Optic nerve sheath diameter and lumbar puncture opening pressure in nontrauma patients suspected of elevated intracranial pressure

ObjectiveThe purpose of this study was to determine if patients with nontraumatic causes of elevated intracranial pressure (ICP) could be identified by ultrasound measurement of optic nerve sheath diameter (ONSD). It was hypothesized that an ONSD greater than or equal to 5 mm would identify patients with elevated ICP.MethodThis was a prospective observational trial comparing ONSD with ICP measured by opening pressure manometry on lumbar puncture (LP). The cohort consisted of a convenience sample of adult patients presenting to the emergency department, requiring LP. The ONSD measurement was performed before computed tomography and LP. The physician performing the LP was blinded to the result of the ONSD measurement. An opening pressure on manometry of greater than or equal to 20 cm H₂O and an ONSD greater than or equal to 5 mm were considered elevated.ResultsFifty-one patients were included in our study, 24 (47%) with ICP greater than or equal to 20 cm H₂O and 27 (53%) with ICP less than 20 cm H₂O. The sensitivity of ONSD greater than or equal to 5 for identifying elevated ICP was 75% (95% confidence interval, 53%-90%) with specificity of 44% (25%-65%). The area under the receiver operator characteristic curve was 0.69 (0.54-0.84), suggesting a relationship between ONSD and ICP.ConclusionAn ONSD greater than or equal to 5 mm was associated with elevated ICP in nontraumatic causes of elevated ICP. Although a relationship exists, a sensitivity of 75% does not make ONSD measurement an adequate screening examination for elevated ICP in this patient population.     

Optic nerve sheath diameter measurement: a means of detecting raised ICP in adult traumatic and non-traumatic neurosurgical patients

Introduction

Bedside ultrasound measurement of optic nerve sheath diameter (ONSD) is emerging as a non-invasive technique to evaluate and predict raised intracranial pressure (ICP). It has been shown in previous literature that ONSD measurement has good correlation with surrogate findings of raised ICP such as clinical and radiological findings suggestive of raised ICP.

Correlation of optic nerve sheath diameter measurements by computed tomography and magnetic resonance imaging

BackgroundTraditionally, intracranial pressure is measured by direct ventriculostomy, which is invasive. Noninvasive measures such as bedside ultrasound and magnetic resonance imaging have been advocated and utilized recently to assess the intracranial pressure. The role of this study is to determine the degree of agreement between measurements of the optic nerve sheath diameter by computed tomography (CT) and magnetic resonance imaging (MRI).Materials and MethodsRetrospective chart review of 100 consecutive patients who had both MRI and CT scan of the head from January 1, 2011, until March 31, 2013, at our center was performed. A discrepancy of 0.2 mm between the 2 measurements was set as acceptable difference. The measurements of optic nerve sheath diameter (ONSD) were compared for agreement between the 2 modalities using the method by Bland and Altman.ResultsA total of 100 patients with both MRI and CT scan of the head were selected. Of these 100 patients, 24 were male and 76 were female. The average age was 63 years. No ONSD abnormality was detected in any of the patients. The discrepancy in measurements of the ONSD between CT and MRI in transverse plane was less than the predetermined cut-off value of 0.2 mm. Within-subject variance was estimated at 0.0058 for both CT and MRI.ConclusionComparable results without significant discrepancy as predetermined by the study groups were obtained from CT scan. Measurement of ONSD by CT scan can be used to indirectly asses the intracranial pressure in addition to clinical assessment and other signs of increased intracranial pressure on CT scan.     

超声测量视神经鞘直径与眼球横径比值在重症颅脑损伤患者颅内压监测中的应用

目的研究重症颅脑损伤(TBI)患者颅内压监测中超声测量视神经鞘直径(ONSD)与眼球横径(ETD)比值的应用价值。方法回顾性选取2020年1月至2021年1月保定市第二中心医院收治入院的98例重症TBI患者为研究对象。所有患者均于入院24 h内接受开颅手术治疗,采用腰椎穿刺术测定颅内压,手术完成后24 h内选取索诺声超声M-Turbo与6-13 MHz线阵超声探头测定ETD、ONSD,选取颅内压监护仪记录颅内压值。参考颅内压值分为研究组(n=58,颅内压≤20 mmHg)与对照组(n=40,颅内压>20 mmHg)。分析并比较两组入院后同期监测指标水平及与ONSD/ETD比值相关性;分析两组超声测量ONSD/ETD比值、ONSD与颅内压相关性;超声测量ONSD/ETD比值、ONSD预测颅内压水平上升的准确性经受试者工作特征(ROC)曲线评价,并比较金标准脑室内测压与超声测量ONSD/ETD比值、ONSD诊断一致性。结果研究组较对照组GSC评分、颅内温度、ETD更高,颅内压、ONSD、ONSD/ETD比值更低,差异均有统计学意义(P <0.05)。两组患者GCS与ONSD/E...     

Using MRI of the optic nerve sheath to detect elevated intracranial pressure

The current gold standard for the diagnosis of elevated intracranial pressure (ICP) remains invasive monitoring. Given that invasive monitoring is not always available or clinically feasible, there is growing interest in non-invasive methods of assessing ICP using diagnostic modalities such as ultrasound or magnetic resonance imaging (MRI). Increased ICP is transmitted through the cerebrospinal fluid surrounding the optic nerve, causing distention of the optic nerve sheath diameter (ONSD). In this issue of Critical Care, Geeraerts and colleagues describe a non-invasive method of diagnosing elevated ICP using MRI to measure the ONSD. They report a positive correlation between measurements of the ONSD on MRI and invasive ICP measurements. If the findings of this study can be replicated in larger populations, this technique may be a useful non-invasive screening test for elevated ICP in select populations.     

Correlation of Optic Nerve Sheath Diameter with Direct Measurement of Intracranial Pressure

Background: Measurements of the optic nerve sheath diameter (ONSD) using bedside ultrasound (US) have been shown to correlate with clinical and radiologic signs and symptoms of increased intracranial pressure (ICP). Objectives: Previous literature has identified 5 mm as the ONSD measurement above which patients exhibit either clinical or radiologic signs of elevated ICP. The goals of this study were to evaluate the association between ONSD and ICP and to validate the commonly used ONSD threshold of 5 mm using direct measurements of ICP as measured by ventriculostomy. Methods: A prospective blinded observational study was performed using a convenience sample of adult patients in both the emergency department (ED) and the neurologic intensive care unit (ICU) who had invasive intracranial monitors placed as part of their clinical care. Ocular USs were performed with a 10–5 MHz linear probe. Emergency physicians (EPs) with previous ocular US experience performed ONSD measurements while blinded to the contemporaneous ICP reading obtained directly from invasive monitoring. The association between ONSD and ICP was assessed with the Spearman rank correlation coefficient, and a receiver operator characteristic (ROC) curve was created to determine the optimal ONSD cutoff to detect ICP > 20 cm H₂O. Results: Thirty‐eight ocular USs were performed on 15 individual patients. Spearman rank correlation coefficient of ONSD and ICP was 0.59 (p < 0.0005) demonstrating a significant positive correlation. An ROC curve was created to assess the ability of ONSD to distinguish an abnormal ICP greater than 20 cm H₂O. The area under the ROC curve was 0.93 (95% confidence interval [CI] = 0.84 to 0.99). Based on inspection of the ROC curve, ONSD > 5 mm performed well to detect ICP > 20 cm H₂O with a sensitivity of 88% (95% CI = 47% to 99%) and specificity of 93% (95% CI = 78% to 99%). Conclusions: Using an ROC curve the authors systematically confirmed the commonly used threshold of ONSD > 5 mm to detect ICP > 20 cm H₂O. This study directly correlates ventriculostomy measurements of ICP with US ONSD measurements and provides further support for the use of ONSD measurements as a noninvasive test for elevated ICP.     

Elevated Intracranial Pressure Detected by Bedside Emergency Ultrasonography of the Optic Nerve Sheath

Patients with altered level of consciousness may be suffering from elevated intracranial pressure (EICP) from a variety of causes. A rapid, portable, and noninvasive means of detecting EICP is desirable when conventional imaging methods are unavailable. OBJECTIVES: The hypothesis of this study was that ultrasound (US) measurement of the optic nerve sheath diameter (ONSD) could accurately predict the presence of EICP. METHODS: The authors performed a prospective, blinded observational study on emergency department (ED) patients with a suspicion of EICP due to possible focal intracranial pathology. The study was conducted at a large community ED with an emergency medicine residency program and took place over a six-month period. Patients suspected of having EICP by an ED attending were enrolled when study physicians were available. Unstable patients were excluded. ONSD was measured 3 mm behind the globe using a 10-MHz linear probe on the closed eyelids of supine patients, bilaterally. Based on prior literature, an ONSD above 5 mm on ultrasound was considered abnormal. Computed tomography (CT) findings defined as indicative of EICP were the presence of mass effect with a midline shift 3 mm or more, a collapsed third ventricle, hydrocephalus, the effacement of sulci with evidence of significant edema, and abnormal mesencephalic cisterns. For each patient, the average of the two ONSD measurements was calculated and his or her head CT scans were evaluated for signs of EICP. Student's t-test was used to compare ONSDs in the normal and EICP groups. Sensitivity, specificity, and positive and negative predictive values were calculated. RESULTS: Thirty-five patients were enrolled; 14 had CT results consistent with EICP. All cases of CT-determined EICP were correctly predicted by ONSD over 5 mm on US. One patient with ONSD of 5.7 mm in one eye and 3.7 mm in the other on US had a mass abutting the ipsilateral optic nerve; no shift was seen on CT. He was placed in the EICP category on his data collection sheet. The mean ONSD for the 14 patients with CT evidence of EICP was 6.27 mm (95% CI = 5.6 to 6.89); the mean ONSD for the others was 4.42 mm (95% CI = 4.15 to 4.72). The difference of 1.85 mm (95% CI = 1.23 to 2.39 mm) yielded a p = 0.001. The sensitivity and specificity for ONSD, when compared with CT results, were 100% and 95%, respectively. The positive and negative predictive values were 93% and 100%, respectively. CONCLUSIONS: Despite small numbers and selection bias, this study suggests that bedside ED US may be useful in the diagnosis of EICP.     

Optic nerve sheath diameter on initial brain CT,raised intracranial pressure and mortality after severe TBI: an interesting link needing confirmation

Optic nerve sheath diameter (ONSD) enlargement on initial computed tomography (CT) scan has been found to be associated with increased mortality after severe traumatic brain injury. This could offer the possibility to detect patients with raised intracranial pressure requiring urgent therapeutic interventions and/or invasive intracranial monitoring to guide the treatment. The method to measure ONSD using CT scan, however, needs further confirmation. Moreover, the link between ONSD enlargement on initial CT scan and raised intracranial pressure also needs to be confirmed by further studies.In a very interesting study performed on 77 severe traumatic brain injury patients, Legrand and colleagues found that the optic nerve sheath diameter (ONSD) measured on the initial brain computed tomography(CT) scan (performed within the first 3 hours of injury) was a very good predictor of ICU mortality [1]. In the multivariate analysis, ONSD >7.3 mm was independently associated with ICU mortality, and performed better than age >32 years, anisocoria at admission, and basal cistern compression on initial CT scan.The optic nerve is surrounded by a dural sheath that can inflate in cases of raised pressure in the cerebrospinal fluid. An enlarged ONSD, measured using ocular sonography, has been found in patients with raised intracranial pressure (ICP) [2]. Even if in Legrand and colleagues'' study the ICP was measured in only 9% of the patients, we can assume that the strong association between ONSD enlargement of initial CT and mortality was related to raised ICP occurring very early after trauma, as suggested by the fact that ONSD enlargement was also associated with other signs of raised ICP in the first CT scan as basal cistern effacement and midline shift. This is probably the major interest of this study: ONSD measurement on initial CT scan could offer the possibility to detect patients with raised ICP needing urgent therapeutic interventions and/or invasive intracranial monitoring to guide the treatment.Our enthusiasm must be tempered, however, as the method to measure ONSD using CT scan needs clarification and confirmation. ONSD has been measured 3 mm behind the globe - where the dural sheath is distensible, as has previously been determined using sonography [2-4] and magnetic resonance imaging [5]. In Legrand and colleagues'' study, ONSD has been measured on a millimetric slice brain CT scan but only in one plane. As suggested by Unsold and colleagues [6], since the optic nerve has a sinuous course in the horizontal and the vertical plane, a section of the nerve in a single plane can conduce one to overestimate ONSD. Actually, the values of ONSD in Legrand and colleagues'' study are larger than values obtained with ultrasound or magnetic resonance imaging or even with CT [7]. Moreover, the precise limits of the sheath and the orbital fat surrounding the sheath can be very difficult to determine. This study probably needs further confirmation of the reliability of the ONSD measurement, after realignment in the optic nerve plane and measurement in several axes.     

Optic nerve ultrasound for the detection of elevated intracranial pressure in the hypertensive patient

Purpose

We sought to determine whether dilation of the optic nerve sheath diameter (ONSD), as detected at the bedside by emergency ultrasound (US), could reliably correlate with patient blood pressure and whether there was a blood pressure cutoff point where you would start to see abnormal dilation in the ONSD.

Methods

This was a single-blinded, prospective, observational trial from September 2010 to April 2011. One hundred fifty patients presenting to the emergency department were enrolled. There were 3 arms to the study with 50 patients in each arm: (1) ONSD in normotensive/asymptomatic patients; (2) ONSD in hypertensive/asymptomatic patients; and (3) ONSD in hypertensive/symptomatic patients. Ocular US was conducted on all subjects.

Results

Neither the number of symptoms nor the type of symptom present in the hypertensive/symptomatic group was able to significantly predict the average ONSD before treatment (P = .818 and .288, respectively). There was a significant correlation between both systolic blood pressure (SBP) and diastolic blood pressure (DBP) with the ONSD in all hypertensive patients. The best SBP and DBP cutoff point for abnormal ONSD was 166/82 mm Hg. Decrease in ONSD observed after blood pressure treatment was not statistically significant (P = .073).

Conclusions

In conclusion, our study shows that practitioners can use bedside ocular US and a blood pressure cutoff point to help predict whether patients require more aggressive management of their symptomatic hypertension. Knowing the SBP and DBP readings that lead to increased ONSD and increased intracranial pressure can help guide management and treatment decisions at the bedside.     

Optic nerve sheath diameter does not change with patient position

OBJECTIVES: Optic nerve sheath diameter (ONSD) has been proposed as a marker for increased intracranial pressure. Trendelenburg's position is often used in hypotensive patients and reverse Trendelenburg's position (30 degrees head up) is often used in head injury patients. We asked if there would be any change in OSND in healthy human adults between the supine, Trendelenburg's, and reverse Trendelenburg's positions. METHODS: Prospective case-control blinded study using consenting healthy adults. Three separate investigators measured the ONSD in each eye of 10 separate volunteers in the supine, Trendelenburg's, and reverse Trendelenburg's positions with 30 degrees angulation from the horizontal. Data were analyzed using the paired t test. RESULTS: In the supine position, the mean ONSD was 4.6 +/- 0.71 (SD) mm in the right eye and 4.5 +/- 0.56 (SD) mm in the left eye. In Trendelenburg's position, the mean ONSD was 4.4 +/- 0.72 (SD) mm in the right eye and 4.7 +/- 0.53 (SD) mm in the left eye. In reverse Trendelenburg's position, the mean ONSD was 4.4 +/- 0.49 (SD) mm in the right eye and 4.8 +/- 0.76 (SD) mm in the left eye. There was no significant difference in OSND between positions for either eye by analysis of variance. Interobserver agreement was +/-1 mm in at least 90% of the subjects regardless of position. CONCLUSION: Optic nerve sheath diameter measurement by ultrasound does not significantly change with Trendelenburg's or reverse Trendelenburg's position in comparison with the supine position in healthy individuals.     

超声测量视神经鞘直径预测颅内压增高的围手术期应用进展

视神经鞘(ONS)是颅内硬脑膜的直接延续,内有横梁式的蛛网膜下腔。当患者颅内压(ICP)升高时,脑脊液会经蛛网膜滤出使视神经鞘增宽,因此可以用视神经鞘直径(ONSD)预测ICP增高。目前,围手术期ICP监测手段较少,超声测量ONSD预测ICP的技术因具有无创、床旁、快速等优势在临床上被广泛应用,将该技术应用于围术期患者中可以提供术中ICP监测。本文就ICP监测现状、ONSD与ICP的关系、ONSD预测ICP增高的临界值及ONSD预测围术期ICP增高的应用前景作一综述,以期为围手术期应用超声测量ONSD预测ICP增高提供支持。     

Comparison of accuracy of optic nerve ultrasound for the detection of intracranial hypertension in the setting of acutely fluctuating vs stable intracranial pressure: post-hoc analysis of data from a prospective, blinded single center study

ABSTRACT: INTRODUCTION: Optic nerve sheath diameter (ONSD) measurement with bedside ultrasound has been shown in many studies to accurately detect high intracranial pressure (ICP). The accuracy of point-in-time ONSD measurement in the presence of ongoing fluctuation of ICP between high and normal is not known. Recent laboratory investigation suggests that reversal of optic nerve sheath distension may be impaired following bouts of intracranial hypertension. Our objective was to compare the accuracy of ONSD measurement in the setting of fluctuating versus stable ICP. METHODS: This was a retrospective analysis of data from prospective study comparing ONSD to invasive ICP. Patients with invasive ICP monitors in the ICU underwent ONSD measurement with simultaneous blinded recording of ICP from the invasive monitor. Three measurements were made in each eye. Significant acute ICP fluctuation (SAIF) was defined in two different ways; as the presence of ICP both above and below 20 mmHg within a cluster of six measurements (Definition 1) and as a magnitude of fluctuation >10 mmHg within the cluster (Definition 2). The accuracy of point-in-time ONSD measurements for the detection of concurrent ICP >20 mmHg within clusters fulfilling a specific definition of SAIF was compared to the accuracy of ONSD measurements within clusters not fulfilling the particular definition by comparison of independent receiver operating characteristic (ROC) curves. RESULTS: A total of 613 concurrent ONSD-ICP measurements in 109 clusters were made in 73 patients. Twenty-three (21%) clusters fulfilled SAIF Definition 1 and 17 (16%) SAIF Definition 2. For Definition 1, the difference in the area under the curve (AUC) of ROC curves for groups with and without fluctuation was 0.10 (P = 0.0001). There was a fall in the specificity from 98% (95% CI 96 to 99%) to 74% (63 to 83%) and in the positive predictive value from 89% (80 to 95%) to 76% (66 to 84%) with fluctuation. For Definition 2, also, there was a significant difference between the AUC of ROC curves of groups with fluctuation-magnitude >10 mmHg and those with fluctuation-magnitude 5 to 10 mmHg (0.06, P = 0.04) as well as <5 mmHg (0.07, P = 0.01). CONCLUSIONS: Specificity and PPV of ONSD for ICP >20 mmHg are substantially decreased in patients demonstrating acute fluctuation of ICP between high and normal. This may be because of delayed reversal of nerve sheath distension.     

Optic nerve sonography in the diagnostic evaluation of adult brain injury

Introduction  

The optic nerve sheath diameter (ONSD) may be increased in brain-injured patients, especially children, with intracranial hypertension. We investigated whether measurements of ONSD correlated with simultaneous noninvasive and invasive measurements of the intracranial pressure (ICP) in brain-injured adults.     

Utility of Point-of-Care Ultrasound in the Diagnosis of Idiopathic Intracranial Hypertension in the Emergency Department

BackgroundEmergency physicians are frequently required to identify and triage patients with increased intracranial pressure (ICP). Idiopathic intracranial hypertension (IIH) is a possible cause that must be considered. Its prognosis depends on prompt recognition and treatment, and progression of the disease can lead to permanent vision loss and considerable morbidity. Point-of-care ultrasound can rapidly identify elevated ICP. Measurements of the optic nerve sheath diameter (ONSD) and optic disc elevation (ODE) can act as surrogates for ICP.Case SeriesWe describe five cases in which ultrasound was used to identify increased ICP and aid clinical decision-making. In several of the cases, ultrasound was used to confirm a suspicion for IIH and initiate therapy while awaiting the results of a more time-consuming and technically challenging test, such as lumbar puncture or optical coherence tomography. One of the patients was pregnant, and sonographic evidence of elevated ICP helped avoid exposing the patient to unnecessary radiation.Why Should an Emergency Physician Be Aware of This?Ultrasound is a quick and versatile tool for screening patients with neurologic symptoms, and when integrated into the proper clinical context, can reduce the use of more invasive tests. It can be particularly useful in patients with pathology that may not show abnormalities on computed tomography scan or in whom lumbar puncture is technically difficult, making patients at risk for IIH well-suited to examination by ultrasound. We use a cutoff of 5 mm for ONSD and 0.6 mm for ODE, though there are no universally agreed on cutoff values.     

Use of T2-weighted magnetic resonance imaging of the optic nerve sheath to detect raised intracranial pressure

Introduction  

The dural sheath surrounding the optic nerve communicates with the subarachnoid space, and distends when intracranial pressure is elevated. Magnetic resonance imaging (MRI) is often performed in patients at risk for raised intracranial pressure (ICP) and can be used to measure precisely the diameter of optic nerve and its sheath. The objective of this study was to assess the relationship between optic nerve sheath diameter (ONSD), as measured using MRI, and ICP.     

Non-invasive assessment of intracranial pressure using ocular sonography in neurocritical care patients

Objective  To assess the relationship between optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in neurocritical care patients. Design  Prospective, observational study. Setting  Surgical critical care unit, level 1 trauma center. Patients  A total number of 37 adult patients requiring sedation and ICP monitoring after severe traumatic brain injury, subarachnoid hemorrhage, intracranial hematoma, or stroke. Measurements and main results  Optic nerve sheath diameter was measured with a 7.5 MHz linear ultrasound probe. ICP was measured invasively via a parenchymal device. Simultaneous measurements were performed atleast once a day during the first 2 days after ICP insertion and in cases of acute changes. There was a significant relationship between ONSD and ICP (78 simultaneous measures, r = 0.71, P < 0.0001). Changes in ICP were strongly correlated with changes in ONSD (39 measures, r = 0.73, P < 0.0001). Enlarged ONSD was a suitable predictor of elevated ICP (>20 mmHg) (area under ROC curve = 0.91). When ONSD was less than 5.86 mm, the negative likehood ratio for raised ICP was 0.06. Conclusion  In sedated neurocritical care patients, non-invasive sonographic measurements of ONSD are correlated with invasive ICP, and the probability to have raised ICP if ONSD is less than 5.86 mm is very low. This method could be used as a screening test when raised ICP is suspected. The authors received no financial support for this work.     

Dynamic optic nerve sheath diameter changes upon moderate hyperventilation in patients with traumatic brain injury

BackgroundSonographic assessment of optical nerve sheath diameter (ONSD) has the potential for non-invasive monitoring of intracranial pressure (ICP). Hyperventilation (HV) -induced hypocapnia is used in the management of patients with traumatic brain injury (TBI) to reduce ICP. This study investigates, whether sonography is a reliable tool to detect dynamic changes in ONSD.MethodsThis prospective single center trial included patients with TBI and neuromonitoring within 36 h after injury. Data collection and ONSD measurements were performed at baseline and during moderate HV for 50 min. Patients not suffering from TBI were recruited as control group.ResultsTen patients with TBI (70% males, mean age 35 ± 14 years) with a median of first GCS of 5.9 and ten control patients (40% males, mean age 45 ± 16 years) without presumed intracranial hypertension were included. During HV, ICP decreased significantly (p < .0001) in the TBI group. An ONSD response was found for HV (p = .05).ConclusionWe observed a dynamic decrease of ONSD during moderate HV. This suggests a potential use of serial ONSD measurements when applying HV in cases of suspected intracranial hypertension.     

Ultrasonography of the optic nerve sheath may be useful for detecting raised intracranial pressure after severe brain injury

Objective To assess at admission to the ICU the relationship between optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) and to investigate whether increased ONSD at patient admission is associated with raised ICP in the first 48 h after trauma. Design and setting Prospective, blind, observational study in a surgical critical care unit, level 1 trauma center. Patients and participants 31 adult patients with severe traumatic brain injury (TBI; Glasgow coma scale ≤ 8) requiring sedation and ICP monitoring, and 31 control patients without brain injury requiring sedation. Measurements and results ONSD was measured with a 7.5-MHz linear ultrasound probe. Two TBI groups were defined on the basis of ICP profile. If ICP exceeded 20 mmHg for more than 30 min in the first 48 h (before any specific treatment), patients were considered to have high ICP; if not, they had normal ICP. The largest ONSD value (the highest value for the right and left eye) was significantly higher in high ICP patients (6.3 ± 0.6 vs. 5.1 ± 0.7 mm in normal ICP patients and 4.9 ± 0.3 mm in control patients). There was a significant relationship between the largest ONSD and ICP at admission (r = 0.68). The largest ONSD was a suitable predictor of high ICP (area under ROC curve 0.96). When ONSD was under 5.7 mm, the sensitivity and negative predictive values for high ICP were 100%. Conclusions In the early posttraumatic period, ocular ultrasound scans may be useful for detecting high ICP after severe TBI. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This article is discussed in the editorial available at: .     

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

Objective: In patients with traumatic brain injury (TBI), early detection and subsequent prompt treatment of elevated intracranial pressure (ICP) is a challenge in the prehospital setting, because physical examination is limited in comatose patients and invasive device placement is not possible. The aim of this study was to evaluate the quality and feasibility of optic nerve sheath diameter (ONSD) measurements obtained during the prehospital management of patients with TBI. Methods: This study was a prospective, observational study of 23 patients with moderate and severe TBI during prehospital medical care. The primary endpoint was the quality of ONSD measurements expressed as the percentage of ONSD validated by the experts. Secondary endpoints included the feasibility of ONSD measurements as the percentage of ONSD performed and assessment by operators of ease and duration to perform. Results: Ultrasound ONSD was performed in 19 (82%) patients and 80% of ONSD measurements were validated by the experts. The ONSD measurements were possible in 15 (79%) cases. The physicians have assessed the ease of use at 8 (interquartile range [IQR]?=?2.5–8) on 10 for and the median time to obtain ONSD measurement was 4?min (IQR?=?3–5). ONSD measurement was performed in 12 (63%) cases during the transport and in 7 (37%) cases on scene, with 58% (n?=?7) and 71% (n?=?5) validated ONSD, respectively. The success rate in the helicopter was 43% compared to 80% in the ambulance. Conclusion: This study shows that it is feasible to obtain high-quality ONSD measurements in the management of patients with TBI in a prehospital setting. A randomized study evaluating the usefulness of ONSD to guide management of TBI in the prehospital phase may be of great interest.