter was 7.43 mm on the left and 7.25 mm on the right side. On the 25th day, the diameter was 6.72 mm on the left and 6.41 mm on the right side. Conclusion: Measurement of the optic nerve sheath diameter is a significant additional diagnostic method for the assessment of intracranial hypertension and can help to decide on further treatment.

Effects of Increased Optic Nerve Sheath Diameter on Inadequate Emergence from Anesthesia in Patients Undergoing Robot-Assisted Laparoscopic Prostatectomy: A Prospective Observational Study

(1) Background: Robot-assisted laparoscopic prostatectomy (RALP) is preferred over open prostatectomy because it offers superior surgical outcomes and better postoperative recovery. The steep Trendelenburg position and pneumoperitoneum required in Robot-assisted laparoscopic prostatectomy, however, increase intracranial pressure (ICP). The present study aimed to evaluate the effects of elevated ICP on the quality of emergence from anesthesia. (2) Methods: Sixty-seven patients undergoing RALP were enrolled. We measured optic nerve sheath diameter at four timepoints during surgery. Primary outcome was inadequate emergence in the operating room (OR). Secondary outcomes were postoperative neurologic deficits of dizziness, headache, delirium, cognitive dysfunction, and postoperative nausea and vomiting (PONV). (3) Results: A total of 69 patients were screened for eligibility and 67 patients completed the study and were included in the final analysis. After establishing pneumoperitoneum with the Trendelenburg position, ONSD increased compared to baseline by 11.4%. Of the 67 patients, 36 patients showed an increase of 10% or more in optic nerve sheath diameter (ONSD). Patients with ΔONSD ≥ 10% experienced more inadequate emergence in the OR than those with ΔONSD < 10% (47.2% vs. 12.9%, p = 0.003). However, other variables related to the quality of emergence from anesthesia did not different significantly between groups. Similarly, neurologic deficits, and PONV during postoperative day 3 showed no significant differences. (4) Conclusions: ICP elevation detected by ultrasonographic ONSD measurement was associated with a transient, inadequate emergence from anesthesia.

Ultrasound measurement of the optic nerve sheath diameter in traumatic brain injury: a narrative review

Background : Raised intracranial pressure (ICP) needs to be investigated in various situations, especially in traumatic brain injury (TBI). Ultra-sonographic (US) measurement of the optic nerve sheath diameter (ONSD) is a promising noninvasive tool for assessing elevated ICP. Objectives : This narrative review aimed to explain the history of and indications forUS measurement of ONSD. We focused on the detection of elevated ICP after TBI and discussed the possible improvements in detection methods. Conclusions : US measurement of ONSD in TBI cases provides a qualitative but no quantitative assessment of ICP. Current studies usually calculate their own optimum cutoff value for detecting raised ICP based on the balance between sensitivity and specificity of the method when compared with invasive methods. There is no universally accepted threshold. We did not find any paper focusing on the prognosis of patients benefiting from it when compared with usual care. Another limitation is the lack of standardization. US measurement of ONSD cannot be used as the sole technique to detect elevated ICP and monitor its evolution, but it can be a useful tool in a multimodal protocol and it might help to determine the prognosis of patients in various situations.

Comparison of transorbital ultrasound measurements to predict intracranial pressure in brain-injured patients requiring external ventricular drainage

OBJECTIVE

The optic nerve sheath diameter (ONSD) excluding the dura mater (ONSDE; i.e., the subarachnoid diameter) and the ONSD including the dura mater (ONSDI) have been used differently in studies, but the predictive ability of these two different measurements of the ONSD as measured by invasive intracranial pressure (ICP) monitoring has never been compared. Additionally, studies on the prediction of ICP using central retinal artery (CRA) Doppler ultrasonography are scarce. The authors aimed to determine how the two different ONSD measurements, the ONSD/eyeball transverse diameter (ETD) ratio, and transorbital Doppler ultrasonography parameters are associated with ICP via external ventricular drainage (EVD).

METHODS

This prospective observational study included 50 patients with brain injury who underwent EVD between August 2019 and September 2020. The mean of three repeated measurements of the ONSDI and ONSDE was calculated to reduce artifact and off-axis measurements. ETD, an immutable value, was measured from the initial brain CT with a clear outline of the eyeball. Simultaneously, flow velocities in the CRA and posterior ciliary artery (PCA) were compared with the ICP.

RESULTS

The ONSDE, ONSDI, and ONSD/ETD ratio were significantly associated with ICP (p = 0.005, p < 0.001, and p < 0.001, respectively). The ONSD/ETD ratio showed the highest predictive power of increased ICP (area under the curve [AUC] 0.897). The ONSDI was correlated more with the ICP than was the ONSDE (AUC 0.855 vs 0.783). None of the Doppler ultrasonography parameters in the CRA and PCA were associated with ICP.

CONCLUSIONS

The ONSD/ETD ratio is a better predictor of increased ICP compared with the ONSDI or ONSDE in brain-injured patients with nonsevere ICP. The ONSDI may be more available for predicting the ICP than the ONSDE.

Non-invasive detection of intracranial pressure related to the optic nerve

Intracranial pressure (ICP) is associated with a variety of diseases. Early diagnosis and the timely intervention of elevated ICP are effective means to clinically reduce the morbidity and mortality of some diseases. The detection and judgment of reduced ICP are beneficial to glaucoma doctor and neuro ophthalmologist to diagnose optic nerve disease earlier. It is important to evaluate and monitor ICP clinically. Although invasive ICP detection is the gold standard, it can have complications. Most non-invasive ICP tests are related to the optic nerve and surrounding tissues due to their anatomical characteristics. Ultrasound, magnetic resonance imaging, transcranial Doppler, papilledema on optical coherence tomography, visual evoked potential, ophthalmodynamometry, the assessment of spontaneous retinal venous pulsations, and eye-tracking have potential for application. Although none of these methods can completely replace invasive technology; however, its repeatable, low risk, high accuracy, gradually attracted people's attention. This review summarizes the non-invasive ICP detection methods related to the optic nerve and the role of the diagnosis and prognosis of neurological disorders and glaucoma. We discuss the advantages and challenges and predict possible areas of development in the future.

The role of optic nerve sheath diameter ultrasound in brain infection

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