Ultrasonography Of Optic Nerve Sheath Research Articles

Ultrasonographic Assessment of Optic Nerve Sheath Diameter as a Screening Tool for Intracranial Hypertension in Traumatic Brain Injury

BackgroundSevere traumatic brain injury (TBI) is a condition burdened by high morbidity and mortality. Prevention of secondary insults is one of the main goals of management and intracranial pressure monitoring is a cornerstone in management of TBI. The relationship between intracranial pressure and optic nerve sheath is known from the literature. Optic nerve sheath ultrasonography could represent a method added to our armamentarium for monitoring intracranial pressure. MethodsWe investigated how ultrasound-measured optic nerve sheath diameter varies as a function of intracranial pressure in a cohort of patients with severe blunt head injury in whom an intraparenchymal sensor was placed. We evaluated the accuracy of optic nerve sheet diameter (ONSD) in distinguishing dichotomized ICP cut-offs and analyzed the learning curve and its potential as screening tool to select TBI patients most in need of invasive ICP monitoring in a setting with constraints on resources. ResultsONSD and ICP have a linear relationship. Nevertheless, there are limits of evaluating the one-to-one correspondence between those two variables. We selected a cut-off of sonographic ONSD above which there is a concernable elevation of intracranial pressure (ICP>15 mmHg) worthy of invasive second line invasive monitoring. Thus, it is possible to use ONSD as a first line non-invasive tool to intercept patients at risk of developing frank intracranial hypertension. ConclusionsWe propose the use of ONSD ultrasound as a screening investigation for post-traumatic intracranial hypertension in the context of an emergency department, especially in contexts where there is limited availability of intracranial pressure monitors.

Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

BackgroundUltrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels. MethodsAn experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter. ResultsAll variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: −80.5 + 238.2 × AON. ConclusionIn the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.

Optic Nerve Sheath Ultrasonography: Should We Be Using It for Bedside Diagnosis of Increased Intracranial Pressure?

In their systematic review, Koziarz and colleagues examine optic nerve ultrasonography for diagnosing increased intracranial pressure in children and adults. The editorialists encourage cautious in...

Bedside Ultrasonography as an Alternative to Computed Tomography Scan for the Measurement of Optic Nerve Sheath Diameter.

Background:Optic nerve sheath diameter (ONSD) as measured by optic nerve sheath ultrasonography (ONSU) is used as a surrogate marker of intracranial pressure (ICP), especially in resource-limited settings. There is a growing interest in the use of ONSU in emergency and high-altitude setups. Notwithstanding multiple studies done on this subject, there is a paucity of data regarding standardization of techniques and comparison of ONSU with computed tomography (CT).Materials and Methods:Thirty-five patients with a diagnosis of high-altitude cerebral edema were enrolled in the study. ONSD was measured in all patients using ONSU, along visual and coronal axis, and CT scan. We repeated ONSU in these patients on days 3, 7, 10, and 15 (day of discharge). Correlation between visual and coronal axis as well as CT scan was analyzed.Results:The correlation of visual to coronal and coronal to visual was equally significant (both correlation coefficients being R2 = 0.983). Correlation of ONSD by visual axis to CT scan was better than coronal axis (correlation coefficient R2 = 0.986 vs. 0.96, respectively).Conclusion:In our study, we found a strong correlation between the visual and coronal axes. Thus, either of the two axes can be used for monitoring ICP. However, it has been found that measurements along the coronal axis are challenging, especially in the emergency setup. ONSD measured along visual axis correlated better with CT scan as compared to the coronal axis.

Diagnostic Accuracy of Optic Nerve Ultrasonography and Ophthalmoscopy in Prediction of Elevated Intracranial Pressure.

Elevated intracranial pressure (ICP) is a major and potentially lethal disorder in patients admitted to the emergency department (ED). Several methods are being used to investigate for elevated ICP. Here we assessed and compared the diagnostic accuracy of two existing tools of ophthalmoscopy and optic nerve ultrasonography in detection of elevated ICP. 131 participants with probable elevation of ICP referred to the emergency department of Al-Zahra Hospital, Isfahan, Iran, from 2012 to 2014, were enrolled. Brain computed tomography (CT) scan, ultrasonography of optic nerve sheath, and ophthalmoscopy were performed for them. The optic nerves sheath with diameter more than 5 millimeters was considered as elevated ICP. Widening of optic nerve, ocular venous engorgement, blurring, hemorrhage over optic disk, elevation of optic disk, and retinal venous tortuosity were recorded as evidences of ICP rising in ophthalmoscopy. Diagnostic accuracy of the two tools in prediction of ICP rising were compared with the results of brain CT scan as a gold standard. The mean age of participants was 46.29 ± 10 years (77% male). The number of diagnosed elevated ICPs with ophthalmoscopy and ultrasound were 98 (74.8%) and 102 (77.9%) cases, respectively. The calculated sensitivity and specificity of ophthalmoscopy and ultrasonography in detection of ICP rising were 100.0% (95% CI: 88.6-100.0) and 35.4% (95% CI: 26.0-46.2), 100.0% (95% CI: 84.0-100.0) and 31.9% (95% CI: 23.0-41.7), respectively. The present study revealed that bedside ultrasonography of optic nerve sheath and ophthalmoscopy have enough accuracy for the screening of patients with probable elevation of ICP. Of course, it should be considered that despite the high sensitivity of both tools, their specificity is low.

Intracranial Pressure Monitoring in Severe Traumatic Brain Injury

Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels.An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter.All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: −80.5 + 238.2 × AON.In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.

Ultrasonography of the optic nerve sheath in brain death

Evaluation of optic nerve sheath by means of optic nerve ultrasonography (ONUS) is a reliable tool for assessment of patients with increased intracranial pressure. The aim of this study was to present the usefulness of optic nerve sheath ultrasonography in patients with brain death. Ten patients with brain death as a result of traumatic or non-traumatic causes were evaluated by ONUS. Optic nerve sheath diameter (ONSD) was measured with a 12 MHz linear ultrasound probe (Terason T3000, Teratech Corporation, USA). The probe was adjusted to give a suitable angle for displaying the entry of the optic nerve into the globe, at the depth of 3 mm behind the globe. For each optic nerve four measurements were made, twice in transversal and twice in the sagittal plane, by rotating the probe clockwise. Mean ONSD for brain death patients were compared with mean ONSD of 17 healthy controls. Ten individuals (7 males) with confirmed brain death (5 due to neurotrauma, 2 due to subarachnoid hemorrhage, 2 as a result of ischemic strokes and one of parenchymal hemorrhage), were evaluated. On the left side mean ONSD was 0.71 ± 0.06 cm on transversal plane and 0.72 ± 0.04 cm on sagittal plane. On the right side mean ONSD was 0.73 ± 0.05 cm on transversal plane and 0.73 ± 0.06 on sagittal plane. In controls left mean ONSD was 0.51 ± 0.05 cm on transversal plane and 0.55 ± 0.06 cm on sagittal plane. On the side right mean ONSD was 0.52 ± 0.05 cm on transversal plane and 0.54 ± 0.07 on sagittal plane. Mean ONSD in brain death was 0.72 ± 0.05 cm and 0.53 ± 0.06 cm in controls (p < 0.01). Measurements of ONSD may be useful in distinguishing brain death persons from healthy controls.

Evidence for Increased Intracranial Pressure in High Altitude Pulmonary Edema

We sought to determine if optic nerve sheath diameter (ONSD), a surrogate measure of ICP, is increased in high altitude pulmonary edema (HAPE). Five HAPE patients (one with a codiagnosis of high altitude cerebral edema [HACE]) treated at the Himalayan Rescue Association clinic in Pheriche, Nepal (4240 m), underwent optic nerve sheath ultrasonography (ONSU) at admission to determine ONSD. Results were compared to ONSD in 32 control subjects at the same altitude without evidence of altitude illness. Four of the five HAPE patients underwent repeat ONSU at discharge. All exams were read by two blinded observers. The mean ONSD for HAPE patients on presentation was 5.7 +/- 0.44 mm and for controls was 4.7 +/- 0.56 mm (p = 0.003). Excluding the patient with a coexistent clinical diagnosis of HACE, mean ONSD at presentation for the other four HAPE patients was 5.7 +/- 0.50 mm and was significantly different from controls (p = 0.007). In the four HAPE patients with repeat exams, ONSD decreased by 17% +/- 15% (95% CI 4-30%) between admission and discharge. We conclude that HAPE is associated with increased ONSD, a surrogate measure of increased ICP.

Optic Nerve Sheath Ultrasonography: A Novel Method for Assessing Intracranial Pressure in Acute Mountain Sickness

Optic Nerve Sheath Ultrasonography: A Novel Method for Assessing Intracranial Pressure in Acute Mountain Sickness

Optic Nerve Sheath Ultrasonography: A Novel Way to Assess Intracranial Pressure in Acute Mountain Sickness

Optic Nerve Sheath Ultrasonography: A Novel Way to Assess Intracranial Pressure in Acute Mountain Sickness