Optic Nerve Sheath Diameter Values Research Articles

Can optic nerve sheath diameter assessment be used as a non-invasive tool to dynamically monitor intracranial pressure?

This study aims to detect whether the optic nerve sheath diameter (ONSD) can be used to dynamically monitor intracranial pressure (ICP). Adult patients undergoing invasive ICP monitoring on the day of admission are included in this study. For each patient, the ONSD is first measured in the supine position and then in the 30° head-up position. Subsequently, a dynamic test is conducted on 16 patients. The ONSD is measured in the supine position once a day for three consecutive days starting on the day of admission. There is a strong correlation between the ONSD and ICP values in the supine position on admission (r = 0.799), and when patients are changed from the supine to the 30° head-up position, the ICP and ONSD values decrease correspondingly. However, the change in ICP is not strongly correlated with the change in ONSD (r = 0.358). In the dynamic test, a good agreement between the ICP and ONSD only exists in three patients (18.8%), and three patients have completely different profiles for ICP and ONSD. These results suggest that the changes in the ONSD and ICP values are not closely correlated after dynamic observation. Therefore, measurement of the ONSD may not be a suitable tool to dynamically monitor ICP.

Ocular Ultrasound to detect raised intracranial pressure in non-traumatic emergencies in Emergency Department

Background: Bedside optic nerve sheath diameter (ONSD) measurement is increasingly being used to monitor raised intracranial pressure (ICP) in patients coming to an emergency department. This study aims to measure the accuracy of optic nerve sheath diameter (ONSD) measurement by ultrasound as a non-invasive method for early detection of raised intracranial pressure (ICP) in patients with non-traumatic emergencies presenting in emergency department settings, in comparison to CT/MRI brain scan findings of raised ICP. Methods: A total of 100 patients with non-traumatic emergencies suspected of raised ICP were seen in the emergency department. Bedside ONSD measurement was done within one hour of arrival. Patients underwent a CT/MRI brain scan within one hour of the ONSD in search of raised ICP. MS Excel spreadsheet was used for coding, SPSS v23 for data analysis, independent sample ‘t-test for group comparison, Wilcoxon test for non-normally distributed data, Chi-square test for group comparison for categorical data, Fischer's exact test for frequency < 5 and 25 % of the cells, Pearson's and Spearman's correlation for linear correlation and statistical significance were kept at p < 0.05. Results: Using a cut-off ONSD value (mm) of 6.3 mm, this study found a sensitivity of 100%, specificity of 89.2%, PPV of 83.3%, NPV of 100%, and diagnostic accuracy of 93% for detection of raised ICP by bedside USG ONSD measurement compared to CT/MRI brain. Conclusions: The study shows that bedside ONSD measurement is a useful and acceptably reliable technique for detecting raised ICP of emergency department patients with non-traumatic emergencies and raised ICP.

CAN BRAIN EDEMA BE PREDICTED WITH OPTIC NERVE SHEATH DIAMETER MEASUREMENT IN CASES WITH DIABETIC KETOACIDOSIS?: A PRELIMINARY STUDY

Objective: The clinical signs and symptoms of brain edema resulting from diabetic ketoacidosis (DKA) may not always be ob vious. When the intracranial pressure increases, the optic nerve sheath diameter (ONSD) simultaneously increases and can be imaged with ultrasonography. We aimed to discuss the determinative features of ONSD measurements in brain edema (BE) in DKA. Materials and Methods: Patients who were classified as having mild, moderate and severe DKA were included in the study. Transorbital ultrasonography was performed during the first two hours of treatment while the patients remained in the supine neutral position with their eyes closed. The optic nerve sheath diameters, which appeared as a hypoechoic double-edged line 3 mm deep to the globe, were measured. The same measurements were repeated in outpatient clinic controls. The ONSD values and metabolic, neurological conditions of the patients were compared. Results: Eight patients with a mean age of 8.8±3 (Standard Deviation (SD)) years were included in the study. Seven of them presented with moderate to severe DKA. Two patients suffering from headaches were found to have mild BE according to the brain computerized tomography (CT). The ONSD was 5.7±0.93 mm (mean±SD) in the patients with moderate-severe DKA and 4 mm in the single patient with mild DKA. The ONSDs of the two patients with BE on the CT were 6.8 mm and 5.9 mm. The mean ONSD of the five patients with severe DKA was 4.4±0.32 mm in the outpatient clinic checks. Conclusion: The measurement of ONSD by USG may be a supportive method for predicting BE in children with DKA.

The magnetic resonance imaging assessment of optic nerve sheath diameter in pediatric acute liver failure patients.

To evaluate the diagnostic value of optic nerve sheath diameter (ONSD) using brain MRI in the pretransplantation period in the pediatric acute liver failure patients, and correlate the ONSD with clinical grade of hepatic encephalopathy (HE) and MRI findings. Forty acute liver failure patients and 40 control group patients were retrospectively analyzed. The high signal intensities in T2W (T2-weighted image), FLAIR (Fluid Attenuated Inversion Recovery) and DWI (diffusion-weighted imaging) sequences were evaluated and ONSD was measured. The patients were grouped first into 5 according to their West Haven score, and HE grade 0 and grade 1 were accepted as low grade HE, HE grade 2, 3 and 4 were accepted as high grade HE. The patients were grouped to 2 according to the MRI findings as low grade and high grade MRI group. The mean value of ONSD was 6.0 ± 1.80 and 4.94 ± 1.27 in the all patients and in the control group, respectively. There was statistically significant difference between both the ONSD and the low grade-high grade HE groups (p=0.01), and between the ONSD and the low grade-high grade MRI groups (p<0.001). Although high ONSD values do not make the diagnosis of cerebral edema, it may cause suspicion in the early period. MRI can be helpful in the diagnoses of increased intracranial pressure like ultrasound. Our study is the first study to compare ONSD and MRI findings in addition to HE grades. The widespread use of MRI in children in recent years may help determine the normal range of ONSD values.

Optic Nerve Sheath Diameter Detects Intracranial Hypertension in Acute Malignant Middle Cerebral Artery Infarction

ObjectivesTo evaluate optic nerve sheath diameter in the acute phase of patients with malignant ischemic middle cerebral artery stroke submitted or not to decompressive craniectomy surgery. Materials and MethodsForty patients participated in the study and were evaluated bilaterally by ultrasound on admission and at 24h, 48h and 72 h after admission. Optic nerve sheath diameter values were correlated with tomographic and/or clinical criteria compatible with severe intracranial hypertension. ResultsA Receiver Operating Characteristic curve was drawn for each eye, determining a cut-off value for severe intracranial hypertension in the right eye of 5.4 mm (sensitivity: 62%; specificity: 100%; AUC: 0.82) and in the left eye 5.4 mm (sensitivity: 76%; specificity: 84%; AUC: 0.77). In patients undergoing craniectomy, there was a decrease in the mean value of 1.04mm in the right eye (pre: 5.84 ± 0.47 mm; post: 4.80 ± 0.84 mm; p = 0.001), while in the left, it decreased around 0.86mm (pre: 5.59 ± 0.69 mm; post: 4.73 ± 0.74 mm; p = 0.003). Patients with fatal outcome showed a persistent high mean ocular nerve sheath diameter. ConclusionsMonitoring optic nerve sheath by ultrasound can be considered a reliable method for identifying severe intracranial hypertension in patients with large vessel occlusion, as well as for monitoring patients undergoing craniectomy. Additional studies will be necessary to include this parameter in craniectomy indication algorithms in the future.

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

Establish an association between ONSD and CCBF in neurocritical patients admitted to an ICU. Cross-sectional study of patients admitted in a third level ICU, between April 2017 and April 2018, with neurological pathology. ONSD ultrasound was performed in the first 24hours and as the patient was diagnosed of CCBF. The ONSD values of patients with and without diagnosis of CCBF were compared. 99 patients were included, 29 of whom showed CCBF in transcranial Doppler. The ONSD measurement did not demonstrate significant differences between both groups, 6,59 ± 0,75 in the group with CCBF and 6,39 ± 0,56 in the group without CCBF p=0.141. In our study, ONSD values capable of recognizing CCBF were not identified.

Ultrasonographic Measurement of Optic Nerve Sheath Diameter in Patients Undergoing Open Heart Surgery: A Prospective Cross-sectional Study

Introduction: Adverse neurologic outcomes following cardiac surgery can be catastrophic to the patient, next of kin, healthcare facility and community at large. Ultrasonographic measurement of Optic Nerve Sheath Diameter (ONSD) has emerged as a promising modality to reflect Intracranial Pressure (ICP) and neurological status in various neurological settings. Aim: To explore ONSD as a tool to reflect ICP changes and predict neurologic outcomes in a cardiac surgical perioperative setting during Cardiopulmonary Bypass (CPB). Materials and Methods: This was an open-label, prospective and observational study conducted in Department of Anaesthesia, Command Hospital, Karnataka, India, from June 2016 to July 2018. All patients aged between 15 and 80 years who underwent open heart surgeries irrespective of gender, primary diagnosis and preoperative American society of Anaesthesiologist’s Physical Status (ASA PS) grade were enrolled in the study. Serial ultasonographic ONSD of both eyes in two planes (viz. sagittal and transverse) were acquired by a single observer at the following time intervals: baseline (prior to general anaesthesia induction, immediately postintubation, and every 15 minutes interval during CPB (until 150 minutes or end of the CPB whichever was earlier). Postoperative neurologic reassessment was done at 6 hours/postextubation (whichever earlier), at 24 hours and after 7 days, postoperatively. Continuous variables were compared using the student t-tests, while Chi-square or Fisher’sexact test was used to compare categorical variables. To assess inter-rater reliability for categorical variables, the Cohen’s Kappa statistic was used. Results: The mean age of the study cohort was 56.30±11.42 years. A slight male preponderance (56%) was observed. With regards to mean of total CPB time, it was insignificantly higher in patients with adverse neurologic outcomes as compared to those without adverse neurological outcomes (165.83±53.61 minutes vs. 121.36±21.41 minutes; p-value=0.098). Patients with adverse neurologic outcomes had significantly higher ONSD (average of both planes) on CPB from 60 minutes through 150 minutes/end of CPB timeline for right eye (p-value &lt; 0.001), left eye (p-value &lt;0.001), and both eyes (p-value &lt;0.001). For patients with ONSD value (average of both eyes in both planes of each eye) ≥5.5 mm had more likelihood to develop adverse neurologic outcomes, postoperatively. With respect to maximum ONSD anytime during CPB (average of both eyes in both planes of each eye), an arbitrary cut-off of ≥5.5 mm showed a sensitivity of 100%, specificity of 95%, diagnostic accuracy of 100%, and predictive value of 100% with significant p-value of &lt;0.001. Conclusion: Serial ultrasonographic ONSD measurement is assuredly a promising tool to monitor elevated level of ICP as well as a good predictor for the assessment of major adverse neurologic outcomes secondary to open heart cardiac surgeries.

Optic nerve sheath diameter and its implications in the evaluation of cerebral venous sinus thrombosis.

PurposeTo ascertain the role of optic nerve sheath diameter (ONSD) in the evaluation of cerebral venous sinus thrombosis (CVST).Material and methodsA retrospective study with convenient sampling was done during the period November 2018 to January 2020. Forty-one patients across all age groups with magnetic resonance venography (MRV) diagnosis of CVST and 82 gender-matched controls were included in the study. ONSD was measured on axial T2-weighted magnetic resonance images. CVST was identified on axial TOF-MRV including the stage, degree, and location. Intraparenchymal infarction and haemorrhage were also noted with their stage and size. The distribution of values for ONSD was tested for equality of variances using independent samples t-test. A cut-off value for ONSD was derived using ROC analysis.ResultsThe mean difference between ONSD of cases and controls was 0.84 mm (95% CI: 0.61-1.06) and was statistically significant at p < 0.001. Mean ONSD in cases was 5.33 ± 0.66, and in the control group it was 4.49 ± 0.31. The cut-off value for ONSD was taken as 4.57 mm, derived using the ROC analysis (AUC was 0.876 suggesting good diagnostic accuracy). ONSD showed a sensitivity of 87% and a negative predictive value of 89% in predicting CVST. However, we found no statistical significance between ONSD in patients with acute or chronic thrombosis or in those with neuroparenchymal complications.ConclusionsONSD is a valid triage tool with high sensitivity and negative predictive value, and it can be used in the evaluation of CVST.

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.

Diagnostic value of ONSD in sepsis associated encephalopathy of New Zealand rabbits

ObjectiveThe purpose of the present study was to assess whether optic nerve sheath diameter (ONSD) measured by ultrasound could predict brain injury in sepsis associated encephalopathy (SAE). MethodsA total of 48 male New Zealand White rabbits were used to establish sepsis model. The levels of neuro-specific enolase (NSE), S100B, myeloperoxidase (MPO), and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immuno sorbent assay and ONSD were measured before modeling, 6 h, 12 h and 24 h after modeling. Sixteen rabbits were sacrificed for hematoxylin-eosin (HE) staining of brain tissue and the brain water content at above time points. Rabbits demonstrated brain injury by HE staining were included in the SAE group, the others were enrolled in the control group. The correlation between ONSD and MPO, NSE and S100B in the SAE group were analyzed. Receiver operator characteristic curves were generated to analyze the area under the curve (AUC), specificity and sensitivity of ONSD values for SAE. ResultsTwenty-nine of 48 rabbits had brain injury, while 19 cases were enrolled in the control group. The level of MPO, NSE, S100B, TNF-α at 6 h, 12 h and 24 h in SAE group were all higher than those of the control group with statistical significance. The ONSD in SAE group increased with time and significantly wider than those in the control group. Correlation analysis revealed that ONSD was positively correlated with MPO, NSE and S100B in the SAE group. The AUCs for the ONSD value in diagnosing SAE at 6 h, 12 h and 24 h were 0.864, 0.957, 0.877, respectively. ConclusionsAlterations in ONSD strongly correlated with MPO, NSE and S100B among SAE rabbits. Monitoring of ONSD exhibited a high predictive value for SAE.

The association between intracranial pressure and optic nerve sheath diameter on patients with head trauma.

Although intracranial pressure (ICP) monitoring is the gold standard method for measuring intracranial pressure after traumatic brain injury, optic nerve sheath diameter (ONSD) measurement with ultrasound (US) is also used in the evaluation of ICP. To investigate the association between a series of OSND measurements by US and changes in clinical presentation of the patient. Prospective study including 162 patients with traumatic brain injury. Age, sex, cerebral CT findings, ONSD levels by US at minutes 0, 60, and 120, Glasgow Coma Scale (GCS) within same period, change of consciousness, treatment, and mortality data were reviewed. The association of ONSD levels with GCS, change of consciousness, treatment, and mortality was evaluated. There was no difference in ONSD changes in the patients' sample within the period (p=0.326). ONSD significantly increased in patients who died (p<0.001), but not in those who survived (p=0.938). There was no significant change in ONSD of the patients who received anti-edema therapy (p=801), but significantly increased ONSD values were found in those who received anti-edema therapy (p=0.03). Patients without change of consciousness did not have any significant change in ONSD (p=0.672), but ONSD values increased in patients who consciousness became worse, and decreased in those who presented a recovery (respectively, p<0.001, p=0.002). A negative correlation was detected between ONSD values and GSC values measured at primary, secondary, and tertiary time periods (for all p<0.001). ONSD follow-up may be useful to monitor ICP increase in patients with acute traumatic brain injury.

Dilated Optic Nerve Sheath Diameter Predicts Poor Outcome in Acute Spontaneous Intracerebral Hemorrhage

Background and Purpose: Optic nerve sheath diameter (ONSD) enlargement occurs in patients with intracerebral hemorrhage (ICH). However, the relationship between ONSD and prognosis of ICH is uncertain. This study aimed to investigate the predictive value of ONSD on poor outcome of patients with acute spontaneous ICH. Methods: We studied 529 consecutive patients with acute spontaneous ICH who underwent initial CT within 6 h of symptom onset between October 2016 and February 2019. The ONSDs were measured 3 mm behind the eyeball on initial CT images. Poor outcome was defined as having a Glasgow Outcome Scale (GOS) score of 1–3, and favorable outcome was defined as having a GOS score of 4–5 at discharge. Results: The ONSD of the poor outcome group was significantly greater than that of the favorable outcome group (5.87 ± 0.86 vs. 5.21 ± 0.69 mm, p < 0.001). ONSD was related to hematoma volume (r = 0.475, p < 0.001). Adjusting other meaningful predictors, ONSD (OR: 2.83; 95% CI: 1.94–4.15) was associated with poor functional outcome by multivariable logistic regression analysis. Receiver operating characteristic curve showed that the ONSD improved the accuracy of ultraearly hematoma growth in the prediction of poor outcome (AUC: 0.790 vs. 0.755, p = 0.016). The multivariable logistic regression model with all the meaningful predictors showed a better predictive performance than the model without ONSD (AUC: 0.862 vs. 0.831, p = 0.001). Conclusions: The dilated ONSD measured on initial CT indicated elevated intracranial pressure and poor outcome, so appropriate intervention should be taken in time.

Determination of normal values of optic nerve sheath diameter in Turkish adult population using magnetic resonance imaging

The measurement of optic nerve sheath diameter (ONSD) is a reliable tool for the estimation of increased intracranial pressure (ICP). However, it is known that racial changes can occur in human anatomy. In the present study we aimed to determine the normal values of ONSD in Turkish adult population. This retrospective study involved the collection of data between June 1, 2015, and May 31, 2019, and was conducted on 291 adults known to have no increased cranial/intraocular pressure. The ONSD was measured at 3 mm posterior to the globe on MR images. 291 subjects were enrolled, 63.6% of whom were female. The total median ONSD was 4.40mm (4.20- 4.70). The median ONSD of the male participants was 4.50mm (4.25-4.75), of the female participants was 4.35mm (4.15-4.50) and the difference was statistically significant (p = 0.001). According to statistical analysis, it was found that only the presence of chronic renal failure altered the median of ONSD among the comorbid diseases (p = 0.042). Monitoring and treating increased ICP is crucial. Thanks to an ONSD with a known normal value, recognition and emergency management of this pathology would be easier. We think our study is noteworthy because it is the first study investigating the normal ONSD value in Turkish adult population.

The significance of ONSD, ONSD/ETD ratio, and other neuroimaging parameters in idiopathic intracranial hypertension

ABSTRACT Background: The measurement of the optic nerve sheath diameter (ONSD) has been suggested to be used in the evaluation of intracranial pressure of several etiologies. However, its potential utility in the clinical evaluation of patients with idiopathic intracranial hypertension (IIH) needs to be clarified. Methods: We recruited all the IIH patients who had been admitted to our neurology clinics and had a cranial MRI before lumbar puncture investigation. A control group of patients with migraine was also included. Studies were reviewed blindly by a radiologist, and ONSD and ONSD/ eyeball transverse diameter (ETD) for both eyes were measured. Results: Ultimately, we have enrolled 50 patients with IIH and 53 migraineurs. The right ONSD values were higher in the IIH group (p = 0.024) whereas the values of ONSD/ETD were found to be both higher in the IIH group (right: p = 0.006, left: p = 0.043). The ROC curve demonstrated an area under the curve of 0.620 (95% CI = 0.508 to 0.731) for ONSD, and it was 0.642 for ONSD/ETD. Using a cut-off of 6.3 mm, ONSD had the following performance characteristics: sensitivity 18%, specificity 81%. Conclusions: The ONSD and ONSD/ETD values may be utilizable in the evaluation processes of IIH patients; however, they do not solely reach sufficient discriminative accuracy. The potential significance of these parameters in rather monitoring the IIH patients may constitute a strictly crucial topic of interest for future research.

Comparison of B-Scan Ultrasound and MRI-Based Optic Nerve Sheath Diameter (ONSD) Measurements in Children

BackgroundQualitative, noninvasive assessment of intracranial pressure is of eminent importance in pediatric patients in many clinical situations and can reliably be performed using transorbital ultrasonographic measurement of the optic nerve sheath diameter (ONSD). MRI-based determination of ONSD can serve as an alternative if ultrasound (US) is not possible or available for various reasons, for example, in small, incompliant children. This study investigates repeatability and observer reliability of US ONSD and correlation and bias of US- versus MRI-based ONSD assessment in pediatric patients. MethodsOne hundred fifty children diagnosed with tumor (n = 40), hydrocephalus (n = 42), and other cranial pathologies (n = 68) were included. Bilateral ONSD was quantified by US using a 12-MHz linear array transducer. This was compared with ONSD measured in simultaneously acquired (≤24 h) T2-weighted MRI scans of the orbit. ResultsRepeatability of individual US values and intraobserver ONSD was outstanding (Cronbach's α = 0.984 and 0.996, respectively). Overall mean values for ONSD were 5.8 ± 0.88 mm and 5.7 ± 0.89 mm for US and MRI, respectively. Correlation between US and MRI-based ONSD was strong (r = 0.976, P < 0.01). Bland and Altman analysis showed a mean bias of 0.078 mm. A repeated-measures correlation (rrm) in 9 patients showed an excellent value (rrm = 0.94, P < 0.01). ConclusionsRepeatability and reliability of US ONSD determination is excellent. In case US ONSD assessment is not possible or available, MRI scans can serve as an excellent alternative. The difference of US and MRI ONSD is minimal and insignificant, and thus, both techniques can complement each other.

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

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

Optic nerve sheath diameter assessment by neurosonology: A review of methodologic discrepancies.

Reported cutoff values of the optic nerve sheath diameter (ONSD) for the diagnosis of elevated intracranial pressure (ICP) are inconsistent. This hampers ONSD as a possible noninvasive bedside monitoring tool for ICP. Because the influence of methodological differences on variations in cutoff values is unknown, we performed a narrative review to identify discrepancies in ONSD assessment methodologies and to investigate their effect on reported ONSD values. We used a structured and quantitative approach in which each ONSD methodology found in the reviewed articles was categorized based on the characteristic appearance of the ultrasound images and ultrasound marker placement. Subsequently, we investigated the influence of the different methodologies on ONSD values by organizing the ONSDs with respect to these categories. In a total of 63 eligible articles, we could determine the applied ONSD assessment methodology. Reported ultrasound images either showed the optic nerve and its sheath as a dark region with hyperechoic striped band at its edges or as a single dark region surrounded by lighter retrobulbar fat. Four different ultrasound marker positions were used to delineate the optic nerve sheath, which resulted in different ONSD values and more importantly, different sensitivities to changes in ICP. Based on our observations, we recommend to place ultrasound markers at the outer edges of the hyperechoic striped bands or at the transitions from the single dark region to the hyperechoic retrobulbar fat because these locations yielded the highest sensitivity of ONSD measurements for increased ICP.

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

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. 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. 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 day7. 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.

Ultrasonographic Optic Nerve Sheath Diameter as A Surrogate Measurement of Intracranial Pressure in Preeclampsia

Background: Preeclampsia affects five to ten percent of pregnant women and accounts for about twelve percent of maternal mortality. It is the third most common cause of maternal mortality worldwide. Papilledema is an indirect and late indicator of raised intracranial pressure (ICP), whereas a pressure rise in optic nerve sheath (and the resulting enlargement of the optic nerve diameter) is a more dynamic process. The retrobulbar optic nerve sheath diameter (ONSD) can be measured at a position 3 mm posterior to the globe, where ultrasound contrast is greatest with more reproducible results. Objective: To evaluate the correlation between ultrasonographic measurement of ONSD with the degree of severity of preeclampsia. Patients and methods: This prospective observational study was conducted at Mansoura University Hospital Intensive Care Unit from July 2019 to June 2020. Just after delivery, 175 pregnant females aged between 18 and 45 years old were enrolled for participating in this study. Out of them, 25 females were excluded. Results: As regarding body weight, there was a significant difference between the control group (79.9±6.36 kg) and preeclamptic without severe feature group (87.7±10.58 kg). The mean body weight in severe preeclampsia group was (91.5 ±14.73kg) which showed no significant difference from that of the non-severe group. ONSD values showed significant difference between the studied groups. The control group had ONSD mean value of 4.85±0.32 mm, mild preeclamptic group had mean value of 6.05±0.096 mm, while severe preeclampsia group had a mean value of 6.76±0.25 mm. Conclusion: Ultrasonographic measurement of ONSD provides a non-invasive, quick and readily accessible tool for evaluation of raised intracranial pressure (ICP).

The assessment of the effect of different intraabdominal pressures used for laparoscopic cholecystectomy surgery on optic nerve sheath diameter: a prospective observational cohort study

Background/aimDuring laparoscopic cholecystectomy operations, increases in intraabdominal, intrathoracic, and intracranial pressures (ICP) can be seen after pneumoperitoneum created for surgical imaging. Orbital ultrasonography (USG), which has been developed in recent years, is a method that can evaluate the ICP by measuring the optic nerve sheath diameter (ONSD) from the eyeball.In our study, we aimed to evaluate whether different intraabdominal pressure values created during laparoscopic cholecystectomy operations correlate with ICP by measuring ONSD.Materials and methodsThe study included a total of 90 patients with American Society of Anesthesiologists (ASA) physical status classification I (ASA I) and II (ASA II) and ages from 18 to 65 years with laparoscopic cholecystectomy planned.After the patients were intubated, at the 5th min, bilateral ONSD measurements were performed. The same measurements were performed at the 15th and 30th min after CO2 insufflation and additionally 10 min after CO2 was released at the end of the operation. During intrabdominal CO2 insufflation, patients with 10 mmHg pressure applied comprised Group 1, patients with 12 mmHg pressure applied comprised Group 2, and patients with 14 mmHg pressure applied comprised Group 3.Results The study was completed with 89 patients, 51 female and 38 males. One patient was excluded from the study due to erroneous values. The variations in ONSD measured in the right-left eye before pneumoperitoneum and at the 15th and 30th min after abdominal CO2 insufflation were observed to be statistically significant (p < 0.01). In all three groups, the right and left eye ONSD values were not identified to be statistically significantly different (p > 0.01).A significant increase was observed in ONSD values in direct proportion to the increase in intraabdominal pressure in patients undergoing laparoscopic cholecystectomy surgery.Conclusion USG-guided ONSD measurements appear be a guide to ensure optimization of intraabdominal pressures and safe anesthesia administration for patients, especially those at risk of ICP increase, during laparoscopic surgery.