Changes In Optic Nerve Sheath Diameter Research Articles

Changes in optic nerve sheath diameter and its correlation with degree of consciousness, pupil diameter, and light reflex in children with central nervous system infection after osmotherapy.

High intracranial pressure (ICP) is one of the most common complications of central nervous system (CNS) infection. Failure to control high intracranial pressure results in brain herniation and death. One of the treatments for high ICP involves the administration of osmotherapy in the form of 3% NaCl or 20% mannitol with observation during administration. Observation of ICP during administration of osmotherapy is possible through measurement of optic nerve sheath diameter (ONSD), which could be correlated with degree of consciousness, pupil diameter, and light reflex. Previous studies have not correlated ONSD with degree of consciousness, pupil diameter, and light reflex during the administration of osmotherapy. To provide insights of incorporating ONSD measurement as a form of non-invasive bedside method for ICP monitoring by correlating it with degree of consciousness, pupil diameter, and light reflex at several time points. This study is a prospective cohort study, performed at Dr. Hasan Sadikin General Central Hospital Bandung, Cibabat General Regional Hospital, and General Regional Hospital Bandung Kiwari on children aged 2-18 years with decreased consciousness and CNS infection, from June 2023. Inter-rater reliability was performed with a correlation coefficient of 0.90. Measurement of ONSD, degree of consciousness, pupil diameter, and light reflex simultaneously up to 48 h after initiation of osmotherapy to 30 patients. Correlational analyses were performed using Spearman's rank. Observation for 48 h after administration of osmotherapy showed changes in ONSD. A significant positive correlation was found between ONSD and degree of consciousness (r = 0.621 for the right eye and r = 0.602 for the left eye, p < 0.001). A significant positive correlation was found between ONSD and light reflex (r = 0.801 for the right eye and r = 0.812 for the left eye, p < 0.001). No significant correlation was found with changes of pupil diameter (r = -0.136 for the right eye and r = -0.141 for the left eye, p > 0.05). A significant correlation was found between ONSD and degree of consciousness and light reflex in children aged 2-18 years with CNS infection during administration of osmotherapy.

Perioperative optic nerve sheath diameter variations in patients with end-stage renal failure undergoing robotic-assisted kidney transplant: a prospective observational study.

Patients with chronic kidney disease (CKD) who undergo hemodialysis are predisposed to interstitial cerebral edema. Robotic-assisted laparoscopic surgery can increase optic nerve sheath diameter (ONSD) and intracranial pressure. The impact of robotic-assisted kidney transplant (RAKT) on ONSD is complicated by the presence of CKD, the administration of furosemide and mannitol, and the manipulation of hemodynamics. We examined ONSD variations in patients undergoing RAKT over a 1-year period at our institution. Furthermore, we attempted to identify any perioperative hemodynamic factors influencing these changes. This prospective study included 20 patients undergoing RAKT. ONSD, heart rate, central venous pressure, systolic blood pressure, diastolic blood pressure (DBP), and mean arterial pressure (MAP) were measured following intubation (T1), after assuming the steep Trendelenburg position (T2), 1 hour after docking (T3), upon reperfusion (T4), after transition to the supine position (T5), and 3 hours postextubation (T6). Repeated measures analysis of variance with post hoc Bonferroni correction was employed to compare variables at each time point. Pearson correlation analysis was utilized to assess relationships between variables. P-values ≤0.05 were considered to indicate statistical significance. ONSD (in mm) increased from T1 (3.60±0.44) to T3 (4.06±0.45, P=0.002) and T4 (3.99±0.62, P=0.046), before falling to its lowest value at T6 (3.42±0.64, P=0.002). Pearson correlation analysis revealed significant correlations (P<0.05) between changes in ONSD at T3 and both DBP (r=0.637) and MAP (r=0.522). During RAKT with open ureteric anastomosis, ONSD initially increased, then decreased following reperfusion. DBP and MAP displayed positive correlations with ONSD changes at T3.

Optic Nerve Sheath Diameter is not a predictor of functional outcomes in ICH Patients

Objectives: Optic nerve sheath diameter (ONSD) may serve as an early marker of increasing intracranial pressure resulting from intracerebral hemorrhage (ICH). We investigated if changes in ONSD can predict 90-day functional outcomes in ICH patients.Materials and Methods: We utilized ERICH (Ethnic/Racial Variations of Intracerebral Hemorrhage), a prospective, multi-center, case-control study of 3000 patients. We included patients with baseline and follow-up head CT with available outcomes. We measured change in ONSD from baseline and follow-up CT within a 6 (±1) hour window. Our primary outcome was the 90-day Modified Rankin (mRS) score. We compared patients with good (mRS 0-3) versus poor outcomes (mRS 4-6) to presence of significant change in ONSD using univariate analysis. We did an analysis of variance to assess for differences in ONSD.Results: Of 93 ICH patients who fit the inclusion criteria, the mean age was 64.1 (SD +/- 14.6), with 36.6 % being females. Forty-nine patients (47.1 %) had significant ONSD change between baseline and follow-up CT. ONSD change in the poor outcome group was not significantly different than that of the good outcome group in both the right and left hemispheres (p = 0.21 and p = 0.63 respectively).Conclusions: We found that early change in the ONSD within the first 6 h of presentation in patients with ICH does not predict functional outcomes at three months.

Optic nerve sheath diameter correlates with both success and failure of hydrocephalus treatment in pediatric patients with pineal region lesions.

Pineal region lesions in children are heterogenous pathologies often symptomatic due to occlusive hydrocephalus and thus elevated intracranial pressure (ICP). MRI-derived parameters to assess hydrocephalus are the optic nerve sheath diameter (ONSD) as a surrogate for ICP and the frontal occipital horn ratio (FOHR), representing ventricle volume. As elevated ICP may not always be associated with clinical signs, the adjunct of ONSD could help decision making in patients undergoing treatment. The goal of this study is to assess the available magnetic resonance imaging (MRI) of patients with pineal region lesions undergoing surgical treatment with respect to pre- and postoperative ONSD and FOHR as an indicator for hydrocephalus. Retrospective data analysis was performed in all patients operated for pineal region lesions at a tertiary care center between 2010 and 2023. Only patients with pre- and postoperative MRI were selected for inclusion. Clinical data and ONSD at multiple time points, as well as FOHR were analyzed. Imaging parameter changes were correlated with clinical signs of hydrocephalus before and after surgical treatment. Thirty-three patients with forty operative cases met the inclusion criteria. Age at diagnosis was 10.9 ± 4.6years (1-17years). Hydrocephalus was seen in 80% of operative cases preoperatively (n = 32/40). Presence of hydrocephalus was associated with significantly elevated preoperative ONSD (p = 0.006). There was a significant decrease in ONSD immediately (p < 0.001) and at 3months (p < 0.001) postoperatively. FOHR showed a slightly less pronounced decrease (immediately p = 0.006, 3months p = 0.003). In patients without hydrocephalus, no significant changes in ONSD were observed (p = 0.369). In 6/6 patients with clinical hydrocephalus treatment failure, ONSD increased, but in 3/6 ONSD was the only discernible MRI change with unchanged FOHR. ONSD measurements may have utility in evaluating intracranial hypertension due to hydrocephalus in patients with pineal region tumors. ONSD changes appear to have value in assessing hydrocephalus treatment failure.

P.106 Using optic nerve sheath diameter over ventricular size to assess elevated intracranial pressure in pediatric patients with pineal region tumors

Background: Pineal region tumors are a heterogenous group of pathologies often symptomatic due to occlusive hydrocephalus leading to elevated intracranial pressure (ICP). High ICP may not always be associated with clinical signs. A non-invasive technique for assessment of ICP is measuring the optic nerve sheath diameter (ONSD). The goal of this study was to determine the utility of preoperative and postoperative ONSD measurements for assessment of elevated ICP in children with pineal region tumors. Methods: Retrospective data analysis was performed in patients operated for pineal region tumors at our tertiary care center between 2003 and 2022. Preoperative and postoperative MRI scans were reviewed. Clinical data and ONSD at multiple time points were analyzed and correlated. Results: Thirty-four patients with forty operative cases met the inclusion criteria. Hydrocephalus was seen in 80% of patients preoperatively (n=32/40). Presence of hydrocephalus was associated with significantly elevated ONSD preoperatively (p=0.006) and postoperatively (p=0.017). There was significant decrease in ONSD immediately postoperatively (p&lt;0.001), at 3 months (p&lt;0.001) and 12 months (p&lt;0.001). In patients without hydrocephalus, no significant changes in ONSD were observed (p=0.369). Conclusions: ONSD is a useful adjunct for the identification of high ICP preoperatively and evaluation of treatment response postoperatively in patients presenting with pineal region tumors.

435 Use of Optic Nerve Sheath Diameter in Extraventricular Drain Weaning in Adults With Post-hemorrhagic Hydrocephalus

INTRODUCTION: Optic nerve sheath diameter (ONSD) can be used as a noninvasive measurement of intercranial pressure. Few studies have evaluated the value of ONSD in predicting the need for ventriculoperitoneal shunt (VPS) placement after development of post-hemorrhagic hydrocephalus (PHH) in adults. METHODS: Adult patients 18 years or older, admitted with intracranial hemorrhage and hydrocephalus requiring EVD placement were included in the study. Demographics were recorded. CT imaging of ONSD was measured (mm) upon initial ED visit before EVD placement (pre-EVD), immediately after successful EVD removal (post-EVD), and if applicable, after EVD removal but immediately before VPS placement. Change in ONSD was calculated and groups were stratified by EVD only patients and EVD+VPS patients. RESULTS: Imaging for 30 patients were successfully retrieved and analyzed for bilateral ONSD values at all timepoints. A statistically significant convergence to a normally distributed mean ONSD was found for both groups (EVD and EVD+VPS). Additionally, a statistically significant increase was found in ONSD between the EVD+VPS group compared to the EVD only group. The EVD only group showed a mean EVD placement time of only 14 days (2 weeks) with an average decrease in ONSD (-0.905mm) compared with the EVD+VPS group who had an increase in ONSD at 14-days (+1.089 mm). CONCLUSIONS: Patients with hydrocephalus due to intracranial hemorrhage who went on to require VPS developed an increase in ONSD despite EVD use while patients who were successfully weaned from the EVD developed a decrease in ONSD. ONSD may be a useful adjunct tool to aid in the process of EVD weaning in this patient population.

High myopia at high altitudes.

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

A prospective observational study on evaluating the efficacy of bedside optic nerve sheath diameter in assessing clinical progression of patients admitted in neurosurgical ICU with comparisons to CT scans and GCS score

Background: Ultrasound of the optic nerve sheath diameter (ONSD) is a non-invasive, repeatable tool that can be used to measure intracranial pressure in a dynamic way with high diagnostic accuracy. The goal of this study was to find out if a bedside ultrasonographic measurement of optic nerve sheath diameter (ONSD) can accurately predict the computed tomography (CT) findings of high intracranial pressure (ICP) and changes to the Glasgow Coma Scale (GCS) in adult head injury patients in the Neurosurgery ICU. Methods: For 54 patients in the neurosurgical intensive care unit, we conducted a retrospective analysis of the results of cranial ultrasounds. Those under the age of 18 and those with apparent visual injuries were ineligible. Both horizontal and vertical optic nerve sheath diameters were measured 3 mm beneath the globe in each eye using a 7.5-10MHz ultrasonographic probe. A binocular change in optic nerve sheath diameter of more than 2.00 mm was deemed abnormal in two consecutive readings in the same patient. Patients in the neurosurgical ICU were given a GCS score, which was used to classify their level of brain damage as mild, moderate, or severe. The accuracy of the optic nerve sheath diameter was evaluated using cranial CT findings of shift, oedema, or effacement that suggested an increased intracranial pressure. Results: The research has 54 participants. According to the results, 68.5% of those who took the study were men, while 31.5% of those who did so were women. Nearly 16.7 per cent of respondents were between the ages of 18 and 40, while 40.7% of respondents were between the ages of 40 and 60, and 42.6% of respondents were above 60. The significant change in ONSD- fall in GCS and CT-progression scan-findings correlation was very strong. When compared to CT scan progression, the ONSD bedside sonographic test had an 86.7% sensitivity and an 89.7% specificity for detecting elevated ICP. The Positive Predictive Value of the reduction in GCS with advancement in CT scan was 80% and the Negative Predictive Value was 89.7%, respectively. Conclusions: The sensitivity, specificity, and positive predictive value of bedside ONSD ultrasonography in predicting high intracranial pressure are significant to those of progression in CT scan and drop in GCS. An ONSD bedside measurement may be used to determine elevated ICP since it is non-invasive and repeatable.

Effects of head-down tilt on optic nerve sheath diameter in healthy subjects.

Intracranial pressure increases in head-down tilt (HDT) body posture. This study evaluated the effect of HDT on the optic nerve sheath diameter (ONSD) in normal subjects. Twenty six healthy adults (age 28 [4.7] years) participated in seated and 6° HDT visits. For each visit, subjects presented at 11:00 h for baseline seated scans and then maintained a seated or 6° HDT posture from 12:00 to 15:00 h. Three horizontal axial and three vertical axial scans were obtained at 11:00, 12:00 and 15:00 h with a 10 MHz ultrasonography probe on the same eye, randomly chosen per subject. At each time point, horizontal and vertical ONSD (mm) were quantified by averaging three measures taken 3 mm behind the globe. In the seated visit, ONSDs were similar across time (p > 0.05), with an overall mean (standard deviation) of 4.71 (0.48) horizontally and 5.08 (0.44) vertically. ONSD was larger vertically than horizontally at each time point (p < 0.001). In the HDT visit, ONSD was significantly enlarged from baseline at 12:00 and 15:00 h (p < 0.001 horizontal and p < 0.05 vertical). Mean (standard error) horizontal ONSD change from baseline was 0.37 (0.07) HDT versus 0.10 (0.05) seated at 12:00 h (p = 0.002) and 0.41 (0.09) HDT versus 0.12 (0.06) seated at 15:00 h (p = 0.002); mean vertical ONSD change was 0.14 (0.07) HDT versus -0.07 (0.04) seated at 12:00 h (p = 0.02) and 0.19 (0.06) HDT versus -0.03 (0.04) seated at 15:00 h (p = 0.01). ONSD change in HDT was similar between 12:00 and 15:00 h (p ≥ 0.30). Changes at 12:00 h correlated with those at 15:00 h for horizontal (r = 0.78, p < 0.001) and vertical ONSD (r = 0.73, p < 0.001). The ONSD increased when body posture transitioned from seated to HDT position without any further change at the end of the 3 h in HDT.

The effect of restrictive vs. liberal fluid protocols on ocular parameters in patients undergoing prone spine surgery: a randomized controlled trial

BackgroundElevated intraocular pressure (IOP) and optic nerve edema occurring during prone surgeries may cause ocular and optic nerve ischaemia injury. We hypothesized that a liberal fluid protocol might further increase IOP and optic nerve sheath diameter (ONSD) than a restrictive fluid protocol for patients in the prone position.MethodsA single-centre, prospective and randomized trial was conducted. Patients were randomly allocated into 2 groups: the liberal fluid infusion group, in which repeated bolus doses of Ringer’s lactate solution were given to maintain pulse pressure variation (PPV) within 6~9%, and the restrictive fluid infusion group, where PPV was maintained within 13–16%. IOP and ONSD were measured in both eyes at 10min after the anaesthesia induction in the supine position, 10min after the prone position placement, and 1h and 2h since the prone position was placed, at the conclusion of surgery, and returned to the supine position.ResultsA total of 97 patients were recruited and completed the study. IOP increased significantly from 12±3mmHg in the supine position to 31±5 mmHg (p<0.001) at the end of surgery in the liberal fluid infusion group and from 12±2 to 28±4 mmHg (p<0.001) in the restrictive fluid infusion group. There was a statistically significant difference in the change of IOP over time between the two groups (p=0.019). ONSD increased significantly from 5.3±0.3mm in the supine position to 5.5±0.3mm (p<0.001) at the end of surgery in both groups (both p<0.001). There was no statistically significant difference in the change of ONSD over time between the two groups (p>0.05).ConclusionsCompared to the restrictive fluid protocol, the liberal fluid protocol increased IOP but not ONSD in patients undergoing prone spine surgery.Trial registrationThe study was registered in ClinicalTrials.gov (https://clinicaltrials.gov) prior to patient enrollment, ID: NCT03890510, on March 26, 2019. The principal investigator was Xiao-Yu Yang.

Evaluation of postictal optic nerve sheath diameter at epileptic patients

IntroductionDuring a seizure, metabolic rate and, consequently, cerebral blood flow increase to provide the required maintenance energy. It is thought that this causes an increase in intracranial pressure, but there is no comprehensive research on this subject. In this study, we aimed to measure and follow optic nerve sheath diameter (ONSD) in patients who applied to the emergency department (ED) after generalized tonic-clonic (GTC) seizures and to gain information about intracranial pressure changes in epilepsy patients in the postictal period. Materials and MethodsThis was a prospective observational study. Patients already diagnosed with epilepsy who applied to the ED within one hour after GTC seizures were included. The ONSD of the patients was measured by the same radiologist three times in both eyes using ultrasonography at the time of admission and the fourth hour of follow-up. The seizure characteristics and measurements of the patients were recorded, and the changes in ONSD over time and correlations between seizure characteristics and ONSD were examined. ResultsSixty-six patients were included in the study. Thirty-four (51.5%) of the patients had seizures with auras. For both eyes, the first-hour ONSD values of the patients [right: 5.90 (5.73–6.16) mm, left: 5.86 (5.73–6.13) mm] were significantly higher than the fourth-hour ONSD values [right: 5.26 (5.19–5.40) mm, left: 5.28 (5.16–5.36) mm)] (p < 0.001 for both eyes). Additionally, the first- and fourth-hour ONSD values of patients with seizures with auras were significantly higher than those with seizures without auras (p < 0.001 for each condition). There was no correlation between other variables related to seizure type and ONSD. ConclusionThis study showed that after GTC seizures in epilepsy patients, ONSD increases in the first hour postictal and decreases over time. Another important result is that the increase in ONSD values in seizures with auras is significantly higher than in seizures without auras.

Measurement of Optic Nerve Sheath Diameter by Computed Tomography in the Pediatric Population: Normal Values.

To determine the normal values of optic nerve sheath diameter (ONSD) by computed tomography (CT) in the pediatric population. The CT scans of pediatric patients aged 1 to 16 years who underwent brain CT for different reasons, who did not have intracranial pathology or increased intracranial pressure, and who had no pathology on CT were included in the study. Four age groups were defined with the following ranges: 1 to 2, 3 to 6, 7 to 10, and 11 to 16 years. ONSD was measured from axial CT images, 3 and 10 mm behind the optic globe. The normative values of ONSD measured on CT imaging in children aged 1 to 16 years were reported. The change in ONSD according to age was investigated. ONSD was found to increase with age at both levels measured. The difference was statistically significant. Normal values should be known to detect pathologies that may cause an increase in optic nerve diameter. The values reported in this study can serve as a reference for normal optic nerve sheath diameter in the pediatric age group. [J Pediatr Ophthalmol Strabismus. 2024;61(1):38-43.].

Sonographic Optic Nerve Sheath Diameter as a Guide for Correction of Hyponatremia in the Emergency Department: A Cross-sectional Study.

Monitoring sodium levels during the correction of hyponatremia is essential. There is cell swelling due to the movement of water from extracellular to intracellular by osmotic effect in hyponatremia. The cellular swelling in a closed space causes increased intracranial pressure (ICP). The raised ICP correlates with the optic nerve sheath diameter (ONSD). So, the research question was whether the ONSD can be used as a guide for the correction of hyponatremia. It was a prospective observational study conducted on patients with serum sodium below 135 mEq/L presented to the emergency department (ED). The ONSD was measured at the time of presentation and discharge of the patient. The receiver operating characteristic curve (ROC) and area under the curve (AUC) were used to test the predictive ability of the ONSD to diagnose hyponatremia. A total of 54 subjects were included in the study. The mean sodium level was 109.3 mEq/L at presentation. The mean ONSD on the right side was 6.24 ± 0.71 mm and on the left side was 6.26 ± 0.64 mm at presentation to ED. The mean ONSD on the right side was 5.81 ± 0.58 mm and on the left side was 5.79 ± 0.56 mm at discharge. The ONSD was not able to predict the sodium level measured both by laboratory and POC methods. The ONSD failed to predict the sodium level in patients with hyponatremia during the correction. The change in ONSD did not correlate with the change in sodium level. Uttanganakam S, Hansda U, Sahoo S, Shaji IM, Guru S, Topno N, et al. Sonographic Optic Nerve Sheath Diameter as a Guide for Correction of Hyponatremia in the Emergency Department: A Cross-sectional Study. Indian J Crit Care Med 2023;27(4):265-269.

Effect of intravenous administration of 20% Mannitol on optic nerve sheath diameter in patients with raised intracranial pressure

Background and aims: Mannitol is commonly used to reduce elevated intracranial pressure (ICP) in patients with traumatic brain injury, intracranial hemorrhage and acute cerebrovascular accident. Optic nerve sheath diameter (ONSD) has high sensitivity and specificity in diagnosing raised ICP. This study aims to evaluate effect of Mannitol on ONSD in patients with raised ICP.&#x0D; Methods: This was a prospective cohort observational study of adult patients receiving osmotherapy for increased ICP admitted to the ICU. Baseline ONSD (T1) was recorded bilaterally followed by administration of Mannitol. ONSD was remeasured bilaterally at 30 (T2), 60 (T3) and 120 (T4) minutes after completion of administration of mannitol. Peak inspiratory pressures and PEEP were recorded for patients on mechanical ventilation.&#x0D; Results: Of the 40 patients included in the study, the mean age of patients was 54.03 ±19.15 years. Among them 26 were mechanically ventilated. Compared to the baseline values of 6.1 ± 0.74 mm, the mean ONSDs at T2, T3 and T4 were significantly lower after administration of 20% Mannitol with all p values &lt; 0.001. A statistically significant correlation between change in ONSD (ΔONSD) at each time point and the dose of Mannitol administered was observed.&#x0D; Conclusion: ONSD can be used for monitoring effectiveness of osmotherapy on a point-of-care basis in patients with elevated ICP.

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

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

Optic nerve sheath diameter correlates to intracranial pressure in spontaneous CSF leak patients.

Spontaneous cerebrospinal fluid (sCSF) leaks develop from pressure erosion due to idiopathic intracranial hypertension, treatment of which is paramount to preventing recurrence. Direct measurements of intracranial pressure (ICP) for monitoring response to treatment via lumbar drain (LD) or ventriculostomy are invasive and have risks. The objectives of this study are to determine whether ultrasonographic measurements of optic nerve sheath diameter (ONSD) correlate with LD ICP in patients with sCSF leaks undergoing treatment, and whether ONSDs are larger in patients with sCSF leaks than controls. Subjects with sCSF leaks and controls were prospectively recruited. ONSD, sex, and body mass index (BMI) were analyzed. For sCSF leak subjects, ultrasonography was performed at the time of LD opening and each pressure check postoperatively, including the acetazolamide response. In control patients, measurements were obtained at the time of surgery. Pearson's correlation between ONSD and ICP was performed. Subjects with sCSF leaks (n=9, age 52.4±9.5, all female) and controls (n=8, age 60.1±14.8, two females) had significantly different BMIs, 38.4±8.1 vs. 29.2±4.8, t(15)=2.793, p=0.014. ONSD was strongly correlated with ICP measurements (r=0.583, p=0.002). However, percentage change in ONSD and ICP measurements were more strongly correlated (r=0.733, p<0.001). Patients with sCSF leaks had significantly higher ONSDs than controls, 0.63cm±0.044 vs. 0.56cm±0.074, t(15)=2.329, p=0.034. ONSD significantly correlated with ICP in sCSF leak patients and was wider in sCSF leak subjects than controls. Ultrasonography has utility in monitoring the ICP response to acetazolamide.

Analysis of dynamic changes in optic nerve sheath diameter (ONSD) with ultrasound in post-craniotomy patients: Trends and correlation with computed tomography ONSD and Glasgow coma scale in post-operative period.

Intracranial pressure (ICP) monitoring in patients with intracranial tumors undergoing craniotomy is usually done in perioperative period in intensive care unit. Invasive measurement of ICP, though considered as the gold standard, has its own limitations such as availability of expertise, equipment, and associated complications. Period of raised ICP in post-operative period may impact patient outcomes. Post-craniotomy computed tomography (CT) assessment is done routinely and may need to be repeated if indicated during post-operative stay. Utility of sonographic serial optic nerve sheath diameter (ONSD) assessment in post-operative monitoring of patients who have undergone elective craniotomy was explored in this study. The primary objective of the study was to measure the dynamic change in ONSD as compared to baseline pre-operative measurement in the first 3 postoperative days after elective craniotomy. The secondary objective of the study was to evaluate correlation between ONSD value with Glasgow Coma Scale (GCS) and post-operative CT findings. In this prospective, observational, and cohort study, we studied adult patients undergoing craniotomy for intracranial tumors. GCS assessment and sonographic measurement of ONSD were done preoperatively, immediate post-operative period, and 12, 24, and 48 h after surgery. CT scan to detect raised ICP was done at 24 h post-operative. Correlation of ONSD with GCS at respective period and correlation of CT scan finding with respective ONSD assessment were evaluated. A total of 57 patients underwent elective craniotomy for intracranial tumors. Significant difference was observed in ONSD value depending on time of measurement perioperatively (χ2 = 78.9, P = 0.00). There was initial increase in the first 12 h followed by decrease in ONSD in the next 48 h. Negative correlation was observed between baseline ONSD and 12 h GCS (ρ = -0.345, P = 0.013). There was significant change in GCS scores based on the status of ONSD (raised or normal) at 12 h after surgery (P = 0.014). Significant correlation between USG ONSD and CT ONSD was observed (ρ = 0.928, P = 0.000). Optimal cutoff value of ONSD to detect raised ICP with reference to CT signs was 4.8 mm with 80% sensitivity and 95% specificity. ONSD undergoes dynamic changes, correlates with CT scan, and has good diagnostic accuracy to detect raised ICP post-craniotomy for intracranial tumors. It may serve as a useful tool in monitoring in resource-limited setup.

Optic nerve sheath diameter changes at altitude

AbstractPurpose: This study aimed to assess variations in Optic Nerve Sheath Diameter (ONSD) as a correlate of Intracranial Pressure (ICP) during ascent to high‐altitude and to explore the relationship between ONSD and Acute Mountain Sickness (AMS). AMS is a high‐altitude illness characterized by headaches, lethargy, nausea and vomiting. At present there is no consensus on the pathophysiology of AMS. There are similarities in symptomology between AMS and raised ICP. A greater understanding of ICP at altitude and its role in AMS may yield new strategies for management of the illness.Methods: We conducted a longitudinal cohort study involving 10 mountaineers climbing Mt Toubkal (4167 m). Participants underwent daily binocular ultrasound B‐scans at interval altitudes during the ascent. Altitude, AMS diagnosis and severity (using Lake Louise Score [LLS]) were recorded concurrently with ultrasound examinations. Ultrasound scans were reviewed by a blinded observer who measured ONSD and assessed image quality (1 = poor, 2 = moderate, 3 = good).Results: During the ascent to 4167 m and return to low‐land, there was no significant variation in left (p = 0.97), right (p = 0.68) or mean (p = 0.86) ONSD. The ratio of ONSD to baseline was significantly (p = 0.038) greater in participants with AMS on Day 5; this was not consistent across all time points. No significant correlation between the ratio of ONSD to baseline and LLS was observed at any time point. Mean image quality was 2.12 (SD ± 0.65); images largely scored in the ‘Moderate’ – ‘Good’ range.Conclusions: This study is reflective of changes in ONSD during slow ascent profiles commonly used in mountaineering. This suggests that ONSD and therefore ICP does not significantly vary during this style of ascent to 4167 m. We did not identify any convincing relationship between AMS and ONSD, adding to previous research suggesting the same. Considering the limitations of this study, it cannot stand alone to disapprove a causal relationship between ONSD and AMS.

Optic Nerve Sheath Diameter Affected by Cervical Collar Placement in Minor Head Trauma Patients

Background: Head trauma may cause an increase in intracranial pressure (ICP). The use of ocular ultrasound to measure optic nerve sheath diameter (ONSD) is a method to determine the ICP. The use of the rigid cervical collar in head trauma patients contribute to elevating ICP, and therefore, potentially causing further deterioration in their condition. Objectives: This study aimed to describe changes in ONSD after the placement of a c-collar and analyze these changes depending on the time in the c-collar. Methods: This prospective study measured the ONSD of minor head trauma patients before and after the placement of a c-collar. Patients aged ³18 with blunt head trauma and Glasgow Coma Score ³13 were included in the study. Each eye was scanned twice. This was done before c-collar placement, at 5 and 20 min after placement. The mean values of both eyes were calculated and analyzed. Results: This study investigated 50 patients. The mean baseline ONSD was obtained at 4.71mm±0.22 (4.54-4.77). Furthermore, T5 and T20 measurements were 5.19±0.41 (5.07-5.31) and 5.26±0.45 (5.14-5.39), respectively. The ONSD increased at T5 and T20. The changes from the baseline measurements were statistically significant (P=0.000, P=0.000). The difference between T5 and T20 groups was an increase in ONSD, and these differences were also statistically significant (0.07±0.19; P=0.008). Conclusion: Our results revealed that minor head trauma patients using a c-collar may increase ONSD by timeline the clinical effects of which have to be determined with further studies. Enlargement in ONSD should be considered when interpreting ICP.

Abstract 204: Optic Nerve Sheath Diameter Trajectories During Targeted Temperature Management

Introduction: The extent of hypoxic-ischemic injury (HII) after cardiac arrest (CA) remains an important knowledge deficit with lack of objective clinical data that is measurable repeatedly. There is a need to better understand an individual patient’s level of HII. Optic nerve sheath diameter (ONSD) has not been explored after CA as a possible bedside modality to measure the extent of HII over time, at the bedside, during targeted temperature management (TTM). Objective: We sought to characterize the temporal trajectories of point-of-care ultrasound obtained ONSD during the post- return of spontaneous circulation (ROSC) phase, in patients with and without TTM. Methods: Adult CA patients at an urban academic ED were included from 2017-2021. ONSD was measured by emergency ultrasound fellowship trained faculty at 1, 6, 24, 48, and 72 hours after ROSC using an ocular preset on a 15MHz linear probe. ONSD measurements at these time points were compared with patient demographic information and intervention of TTM . Results: A total of 78 participants had ONSD measurements. The mean age was 62 (+/-15) and 46% were female. Of the 65% of the cases with TTM, a sex disparity was noted with 73% of males receiving TTM versus 56% of females. There was a trend toward a decrease in mean ONSD by 0.015cm for TTM patients during the early time points of 1 to 6 hours compared to an increase in 0.006cm in those without TTM. Similar trend was noted between 1 to 24 hours, with a decrease in ONSD by 0.025cm in those with TTM relative to an average increase of 0.008 cm in those without TTM. However, neither delta ONSD was statistically significant between the two cohorts. When further assessing if delay in cooling had an impact on ONSD change, we found that the ONSD change between 24 to 48 hours was significantly increased in those in whom TTM was not initiated within 14 hours (beta=0.036; p=0.016). Conclusion: This pilot study revealed ONSD changes during TTM. There is potential for monitoring brain injury through ONSD trajectories to evaluate responders vs non-responders to TTM. Additional research is needed to evaluate ONSD changes during the rewarming time frame and may further distinguish patients with worse HII. Correlation to survival outcomes can be possible with a larger sample size.