Correlation of optic nerve sheath diameter with direct measurement of intracranial pressure

Optic nerve ultrasonography in monitoring treatment efficacy in pediatric idiopathic intracranial hypertension

PURPOSE

Measurement of optic nerve sheath diameter (ONSD) with ocular ultrasonography (USG) is a noninvasive technique that can be readily used to determine clues of increased intracranial pressure. In this study, we aimed to determine the role of optic nerve sheath diameter measurements in the diagnosis and follow-up of pediatric patients with idiopathic intracranial hypertension (IIH).

METHODS

Eight patients with a diagnosis of IIH with a median age of 11.7 (range 4.5-17) years were examined prospectively. During follow-up, orbital ultrasonography (USG) was performed immediately prior to lumbar puncture (LP) and at 24 h, at 1 week, and between 1 and 18 months after LP. Cranial MRI examinations and automated visual field assessments were performed at baseline and at 3 months, and both measurements were compared with each other.

RESULTS

The mean cerebrospinal fluid opening pressure (37.75 ± 12.64 cm H₂O) and the mean ONSD (5.94 ± 0.46 mm) were correlated. The median follow-up was 16 (range, 12-18 months), and ONSD regressed gradually consistent with clinical and radiologic improvement during follow-up.

CONCLUSIONS

To the best of our knowledge, this is the first prospective pilot study performed on pediatric patients with IIH using orbital USG for ONSD measurements. Despite the small sample size, the present study indicated that orbital USG may be used as a promising noninvasive tool to diagnose increased intracranial pressure and for monitoring treatment efficacy in this special patient population.

Review: pathophysiology of intracranial hypertension and noninvasive intracranial pressure monitoring

Measurement of intracranial pressure (ICP) is crucial in the management of many neurological conditions. However, due to the invasiveness, high cost, and required expertise of available ICP monitoring techniques, many patients who could benefit from ICP monitoring do not receive it. As a result, there has been a substantial effort to explore and develop novel noninvasive ICP monitoring techniques to improve the overall clinical care of patients who may be suffering from ICP disorders. This review attempts to summarize the general pathophysiology of ICP, discuss the importance and current state of ICP monitoring, and describe the many methods that have been proposed for noninvasive ICP monitoring. These noninvasive methods can be broken down into four major categories: fluid dynamic, otic, ophthalmic, and electrophysiologic. Each category is discussed in detail along with its associated techniques and their advantages, disadvantages, and reported accuracy. A particular emphasis in this review will be dedicated to methods based on the use of transcranial Doppler ultrasound. At present, it appears that the available noninvasive methods are either not sufficiently accurate, reliable, or robust enough for widespread clinical adoption or require additional independent validation. However, several methods appear promising and through additional study and clinical validation, could eventually make their way into clinical practice.

Bedside Ultrasonographic Assessment of Optic Nerve Sheath Diameter As a Means of Detecting Raised Intracranial Pressure in Neuro-Trauma Patients: A Cross-Sectional Study

Background:

Optic nerve sheath diameter (ONSD) measurement is emerging as a noninvasive method to estimate raised ICP. It is helpful in situations where imaging of brain or direct ICP monitoring is not available or feasible. Use of ONSD is still limited, so this study was planned to determine whether the bedside sonographic measurement of ONSD can reliably predict elevated ICP in neuro-trauma patients.

Methodology:

After approval from Hospital Ethics Committee, this cross-sectional study was conducted in hundred traumatic brain injury (TBI) patients with suspected elevated ICP, admitted to neurosurgical ICU. The severity of brain injury was assessed according to Glasgow coma scale (GCS), initial CT scan findings, and revised trauma score (RTS). All patients underwent ONSD sonography of the eye and CT scan subsequently. ONSD of ≥5.0 mm was considered as a benchmark of raised ICP.

Results:

Mean ONSD of the study group with ONSD ≥5.0 mm was 5.6 ± 0.3 mm. ONSD was raised in 46% of patients, more so in patients with low GCS (3-6). The relationship of ONSD with GCS, CT scan findings, and RTS was highly significant. The sensitivity of the bedside sonographic measurement ONSD to detect raised ICP was 93.2% and specificity was 91.1% when compared with CT scan. Positive Predictive Value of the ONSD measurement was 89.1% and the negative predictive value was 94.4%.

Conclusion:

Ultrasonographic assessment of ONSD is a reliable modality to detect raised ICP in neurotrauma patients. It can be helpful in the early initiation of treatment of elevated ICP, thus preventing secondary brain damage.

Effects of prone positioning with neck extension on intracranial pressure according to optic nerve sheath diameter measured using ultrasound in children

PURPOSE

Optic nerve sheath diameter has been used for measure of intracranial pressure. The aim of this study was to evaluate the effect of prone positioning with neck extension on intracranial pressure in infants undergoing craniosynostosis surgery and to determine precautions using optic nerve sheath diameter measurement.

METHODS

We enrolled 30 infants who were scheduled for correction of craniosynostosis in which planning included the prone position with neck extension. Optic nerve sheath diameter (anterior/lateral transbulbar approach) was measured 5 times in each eyeball at the following time points: 15 min after intubation in supine position as the baseline value (supine 1); 10 min after final surgical position before skin incision (prone); and 10 min after returning to supine position at the conclusion of surgery (supine 2). Hemodynamic parameters, airway peak pressure, oxygen saturation, and E_TCO₂ were monitored. Data were analyzed using repeated-measures multivariate analysis of variance to evaluate the effect of different positions under anesthesia on changes in using optic nerve sheath diameter and P < 0.05 was considered to be statistically significant.

RESULTS

There was no difference in optic nerve sheath diameter after prone position with neck extension in all the measure. After surgery, optic nerve sheath diameter was decreased compared with the preoperative baseline values (Rt anterior/lateral 5.6/5.5: 5.4/5.2; Lt anterior/lateral 5.6/5.5: 5.4/5.3, P < 0.05, respectively).

CONCLUSIONS

In conclusion, prone positioning with head extension did not further increase intracranial pressure, although the surgical procedure could reduce intracranial pressure in the immediate postoperative period in infants undergoing craniosynostosis surgery.

Optic nerve sheath diameter as a predictor of acute cerebellar infarction in acute vertigo patients without brain computed tomography abnormalities

Background and objectives:

To date, no study has investigated the ability of optic nerve sheath diameter calculated from non-contrast brain computed tomography to predict acute cerebellar infarction in patients with acute vertigo. The aim of our study was to evaluate the predictive utility of optic nerve sheath diameter for diagnosing acute cerebellar infarction in patients with acute vertigo without computed tomography abnormalities.

Methods:

We retrospectively enrolled patients with acute vertigo without computed tomography abnormalities who underwent magnetic resonance imaging including diffusion-weighted imaging at our emergency department between January 2016 and December 2017. Two emergency physicians independently measured optic nerve sheath diameter at 3 mm (ONSD3) and 10 mm (ONSD10) behind the globe in each patient. Final magnetic resonance imaging reports with clinical progress notes were used as the reference standard. A multivariate logistic regression analysis, receiver operating characteristic curves, and intra-class correlation coefficients were calculated to estimate predictive value.

Results:

A total of 34 patients (16.1%) were diagnosed with acute infarction and 177 patients (83.9%) were diagnosed with peripheral vertigo. Mean ONSD3 ( p < 0.001) and ONSD10 ( p < 0.001) were independent predictive factors for distinguishing acute infarction and peripheral vertigo. ONSD3 (cut-off = 4.22 mm) had 100% (95% confidence interval = 89.7–100.0) sensitivity and 97.7% (95% confidence interval = 95.1–99.6) specificity with area under the receiver operating characteristic curve of 0.988 (95% confidence interval = 0.978–1.0), while ONSD10 (cut-off = 3.63 mm) had 100% (95% confidence interval = 89.7–100.0) sensitivity and 87.6% (95% confidence interval = 81.8–92.0) specificity with area under the receiver operating characteristic curve of 0.976 (95% confidence interval = 0.959–0.997). There were good inter- and intra-observer agreements for both sides of ONSD3 and ONSD10 (intra-class correlation coefficient range = 0.652–0.773).

Conclusion:

Optic nerve sheath diameter, in particular OSND3, is a feasible predictive marker for acute infarction in patients with acute vertigo without computed tomography abnormalities. This information can assist decision-making in ordering brain magnetic resonance imaging for the assessment of acute vertigo.

Point-of-care ultrasound of optic nerve sheath diameter to detect intracranial pressure in neurocritically ill children - A narrative review

The rapid diagnosis of increased intracranial pressure is urgently needed for therapeutic reasons in neurocritically ill children, however this can rarely be achieved without invasive procedures. Point-of-care ultrasound of the optic nerve sheath diameter has been proposed as a non-invasive and reliable means to detect increased intracranial pressure in adults. Accordingly, clinicians may be able to use this technique to initiate early treatment and monitor the effectiveness of treatment in conjunction with other clinical examination and diagnostic modalities. Two meta-analyses and a systematic review have been published on this topic in adults. However, data on the correlation between optic nerve sheath diameter and intracranial pressure in neurocritically ill children are scarce. The aim of this review was to briefly describe what is being measured with point-of-care ultrasound of the optic nerve sheath diameter, summarize the most recent findings from adult literature, and provide an update of current work in children.

Comparison of Two Techniques to Measure Optic Nerve Sheath Diameter in Patients at Risk for Increased Intracranial Pressure

OBJECTIVES

Intracranial pressure over 20 mm Hg is associated with poor neurologic prognosis, but measuring intracranial pressure directly requires an invasive procedure. Dilation of the optic nerve sheath on axial ultrasound of the eye has been correlated with elevated intracranial pressure, but optimal cutoffs have been inconsistent possibly related to the measurement technique. A coronal technique has been studied on healthy volunteers but not on patients with high intracranial pressure. We compared two measurement techniques (axial and coronal) in patients with suspected high intracranial pressure due to trauma, bleeding, tumor, or infection.

DESIGN

Prospective blinded observational study.

SETTING

Two tertiary referral center ICUs.

PATIENTS

Twenty adults admitted to the ICU at risk for increased intracranial pressure expected to receive invasive intracranial monitoring.

INTERVENTIONS

Ultrasound measurements of the optic nerve sheath in axial and coronal views either averaged between eyes or the highest in either eye.

MEASUREMENTS AND MAIN RESULTS

Coronal measurements showed less variability between each eye than axial measurements (mean difference 0.5 mm vs 1 mm; p = 0.03) and were associated with high intracranial pressure at first measurement and over 24 hours (area under the receiver operating characteristic range 0.7-0.8). Mean and highest axial measurements showed improved association with first (area under the receiver operating characteristic 0.87-0.94) and highest intracranial pressure measurement (area under the receiver operating characteristic 0.89-0.96) within 24 hours. A cutoff of highest axial measurement in either eye greater than 6.2 mm or mean axial measurement between eyes of 5.6 mm had a sensitivity of 100% in predicting high intracranial pressure over the following 24 hours.

CONCLUSIONS

The highest axial measurement of optic nerve sheath diameter in either eye is the most predictive of patients with high intracranial pressure in our population. This comparison of measurement techniques has not previously been described and should be further explored to set test cutoffs for ultrasound of the optic nerve sheath diameter.

Neurosurgery and Manned Spaceflight

There has been a renewed interest in manned spaceflight due to endeavors by private and government agencies. Publicized goals include manned trips to or colonization of Mars. These missions will likely be of long duration, exceeding existing records for human exposure to extra-terrestrial conditions. Participants will be exposed to microgravity, temperature extremes, and radiation, all of which may adversely affect their physiology. Moreover, pathological mechanisms may differ from those of a terrestrial nature. Known central nervous system (CNS) changes occurring in space include rises in intracranial pressure and spinal unloading. Intracranial pressure increases are thought to occur due to cephalad re-distribution of body fluids secondary to microgravity exposure. Spinal unloading in microgravity results in potential degenerative changes to the bony vertebrae, intervertebral discs, and supportive musculature. These phenomena are poorly understood. Trauma is of highest concern due to its potential to seriously incapacitate crewmembers and compromise missions. Traumatic pathology may also be exacerbated in the setting of altered CNS physiology. Though there are no documented instances of CNS pathologies arising in space, existing diagnostic and treatment capabilities will be limited relative to those on Earth. In instances where neurosurgical intervention is required in space, it is not known whether open or endoscopic approaches are feasible. It is obvious that prevention of trauma and CNS pathology should be emphasized. Further research into neurosurgical pathology, its diagnosis, and treatment in space are required should exploratory or colonization missions be attempted.

OPTIC NERVE SHEATH SONOGRAPHY IS A PROMISING TOOL FOR ASSESSMENT OF RAISED INTRACRANIAL PRESSURE IN PATIENTS ADMITTED TO NEUROLOGICAL INTENSIVE CARE UNIT

Optic nerve sheath diameter (ONSD) enlargement is detectable in traumatic brain injury patients with raised intracranial pressure (ICP). The aim was to assess its value in neurological patients suspected to have increased ICP. Patient clinical imaging data and hospitalization outcome were analyzed. Patients were divided into groups according to brain pathology and level of consciousness with Glasgow Coma Score (GCS). Poor hospitalization outcome was assessed by modified Rankin scale (mRS) >3. Data obtained by ocular sonography performed in acute setting were compared with data of 100 control subjects. Data were expressed as mean ± SD. Intergroup comparison was performed by Student’s t-test. Data of 34 patients (63+16 years) were suitable for analysis, including 8 primary intracerebral hemorrhage (PICH), 8 subarachnoid hemorrhage (SAH), 12 PICH or SAH and intraventricular hemorrhage (IVH), 4 tumors and 2 ischemic strokes. The mean ONSD was 5.86+0.69 mm in patients versus 4.38+0.41 mm in controls (p<0.01). ONSD was 6.28+0.61 mm in patients with GCS <8 and 5.77+0.55 mm in other patients (p<0.05). ONSD was 5.72+0.59 mm in PICH versus 6.20+0.65 mm in PICH/SAH with IVH (p=0.1). ONSD was 5.73+0.38 mm in SAH in comparison to PICH/SAH with IVH (p=0.05). There was no statistically significant difference in optic nerve diameter between patients and controls (2.48+0.28 mm vs. 2.39+0.33 mm; p>0.05). Pronounced enlargement of ONSD was observed in patients with ICH or SAH with IVH, and in patients with GCS <8. Enlarged ONSD was associated with poor neurological outcome (mRS >3).

Point-of-care handheld ophthalmic ultrasound in the diagnosis and evaluation of raised intracranial pressure and Terson syndrome: a description of two cases

BACKGROUND

Ultrasound (US) examination of the eye can be used to detect and monitor elevated intracranial pressure (ICP) and its consequences. Elevated ICP is transmitted to the contiguous optic nerve and its sheath (dura mater), thus underlying the development of papilledema and a widened sheath diameter. The US measurement of the optic nerve sheath diameter (ONSD) has previously been validated to diagnose and monitor raised ICP. The occurrence of vitreous hemorrhage in association with subarachnoid hemorrhage (SAH)-i.e., Terson syndrome-can also be easily diagnosed using ophthalmic US. Because of its relevance in anesthesia and critical care, we describe how to perform the technique illustrated by two cases.

CASE PRESENTATIONS

A 72-yr-old man with hydrocephalus secondary to a SAH developed raised ICP following the removal of an external ventricular drainage (EVD) system. Daily ONSD measurements using handheld US allowed us to diagnose and monitor the progression and resolution of the intracranial hypertension following the placement of a second EVD system. We also describe the steps used to obtain ONSD measurements during the ophthalmic US examination of a 53-yr-old woman who presented with a stage IV SAH with concomitant bilateral vitreous hemorrhages or Terson syndrome.

CONCLUSION

Ophthalmic US using a handheld device to measure and monitor ONSD at the bedside is useful in diagnosing and monitoring the progression of intracranial hypertension following EVD removal in a patient with hydrocephalus secondary to SAH. Ophthalmic US can also be used to identify concomitant vitreous hemorrhage that is associated with a worse prognosis.

Intracranial pressure patterns in children with craniosynostosis utilizing optical coherence tomography

BACKGROUND

Better understanding the incidence and patterns of elevated intracranial pressure (ICP) in patients with craniosynostosis may facilitate more timely intervention to alter neurocognitive outcomes. Spectral-domain optical coherence tomography (OCT) of the retina can non-invasively diagnose elevated ICP, and has demonstrated high sensitivity and specificity among patients with craniosynostosis. This study sought to characterize patterns of elevated ICP among patients with craniosynostosis.

METHODS

Quantitative retinal parameters were prospectively assessed in both eyes of patients with craniosynostosis using spectral-domain OCT. Based on retinal OCT thresholds associated with elevated ICP (> 15 mmHg), subjects were assigned an OCT diagnosis of elevated or non-elevated ICP which was analyzed relative to clinical characteristics and craniosynostosis patterns.

RESULTS

Eighty subjects (aged 0.2-18 years) with craniosynostosis were enrolled; among these, 67 (84%) were nonsyndromic. OCT evaluation was performed at initial vault expansion in 56 (70%) patients. Among this subset, 27 (48%) patients had peri-papillary changes suggestive of elevated ICP, reflecting a 44% incidence in nonsyndromic and 83% in syndromic patients. The median age at initial vault expansion was higher among those with elevated ICP (11.1 months) than those without (7.8 months; p = 0.04.) Multi-suture synostosis was associated with changes consistent with elevated ICP in 9 (75%) patients compared with 18 (41%) with single suture synostosis (p = 0.05).

CONCLUSIONS

OCT of the retina produces a potentially sensitive indicator of ICP in craniosynostosis patients. Elevated ICP may be associated with number of involved sutures and older patient presentation, and refining appropriate "cutoffs" will be important as the technology becomes more widespread.

Clinical Guidance for Point-of-Care Ultrasound in the Emergency and Critical Care Areas after Implementing Insurance Coverage in Korea

Point-of-care ultrasound (POCUS) is a useful tool that is widely used in the emergency and intensive care areas. In Korea, insurance coverage of ultrasound examination has been gradually expanding in accordance with measures to enhance Korean National Insurance Coverage since 2017 to 2021, and which will continue until 2021. Full coverage of health insurance for POCUS in the emergency and critical care areas was implemented in July 2019. The National Health Insurance Act classified POCUS as a single or multiple-targeted ultrasound examination (STU vs. MTU). STU scans are conducted of one organ at a time, while MTU includes scanning of multiple organs simultaneously to determine each clinical situation. POCUS can be performed even if a diagnostic ultrasound examination is conducted, based on the physician's decision. However, the Health Insurance Review and Assessment Service plans to monitor the prescription status of whether the POCUS and diagnostic ultrasound examinations are prescribed simultaneously and repeatedly. Additionally, MTU is allowed only in cases of trauma, cardiac arrest, shock, chest pain, and dyspnea and should be performed by a qualified physician. Although physicians should scan all parts of the chest, heart, and abdomen when they prescribe MTU, they are not required to record all findings in the medical record. Therefore, appropriate prescription, application, and recording of POCUS are needed to enhance the quality of patient care and avoid unnecessary cut of medical budget spending. The present article provides background and clinical guidance for POCUS based on the implementation of full health insurance coverage for POCUS that began in July 2019 in Korea.

A New Inexpensive Simulation Model for Ultrasound Assessment of Optic Nerve Sheath Diameter

BACKGROUND

Sonographic measurement of optic nerve sheath diameter (ONSD) is becoming increasingly accepted as a diagnostic modality to detect elevations in intracranial pressure. As this technique becomes more widespread, methods to address the inherent operator-dependent nature of this modality will need to be developed. We propose a novel low-cost model to accurately simulate sonographic ONSD measurement for purposes of training and assessment.

METHODS

We designed models composed of medical tubing of various diameters readily available from typical hospital supplies and suspended them in gelatin. The models were evaluated by ultrasound by three expert point-of-care sonographers using a standard linear array probe and technique proposed in the literature.

RESULTS

This model generates faithful simulation of the ONS that closely approximates in vivo images and can be used to produce accurate, reproducible measurements. Materials are low cost and easy to acquire and assemble.

CONCLUSIONS

Our model provides realistic simulated images of the ONS. Through comparison of sonographic measurements to the known tube diameters, this model serves as a promising inexpensive tool to teach the method of ultrasound assessment of ONSD or as a way to determine accuracy of this novel ultrasound technology.

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.

Trans-orbital sonography versus visual evoked potentials in acute demyelinating optic neuritis

Optic neuritis (ON) is an inflammatory demyelinating condition that causes acute - usually monocular - visual loss. It is highly associated with multiple sclerosis (MS). In general, ON is a clinical diagnosis based upon the history and examination findings.

OBJECTIVE

The aim was to assess the diagnostic accuracy of measuring optic nerve sheath diameter (ONSD) by ultrasound in acute optic neuritis.

METHODS

This is a prospective observational study with matched controls carried out on 25 patients and 25 controls. All patients presented with first attack of an acute demyelinating ON. Both patients and controls were submitted to clinical assessment, pattern and flash visual evoked potential and trans-orbital sonography (TOS) to measure the optic nerve sheath diameter (ONSD).

RESULTS

The ONSD was significantly thicker in patients with unilateral (0.6 ± 0.05 cm) and bilateral (0.6 ± 0.1 cm) optic neuritis compared to controls (0.52 ± 0.06 cm). P-value was < 0.001 and 0.04 respectively, with a cutoff value 0.57 cm. A significant negative correlation was found between the thickness of the ONSD and the visual acuity (r= -0.613, P-value <0.05). No correlation was found between the age of the patients and ONSD or between ONSD and latency of P-VEP. TOS showed 68% sensitivity and 88% specificity in diagnosing cases of ON.

CONCLUSION

ONSD measured by TOS is a noninvasive, inexpensive bed-side test, which represent a supporting tool to confirm the clinical diagnosis of ON. Yet its sensitivity and specificity are lower than P-VEP.

Intraosseous Administration of 23.4% NaCl for Treatment of Intracranial Hypertension

BACKGROUND/OBJECTIVE

Prompt treatment of acute intracranial hypertension is vital to preserving neurological function and frequently includes administration of 23.4% NaCl. However, 23.4% NaCl administration requires central venous catheterization that can delay treatment. Intraosseous catheterization is an alternative route of venous access that may result in more rapid administration of 23.4% NaCl.

METHODS

Single-center retrospective analysis of 76 consecutive patients, between January 2015 and January 2018, with clinical signs of intracranial hypertension received 23.4% NaCl through either central venous catheter or intraosseous access.

RESULTS

Intraosseous cannulation was successful on the first attempt in 97% of patients. No immediate untoward effects were seen with intraosseous cannulation. Time to treatment with 23.4% NaCl was significantly shorter in patients with intraosseous access compared to central venous catheter (p < 0.0001).

CONCLUSIONS

Intraosseous cannulation resulted in more rapid administration of 23.4% NaCl with no immediate serious complications. Further investigations to identify the clinical benefits and safety of hypertonic medication administration via intraosseous cannulation are warranted.

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.

The relation of optic nerve sheath diameter (ONSD) and intracranial pressure (ICP) in pediatric neurosurgery practice - Part I: Correlations, age-dependency and cut-off values

PURPOSE

It is assumed that the width of the optic nerve sheath diameter (ONSD) is dependent on intracranial pressure (ICP) and pulsatility and thus constitutes a non-invasively accessible "window" for qualitative assessment of ICP. Data on the correlation to invasively measured ICP in children are scarce and have often been obtained from sedated patients in intensive care unit (ICU) or intraoperatively. We report on a mixed cohort of pediatric neurosurgical patients, ICP and ONSD measurements were available from both sedated and awake children, only a minority from ICU patients.

METHODS

Seventy-two children were investigated. Ultrasound ONSD determination was performed immediately prior to invasive ICP measurement and the mean binocular ONSD was compared with ICP. The investigations were performed in children awake, sedated, or under general anesthesia.

RESULTS

In the entire patient cohort, the correlation between ONSD and ICP was good (r = 0.52, p < 0.01). Children > 1 year revealed a better correlation (r = 0.63; p < 0.01) and those ≤ 1 year did worse (r = 0.21). Infants with open fontanelle had no correlation. In the entire cohort, the best ONSD cut-off value for detecting ICP ≥ 15 and ≥ 20 mmHg was 5.28 and 5.57 mm (OR 22.5 and 7.2, AUC 0.782 and 0.733).

CONCLUSION

Transorbital ultrasound measurement of ONSD is a reliable non-invasive technique to assess increased ICP in children in every clinical situation; however, the impact of age and fontanelle status needs to be considered. ONSD thresholds enable qualitative first orientation regarding ICP categories with a very satisfying diagnostic accuracy.

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.

Role of ultrasonographic optic nerve sheath diameter in the diagnosis and follow-up of papilledema and its correlation with Frisén's severity grading

Purpose:

The aim of this study was to compare the ultrasonographic optic nerve sheath diameter (ONSD) in different grades of papilledema and in controls and to evaluate ONSD in atrophic papilledema/optic atrophy when raised ICP was suspected.

Methods:

Prospective cross-sectional case–control study. Following an ocular examination, papilledema was graded clinically using modified Frisén's grading. An ultrasonographic cross section of the retrobulbar optic nerve was obtained with a posterior transverse scan. Independent t-test and analysis of variance were the statistical tools used in the study.

Results:

The study included 55 cases and 55 age- and gender-matched controls; mean (± standard deviation) age was 37.17 (±11.25) years and male: female ratio was 49:61. There was a statistically significant difference in the mean ultrasonographic ONSD between cases [4.89 (±0.65) mm] and controls [3.12 (±0.22) mm] (P < 0.001). There was a significant difference in the mean ONSD across Frisén's grades of papilledema (P < 0.001). The mean ONSD in atrophic papilledema was 6.2 (±0.75) mm.

Conclusion:

In the presence of symptoms, ultrasonographic ONSD >4 mm is diagnostic of papilledema. Ultrasonographic ONSD correlates well with the severity of papilledema and can be used to follow-up patients with chronically elevated ICP. It is useful in detecting raised ICP in the presence of optic atrophy and to distinguish true papilledema from pseudopapilledema.

Propofol Affects Optic Nerve Sheath Diameter less than Sevoflurane during Robotic Surgery in the Steep Trendelenburg Position

Background

Robot-assisted laparoscopic radical prostatectomy (RLRP) can increase intracranial pressure (ICP) related to a change in position. Increasing ICP may result in various ocular complications, which are rare but serious, such as a corneal abrasion and ischemic optic neuropathy. We performed a prospective observational trial using ultrasonographic measurements to compare optic nerve sheath diameter (ONSD) related to ICP between patients who received either propofol or sevoflurane and underwent RLRP.

Methods

Thirty-two male patients scheduled to undergo RLRP were assigned into groups according to the anesthetic agent used (group P: propofol, n = 16; group S: sevoflurane, n = 16). ONSD, end-tidal partial pressure of CO₂, and blood pressure were measured 10 min after induction of anesthesia (T0), 30 min (T1), 60 min (T2), and 90 min after changing to the steep Trendelenburg position and introducing a pneumoperitoneum (T3) and 10 min after returning the patient's position to supine (T4) during surgery.

Results

No significant differences were observed in the demographic data of the patients, surgery time, or intraoperative variables, including hemodynamic and respiratory variables, at any of the time points. The mean right ONSDs in the propofol and sevoflurane groups were 37.3 and 40.1 mm at 30 min (p=0.003), respectively. The mean left ONSDs were 38.4 and 40.8 mm at 30 min (p=0.021) after changing to the Trendelenburg position. The ONSDs between the two groups were significantly different during surgery.

Conclusions

ONSD increased more in the sevoflurane group than in the propofol group during RLRP. Intravenous anesthetics could alleviate the increase in ICP during RLRP.

The Cushing reflex and the vasopressin-mediated hemodynamic response to increased intracranial pressure during acute elevations in intraabdominal pressure

BACKGROUND

Abdominal compartment syndrome has been linked to detrimental hemodynamic side effects that include increased intracranial pressure and diminished renal function, but the mechanisms behind this continue to be elucidated. In this study, we sought to investigate any direct association between acute elevations in intra-abdominal pressure and intracranial hypertension during experimentally induced abdominal compartment syndrome and between acutely elevated intracranial pressure and the hemodynamic response that might be elicited by a vasopressin-induced Cushing reflex affecting urine osmolality and urine output. The aim of this study is to explain the Cushing reflex and the vasopressin-mediated hemodynamic response to intracranial pressure during acute elevations in intra-abdominal pressure.

METHODS

We measured intra-abdominal pressure, intrathoracic pressure, optic nerve sheath diameter as an indirect sign of intracranial pressure, vasopressin levels in blood, urine osmolality, and urine output at 4 time points during surgery in 16 patients undergoing sleeve gastrectomy for morbid obesity. Values for the 4 time points were compared by repeated-measures analysis of variance.

RESULTS

More than 50-fold elevations in serum vasopressin paralleled increases in optic nerve sheath diameter, rising throughout prepneumoperitoneum and tapering off afterward, in conjunction with a marked decrease in urine but not serum osmolality. Mean arterial pressure rose transiently during pneumoperitoneum without elevated positive end-expiratory pressure but was not significantly elevated thereafter.

CONCLUSIONS

These findings support our hypothesis that the oliguric response observed in abdominal compartment syndrome might be the result of the acutely elevated intra-abdominal pressure triggering increased intrathoracic pressure, decreased venous outflow from the central nervous system, increased intracranial pressure, and resultant vasopressin release via a Cushing reflex.

Increased Intracranial Pressure Damages Optic Nerve Structural Support

Optic nerve sheath diameter (ONSD) is used clinically as a noninvasive measure for elevated intracranial pressure (ICP). This study had two purposes: to investigate the immediate effects optic nerve sheath (ONS) dilation post-ICP increase on trabecular fibers connecting the optic nerve to the ONS and to document any changes in these fibers 30 days post-increased ICP. In a swine model, ICP was increased by inflating a Foley catheter balloon in the epidural space. Three control pigs received the catheter insertion without inflation (no increase in ICP) and four experimental pigs received the catheter with inflation (increased ICP). The control and two randomly selected pigs with increased ICP were euthanized immediately after the procedure. The two other pigs were euthanized 30 days post-catheter inflation. For all pigs, the ONS was removed and imaged using a scanning electron microscope, calculating percent porosity values. Porosity values for the experimental groups (Immediately measured [IM] μ = 0.5749; Delayed measured [DM] μ = 0.5714) were larger than the control group (μ = 0.4336) and statistically significant (IM vs. Control, p = 0.0018; DM vs. Control, p = 0.0092). There was no significant difference (p = 0.9485) in porosity of the DM group when compared with the IM group. This study demonstrated that the trabecular fibers immediately post-increased ICP (ONS dilation) were more porous than the control and remained statistically different (more porous) after 30 days. These results suggest a structural change that occurs in the ONS with elevations in ICP.

Review of non-invasive intracranial pressure measurement techniques for ophthalmology applications

Assessment and monitoring of intracranial pressure (ICP) are important in the management of traumatic brain injury and other cerebral pathologies. In the eye, ICP elevation and depression both correlate with optic neuropathies, the former because of papilledema and the latter related to glaucoma. While the relationship between ICP elevation and papilledema is well established, the relationship between low ICP and glaucoma is still poorly understood. So far, ICP monitoring is performed invasively, but this entails risks including infection, spurring the study of non-invasive alternatives. We review 11 methods of non-invasive estimation of ICP including correlation to optic nerve sheath diameter, intraocular pressure, ophthalmodynamometry and two-depth transcranial Doppler of the ophthalmic artery. While none of these methods can fully replace invasive techniques, certain measures show great potential for specific applications. Although only used in small studies to date, a MRI based method known as MR-ICP, appears to be the best non-invasive technique for estimating ICP, with two-depth transcranial ultrasound and ophthalmodynamometry showing potential as well.

Optic nerve sheath diameter changes during gynecologic surgery in the Trendelenburg position: comparison of propofol-based total intravenous anesthesia and sevoflurane anesthesia

Background

Elevated intracranial pressure (ICP), a disadvantage of laparoscopic or robotic surgery, is caused by the steep angle of the Trendelenburg position and the CO₂ pneumoperitoneum. Recently, sonographically measured optic nerve sheath diameter (ONSD) was suggested as a simple and non-invasive method for detecting increased ICP. This study aimed to explore the changes in ONSD in relation to different anesthetic agents used in gynecologic surgery.

Methods

Fifty patients were randomly allocated to two groups, sevoflurane (group SEV, n = 25) and propofol-based total intravenous anesthesia (TIVA) group (group TIVA, n = 25). The ONSD was measured at five time points (T0–T4): T0 was measured 5 min after induction of anesthesia in the supine position; T1, T2, and T3 were measured at 5, 15, and 30 min after CO₂ pneumoperitoneum induction in the Trendelenburg position; and T4 was measured at 5 min after discontinuation of CO₂ pneumoperitoneum in the supine position. Respiratory and hemodynamic variables were also recorded.

Results

The intra-group changes in mean ONSD in the Trendelenburg position were significantly increased in both groups. However, inter-group changes in mean ONSD were not significantly different at T0, T1, T2, T3, and T4. Heart rates in group TIVA were significantly lower than those in group SEV at points T1–T4.

Conclusions

There was no significant difference in the ONSD between the two groups until 30 min into the gynecologic surgery with CO₂ pneumoperitoneum in the Trendelenburg position. This study suggests that there is no difference in the ONSD between the two anesthetic methods.

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.

Optic Nerve Sheath Measurements by Computed Tomography to Predict Intracranial Pressure and Guide Surgery in Patients with Traumatic Brain Injury

BACKGROUND

Research has shown that the optic nerve sheath diameter (ONSD) is a good predictor of intracranial pressure (ICP) and may predict the need for surgery in patients with head injury. The objective was to test the value of ONSD in predicting the requirement for surgery in patients with traumatic brain injury (TBI).

METHODS

In this retrospective cohort study, we first verified the correlation between ICP and ONSD using data from 62 patients with TBI who had undergone ICP monitoring. Second, we analyzed head computed tomography images from patients with TBI who were admitted to the emergency department where patients had been divided into surgery or conservative treatment groups, dependent on the assessment of a neurosurgeon. The correlation between ICP and ONSD was measured using linear regression analysis. Biologistic and receiver operating characteristic curve analyses were used to test the diagnostic value of ONSD to predict surgery.

RESULTS

ONSD was significantly correlated with ICP (r = 0.606; P < 0.01), and there was a significant linear regression equation (ŷ = 0.071 × ICP + 3.533; P < 0.01), with ONSD predicting the requirement for surgery in patients with TBI (area under the curve, 0.920; P < 0.01; 95% confidence interval, 0.877-0.962).

CONCLUSIONS

ONSD measured via head computed tomography correlates with ICP and can predict the requirement for surgery in patients with TBI following admission to the emergency department.

The Role of Transocular Ultrasound in the Assessment of Neurotoxicity-Related Encephalopathy in Mushroom Poisoning

Objective

Mushroom poisonings can lead to life-threatening organ dysfunctions and neurotoxicity-related encephalopathy. This study aimed to detect increased intracranial pressure by measuring optic nerve sheath diameter (ONSD) ultrasonographically and to determine its association with clinical and laboratory parameters.

Methods

In this prospective case-control study, we evaluated the patients aged above 18 years who presented to the emergency department with mushroom poisoning. Vital signs, clinical and laboratory parameters and ONSD of both eyes measured with transocular ultrasound were noted at initial admission and the 24th hour.

Results

We measured ONSD in 26 cases with mushroom poisoning and 26 healthy volunteers. Baseline ONSD measurements of the poisoning group were significantly higher than those of the control group (5.94±0.73 vs. 4.11±0.64, p<0.0001). ONSD values significantly regressed at 24th hour compared with the baseline measurements in the poisoning group (5.94±0.73 vs. 5.06±0.56, p<0.001).The ONSD values were significantly higher in patients who had a clinical picture of encephalopathy compared with patients who didn’t have (6.05±0.72 vs. 4.36±1.03, p<0.001). No significant deterioration was observed in ammonium levels, hepatic and renal functions of the patients.

Conclusion

We detected increased ONSDs in patients with mushroom poisoning compared with those in the control healthy volunteers. Our findings suggest that ONSD, measured by ultrasonography, may be safely and effectively used to diagnose transient encephalopathy associated with neurotoxicity.

Dynamic assessment of cerebral blood flow and intracranial pressure during inversion table tilt using ultrasonography

CONTEXT

Inversion tables are used as treatment for back pain, but there is a lack of agreement on systemic effects of inversion.

OBJECTIVE

To assess intracranial pressure (ICP) and cerebral blood flow using ultrasonography during inversion table tilt.

METHODS

Optic nerve sheath diameter (ONSD), heart rate (HR), blood pressure, internal carotid artery (ICA) and middle cerebral artery (MCA) blood flow of participants were measured in 3 positions: supine before inversion, during inversion with head down, and supine post-inversion. ONSD was evaluated with ocular ultrasonography and blood flow (ICA and MCA) with Doppler ultrasonography.

RESULTS

The ONSD changed significantly between the supine position, at 3 min of inversion, and after returning to supine position (all P < .001). The post-inversion HR was less than pre-inversion (P = .03) and 3-min inversion HR (P = .003). There were significant changes in ICA and MCA flow caused by inversion, which affected blood flow velocity, resistance, and pulsatility index (all P ≤ .005).

CONCLUSION

Inversion caused significant changes in ICP and blood flow. Thus, increased chance of complications may exist when using inversion as a therapeutic tool or during surgical procedures in patients with previous history of elevated ICP. These results demonstrate that inversion therapy should be used with caution.

Assessment of Optic Nerve Sheath Diameter in Patients Undergoing Epiduroscopy

Background

Epiduroscopy is commonly used for the evaluation and treatment of low back pain. Saline with or without local anesthetic addition was used to visualize epidural space structure during this procedure. A rapid increase in epidural space pressure is transmitted into the spinal space to the optic nerve sheath. This study aimed to estimate the effects of epiduroscopy on optic nerve sheath diameter (ONSD) according to the volume of fluid using the ultrasonographic measurement of optic nerve diameter in adult patients.

Material/Methods

Sixty patients who had been treated for low back pain with epiduroscopy using low-volume (LV) or high-volume (HV) fluid application were enrolled into the study. Measurement of ONSD was performed before (T0) and immediately after epiduroscopy (T1), at 10 min (T2), and 20 min (T3) after the epiduroscopy.

Results

Both groups showed significant differences over time in ONSD (PGroup×Time=0.001). The HV group showed greater changes from T0 to T2 and T3 than the LV group in ONSD. However, in both groups, ONSDs at T2 and T3 were significantly larger than those with the highest values at T2 compared to T0.

Conclusions

Ultrasonography of ONSD presents a good level of diagnostic accuracy for identifying epidural hypertension. In the clinical decision-making phase, this may help physicians to be more cautious about volume when performing epidural injections to treat this disease.

Ultrasonography Assessments of Optic Nerve Sheath Diameter as a Noninvasive and Dynamic Method of Detecting Changes in Intracranial Pressure

Importance

The crtierion standard method for monitoring intracranial pressure (ICP) can result in complications and pain. Hence, noninvasive, repeatable methods would be valuable.

Objective

To examine how ultrasonographic optic nerve sheath diameter (ONSD) correlated with noninvasive and dynamically monitored ICP changes.

Design, Setting, and Participants

The ONSD was measured before the lumbar puncture (LP) in 60 patients on admission. Patients with elevated ICP were divided into group 1 (200 < LP ≤ 300 mm H2O) and group 2 (LP > 300 mm H2O). Patients underwent follow-up ONSD and LP measurements within 1 month. We analyzed the correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP, which were the respective changes in ONSD and ICP from admission to follow-up.

Main Outcomes and Measures

The ultrasonographic ONSD and ICP were measured on admission and follow-up. The correlations between the ONSD and ICP on admission and between the changes in ONSD and ICP were analyzed using Pearson correlation analyses.

Results

For 60 patients (Han nationality; mean [SD] age, 36.2 [12.04] years; 29 [48%] female) on admission, the ONSD and ICP values were strongly correlated, with an r of 0.798 (95% CI, 0.709-0.867; P < .001). Twenty-five patients with elevated ICP who completed the follow-up were included. The mean (SD) ONSD and ICP on admission were 4.50 (0.54) mm and 302.40 (54.26) mm H2O, respectively. The ONSD and ICP values obtained on admission were strongly correlated , with an r of 0.724 (95% CI, 0.470-0.876; P < .001). The mean (SD, range) changes in ICP and ONSD were 126.64 (52.51 mm H2O, 20-210 mm H2O) (95% CI, 106.24-146.07) and 1.00 (0.512 mm, 0.418-2.37 mm) (95% CI, 0.83-1.20), respectively. The change in ONSD was strongly correlated with the change in ICP, with an r of 0.702 (95% CI, 0.425-0.870; P < .001). The follow-up evaluations revealed that the elevated ICP and dilated ONSD had returned to normal, and no evidence of difference was found in the mean ONSDs between group 1 (3.49 mm; 95% CI, 3.34-3.62 mm) and group 2 (3.51 mm; 95% CI, 3.44-3.59 mm) (P = .778) at follow-up.

Conclusions and Relevance

The dilated ONSDs decreased along with the elevated ICP reduction. Ultrasonographic ONSD measurements may be a useful, noninvasive tool for dynamically evaluating ICP.

Point-of-Care Ultrasound in the Evaluation of the Acutely Painful Red Eye

BACKGROUND

Visual loss, ocular pain, and red eye are common presentations to front-line physicians in the emergency department, urgent care centers, or the primary care office. In recent decades, point-of-care ultrasound (POCUS) has been used by clinicians at the bedside in the evaluation and management of a vast array of patients, including those with ocular complaints.

CASE REPORT

A 33-year-old man presented to the emergency department with left eye pain for 4 weeks' duration. The physical examination revealed visual acuity of 20/400 in the affected eye and diffuse conjunctival injection with perilimbal sparing and scleral edema. Using POCUS, he was noted to have diffuse thickening of the globe wall in the symptomatic eye with a thin layer of fluid posterior to the globe in Tenon's space and mild enlargement of the optic nerve sheath diameter. He was ultimately diagnosed with posterior scleritis. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Posterior scleritis carries the potential for significant visual impairment when the diagnosis is missed or delayed. POCUS findings can aid the front-line physician in making the diagnosis of posterior scleritis allowing earlier initiation of appropriate therapy and follow-up.

Diagnosis of elevated intracranial pressure in critically ill adults: systematic review and meta-analysis

OBJECTIVES

To summarise and compare the accuracy of physical examination, computed tomography (CT), sonography of the optic nerve sheath diameter (ONSD), and transcranial Doppler pulsatility index (TCD-PI) for the diagnosis of elevated intracranial pressure (ICP) in critically ill patients.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Six databases, including Medline, EMBASE, and PubMed, from inception to 1 September 2018.

STUDY SELECTION CRITERIA

English language studies investigating accuracy of physical examination, imaging, or non-invasive tests among critically ill patients. The reference standard was ICP of 20 mm Hg or more using invasive ICP monitoring, or intraoperative diagnosis of raised ICP.

DATA EXTRACTION

Two reviewers independently extracted data and assessed study quality using the quality assessment of diagnostic accuracy studies tool. Summary estimates were generated using a hierarchical summary receiver operating characteristic (ROC) model.

RESULTS

40 studies (n=5123) were included. Of physical examination signs, pooled sensitivity and specificity for increased ICP were 28.2% (95% confidence interval 16.0% to 44.8%) and 85.9% (74.9% to 92.5%) for pupillary dilation, respectively; 54.3% (36.6% to 71.0%) and 63.6% (46.5% to 77.8%) for posturing; and 75.8% (62.4% to 85.5%) and 39.9% (26.9% to 54.5%) for Glasgow coma scale of 8 or less. Among CT findings, sensitivity and specificity were 85.9% (58.0% to 96.4%) and 61.0% (29.1% to 85.6%) for compression of basal cisterns, respectively; 80.9% (64.3% to 90.9%) and 42.7% (24.0% to 63.7%) for any midline shift; and 20.7% (13.0% to 31.3%) and 89.2% (77.5% to 95.2%) for midline shift of at least 10 mm. The pooled area under the ROC (AUROC) curve for ONSD sonography was 0.94 (0.91 to 0.96). Patient level data from studies using TCD-PI showed poor performance for detecting raised ICP (AUROC for individual studies ranging from 0.55 to 0.72).

CONCLUSIONS

Absence of any one physical examination feature is not sufficient to rule out elevated ICP. Substantial midline shift could suggest elevated ICP, but the absence of shift cannot rule it out. ONSD sonography might have use, but further studies are needed. Suspicion of elevated ICP could necessitate treatment and transfer, regardless of individual non-invasive tests.

REGISTRATION

PROSPERO CRD42018105642.

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.

Role of Orbital Ultrasound in the Assessment of Clinically Detected Papilledema

BACKGROUND

Increased intracranial pressure (ICP) is frequently seen, and it is considered a serious problem that needs a careful assessment and management, especially by easy and least invasive modalities.

OBJECTIVE

The objective of the study is to assess the optic nerve sheath diameter (ONSD) using transorbital ultrasound (US) as a marker and indicator for diagnosing raised intracranial pressure.

PATIENTS AND METHODS

It is a prospective study that was carried out in Neurology and/or Ophthalmology Clinics, Baghdad Teaching Hospital in the Medical City Complex during the period from June 2016 to May 2017; in this study, 40 patients seeking medical help for other causes were considered to be a control group and the other 40 patients who were complaining of raised ICP symptoms and suggested of having optic disc swelling by ophthalmoscopy examination. All the patients and the control group were examined by transorbital US to measure the ONSD, and then, only the patients with symptoms of raised intracranial underwent a lumbar puncture (LP).

RESULTS

Pearson's correlation test was used, demonstrating a very significant correlation between the ultrasonographic ONSD and the measurements of LP (R > 0.9) and (P < 0.001). Transorbital US yielded high sensitivity (91.6%) with modest specificity (75%) and high accuracy (90.0%) of ONSD was considered the normal the cutoff value of (5 mm) obtained from the control group. The US also showed the crescent sign and the optic disc bulging with lower sensitivity than the ONSD (61.1% and 41.6%, respectively) but with very high specificity (100%) for both.

CONCLUSION

ONSD by transorbital ultrasonography is highly accurate, easily performed, and noninvasive procedure for the detection of raised ICP. Routine daily monitoring of ONSD could be of help in intensive care units when invasive ICP monitoring is not available or contraindicated; it also has a good role in early recognition of intracranial hypertension.

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.

Utilization of Ocular Ultrasound in the Evaluation of Posterior Reversible Encephalopathy Syndrome: A Case Report

Posterior reversible encephalopathy syndrome (PRES) is an infrequently encountered cause of altered mental status and seizure activity in the emergency setting. Diagnosis is often delayed by extensive testing and failure to consider PRES in the differential. Though MRI remains the gold standard for diagnosis, ultrasound-guided measurement of intra-ocular pressure is a safe, effective alternative that can expedite the diagnosis. The treatment of PRES involves the rapid reversal of offending agents and aggressive blood pressure management. The prognosis of PRES is favorable and neurologic sequelae are uncommon. This clinical case highlights the importance of the emergency physicians’ consideration of this pathology and the utilization of ultrasound as a non-invasive means of assessing intra-ocular pressure.

Brain ultrasonography: methodology, basic and advanced principles and clinical applications. A narrative review

Brain ultrasonography can be used to evaluate cerebral anatomy and pathology, as well as cerebral circulation through analysis of blood flow velocities. Transcranial colour-coded duplex sonography is a generally safe, repeatable, non-invasive, bedside technique that has a strong potential in neurocritical care patients in many clinical scenarios, including traumatic brain injury, aneurysmal subarachnoid haemorrhage, hydrocephalus, and the diagnosis of cerebral circulatory arrest. Furthermore, the clinical applications of this technique may extend to different settings, including the general intensive care unit and the emergency department. Its increasing use reflects a growing interest in non-invasive cerebral and systemic assessment. The aim of this manuscript is to provide an overview of the basic and advanced principles underlying brain ultrasonography, and to review the different techniques and different clinical applications of this approach in the monitoring and treatment of critically ill patients.

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.

Cerebral Venous Thrombosis: An Uncommon Cause of Papilledema on Bedside Ocular Ultrasound

BACKGROUND

Cerebral venous thrombosis (CVT) is a rare, difficult-to-diagnose form of venous thromboembolic disease and is considered a type of stroke. Its presentation is highly variable and may be easily confused for more common and less debilitating or life-threatening diagnoses such as migraine, seizure, or idiopathic intracranial hypertension.

CASE REPORT

A 25-year-old woman presented with a complaint of bifrontal throbbing headache and blurry vision. A bedside ultrasound of the orbit suggested increased intracranial pressure. A subsequent computed tomography venogram demonstrated a left transverse sinus thrombosis. The patient was started on enoxaparin and admitted for bridging to warfarin and evaluation for hypercoagulable state. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: CVT is a rare form of stroke that carries a high rate of mortality and morbidity and masquerades as more common and benign diagnoses. Emergency department bedside ultrasound of the orbit may make the diagnosis of CVT more attainable by identifying patients with increased intracranial pressure.

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.

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.

Multimodal Neuromonitoring in Neurocritical Care

Neuromonitoring is important for patients with acute brain injury. The bedside neurologic examination is standard for neurologic monitoring; however, a clinical examination may not reliably detect subtle changes in intracranial physiology. Changes found during neurologic examinations are often late signs. The assessment of multiple physiological variables in real time can provide new clinical insights into treatment decisions. No single monitoring modality is ideal for all patients. Simultaneous assessment of cerebral hemodynamics, oxygenation, and metabolism, such as in multimodal monitoring, allows an innovative approach to individualized patient care.