Ultrasonography of optic nerve sheath diameter for detection of raised intracranial pressure: a systematic review and meta-analysis. Intensive Care Med. 2011;37:1059-1068. [PMID: 21505900 DOI: 10.1007/s00134-011-2224-2]

Correlation of optic nerve and optic nerve sheath diameter with intracranial pressure in pigs

Objective

Several studies have shown an association between intracranial pressure and the diameter of the optic nerve sheath measured by transbulbar ultrasonography. To understand the pathophysiology of this phenomenon, we aimed to measure the changes of the optic nerve, optic nerve sheath and perineural space separately with increasing intracranial pressure in a porcine model.

Methods

An external ventricular drain was placed into the third ventricle through a right paramedian burrhole in eight anesthesized pigs. The diameters of the optic nerve and the optic nerve sheath were measured while the intracranial pressure (ICP) was increased in steps of 10mmHg from baseline up to 60 mmHg.

Results

The median diameters of the optic nerve (ON) increased from 0.36 cm (baseline– 95% confidence interval (CI) 0.33 cm to 0.45 cm) to 0.68 cm (95% CI 0.57 cm to 0.82 cm) at ICP of 60 mmHg (p<0.0001) and optic nerve sheath (ONS) from 0.88 cm (95% CI 0.79 cm to 0.98 cm) to 1.24 cm (95% CI 1.02 cm to 1.38 cm) (p< 0.002) while the median diameter of the perineural space (PNS) (baseline diameter 95% CI 0.40 cm to 0.59 cm to diameters at ICP 60 95% CI 0.38 cm to 0.62 cm) did not change significantly (p = 0.399). Multiple comparisons allowed differentiation between baseline and values ≥40 mmHg for ON (p = 0.017) and between baseline and values ≥ 50mmHg for ONS (p = 0.006). A linear correlation between ON (R² = 0.513, p<0.0001) and ONS (R² = 0.364, p<0.0001) with ICP was found. The median coefficient of variation for intra- and inter-investigator variability was 8% respectively 2.3%.

Conclusion

Unexpectedly, the increase in ONS diameter with increasing ICP is exclusively related to the increase of the diameter of the ON. Further studies should explore the reasons for this behaviour.

Optic nerve sheath diameter in children with acute liver failure: A prospective observational pilot study

BACKGROUND & AIMS

Early detection of raised intracranial pressure (ICP) improves outcome in acute liver failure (ALF). We evaluated the feasibility of bedside, ultrasound-guided measurement of optic nerve sheath diameter (ONSD) in normal and ALF children and correlation of ONSD with grade of hepatic encephalopathy (HE), international normalized ratio (INR) and blood ammonia (BA).

METHODS

Forty-one ALF and 47 healthy children (5-18 years) were prospectively enrolled and 12 hourly clinical evaluation was done. Laboratory parameters including INR and BA were recorded. ONSD was measured at admission, change in HE grade and at recovery in ALF, and once in controls.

RESULTS

One hundred and twenty-one ONSD measurements (ALF-74, controls-47) were taken without complications. ONSD was 4.2 (3.9-4.3), 4.4 (4.0-4.6), 5.2 (4.8-5.8) and 3.9 (3.3-4.1) mm in controls, ALF without HE, with HE and at recovery respectively. ONSD was significantly higher in ALF with HE than those without HE. ALF without HE and at recovery had ONSD similar to controls. ONSD was higher in ALF with the clinical signs of raised ICP than those without (5.4 [4.9-5.7] vs 4.6 [4.1-5.3] mm; P = .01). ONSD of 4.6 mm differentiated ALF with HE vs without HE and 5.1 mm between poor vs good non-transplant outcome with ≥80% sensitivity and specificity. ONSD positively correlated with INR (r = .53, P < .001) and BA (r = .42, P = .002).

CONCLUSIONS

ONSD can be safely and easily measured in ALF children and correlates with HE grade, INR and BA. Normal ONSD in children (>4 years) is <4.5 mm and value of >5.1 mm in ALF requires urgent attention.

Checklists to guide the supportive and critical care of tuberculous meningitis

The assessment and management of tuberculous meningitis (TBM) is often complex, yet no standardised approach exists, and evidence for the clinical care of patients, including those with critical illness, is limited. The roles of proformas and checklists are increasing in medicine; proformas provide a framework for a thorough approach to patient care, whereas checklists offer a priority-based approach that may be applied to deteriorating patients in time-critical situations. We aimed to develop a comprehensive assessment proforma and an accompanying 'priorities' checklist for patients with TBM, with the overriding goal being to improve patient outcomes. The proforma outlines what should be asked, checked, or tested at initial evaluation and daily inpatient review to assist supportive clinical care for patients, with an adapted list for patients in critical care. It is accompanied by a supporting document describing why these points are relevant to TBM. Our priorities checklist offers a useful and easy reminder of important issues to review during a time-critical period of acute patient deterioration. The benefit of these documents to patient outcomes would require investigation; however, we hope they will promote standardisation of patient assessment and care, particularly of critically unwell individuals, in whom morbidity and mortality remains unacceptably high.

Optic nerve sheath diameter measurement for predicting raised intracranial pressure in adult patients with severe traumatic brain injury: A meta-analysis

OBJECTIVE

To evaluate and compare the diagnostic feasibility of measuring the optic nerve sheath diameter (ONSD), via brain computed tomography (CT) and ocular ultrasonography (US) for prediction of raised intracranial pressure (ICP) in severe traumatic brain injury (TBI) patients.

METHODS

The PubMed and EMBASE databases were searched for studies assessing the diagnostic accuracy of brain CT or ocular US for predicting raised ICP. Bivariate and hierarchical summary receiver operating characteristic modeling were performed to evaluate and compare the diagnostic feasibility of measuring the ONSD in adult patients with severe TBI according to modality (ocular US vs. brain CT).

RESULTS

Five studies (four with ocular US and one with brain CT) were included. The ONSD had a pooled sensitivity of 0.91, pooled specificity of 0.77, and area under the HSROC curve of 0.92 for predicting raised ICP. More importantly, studies using ocular US found an almost equal sensitivity (0.91 vs. 0.90; p = .35) and higher specificity (0.82 vs. 0.58; p = .01) than those using brain CT.

CONCLUSIONS

Measurement of the ONSD may be a useful method for predicting raised ICP in adult patients with severe TBI.

Ultrasonographic optic nerve sheath diameter monitoring of elevated intracranial pressure: two case reports

Ultrasonography assessments of optic nerve sheath diameter (ONSD) is a non-invasive method that may help identify elevated intracranial pressure (ICP). However, this technique was used to evaluate the elevated ICP caused by traumatic brain injury. The objective of this study was to examine clinical cases of the changes in ICP with venous sinus stenosis and venous sinus thrombosis found the advantage of this technique in the application. And we dynamically monitor ONSD and ICP as a lens for understanding the dynamic assessment for ICP. The first case of venous sinus stenosis with elevated ICP identified in real-time by changes in ONSD, which are correlated with ICP before and after stenting. Another case of venous sinus thrombosis with elevated ICP. And after treatment, the patient underwent an ultrasound ONSD examination and lumbar puncture (LP) at the 1st, the 2nd and 3rd month of follow-up. The previously enlarged ONSDs retracted and LP opening pressure gradually returned to normal. These cases indicate that ONSD examination may help dynamically assess ICP changes and evaluate the efficacy of ICP treatment. These results provide utile, evidence based, preliminary clinical recommendations and indicate that ONSD examination might be a useful method of evaluating ICP, especially if repeated evaluations are needed.

Non-invasive assessment of ICP in children: advances in ultrasound-based techniques

The assessment of intracranial pressure (ICP) in children with neurological disease remains a cornerstone in their routine management. The quest for a reliable, reproducible and radiation-free non-invasive technique for assessing ICP in children remains somewhat of a holy grail for neurosurgery. This work assesses some of the recent advances in ultrasound-based techniques, addressing both novel processes and modifications aimed at improving the accuracy of existing techniques.

Bedside Optic Nerve Ultrasonography for Diagnosing Increased Intracranial Pressure: A Systematic Review and Meta-analysis

BACKGROUND

Optic nerve ultrasonography (optic nerve sheath diameter sonography) has been proposed as a noninvasive, quick method for diagnosing increased intracranial pressure.

PURPOSE

To examine the accuracy of optic nerve ultrasonography for diagnosing increased intracranial pressure in children and adults.

DATA SOURCES

13 databases from inception through May 2019, reference lists, and meeting proceedings.

STUDY SELECTION

Prospective optic nerve ultrasonography diagnostic accuracy studies, published in any language, involving any age group or reference standard.

DATA EXTRACTION

3 reviewers independently abstracted data and performed quality assessment.

DATA SYNTHESIS

Of 71 eligible studies involving 4551 patients, 61 included adults, and 35 were rated as having low risk of bias. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of optic nerve ultrasonography in patients with traumatic brain injury were 97% (95% CI, 92% to 99%), 86% (CI, 74% to 93%), 6.93 (CI, 3.55 to 13.54), and 0.04 (CI, 0.02 to 0.10), respectively. Respective estimates in patients with nontraumatic brain injury were 92% (CI, 86% to 96%), 86% (CI, 77% to 92%), 6.39 (CI, 3.77 to 10.84), and 0.09 (CI, 0.05 to 0.17). Accuracy estimates were similar among studies stratified by patient age, operator specialty and training level, reference standard, sonographer blinding status, and cutoff value. The optimal cutoff for optic nerve sheath dilatation on ultrasonography was 5.0 mm.

LIMITATION

Small studies, imprecise summary estimates, possible publication bias, and no evaluation of effect on clinical outcomes.

CONCLUSION

Optic nerve ultrasonography can help diagnose increased intracranial pressure. A normal sheath diameter measurement has high sensitivity and a low negative likelihood ratio that may rule out increased intracranial pressure, whereas an elevated measurement, characterized by a high specificity and positive likelihood ratio, may indicate increased intracranial pressure and the need for additional confirmatory tests.

PRIMARY FUNDING SOURCE

None. (PROSPERO: CRD42017055485).

Optic nerve sheath diameter measurement for predicting raised intracranial pressure in pediatric patients: A systematic review and meta-analysis

Background and objectives:

No previous studies have investigated the relationship between the optic nerve sheath diameter and raised intracranial pressure in pediatric patients or have evaluated the usefulness of optic nerve sheath diameter in ocular ultrasound and brain computed tomography/magnetic resonance imaging. This study aimed to meta-analyze the diagnostic performance of optic nerve sheath diameter for the diagnosis of raised intracranial pressure in pediatric patients.

Methods:

A database search of PubMed and EMBASE was performed to identify relevant studies. Bivariate modeling and hierarchical summary receiver operating characteristics modeling were performed to evaluate diagnostic performance. A pooled diagnostic odds ratio with a 95% confidence interval, not including 1, was considered informative. Subgroup analysis was performed according to the modality (ocular ultrasound vs brain computed tomography/magnetic resonance imaging). We performed meta-regression analyses for heterogeneity exploration.

Results:

Eleven studies involving 546 patients were included. According to pooled diagnostic odds ratios, optic nerve sheath diameter was informative for the evaluation of raised intracranial pressure (diagnostic odds ratio, 47; 95% confidence interval, 11–206). Optic nerve sheath diameter showed a pooled sensitivity of 0.88 (95% confidence interval, 0.79–0.94), a pooled specificity of 0.86 (95% confidence interval, 0.70–0.95), and an area under the hierarchical summary receiver operating characteristics curve of 0.93 (95% confidence interval, 0.91–0.95) for the diagnosis of raised intracranial pressure. According to the subgroup analysis, ocular ultrasound (sensitivity, 0.91 (95% confidence interval, 0.81–0.96); specificity, 0.86 (95% confidence interval, 0.65–0.96)) showed higher sensitivity and comparable specificity than optic nerve sheath diameter measured on brain computed tomography/magnetic resonance imaging (sensitivity, 0.75 (95% confidence interval, 0.51–0.99); specificity, 0.91 (95% confidence interval, 0.74–1.00)). On meta-regression analysis, the study design, number of patients, and reference standard were the sources of heterogeneity.

Conclusion:

Optic nerve sheath diameter may be a useful method for predicting raised intracranial pressure in pediatric patients. We recommend that the measurement of optic nerve sheath diameter should be performed using ocular ultrasound for a more accurate diagnosis of raised intracranial pressure in pediatric patients.

Salmonella typhi Meningitis in an Immunocompetent Asian Adult

Enteric salmonella infections are common in the United States though nonenteric salmonella infections in immunocompetent adults are exceedingly rare in the United States, and meningitis is one of the least common extra-intestinal sites. In addition, it is very unusual for a patient with bacterial meningitis to present with meningitis signs and symptoms of >72 h duration like aseptic meningitis. 

A 25-year-old Indian male, without any past medical history brought by friends to the ER had fever and irritability for a week. He became increasingly somnolent and confused three days back. Physical exam reveals signs of meningitis and laboratory showed cerebrospinal fluid (CSF) studies suggestive of bacterial meningitis. Culture of CSF grew Salmonella typhi and later on blood culture also grew S. typhi. The patient became worse with cerebral edema and hydrocephalous suspected by change in neurological status and confirmed by ultrasound of eye ball examining optic nerve sheath diameter and CT scan of brain. The patient required neurosurgical intervention and hence external ventricular drain was placed. The patient was also placed on mechanical ventilation. Subsequently he developed ventilator associated pneumonia (VAP) with carbapenem-resistant Pseudomonas aeruginosa. The patient underwent tracheostomy and successfully completed treatment of VAP and was transferred to his home country after four months. Thus we describe a rare case of salmonella meningitis in an immunocompetent adult.

The effect of prolonged steep head-down laparoscopy on the optical nerve sheath diameter

Both the steep head-down position and pneumoperitoneum increase the intracranial pressure (ICP), and their combination for a prolonged period during laparoscopic radical prostatectomy (LRP) might influence the central nervous system homeostasis. Changes in optic nerve sheath diameter (ONSD) may reflect those in ICP. This study aims to quantify the change in ONSD in response to peritoneal CO₂ insufflation and steep Trendelenburg position during LRP. ONSD was measured by ultrasound in 20 patients undergoing LRP and ten awake healthy volunteers. In patients, ONSD was assessed at baseline immediately after induction of general anesthesia in supine position, 10 and 60 min from baseline in a 25° head-down position during pneumoperitoneum, and after deflation of pneumoperitoneum with the patient supine at 0° angle. ONSD in controls was assessed at baseline with the patient lying supine, after 10 and 60 min of 25° head-down position, and 10 min after repositioning at 0° angle. ONSD increased significantly in both patients and controls (p < 0.0001) without between-group differences. The mean increase was 10.3% (95% CI 7.7-12.9%) in patients versus 7.5% (95% CI 2.5-12.6%) in controls (p = 0.28), and didn't affect the time to recovery from anesthesia. In the studied patients, with a limited increase of end-tidal CO₂ and airway pressure, and low volume fluid infusion, the maximal ONSD was always below the cut-off value suspect for increased ICP. ONSD reflects the changes in hydrostatic pressure in response to steep Trendelenburg position, and its increase might be minimized by careful handling of general anesthesia.

Neurocritical care monitoring of encephalopathic children with acute liver failure: A systematic review

Research on non-invasive neuromonitoring specific to PALF is limited. This systematic review identifies and synthesis the existing literature on non-invasive approaches to monitoring for neurological sequelae in patients with PALF. A series of literature searches were performed to identify all publications pertaining to five different non-invasive neuromonitoring modalities, in line with PRISMA guidelines. Each modality was selected on the basis of its potential for direct or indirect measurement of cerebral perfusion; studies on electroencephalographic monitoring were therefore not sought. Data were recorded on study design, patient population, comparator groups, and outcomes. A preponderance of observational studies was observed, most with a small sample size. Few incorporated direct comparisons of different modalities; in particular, comparison to invasive intracranial pressure monitoring was largely lacking. The integration of current evidence is considered in the context of the clinically significant distinctions between pediatric and adult ALF, as well as the implications for planning of future investigations to best support the evidence-based clinical care of these patients.

Checklists to guide the supportive and critical care of tuberculous meningitis

The assessment and management of tuberculous meningitis (TBM) is often complex, yet no standardised approach exists, and evidence for the clinical care of patients, including those with critical illness, is limited. The roles of proformas and checklists are increasing in medicine; proformas provide a framework for a thorough approach to patient care, whereas checklists offer a priority-based approach that may be applied to deteriorating patients in time-critical situations. We aimed to develop a comprehensive assessment proforma and an accompanying 'priorities' checklist for patients with TBM, with the overriding goal being to improve patient outcomes. The proforma outlines what should be asked, checked, or tested at initial evaluation and daily inpatient review to assist supportive clinical care for patients, with an adapted list for patients in critical care. It is accompanied by a supporting document describing why these points are relevant to TBM. Our priorities checklist offers a useful and easy reminder of important issues to review during a time-critical period of acute patient deterioration. The benefit of these documents to patient outcomes would require investigation; however, we hope they will promote standardisation of patient assessment and care, particularly of critically unwell individuals, in whom morbidity and mortality remains unacceptably high.

Reliability of Assessing Non-severe Elevation of Intracranial Pressure Using Optic Nerve Sheath Diameter and Transcranial Doppler Parameters

Background/Aims: Non-invasive measurement of intracranial pressure (ICP) using ultrasound has garnered increasing attention. This study aimed to compare the reliability of ultrasonographic measurement of optic nerve sheath diameter (ONSD) and transcranial Doppler (TCD) in detecting potential ICP elevations. Methods: Patients who needed lumbar puncture (LP) in the Department of Neurology were recruited from December 2016 to July 2017. The ONSD and TCD measurements were completed before LP. Results: One hundred sixty-five participants (mean age, 41.96 ± 14.64 years; 80 men; 29 patients with elevated ICP) were included in this study. The mean ICP was 170 ± 52 mmH₂O (range, 75-400 mmH₂O). Univariate analyses revealed that ICP was non-significantly associated with TCD parameters and significantly associated with ONSD (r = 0.60, P < 0.001). The mean ONSD of the elevated ICP group was significantly higher than that of the normal ICP group (4.53 ± 0.40 mm vs. 3.97 ± 0.23 mm; P < 0.001). Multivariate linear regression determined that the difference between ICP and ONSD is significant. Conclusions: In the early stage of intracranial hypertension, ONSD is more reliable for evaluating ICP than TCD.

Point-of-care ultrasound: its growing application in hospital medicine

Point-of-care ultrasound is emerging as an important adjunct to the clinical examination. Ultrasonography has long been seen as a modality for experts but this is changing and it is hoped that, with appropriate training, point-of-care ultrasound will become a modern-day diagnostic necessity.

Intracranial pressure monitoring: Gold standard and recent innovations

Intracranial pressure monitoring (ICP) is based on the doctrine proposed by Monroe and Kellie centuries ago. With the advancement of technology and science, various invasive and non-invasive modalities of monitoring ICP continue to be developed. An ideal monitor to track ICP should be easy to use, accurate, reliable, reproducible, inexpensive and should not be associated with infection or haemorrhagic complications. Although the transducers connected to the extra ventricular drainage continue to be Gold Standard, its association with the likelihood of infection and haemorrhage have led to the search for alternate non-invasive methods of monitoring ICP. While Camino transducers, Strain gauge micro transducer based ICP monitoring devices and the Spiegelberg ICP monitor are the emerging technology in invasive ICP monitoring, optic nerve sheath diameter measurement, venous opthalmodynamometry, tympanic membrane displacement, tissue resonance analysis, tonometry, acoustoelasticity, distortion-product oto-acoustic emissions, trans cranial doppler, electro encephalogram, near infra-red spectroscopy, pupillometry, anterior fontanelle pressure monitoring, skull elasticity, jugular bulb monitoring, visual evoked response and radiological based assessment of ICP are the non-invasive methods which are assessed against the gold standard.

Ultrasound measurements versus invasive intracranial pressure measurement method in patients with brain injury: a retrospective study

BACKGROUND

The invasive method for intracranial pressure measurement is 'gold standard' but not always feasible because the intraventricular catheter/ intraparenchymal micro transducer used in the measurement of intracranial pressure measurement may cause complications. Imaging modalities with clinical examination protocol have a lack of specificity and accuracy. The objective of the study was to compare the accuracy of diagnostic parameters of ultrasound measurements in patients with brain injury underwent invasive intracranial pressure measurement method.

METHODS

Data of invasive intracranial pressure measurement method and ultrasound measurements of 185 patients with brain injury who required admission diagnosis were included in the analysis. Pearson correlation was tested for diagnostic parameters. Logistical regression analysis was performed for diagnostic parameters of death patients to evaluate independent parameter of mortality.

RESULTS

Straight sinus flow velocities, middle cerebral artery flow velocities, and optic nerve sheath diameter were correlated with intracranial pressure (p < 0.0001 for all). Arterial blood pressure (p = 0.127) and middle cerebral artery pulsatility index (p = 0.06) were not correlated with intracranial pressure. A total of 47 patients died during the study period. Intracranial pressure (p = 0.015) and optic nerve sheath diameter (p = 0.035) were found to be independent predictor of mortality.

CONCLUSIONS

Ultrasound measurement especially optic nerve sheath diameter can be successfully used instead of invasive intracranial pressure measurement method in patients with brain injury.

LEVEL OF EVIDENCE

III.

Automated Optic Nerve Sheath Diameter Measurement Using Super-pixel Analysis

The optic nerve is a part of the central nervous system surrounded by cerebrospinal fluid and is encased in a sheath. Changes to the cerebrospinal fluid due to injury, tumor rupture and so on can increase intracranial pressure (ICP) and can result in changes in the sheath diameter. Measuring the changes in the sheath can be done through ultrasound imaging with which the optic nerve sheath diameter can be measured. Since this approach is non-invasive, it would reduce the cost for patients and healthcare if sheath diameter could be used as a predictor of increase in ICP. However, the manual measurement of the nerve sheath diameter is very time consuming and could be affected by human errors. In this paper we propose an image processing approach in which the optic nerve sheath diameter is measured automatically. In our proposed method, we first denoise images and then detect the region of interest using a simple line integral method. After that by analyzing super-pixels we measure the diameter. We compared the results of the proposed method with manual measurements from two experts. The average percentage of error between the proposed method and the experts' measurements did not substantially differ from the error between the two experts.

A noninvasive method for the estimation of increased intracranial pressure in patients with severe traumatic brain injury using optic nerve sheath diameter measured on computed tomography head

Background:

Measurement of optic nerve sheath diameter (ONSD) using ocular ultrasonography has shown a promise in predicting increased intracranial pressure (ICP). However, this method is dependent on operator technique and equipment availability. We propose an alternative method of measuring ONSD and Marshall score grading by utilizing initial computed tomography (CT) head obtained on admission. We believe that such a technique could help predict patients requiring an invasive ICP monitor on admission.

Methods:

Patients were retrospectively selected from the neurosurgery database of a level II trauma center. Control patients originated from a database of nontraumatic brain injury (TBI) patients with a negative CT head and no intracranial pathology. Study subjects included patients aged 18–90 years, who sustained a severe TBI requiring placement of an ICP monitor on admission. All patients had a non-contrast CT head before the placement of an ICP monitor. Patients receiving any intervention for decreasing suspected elevated ICPs and those with any documented orbital fractures before ICP monitor placement were excluded from the study. All measurements were performed by at least of two independent assessors.

Results:

A total of 242 patients were reviewed, of which 204 (100 control and 104 intervention) met inclusion criteria for this study. T he average age in the control group was 49.1 ± 22.9 years old while the average age of the intervention group was 36.9 ± 15.1 years (P < 0.0001). The average Glasgow Coma Scale was 7 in the intervention group. The average ONSD of the control group was 5.73 ± 0.58 mm compared to 6.76 ± 0.83 mm in the intervention group (P < 0.0001). Linear regression analysis demonstrated a statistically significant correlation between ONSD and opening ICP (r = 0.40, P < 0.001) and peak ICP (r = 0.31, P < 0.0001). An ONSD ≥6.0 mm + Marshall score ≥3 on initial CT head demonstrated a 92.5% sensitivity, 92.6% specificity, and 96.1% positive predictive value for developing an ICP ≥20 mmHg during hospitalization.

Conclusion:

Utilizing ONSD in combination with Marshall score grading on initial CT head is a strong predictor of elevated ICP. These criteria can be used in future studies to develop more objective criteria to guide ICP monitor placement.

Noninvasive Transorbital Assessment of the Optic Nerve Sheath in Children: Relationship Between Optic Nerve Sheath Diameter, Deformability Index, and Intracranial Pressure

BACKGROUND

Measurement of optic nerve sheath diameter (ONSD) is a promising technique for noninvasive assessment of intracranial pressure (ICP), but has certain limitations. A recent study showed that the deformability index (DI), a dynamic parameter quantifying the pulsatile nature of the optic nerve sheath, could differentiate between patients with high vs normal ICP.

OBJECTIVE

To further evaluate the diagnostic accuracy of the DI, when interpreted together with ONSD.

METHODS

This prospective study included children undergoing invasive ICP measurement as part of their clinical management. Ultrasound images of the optic nerve sheath were acquired prior to measuring ICP, the images were further processed to obtain the DI. Patients were dichotomized into high (≥20 mm Hg) or normal ICP groups and compared using the Mann-Whitney U-test. Diagnostic accuracy was described using area under the receiver operating characteristic curve (AUC), sensitivity and specificity, correlation between DI, ONSD, and ICP was investigated using linear regression.

RESULTS

A total of 28 patients were included (19 high ICP). The DI was lower in the high ICP group (0.105 vs 0.28, P = .001). AUC was 0.87, and a cut-off value of DI ≤ 0.185 demonstrated sensitivity of 89.5% and specificity of 88.9%. Diagnostic accuracy improved when combining DI with ONSD (AUC 0.98, sensitivity 94.7%, specificity 88.9%) and correlation with ICP improved when combined analysis of DI and ONSD was performed (Pearson correlation coefficient: 0.82 vs 0.42, respectively, P = .012).

CONCLUSION

The DI was significantly lower for patients with high vs normal ICP. This relationship improved further when the DI and ONSD were interpreted together.

Point-of-Care Ultrasound Abnormalities in Late-Onset Severe Preeclampsia: Prevalence and Association With Serum Albumin and Brain Natriuretic Peptide

BACKGROUND

Pilot studies applying point-of-care ultrasound (POCUS) in preeclampsia indicate the presence of pulmonary interstitial edema, cerebral edema, and cardiac dysfunction. Laboratory markers of oncotic pressure (albumin) and cardiac dysfunction (brain natriuretic peptide [BNP]) may be abnormal, but the clinical application remains unclear. We investigated the prevalence of pulmonary interstitial syndrome (PIS), cardiac dysfunction, and increased optic nerve sheath diameter (ONSD) in late-onset preeclampsia with severe features. The primary aim was to examine the association between PIS or ONSD and maternal serum albumin level. The secondary aims were to explore the association between cardiac dysfunction and PIS, ONSD, BNP, and serum albumin level and between POCUS-derived parameters and a suspicious or pathological cardiotocograph.

METHODS

Ninety-five women were enrolled in this prospective observational cohort study. A POCUS examination of lungs, heart, and ONSD was performed. PIS was defined as a bilateral B-line pattern on lung ultrasound and diastolic dysfunction according to an algorithm of the American Society of Echocardiography. ONSD >5.8 mm was interpreted as compatible with raised intracranial pressure (>20 mm Hg). Serum BNP and albumin levels were also measured.

RESULTS

PIS, diastolic dysfunction, systolic dysfunction, and raised left ventricular end-diastolic pressure (LVEDP) were present in 23 (24%), 31 (33%), 9 (10%), and 20 (25%) women, respectively. ONSD was increased in 27 (28%) women. Concerning the primary outcome, there was no association between albumin level and PIS (P = .4) or ONSD (P = .63). With respect to secondary outcomes, there was no association between albumin level and systolic dysfunction (P = .21) or raised LVEDP (P = .44). PIS was associated with diastolic dysfunction (P = .02) and raised LVEDP (P = .009; negative predictive value, 85%). BNP level was associated with systolic (P < .001) and diastolic dysfunction (P = .003) and LVEDP (P = .007). No association was found between POCUS abnormalities and a suspicious/pathological cardiotocograph (P = .07).

CONCLUSIONS

PIS, diastolic dysfunction, and increased ONSD were common in preeclampsia with severe features. Cardiac ultrasound abnormalities may be more useful than albumin levels in predicting PIS. The absence of PIS may exclude raised LVEDP. The further clinical relevance of PIS and raised ONSD remains to be established. BNP level was associated with cardiac ultrasound abnormalities. Although this study was not designed to directly influence clinical management, the findings suggest that POCUS may serve as a useful adjunct to clinical examination for the obstetric anesthesiologist managing these complex patients.

Diagnostic tool for initial evaluation of the intracranial pressure on computed tomography in pediatric patients with headache

BACKGROUND

Headache is one of the most common complaints among pediatric patients and can be due to many causes, some benign but others potentially seriously. Increased intracranial pressure, which is known to cause papilledema, is a serious cause of headache, and immediate diagnosis is critical, although difficult. The current study evaluates the diagnostic value of optic nerve sheath diameter (ONSD) and eyeball transverse diameter (ETD) ratio in pediatric patients presenting with headache and papilledema.

METHODS

A retrospective analysis of all pediatric patients undergoing head computed tomography scans between January 2013 and December 2015. Patients with normal brain scans were included in the study. Patients presenting with headache underwent funduscopic evaluation and grouped as either headache with papilledema or headache without papilledema. A control group of patients without headache was also included. Studies were reviewed blindly by a neuroradiologist and ONSD and ETD for both eyes were measured.

RESULTS

ONSD/ETD index was found to have significantly higher values (p<0.001) in patients with papilledema (median 0.24, interquartile range (IQR) = 0.22-0.25) compared to patients without papilledema (median 0.18, IQR = 0.16-0.19) and the control group (median 0.17, IQR = 0.15-0.18). The ONSD/ETD index showed excellent discrimination ability for patients with headache and papilledema (AUC = 0.96, 95% CI, 0.94-0.99). The ONSD/ETD index of 0.21 was found to have a sensitivity and specificity of 82% and 93%, respectively, for identifying pediatric patients with headache and papilledema.

CONCLUSION

Our study shows that ONSD/ETD index of 0.21 can be used as an easy-to-use reference tool for diagnosing papilledema and elevated intracranial pressure in pediatric patients.

Prediction of Early Intracranial Hypertension After Severe Traumatic Brain Injury: A Prospective Study

OBJECTIVE

This study aimed to assess the reliability of clinical features, noninvasive transcranial Doppler-related pulsatility index (PI) calculation, and optic nerve sheath diameter (ONSD) measured by ultrasound (US) and initial computed tomography (CT) scan (Marshall CT scan classification) in predicting the occurrence of early (<24 hours) high intracranial pressure (EHICP) (>20 mm Hg) after severe traumatic brain injury (TBI).

METHODS

We conducted an observational prospective study in a level 1 trauma center. Patients were measured simultaneously for PI and US ONSD in the triage zone. Patients were categorized into 2 groups: those who had EHICP after TBI (EHICP+) and those who did not (EHICP-).

RESULTS

Fifty-four patients were included; 32 were categorized as EHICP+ and 22 as EHICP-. PI >1.4 did not correlate with EHICP+ patients (69% vs. 46%, P = 0.09). US ONSD measurement was higher in the EHICP+ group (6.25; range, 6-6.95 vs. 5.7; range, 5.2-6.4; P = 0.005). The area under the receiver operating characteristic curve for US ONSD as a predictor of developing EHICP was 0.73 (95% confidence interval [CI], 0.59-0.86). CT ONSD measurement was higher in the EHICP+ group (6.71; range, 6.35-7.87 vs. 6.25; range, 5.8-6.93; P = 0.04). The area under the receiver operating characteristic curve for CT ONSD measurement as a predictor for EHICP+ was 0.67 (95% CI, 0.53-0.81). The diffuse injury III and IV categories in the Marshall CT scan classification were associated with the occurrence of EHICP (P = 0.004).

CONCLUSIONS

None of the clinical features or noninvasive tools assessed in this study enabled clinicians to strictly ascertain EHICP. Further studies are needed to establish their potential role before intracranial pressure probe insertion.

The Use of Ultrasound-Measured Optic Nerve Sheath Diameter to Predict Ventriculoperitoneal Shunt Failure in Children

OBJECTIVE

The goal of this study was to assess the accuracy of ultrasound-measured optic nerve sheath diameter (ONSD) as a screen for ventriculoperitoneal shunt failure.

METHODS

We prospectively enrolled a convenience sample of children presenting to the ED with suspected shunt failure. The ONSD was measured by ultrasound and compared with computed tomography/magnetic resonance imaging (CT/MRI) and neurosurgical impression. We defined shunt failure on ultrasound as an ONSD greater than 4.0 mm in infants 12 months and younger or greater than 4.5 mm in children older than 12 months. A single emergency radiologist at our institution read all CTs and MRIs for categorical determination of shunt failure. We defined shunt failure based on neurosurgical impression as a decision to admit and perform shunt revision. We report test characteristics and 95% confidence intervals of ONSD as a predictor for shunt failure.

RESULTS

We enrolled 32 subjects. The sensitivities of ONSD compared with CT/MRI and neurosurgical impression, 60.0% and 75.0%, respectively, were low. However, the negative predictive values of ONSD compared with CT/MRI and neurosurgical impression were 90.0% and 95.0%, respectively.

CONCLUSIONS

Optic nerve sonography may be a useful tool to identify children presenting with suspected ventriculoperitoneal shunt failure who do not require further imaging. This would reduce the use of CT scan and exposure to ionizing radiation in children with suspected shunt malfunction who do not require neurosurgical intervention. Consideration of additional risk factors and a larger sample size may yield stronger results.

Measurement of changes in optic nerve sheath diameter using ultrasound and computed tomography scan before and after the ventriculoperitoneal shunt surgery in patients with hydrocephalus - A prospective observational trial

BACKGROUND

The standard methods for measuring intracranial pressure (ICP) are invasive in nature. Non invasive methods such as ONSD may help circumvent these complications and may serve as a surrogate marker for increased ICP. The primary aim of this study was to assess the ONSD (optic nerve sheath diameter) changes using ultrasonography (USG) and computed tomography (CT) scan in hydrocephalus patients before and after the insertion of VP shunt.

MATERIALS AND METHODS

A prospective observational study was conducted among 69 patients undergoing VP shunt surgery between the ages of 2 to 60 years. ONSD variation was measured by USG and CT scan both before and after the surgery. The difference in the pre-operative and post-operative ONSD measurement was analyzed using a paired t-test. Whereas, the measurements of ONSD were compared for agreement between two modalities (USG and CT) using Interclass correlation (ICC) and Bland Altman graph plot.

RESULTS

Among 69 patients 38 were males, 31 were females and 12 were under the age of 10 years. In the adult group, average preoperative and postoperative ONSD measurement by USG was 5.80 ± 0.63 mm and 4.52 ± 0.72 (p < 0.001) and by CT was 5.77 ± 0.83 mm and 4.49 ± 0.76 mm (p < 0.001) respectively. Similarly, in the pediatric population, average preoperative and postoperative ONSD measurement by USG was found to be 4.76 ± 1.14 mm and 3.90 ± 1.08 mm and by CT was found to be 4.75+/-1.11 mm and 3.85 ± 1.09 mm respectively (p <0.001).

CONCLUSION

In patients with hydrocephalus undergoing VP shunt surgery, we found a significant reduction in ONSD after the shunt insertion in both pediatric and adult population. We also found a good correlation between the USG and CT scan measurements of ONSD.

Optic nerve sheath diameter-guided extubation plan in obese patients undergoing robotic pelvic surgery in steep Trendelenburg position: A report of three cases

Robotic pelvic surgery requires steep Trendelenburg positioning with pneumoperitoneum which causes raised thoracic and intracranial pressures. In obese patients, the basal thoracic pressures are high. Increased intrathoracic pressure can decrease the cranial venous flow leading to deficient intracranial absorption of cerebrospinal fluid and a further increase in intracranial pressure. Operating times are also longer due to unfavorable anatomy. Such patients frequently have a delayed awakening from anaesthesia due to a combination of factors such as hypercapnoea, acidosis, and raised intracranial pressures. Normocapnoea can be achieved in a ventilated patient towards the end of surgery. In cases where the anaesthetic agents have been washed out and normocapnoea has been achieved, the intracranial pressure may be an important factor causing delayed emergence. The sonographically measured optic nerve sheath diameter correlates with the intracranial pressure. We report three cases of robot-assisted pelvic surgery in obese patients where we used the optic nerve sheath diameter as a guide for the timing of extubation.

Ultrasonic Assessment of Optic Nerve Sheath to Detect Increased Intracranial Pressure

Purpose

Increased intracranial pressure (ICP) is one of the prevalent symptoms of trauma, especially traumatic headache, which requires quick action for the diagnosis and treatment. The optic nerve sheath diameter (ONSD) is a newly proposed technique for the detection of an increase in ICP. The aim of this study was to assess the efficacy of this new diagnostic method in patients with increased ICP induced by trauma.

Methods

This prospective study was conducted between December 2016 and February 2017. The patients with traumatic headache and who had been diagnosed with increased ICP using clinical signs and computed tomography scan were compared to the voluntary healthy group. In each patient, measurements were performed employing ultrasound three times on each eye in an axial region, and the mean of these sizes was obtained as the ONSD.

Results

A total of 112 participants were examined. The mean ONSD measurement of the patients and the voluntary healthy group was 6.01 ± 0.76 and 3.41 ± 0.56 mm in the right eye, 6.11 ± 0.75 and 3.39 ± 0.54 mm in the left eye, and 6.06 ± 0.75 and 4.02 ± 1.07 mm in both sides, respectively. The ONSD in the right and left sides had high and significant correlation in the patients (r = 0.929, P < 0.000) and voluntary healthy (r = 0.630, P < 0.000) group. The mean ONSD of one of the patients was 6.24 ± 0.56 mm, and in another patient with no clinical sign of increased ICP, the mean ONSD was 4.61 ± 0.09 mm.

Conclusions

Ultrasound performed on the diaphragm of the optic nerve with acceptable sensitivity can detect patients with an increase in ICP and can be efficacious in expediting the action needed to reduce ICP. Due to the sensitivity and specificity of the ultrasound and high accuracy of the diameter of optic nerve sheath in detecting increase in ICP, as well as considering the fact that ultrasound is a noninvasive and available technique; it can be performed at the patient's bedside.

Ultrasonography Monitoring of Optic Nerve Sheath Diameter and Retinal Vessels in Patients with Cerebral Hemorrhage

BACKGROUND AND PURPOSE

Evaluation of the diagnostic accuracy of optic nerve sheath diameter (ONSD) and Doppler indices of central retinal arteries and veins for the detection of increased intracranial pressure (ICP) in intracerebral hemorrhage (ICH) and of the usefulness of a second assessment of these variables in the monitoring of ICH.

METHODS

A total of 46 acute ICH patients with (group 1, n = 25) and without (group 2, n = 21) clinical and radiological computed tomography signs of raised ICP and 40 healthy controls were recruited. The median binocular ONSD and Doppler indices of retinal vessels including resistive index (RI) and retinal venous pulsation (RVP) were compared among groups, both at admission and later during ICH monitoring.

RESULTS

Median binocular ONSD showed higher accuracy for the detection of increased ICP (sensitivity and specificity 100%), while Doppler indices were less accurate (sensitivity 48% and specificity 95% for RI; 80% and 62% for RVP). In ICH patients, ONSD was significantly elevated in group 1 both at admission (6.40 mm [interquartile range [IQR] = .70] vs. 4.70 [.40]) and at control time (6.00 [.55] vs. 4.55 [.40]; P < .01), as well as RI (.79 [.11] vs. .77 [.03] and .80 [.06] vs. .75 [.35]; P = .01). RVP was significantly increased in group 1 only at admission (3.20 cm/s [1.05] vs. 2.00 [1.55], P = .02).

CONCLUSIONS

Median binocular ONSD evaluation showed higher accuracy for the estimation of elevated ICP compared with Doppler indices of retinal vessels. The ONSD enlargement detected in the early phase of ICH persists at control time.

Ultrasonographic optic nerve sheath diameter to detect increased intracranial pressure in adults: a meta-analysis

BACKGROUND

The optimal optic nerve sheath diameter (ONSD) cut-off for identifying increased intracranial pressure (IICP) remains unclear in adult patients.

PURPOSE

To validate the diagnostic accuracy of ultrasonographic (US) ONSD > 5.0 mm as a cut-off for detecting IICP by computed tomographic (CT) through a meta-analysis.

MATERIAL AND METHODS

A systemic literature review was performed of online databases from January 1990 to September 2017. A bivariate random-effects model was used to estimate pooled sensitivity, specificity, and diagnostic odds ratio (DOR) with 95% confidence intervals (CIs). A summary receiver operating characteristic (SROC) graph was used to provide summary points for sensitivity and specificity. Meta-regression tests were performed to estimate the influence of the study characteristics on DOR. Publication bias was assessed using Deeks' funnel plot asymmetry test.

RESULTS

Six studies with 352 patients were included in the meta-analysis. US ONSD > 5.0 mm revealed pooled sensitivity of 99% (95% CI = 96-100) and specificity of 73% (95% CI = 65-80) for IICP detection. DOR was 178. The area under the SROC curve was 0.981, indicating a good level of accuracy. Meta-regression studies showed no significant associations between DOR and study characteristics such as probe mode (relative DOR [RDOR] = 0.60; P = 0.78), study quality (RDOR = 0.52; P = 0.67), IICP prevalence (RDOR = 0.04; P = 0.17), or pathology at admission (RDOR = 1.30; P = 0.87).

CONCLUSION

US ONSD > 5.0 mm can be used to rapidly detect IICP in adults in emergency departments and intensive care units. Further meta-analysis based on individual patient-level databases is needed to confirm these results.

Role of Decompressive Craniectomy in Ischemic Stroke

Ischemic stroke is one of the leading causes for death and disability worldwide. In patients with large space-occupying infarction, the subsequent edema complicated by transtentorial herniation poses a lethal threat. Especially in patients with malignant middle cerebral artery infarction, brain swelling secondary to the vessel occlusion is associated with high mortality. By decompressive craniectomy, a significant proportion of the skull is surgically removed, allowing the ischemic tissue to shift through the surgical defect rather than to the unaffected regions of the brain, thus avoiding secondary damage due to increased intracranial pressure. Several studies have shown that decompressive craniectomy reduces the mortality rate in patients with malignant cerebral artery infarction. However, this is done for the cost of a higher proportion of patients who survive with severe disability. In this review, we will describe the clinical and radiological features of malignant middle cerebral artery infarction and the role of decompressive craniectomy and additional therapies in this condition. We will also discuss large cerebellar stroke and the possibilities of suboccipital craniectomy.

A comparison of non-invasive versus invasive measures of intracranial pressure in hypoxic ischaemic brain injury after cardiac arrest

AIM

Increased intracranial pressure (ICP) in hypoxic ischaemic brain injury (HIBI) can cause secondary ischaemic brain injury and culminate in brain death. Invasive ICP monitoring is limited by associated risks in HIBI patients. We sought to evaluate the agreement between invasive ICP measurements and non-invasive estimators of ICP (nICP) in HIBI patients.

METHODS

Eligible consecutive adult (age>18) cardiac arrest patients with HIBI were included as part of a single centre prospective interventional study. Invasive ICP monitoring and nICP measurements were undertaken using: a) transcranial Doppler ultrasonography (TCD), b) optic nerve sheet diameter ultrasound (ONSD) and c) jugular venous bulb pressure (JVP). Multiple measurements applied in linear mixed-effects models were considered to obtain the correlation coefficient between ICP and nICP as well as their predictive abilities to detect intracranial hypertension (ICP≥20mm Hg).

RESULTS

Eleven patients were included (median age of 47 [range 20-71], 8 males and 3 females). There was a linear relationship between ICP and nICP with ONSD (R=0.53 [p<0.0001]), JVP (R=0.38 [p<0.001]) and TCD (R=0.30 [p<0.01]). The ability to predict intracranial hypertension was highest for ONSD and TCD (area under the receiver operating curve (AUC)=0.96 [95% CI: 0.90-1.00] and AUC=0.91 [95% CI: 0.83-1.00], respectively). JVP presented the weakest prediction ability (AUC=0.75 [95% CI: 0.56-0.94]).

CONCLUSIONS

ONSD and TCD methods demonstrated agreement with invasively-monitored ICP, suggesting their potential roles in the detection of intracranial hypertension in HIBI after cardiac arrest.

Military trainees can accurately measure optic nerve sheath diameter after a brief training session

BACKGROUND

Identification of elevated intracranial pressure is important following traumatic brain injury. We assessed the feasibility of educating military trainees on accurately obtaining optic nerve sheath diameter measurements using a brief didactic and hands-on training session. Optic nerve sheath diameter is a noninvasive surrogate marker for elevated intracranial pressure, and may be of value in remote military operations, where rapid triage decisions must be made without access to advanced medical equipment.

METHODS

Military trainees with minimal ultrasound experience were given a 5-min didactic presentation on optic nerve sheath diameter ultrasound. Trainees practiced optic nerve sheath diameter measurements guided by emergency physician ultrasound experts. Trainees then measured the optic nerve sheath diameter on normal volunteers. Following this, a trained physician measured the optic nerve sheath diameter on the same volunteer as a criterion standard. An average of three measurements was taken.

RESULTS

Twenty-three military trainees were enrolled. A mixed design ANOVA was used to compare measurements by trainees to those of physicians, with a mean difference of - 0.6 mm (P = 0.76). A Bland-Altman analysis showed that the degree of bias in optic nerve sheath diameter measures provided by trainees was very small: d = - 0.004 for the right eye and d = - 0.007 for the left eye.

CONCLUSION

This study demonstrates that optic nerve sheath diameter measurement can be accurately performed by novice ultrasonographers after a brief training session. If validated, point-of-care optic nerve sheath diameter measurement could impact the triage of injured patients in remote areas.

Diagnostic and prognostic value of the optic nerve sheath diameter with respect to the intracranial pressure and neurological outcome of patients following hemicraniectomy

BACKGROUND

In cases showing cerebrospinal fluid (CSF) redistribution as a compensatory mechanism in acute intracranial hypertension, the optic nerve sheath diameter (ONSD) can be used to estimate intracranial pressure (ICP). However, it remains unclear whether the ONSD can be applied in patients with skull defects after a craniectomy, because the primary injury or surgical craniectomy may alter the dynamics of the CSF circulation or structure of the optical nerve sheath. This study explored the value of the ONSD in patients after a hemicraniectomy.

METHODS

This prospective observational study enrolled patients after a hemicraniectomy. All patients underwent invasive ICP monitoring and ocular ultrasound within 6 h postoperatively. We followed the patients for 6 months and evaluated them using the Glasgow Outcome Score (GOS), classifying the outcome as favorable (GOS 4-5) or unfavorable (GOS 1-3). We evaluated the ONSD in both according to the ICP and neurological outcome.

RESULTS

Of the 33 enrolled patients, 20 (60.6%) had an unfavorable outcome at 6 months. Disagreement was seen in the ONSD measurements between the eyes [craniectomy side (ONSDips) and opposite side (ONSDcon)]. The intraclass correlation coefficient between ONSDips and ONSDcon was 0.745 (p < 0.001). ONSD had no significant correlation with ICP in Spearman correlation analysis (ONSDips r = 0.205, p = 0.252; ONSDcon r = 0.164, p = 0.362). Receiver operator characteristic (ROC) curve analysis revealed that the GCS, Helsinki computed tomography (CT) score, pupil reaction, and ONSDcon measured after the craniectomy were significantly associated with a poor outcome. ONSDcon > 5.5 mm predicted a poor outcome, with an area under the ROC curve of 0.717 (95% confidence interval, 0.534-0.860, p = 0.02), 70% sensitivity, and 69.2% specificity.

CONCLUSIONS

After hemicraniectomy, the ONSD measured on ultrasound was unreliable for evaluating ICP, but showed potential prognostic value for a poor neurological outcome.

Optic nerve ultrasound for fluid status assessment in patients with severe preeclampsia

Background There are no data on usefulness of optic nerve sheath diameter (ONSD) as a marker of patient's fluid status in preeclampsia. The objective was to examine potential correlation between ONSD and lung ultrasound estimates of extravascular lung water in severe preeclampsia. Patients and methods Thirty patients with severe preeclampsia were included. Optic and lung ultrasound were performed within 24 hours from delivery. ONSD was measured 3 mm behind the globe. Lung ultrasound Echo Comet Score (ECS) was obtained summing B-lines ("comet tails") in parasternal intercostal spaces bilaterally. Pearson's correlation analysis was used to assess the relationship between ONSD and ECS (p < 0.05 significant). Results Median ONSD was 5.7 mm (range 3.8-7.5 mm). Median ECS value was 19 (range 0-24). Statistically significant correlation was found between ONSD and ECS (r2 = 0.464; p < 0.001). Conclusions Significant correlation between ONSD and ECS suggests optic ultrasound could be used for assessing fluid status and guiding peripartum fluid therapy in patients with severe preeclampsia.

Ultrasonic measurement of optic nerve sheath diameter: a non-invasive surrogate approach for dynamic, real-time evaluation of intracranial pressure

The current study aimed to identify whether ultrasonographic measurements of optic nerve sheath diameter (ONSD) could dynamically and sensitively evaluate real-time intracranial pressure (ICP). ONSD measurements were performed approximately 5  min prior to and after a lumbar puncture (LP). A total of 84 patients (mean±SD age, 43.5±14.7 years; 41 (49%) men; 18 patients with elevated ICP) were included in the study. The Spearman correlation coefficients between the two observers were 0.779 and 0.703 in the transverse section and 0.751 and 0.788 in the vertical section for the left and right eyes, respectively. The median (IQR) change in ONSD (ΔONSD) and change in ICP (ΔICP) were 0.11 (0.05–0.21) mm and 30 (20–40) mmH₂O, respectively, for all participants. With a reduction in cerebrospinal fluid pressure, 80 subjects (95%) showed an immediate drop in ONSD; the median (IQR) decreased from 4.13 (4.02–4.38) mm to 4.02 (3.90–4.23) mm (p<0.001). Significant correlations were found between ONSD and ICP before LPs (r=0.482, p<0.01) and between ΔONSD and ΔICP (r=0.451, p<0.01). Ultrasonic measurement of ONSD can reflect the relative real-time changes in ICP.

Multimodality Monitoring in Neurocritical Care: Decision-Making Utilizing Direct And Indirect Surrogate Markers

Substantial progress has been made to create innovative technology that can monitor the different physiological characteristics that precede the onset of secondary brain injury, with the ultimate goal of intervening prior to the onset of irreversible neurological damage. One of the goals of neurocritical care is to recognize and preemptively manage secondary neurological injury by analyzing physiologic markers of ischemia and brain injury prior to the development of irreversible damage. This is helpful in a multitude of neurological conditions, whereby secondary neurological injury could present including but not limited to traumatic intracranial hemorrhage and, specifically, subarachnoid hemorrhage, which has the potential of progressing to delayed cerebral ischemia and monitoring postneurosurgical interventions. In this study, we examine the utilization of direct and indirect surrogate physiologic markers of ongoing neurologic injury, including intracranial pressure, cerebral blood flow, and brain metabolism.

Automatic Estimation of the Optic Nerve Sheath Diameter from Ultrasound Images

We present an algorithm to automatically estimate the diameter of the optic nerve sheath from ocular ultrasound images. The optic nerve sheath diameter provides a proxy for measuring intracranial pressure, a life threating condition frequently associated with head trauma. Early treatment of elevated intracranial pressures greatly improves outcomes and drastically reduces the mortality rate. We demonstrate that the proposed algorithm combined with a portable ultrasound device presents a viable path for early detection of elevated intracranial pressure in remote locations and without access to trained medical imaging experts.