Optic nerve sheath diameter on MR imaging: establishment of norms and comparison of pediatric patients with idiopathic intracranial hypertension with healthy controls

The sedative effect of intravenous butorphanol in dogs with intracranial space occupying lesions or indicators of intracranial hypertension

OBJECTIVE

To determine whether dogs with magnetic resonance imaging (MRI)-determined intracranial space occupying lesions (MRI-iSOLs) or intracranial hypertension (MRI-ICH) had greater sedation scores and quicker onset of recumbency following premedication with intravenous (IV) butorphanol in comparison with dogs which had normal MRI findings.

STUDY DESIGN

Prospective, observational study.

ANIMALS

A total of 53 dogs presenting for brain MRI were included.

METHODS

Each dog was sedated with 0.2 mg kg-1 butorphanol IV, and the quality of sedation and the onset of recumbency were scored before drug administration and every 5 minutes after IV butorphanol administration for 15 minutes using a modified sedation scale. The maximum sedation score was 18, and onset of recumbency was recorded when a dog lay down without the ability to stand. Each MRI was assessed for the presence or absence of MRI-iSOL and MRI-ICH using T2-weighted sequences. Data were analysed using the Wilcoxon rank sum test or the chi-square test.

RESULTS

Dogs with MRI-iSOL had significantly higher median sedation scores than dogs without MRI-iSOL (12 versus 5, respectively) 15 minutes after butorphanol administration (T15, p < 0.01). A greater number of dogs with MRI-ICH achieved recumbency (n = 9/10; 90%) than those without MRI-ICH (n = 20/43; 46.5%; p = 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

When intracranial disease is suspected, the administration of butorphanol as a premedicant for anaesthesia could be used to predict the presence of MRI-iSOL and MRI-ICH. If a dog becomes recumbent or has a sedation score > 10 within 15 minutes of butorphanol administration, the animal should be treated with an anaesthesia protocol adapted to the presence of ICH.

The utility of MRI radiological biomarkers in determining intracranial pressure

Intracranial pressure (ICP) is a physiological parameter that conventionally requires invasive monitoring for accurate measurement. Utilising multivariate predictive models, we sought to evaluate the utility of non-invasive, widely accessible MRI biomarkers in predicting ICP and their reversibility following cerebrospinal fluid (CSF) diversion. The retrospective study included 325 adult patients with suspected CSF dynamic disorders who underwent brain MRI scans within three months of elective 24-h ICP monitoring. Five MRI biomarkers were assessed: Yuh sella grade, optic nerve vertical tortuosity (VT), optic nerve sheath distension, posterior globe flattening and optic disc protrusion (ODP). The association between individual biomarkers and 24-h ICP was examined and reversibility of each following CSF diversion was assessed. Multivariate models incorporating these radiological biomarkers were utilised to predict 24-h median intracranial pressure. All five biomarkers were significantly associated with median 24-h ICP (p < 0.0001). Using a pair-wise approach, the presence of each abnormal biomarker was significantly associated with higher median 24-h ICP (p < 0.0001). On multivariate analysis, ICP was significantly and positively associated with Yuh sella grade (p < 0.0001), VT (p < 0.0001) and ODP (p = 0.003), after accounting for age and suspected diagnosis. The Bayesian multiple linear regression model predicted 24-h median ICP with a mean absolute error of 2.71 mmHg. Following CSF diversion, we found pituitary sella grade to show significant pairwise reversibility (p < 0.001). ICP was predicted with clinically useful precision utilising a compact Bayesian model, offering an easily interpretable tool using non-invasive MRI data. Brain MRI biomarkers are anticipated to play a more significant role in the screening, triaging, and referral of patients with suspected CSF dynamic disorders.

A narrative review of magnetic resonance imaging findings in pediatric idiopathic intracranial hypertension

Background and Aims

Idiopathic intracranial hypertension (IIH) is a rare neurological disorder in the pediatric population which is defined as an increase in intracranial pressure (ICP) without the presence of brain parenchymal lesions, hydrocephalus, or central nervous system infection. In this study, we have determined the magnetic resonance imaging (MRI) findings in IIH patients.

Methods

A comprehensive literature search was conducted using the electronic databases including Web of Sciences, Scopus, and Pubmed to identify suitable and relevant articles using keyword search methods. The search included keywords such as "idiopathic intracranial hypertension," "pseudotumor cerebri," "MRI," and "pediatrics." The search was limited to the available publications up to January 2024.

Results

MRI plays a crucial role in diagnosing IIH by excluding secondary causes and revealing neuroimaging findings associated with elevated ICP. Despite fewer studies in children compared to adults, MRI serves as a cornerstone in identifying traditional neuroradiological markers such as empty sella turcica, posterior globe flattening, optic nerve tortuosity, optic nerve sheath distension, and transverse venous sinus stenosis. Additional subtle markers include increased Meckel's cave length, cerebellar tonsillar herniation, and slit-like ventricles, although these are less reliable. Diffusion-weighted imaging does not typically show cerebral ADC value changes indicative of cerebral edema in pediatric IIH.

Conclusion

MRI findings provide valuable non-invasive diagnostic indicators that facilitate early detection, clinical management, and potential surgical intervention in pediatric IIH. The reliability of these MRI markers underscores their importance in clinical practice.

Collapse or distention of the perioptic space in children - What does it mean to pediatric radiologists? Comprehensive review of perioptic space evaluation

The perioptic space comprises the subarachnoid space [SAS] of the optic nerve communicating with the SAS of the central nervous system. Pressure variations in the SAS of the central nervous system can be transmitted to the optic papilla through the perioptic space. Variations in the diameter of the perioptic space serve as an important indicator for select intracranial pathologies in the pediatric population. Though the perioptic space can be evaluated using various imaging modalities, MRI is considered highly effective due to its superior soft tissue resolution. With advancement in MR imaging techniques, high-resolution images of the orbits can provide improved visualization of the perioptic space. It is imperative for the pediatric radiologist to routinely assess the perioptic space on brain and orbit MR imaging, as it can prompt exploration for additional features associated with select intracranial pathologies, thus improving diagnostic accuracy. This article reviews basic anatomy of the perioptic space, current understanding of the CSF dynamics between the perioptic space and central nervous system SAS, various imaging modalities utilized in the assessment of the perioptic space, MRI sequences and the optimal parameters of specific sequences, normal appearance of the perioptic space on MR imaging, and various common pediatric pathologies which cause alteration in the perioptic space.

Enhancing Diagnostic Accuracy Through Neuroimaging Revisions in Pediatric Pseudotumor Cerebri Syndrome: A Cross-Sectional Study

BACKGROUND

This cross-sectional study aimed to report all neuroimaging findings suggestive of raised intracranial pressure in children with pseudotumor cerebri syndrome (PTCS), before and after re-review by two neuroradiologists.

METHODS

We included 48 children aged <18 years diagnosed with PTCS between 2016 and 2021. Clinical and radiological data were obtained from their medical files. Two neuroradiologists independently re-reviewed all neuroimages, and the average of their assessments was compared with the initial neuroimaging reports; an additional review was done to analyze inter- and intraclass correlation.

RESULTS

The initial neuroimaging reports showed under-reporting of findings, with only 26 of 48 (54.1%) patients identified with abnormal reports. After revision, the proportion of the reported findings increased to 44 of 48 (91.6%). Distention of the perioptic space was the most commonly reported finding after revision (36.5 of 48; 76%). Flattening of the posterior globe and empty sella were initially under-reported but improved after revision. Moreover, several findings suggestive of increased intracranial pressure not mandated by Friedman criteria were identified, such as narrowing of the Meckel cave, posterior displacement of the pituitary stalk, and narrowing of the cavernous sinus. Analysis of associations between neuroimaging findings and demographic and clinical characteristics yielded no statistically significant results. The inter- and intraclass correlation results demonstrated a significant agreement between raters and within each rater's assessment (P < 0.05).

CONCLUSIONS

This study highlights the impact of image revision in enhancing PTCS diagnosis. Intra- and interclass correlations underscore the reliability of the review process, emphasizing the importance of meticulous image analysis in clinical practice.

Evaluation of the Anatomical and Radiological Morphometry of Optic Nerve and Cranium in Healthy Individuals

This paper determined the morphometric measurements' reference values and relationship of the optic nerve and cranium in Turkish healthy individuals according to age and sex. Five hundred fifty-nine (280 females and 279 males) patients aged from 2 to 90 years were included in this study. The measurements were taken from patients having brain magnetic resonance images in sagittal, axial, and coronal sections in the radiology department. Eyeball transverse diameter, optic nerve sheath thickness (ONST), optic chiasm length, optic chiasm width, and cranium morphometric measurements of all individuals who participated in the study were taken. Except for the width of the optic chiasm, all measurements showed significant differences between the sexes (P < 0.05). In contrast, all measurement values were higher in males than females, except for the clival angle. According to the result of Pearson correlation analysis, in which the existence of a relationship between ONST and craniometric measurements was evaluated, a low but significant correlation was found between ONST and craniometric measurements (r < 0.4; P < 0.05). In the post hoc test performed to compare the decades, it was seen that the most significant changes in our measurements were in the 2 to 10 age range and the measurement values decreased in old age. We think that revealing the age and sex-related changes in the optic nerve and cranium morphometry of our population anatomically and radiologically will be an important source in terms of creating reference values for our population.

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

PURPOSE

To determine the normal values of optic nerve sheath diameter (ONSD) by computed tomography (CT) in the pediatric population.

METHODS

The CT scans of pediatric patients aged 1 to 16 years who underwent brain CT for different reasons, who did not have intracranial pathology or increased intracranial pressure, and who had no pathology on CT were included in the study. Four age groups were defined with the following ranges: 1 to 2, 3 to 6, 7 to 10, and 11 to 16 years. ONSD was measured from axial CT images, 3 and 10 mm behind the optic globe.

RESULTS

The normative values of ONSD measured on CT imaging in children aged 1 to 16 years were reported. The change in ONSD according to age was investigated. ONSD was found to increase with age at both levels measured. The difference was statistically significant.

CONCLUSIONS

Normal values should be known to detect pathologies that may cause an increase in optic nerve diameter. The values reported in this study can serve as a reference for normal optic nerve sheath diameter in the pediatric age group. [J Pediatr Ophthalmol Strabismus. 2024;61(1):38-43.].

Effect of General Anesthesia on MR Optic Nerve Sheath Diameter in the Pediatric Population

BACKGROUND

Papilledema is thought to be the hallmark sign of increased intracranial pressure (ICP). Distension of the subarachnoid space within the optic nerve sheath is also commonly reported in MR studies as an indirect sign of increased ICP.

HYPOTHESIS

General anesthesia and positive pressure ventilation might result in changes in optic sheath diameter (OSD) observed on clinical brain MRI.

STUDY TYPE

Retrospective.

POPULATION

One hundred forty-five  patients (154 MRI scans, 7.3 years ± 5.1); 97 studies in the anesthesia group (4.4 years ± 3.4) of which 22 had papilledema, and 57 in the non-anesthesia group (12.3 years ± 3.2), of which 28 had papilledema.

FIELD STRENGTH/SEQUENCE

1.5T or 3.0T volumetric T2 images. T2 images were obtained from different vendors.

ASSESSMENT

OSD, optic nerve diameter (OND), and peri-optic cerebrospinal fluid (CSF) were measured manually on T2-weighted MR images for various population subgroups (with and without anesthesia; with or without papilledema). The correlation between these measurements and the clinical diagnosis of papilledema was evaluated via receiver operating characteristic (ROC) analysis.

STATISTICAL TESTS

Chi-square test; Mann-Whitney Test; Spearman's test and ROCs; Interclass correlation coefficient, P = 0.05.

RESULTS

General anesthesia resulted in significantly larger mean OSD in patients with or without papilledema (7.3 ± 1.0 mm vs. 6.1 ± 1.1 mm and 6.7 ± 1.0 mm vs. 5.4 ± 0.9 mm, respectively). In the non-anesthesia group, the average OSD values (6.1 ± 1.1 mm) were significantly higher in papilledema patients compared to non-papilledema patients (5.4 ± 0.9 mm), with larger peri-optic CSF rim (1.6 ± 0.4 mm vs. 1.3 ± 0.3 mm). In the anesthesia group, OND was significantly larger in papilledema patients (3.4 ± 0.4 mm vs. 3.1 ± 0.5 mm), though the average peri-optic CSF rim did not reach a significance in papilledema compared with non-papilledema patients (2.0 ± 0.3 mm vs. 1.8 ± 0.4 mm, P = 0.06). In patients with general anesthesia, peri-optic CSF rim had a limited correlation with increased ICP.

DATA CONCLUSION

In the pediatric population, imaging findings of increased OSD on brain MRI might be related to general anesthesia rather than increased ICP. The interpretation of optic nerve sheath distention should be reported cautiously in conjunction with anesthesia status, especially in the pediatric population.

EVIDENCE LEVEL

4 Technical Efficacy: 5.

Variability of the optic nerve sheath diameter on brain computed tomography in Turkish children based on sex and age

BACKGROUND

Optic nerve sheath diameter (ONSD) measurement is a noninvasive method that can be used for intracranial pressure monitoring. Several studies have investigated normal ONSD values in children, but no general consensus has been reached yet.

OBJECTIVES

The aim of our study was to reveal normal ONSD, eyeball transverse diameter (ETD), and ONSD/ETD values on brain computed tomography (CT) in healthy children aged 1 month to 18 years.

METHODS

Children admitted to the emergency department with minor head trauma and had normal brain CT were included in the study. The demographic characteristics of the patients (age and sex) were recorded, and the patients were divided into four age groups: 1 month to 2 years, 2 to 4 years, 4 to 10 years, and 10 to 18 years.

RESULTS

The images of 332 patients were analyzed. When the median values of all measurement parameters (right and left ONSD, ETD, and ONSD/ETD) were compared between the right and left eyes, no statistically significant differences were found. When the same parameters were compared according to age group, the ONSD and ETD values differed significantly (values of males were found to be higher), but the ONSD proximal/ETD and ONSD middle/ETD values did not differ significantly.

CONCLUSION

In our study, normal ONSD, ETD, and ONSD/ETD values were determined according to age and sex in healthy children. As the ONSD/ETD index did not statistically significantly differ according to age and sex, diagnostic studies for traumatic brain injuries can be performed using the index.

Effect of paediatric caudal injection volume on optic nerve sheath diameter and regional cerebral oximetry: A randomised trial

BACKGROUND

Caudal injections commonly used for neuraxial anaesthesia in children can displace cerebrospinal fluid cranially causing safety concerns in terms of raised intracranial pressure. Optic nerve sheath diameter (ONSD) is a noninvasive surrogate for the measurement of intracranial pressure. Regional cerebral oximetry (CrSO 2 ) can monitor brain oxygenation, which may decrease by a reduction in cerebral flow due to increased intracranial pressure.

OBJECTIVES

Comparing how caudal injection volumes of 0.8 and 1.25 ml kg -1 influence ONSD and CrSO 2 within the first 30 min after injection.

DESIGN

Prospective, randomised and parallel group trial.

SETTING

Operating room.

PATIENTS

Fifty-eight elective paediatric surgical patients between ages 1 and 7 years old, ASA class I or II, without previous intracranial or ocular pathology and surgery appropriate for single - shot caudal anaesthesia.

INTERVENTION

Single-shot caudal anaesthesia with 0.8 ml kg -1 (group L, n  = 29) and 1.25 ml kg -1 (group H, n  = 29) of 2 mg kg -1 bupivacaine solution.

MAIN OUTCOME MEASURES

Optic nerve sheath diameter measured with ultrasonography and regional cerebral oximetry measured by near - infrared spectroscopy before (NIRS), immediately after, 10, 20 and 30 min after the block.

RESULTS

Mean ONSD values increased from a baseline of 4.4 ± 0.2 mm to a maximum of 4.5 ± 0.2 mm 20 min after injection in group L and from a baseline of 4.5 ± 0.3 mm to a maximum of 4.8 ± 0.3 mm 10 min after injection in group H. Eight of 29 patients in group H and none in group L had an ONSD increase by more than 10%. Both groups had a reduction of less than 2.5% in CrSO 2 .

CONCLUSION

Caudal injection with 1.25 ml kg -1 increased ONSD, an indirect measurement of ICP, more than 0.8 ml kg -1 and neither volume caused a clinically important reduction in CrSO 2 .

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04491032.

Pediatric optic nerve and globe measurements on magnetic resonance imaging: establishing norms for children

BACKGROUND

Normal optic nerve diameter (OND) and optic nerve sheath diameter (ONSD) may be beneficial for describing optic nerve pathway abnormality reflecting increased intracranial pressure. Nonetheless, magnetic resonance imaging (MRI) measurement of the normal ONSD range and its associations with clinical factors and eyeball transverse diameter (ETD) are not well established in children.

PURPOSE

To establish normal OND, ONSD, ETD, and OND/ONSD and ONSD/ETD measurements in children and their associations with age and sex.

MATERIAL AND METHODS

We evaluated and analyzed 336 brain MRI studies of children aged 0.5 months to 18 years. We measured a total of 672 optic nerves. The OND and ONSD were measured 1 cm anterior to the optic foramina and 3 mm behind the optic disc on an axial T2 sequence.

RESULTS

The mean OND 3 mm and 1 cm, ONSD 3 mm and 1 cm, and ETD were 0.23 ± 0.05 mm and 0.16 ± 0.04 mm, 0.53 ± 0.08 mm and 0.38 ± 0.06 mm, and 2.3 ± 0.13, respectively. Only ONSD 1 cm was independent of age (P = 0.247). ONSD 3 mm and ETD were significantly wider in boys compared to girls and significantly influenced by age (both P < 0.001). Age at scan and ETD were significantly correlated (P < 0.001).

CONCLUSION

We established MRI-based OND, ONSD, ETD, and ONSD/ETD and OND/ONSD ratio normative values in children, which can be helpful in pediatric populations with disease.

The Role of Ultrasound in Pediatric Skull Fractures: Determination of Fracture and Optic Nerve Sheath Diameter Measurements

BACKGROUND

The aim of the present study was to determine the accuracy of point-of-care ultrasound (POCUS) for detecting skull fractures and to evaluate sonographic measurements of optic nerve sheath diameter (ONSD) and ONSD/eyeball vertical diameter (EVD) ratios in children with head trauma.

METHODS

Children who presented with local signs of head trauma and underwent cranial computed tomography (CT) were enrolled. The suspected area was examined by POCUS to identify a skull fracture, and then the ONSD at 3 mm posterior to the globe and the EVD were measured. Ratios of ONSD measurement at 3 mm/EVD were reported. All ONSD measurements and ratios were calculated from cranial CT images.

RESULTS

There were 112 children enrolled in the study. The sensitivity and specificity of POCUS for skull fractures was 93.7% (95% confidence interval [CI], 82.8-98.6) and 96.8% (95% CI, 89.1-99.6), whereas the positive predictive value was 95.7% (95% CI, 85.1-98.8), and the negative predictive value was 95.3% (95% CI, 87.3-98.4). There was high agreement between POCUS and CT for identifying skull fractures (κ, 0.90 [±0.04]). In the group without elevated intracranial pressure findings on CT, patients with space-occupying lesions (SOLs) had higher sonographic ONSD measurements and ratios (P < 0.001) compared with cases without SOLs.

CONCLUSIONS

When used with clinical decision rules to minimize the risk for clinically important traumatic brain injury, POCUS seems to be a promising tool to detect skull fractures and calculate ONSD measurements and rates to predict the risk for SOLs and perform further risk stratification of children with minor head trauma.

Long-term monitoring of children with Pseudo Tumor Cerebri Syndrome by transbulbar sonography

Determination of optic nerve sheath diameter (ONSD) with transbulbar sonography has become an easily accessible and time-effective tool in the assessment of increased intracranial pressure. The aim of our study was to evaluate the usefulness of transbulbar sonography in the initial diagnosis and in follow-up examinations of children and adolescents with the diagnosis of pseudotumor cerebri syndrome (PTCS). We retrospectively reviewed imaging results of 24 patients aged 0.75-17 years with PTCS. Serial transbulbar sonography examinations were performed between 2011 and 2021. Sonographic evaluation included the ONSD, papilledema and subarachnoid space. 240 sonographic measurements taken at 108 time points in 17 patients met the inclusion criteria. All patients underwent serial lumbar punctures and routine fundoscopy in close relation to transbulbar sonography. We found that ONSD values remained high in all patients. The longest follow-up period was dated 2498 days (6.84 years) after initial diagnosis. Papilledema resolved in close correlation to fundoscopy normalization. In 16/17 patients the subarachnoid space remained cystic in appearance. These findings were independent of clinical symptoms and lumbar puncture opening pressure. We conclude that transbulbar sonography is a useful diagnostic tool in the initial diagnostic workup of children with PTCS. On follow-up however ONSD values and the cystic transformation of the subarachnoid space remained pathologic in the majority of cases while papilledema resolved parallel to fundoscopy findings. Serial measurements of ONSD are therefore of limited value in the follow-up of patients with PTCS and cannot be considered a reliable tool in subsequent therapeutic decisions.

Role of Orbital Ultrasound in the Monitoring of Children with Raised Intracranial Pressure—Prospective Observational Study Conducted in Tertiary Care Centre

Our objective was to evaluate the role of optic nerve sheath diameter measurement by orbital ultrasound in monitoring children with nontraumatic coma and increased intracranial pressure (ICP). A single-center prospective observational study was conducted in the pediatric intensive care unit (PICU) of a tertiary care teaching hospital in Puducherry, India. Children admitted to the PICU with features of raised ICP were enrolled. Baseline characteristics and raised ICP characteristics were recorded. Optic nerve sheath diameter (ONSD) measurements were taken in all children in the supine position using bedside ultrasound with a 12 MHz linear probe. The probe was initially placed in the axial plane, and measurements were taken at a distance of 3 mm posterior to the site at which the optic nerve enters the globe. Measurements were recorded sequentially 8th hourly till ICP features got resolved or the patient died. Along with each measurement, clinical parameters were recorded. The ONSD measurements were compared with clinical features. We also recruited children admitted to the PICU for other conditions without features of raised ICP as controls. We compared ONSD measurements of cases with controls. In total, 185 children were recruited, of which 81 had features of raised ICP and 104 were without increased ICP. The ONSD measurements in children with raised ICP were significantly higher as compared with those without ICP. Among children with raised ICP, there was a negative correlation between ONSD and Glasgow Coma Scale scores (r = −0.739, p ≤ 0.0001). In children with raised ICP, there was a significant difference in ONSD at different intervals, demonstrating a falling trend from admission to 32nd-hour readings. ONSD measurements were higher in children with clinical signs of increased ICP compared with controls, thereby suggesting that this noninvasive measure may be helpful in the neuromonitoring of children with neurologic insults.

Dilated Optic Nerve Sheath in Mucopolysaccharidosis I: Common and Not Necessarily High Intracranial Pressure

Hydrocephalus is one of the earliest manifestations of mucopolysaccharidosis I-Hurler syndrome, and delayed treatment of hydrocephalus can lead to neurocognitive delay or even death. Optic nerve sheath diameter has been established as a noninvasive measurement to detect elevated intracranial pressure. This study aimed to establish correlations between optic nerve sheath diameter and opening pressure. Forty-nine MR images and opening pressures in patients with mucopolysaccharidosis I-Hurler syndrome were retrospectively reviewed from 2008 to 2020. The optic nerve sheath diameter was measured 3 mm posterior to the posterior margin of the globe (retrobulbar) and 10 mm anterior to the optic foramen (midpoint segment), and the average was taken between the 2 eyes. Opening pressure was measured with the patient in the lateral decubitus position with controlled end-tidal CO2 on the same day as the MR imaging. The average retrobulbar optic nerve sheath diameter was 5.33 mm, higher than the previously reported measurement in healthy controls, in patients with idiopathic intracranial hypertension, and there was a positive correlation between age and the optic nerve sheath diameter measured at the retrobulbar or midpoint segment (retrobulbar segment, R 2 = 0.27, P < .01; midpoint segment, R 2 = 0.20, P < .01). However, there was no correlation between retrobulbar or midpoint segment optic nerve sheath diameter and opening pressure (retrobulbar segment, R 2 = 0.02, P = .17; midpoint segment, R 2 = 0.03, P < .12). This study shows a higher average optic nerve sheath diameter in patients with mucopolysaccharidosis I-Hurler syndrome than in healthy controls regardless of the location of the measurement. However, the degree of optic nerve sheath dilation does not correlate with opening pressure, suggesting that increased optic nerve sheath diameter is an ocular manifestation of mucopolysaccharidosis I-Hurler syndrome itself rather than a marker of elevated intracranial pressure.

Headache and neuroimaging findings in conditions of cerebrospinal fluid (CSF) circulation disorders: in hydrocephalus, pseudotumor cerebri, and CSF hypotension syndrome

The authors wish in this narrative minireview show and comment on some neuroimaging findings encountered in patients with conditions of cerebrospinal fluid circulation disorders, such as in the hydrocephalus, pseudotumor cerebri, and CSF hypotension syndrome. The MRI of a young woman with a clinical diagnosis of post-dural puncture headache, performed on the fourth postpartum day after cesarean delivery, evolving with headache and diplopia, is shown. Non-contrast-enhanced sagittal T1 magnetic resonance imaging shows that the cerebellar tonsils are at the level of the foramen magnum, therefore still within normal limits, but, despite that, the opening of the cerebral aqueduct in the third ventricle is below the imaginary line connecting the anterior clinoid to the vein of Galen, therefore considered abnormally lower than the expected anatomical position. The axial T1-weighted images with post-contrast fat suppression also show impregnation and thickening of the dura mater. There is also mild engorgement of the cerebral venous sinuses, best demonstrated on T1 with post-contrast fat suppression, which is also identified on post-contrast magnetic resonance angiography, with no signs of venous thrombosis. We conclude that the diagnosis of a patient with intracranial hypotension syndrome can be suspected or confirmed with typical neuroimaging findings.

Population-Based Evaluation of Indirect Signs of Increased Intracranial Pressure

BACKGROUND

The Mayo Clinic Study of Aging (MCSA) is a unique prospective study that systematically evaluates the normal aging population and includes many participants undergoing both MRI and lumbar puncture (LP). Using MCSA date, we aimed to determine the prevalence of indirect signs of raised intracranial pressure (ICP) on MRI and whether these correlate with LP opening pressure (OP). This is a large-scale study that evaluates how often indirect signs of increased ICP occur in a normal population.

METHODS

MCSA participants who had an MRI within 3 months of an LP with recorded OP were included in the study. MRIs were reviewed for indirect signs of raised ICP, including pituitary to sella (P/S) ratio, cerebellar tonsillar ectopia, and optic nerve sheath diameter (ONSD). These signs were evaluated for correlations with OP and influences from body mass index (BMI) and obstructive sleep apnea (OSA).

RESULTS

Five hundred ninety-seven MCSA patients were identified who underwent both LP and MRI. Two hundred sixty (43.6%) were women. The median age was 70.7 years (range 32.6-92.7). Median OP was 152 mm H2O (range 60-314 mm H2O), with 91 (15.2%) participants having an OP ≥ 200 mm H2O. Empty or partially empty sella was seen in 81 (12.8%) of the cohort. The P/S ratio decreased with increasing OP (r = -0.3, P < 0.001). There was a weak correlation between OP and average ONSD (r = 0.184, P = 0.01), which was no longer significant when accounting for age, gender, and BMI (partial r2 = 0.014, P = 0.097). There was no correlation between OP and cerebellar tonsillar ectopia. OSA was associated with increased ONSD (P = 0.004), but this did not remain statistically significant after accounting for age, gender, and BMI (P = 0.085).

CONCLUSION

Smaller pituitary gland size correlated with increasing OP. This suggests that ICP is a continuum with some normal individuals demonstrating asymptomatic radiologic signs of raised ICP.

Clinical features and the role of magnetic resonance imaging in pediatric patients with intracranial hypertension

Increased intracranial hypertension (IIH) is a defined clinical condition; however, an unsolved pathophysiologic background usually creates problems in its diagnosis and proper approach. The aim of this study was to emphasize the clinical conditions and brain magnetic resonce imaging (MRI) clues of pediatric patients, especially this clinical entity with high morbidity. Here, we review the etiology, clinical presentation, brain MRI findings, and prognosis of IIH in children. The symptoms' onset age ranged from 9 months to 16 years. Headache (81%), vomiting (37%), and diplopia (33.3%) were the most frequent symptoms. The most common etiologic factors were found to be obesity and dural venous sinus thrombosis. Cerebrospinal fluid (CSF) opening pressure had mean a mean value of 615.2 ± 248 mm H₂O. A significant relationship was found between visual field impairment and height of CSF pressure (p < 0.001). Optic nerve sheath enlargement (88.8%) and optic nerve tortuosity (85.1%) were found as the most common brain MRI findings. Slit-like ventricle (37%), venous sinus thrombosis (29.6%), posterior globe sclera flattening (29.6%), empty sella (25.9%), and intraocular protrusion of the optic nerve (14.8%) were the other findings. A significant relationship was found between CSF opening pressure and the presence of optic nerve tortuosity (p = 0.002), and distension of the optic nerve sheath (p = 0.006). All patients received acetazolamide, only one patient underwent lumboperitoneal shunt, and only one received steroids. In children, IIH can present with different etiologies and symptoms. Brain MRI provides crucial clues in diagnosis. Urgent diagnosis and treatment planning are required to protect vision functions.

High-resolution MRI assessment of optic nerve sheath diameter in adults: optic nerve sheath variation and a new diagnostic tool for intracranial hypertension

BACKGROUND

Assessment of optic nerve sheath diameter (ONSD) is a non-invasive measure of intracranial pressure (ICP). However, it is not clear whether healthy individuals exhibit ONSD variation or whether factors other than ICP affect the ONSD.

PURPOSE

To investigate whether ONSD was correlated with age, sex, height, weight, eyeball transverse diameter (ETD), or body mass index (BMI), and to develop a new diagnostic model to increase the diagnostic accuracy of intracranial hypertension (IH).

MATERIAL AND METHODS

A total of 145 relatively healthy adults and 40 patients with acute IH who underwent high-resolution magnetic resonance imaging (MRI) were enrolled in this study. Linear regression analyses were used to determine the relationship between ONSD and these variables. If correlations were identified, an index ONSDΔ removing variables effects was calculated. ROC analysis was used to assess the IH predictive value of ONSDΔ in terms of sensitivity and specificity.

RESULTS

In relatively healthy adults, there was a correlation between ONSD and BMI (P = 0.002), which can be presented as an index ONSDΔ. The ONSDΔ model better predicted IH than the ONSD model (P = 0.035), with a sensitivity of 70.00%, a specificity of 71.72%, and an AUC of 0.755.

CONCLUSION

A correlation between ONSD and body mass index (BMI) was found using high-resolution MRI. This result indicates that the effects of BMI should be considered along with the ONSD during ICP monitoring. Meanwhile, the index ONSDΔ was better than the ONSD in predicting IH and could be used to obtain a more precise estimation of ICP.

Apparent diffusion coefficient echoplanar imaging maps of the optic nerves in childhood idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

Dueto motion artifacts, optic nerve (ON) findings of idiopathic intracranial hypertension (IIH) can easily be overlooked on T2-weighted (T2w) turbo spin-echo sequence. This study aimed to investigate the contribution of the apparent diffusion coefficient (ADC) map derived from the interleaved multi-shot (IMS) echoplanar imaging (EPI) to the ON findings of IIH in children.

METHODS

MRIs of 42 pediatric patients aged 3-17 years diagnosed with definite IIH according to modified Dandy criteria were retrospectively re-evaluated, between April 2018 and January 2021. Forty-two age- and sex-matched subjects with no IIH symptoms and reported as normal were included as a control group.

RESULTS

ON sheath distance (ONSD) on the ADC map (p = .005) and vertical tortuosity (p = .030) were significant single MRI parameters for predicting IIH. Other single parameters were not statistically significant. Flattening of the posterior sclera (FPS) and ON protrusion (ONP) were observed on ADC maps more frequently than T2w (42.8% vs. 19% and 19% vs. 4.7%, respectively). From combined MRI parameters, the presence of at least one of ONP, FPS, or ONSD on ADC maps (p = .001) showed greater significance than the presence of T2w (p = .048). The predictive values of other MRI findings evaluated together were not statistically significant (p > .05).

CONCLUSIONS

This study's results show that due to the short readout time and less sensitivity to motion, the ADC map obtained from IMS-EPI can contribute to orbital findings of IIH, in addition to T2w.

MRI of the optic nerve sheath and globe in cats with and without presumed intracranial hypertension

OBJECTIVES

The study aimed to: (1) test MRI repeatability of measurements of optic nerve sheath diameter (ONSD), optic nerve diameter (OND) and eye globe transverse diameter (ETD); (2) investigate the associations between the OND, ONSD and ETD; (3) assess whether these measurements are affected by age or body weight; and (4) test the association between ONSD, OND, ETD and ONSD:ETD ratio with presumed intracranial pressure (ICP) status.

METHODS

This was a retrospective and blinded study where patients were allocated to presumed normal or intracranial hypertension groups based on MRI findings. The ONSD and ETD were measured and recorded. Interclass correlation coefficient (ICC) was calculated to investigate interobserver agreement. Data were analysed using the Pearson correlation coefficient, two-sample t-test and general linear model ANOVA.

RESULTS

Seventy-seven cats were included, 62 with presumed normal ICP and 15 with presumed intracranial hypertension. The ICC showed moderate-to-good reliability for all measurements. Positive correlations were identified for: (1) ETD and weight; (2) ONSD and age; (3) OND and age; (4) ONSD and ETD; (5) ONSD:ETD ratio and presumed ICP status; and (6) ONSD and presumed ICP status. No difference was detected between the presumed normal and intracranial hypertension groups and ONSD, as well as ONSD:ETD ratio and presumed ICP status when patient age was considered.

CONCLUSIONS AND RELEVANCE

The measurement of the ONSD and the ONSD:ETD ratio on T2-weighted MRI might not be reliable as non-invasive tests for diagnosing intracranial hypertension in cats.

Brain MRI and Ophthalmic Biomarkers of Intracranial Pressure

OBJECTIVE

To evaluate the utility of brain MRI and ophthalmic biomarkers for the prediction of intracranial hypertension, we have studied the association between 6 biomarkers and 24-hour intracranial pressure (ICP) monitoring results in 45 patients.

METHODS

This single-center observational study includes patients who underwent 24-hour ICP monitoring, brain MRI (within 3 months), and ophthalmic assessment (during ICP monitoring). Six biomarkers were investigated: pituitary gland shape, vertical tortuosity of the optic nerve, distension of the optic nerve sheath, optic disc protrusion (MRI), papilledema (slit lamp biomicroscopy), and spontaneous venous pulsations (SVP, infrared video recordings).

RESULTS

Forty-five patients (mean age 39 ± 14 years, 38 women) met the inclusion criteria. All 6 biomarkers had a significant association with 24-hour ICP. Concave pituitary gland was observed with moderately elevated median ICP. Protrusion of the optic disc (MRI), papilledema, and absence of SVP were associated with the highest median ICP values. Twenty patients had raised ICP (median 24-hour ICP >5.96 mm Hg, cutoff obtained through Youden index calculation). Patients with all normal biomarkers had normal median ICP in 94% (standard error 6%) of the cases. All patients with ≥3 abnormal biomarkers had intracranial hypertension. The combination of at least 1 abnormal biomarker in MRI and ophthalmic assessments was highly suggestive of intracranial hypertension (area under the curve 0.94, 95% confidence interval 0.93-0.94) CONCLUSIONS: Brain MRI and ophthalmic biomarkers can noninvasively guide the management of patients with suspected CSF dynamics abnormalities. Patients with multiple abnormal biomarkers (≥3) or a combination of abnormal MRI and ophthalmic biomarkers are likely to have intracranial hypertension and should be managed promptly.

Magnetic Resonance Imaging Features and Clinical Findings in Pediatric Idiopathic Intracranial Hypertension: A Case-Control Study

The purpose of this study is to identify salient magnetic resonance imaging (MRI) findings of pediatric IIH, to determine the relevance of these findings with regard to disease pathogenesis, and to relate these findings to the clinical presentation towards identification of risk factors of disease. A retrospective, a case–control study of 38 pediatric patients with and 24 pediatric patients without IIH from the ophthalmology department at a tertiary care center was performed. Clinical data, including ophthalmic findings and lumbar puncture results, were recorded. Neuroimaging, including both MRI and magnetic resonance venography (MRV), was evaluated for perioptic subarachnoid space diameter enlargement, posterior globe flattening, optic nerve head protrusion, empty or partially empty sella turcica, dural venous sinus abnormalities, skull base crowding, and prominent arachnoid granulations. Compared with controls, IIH patients had larger perioptic subarachnoid space diameters, higher incidences of posterior globe flattening, protrusion of the optic nerve heads, an empty sella turcica, and dural venous sinus abnormalities. A perioptic subarachnoid space diameter of ≥5.2 mm was identified as an independent predictor of IIH (p < 0.001) with sensitivity of 87% and specificity of 67%. Several significant MRI findings in pediatric IIH were identified. Using a model that uniquely incorporated clinical and MRI findings at presentation, we provide a framework for risk stratification for the diagnosis of pediatric IIH which may be utilized to facilitate diagnosis. Future prospective work is needed to further validate the model developed in this study.

Distorted Optic Nerve Portends Neurological Complications in Infants With External Hydrocephalus

Background: Benign external hydrocephalus (BEH) is defined by rapid increase in head circumference in infancy, with neuroimaging evidence of enlarged cerebrospinal fluid (CSF) spaces. BEH was postulated to predispose to subdural hematoma, neurocognitive impairments, and autism. There is currently no consensus on BEH diagnostic criteria and no biomarkers to predict neurological sequalae. Methods: MRI-based quantitative approach was used for measurement of potential imaging markers related to external hydrocephalus and their association with neurological outcomes. We scanned 23 infants diagnosed with BEH and 11 age-similar controls. Using anatomical measurements from a large sample of healthy infants (n = 150), Z-scores were calculated to classify subject's CSF spaces as enlarged (≥1.96SD of mean values) or normal. Results: Subjects with abnormally enlarged CSF spaces had a significantly wider and longer ON (p = 0.017 and p = 0.020, respectively), and a significantly less tortuous ON (p = 0.006). ON deformity demonstrated a high diagnostic accuracy for abnormally enlarged frontal subarachnoid space (AUC = 0.826) and interhemispheric fissure (AUC = 0.833). No significant association found between enlarged CSF spaces and neurological complications (OR = 0.330, 95%CI 0.070-1.553, p = 0.161). However, cluster analysis identified a distinct subgroup of children (23/34, 67.6%) with enlarged CSF spaces and a wider, longer and less tortuous ON, to have an increased risk for neurological complications (RR = 7.28, 95%CI 1.07-49.40). Discussion: This is the first report on the association between external hydrocephalus, ON deformity and neurological complications. Our findings challenge the current view of external hydrocephalus as a benign condition. ON deformity is a potential auxiliary marker for risk stratification in patients with enlarged CSF spaces.

The role of ICP monitoring in paediatric IIH

INTRODUCTION

Diagnosis of idiopathic intracranial hypertension (IIH) in children is an extrapolation of the guidelines suggested for adult population. Lumbar puncture (LP) plays a crucial role in the diagnosis. The diagnosis of IIH at times is solely dependent on the interpretation of the opening pressure (OP). Unfortunately, LP-OP can vary due circumstantial parameters and therefore may be an unreliable form of intracranial pressure (ICP) measurement. Confirming the diagnosis based (as suggested by guidelines) on LP-OP in a doubtful clinical situation would be inappropriate. The aim of our study was to analyse the reliability of LP-OP and importance of ICP monitoring in situations where diagnosis of IIH was questionable.

METHODS

Retrospective review of all children with diagnosis of IIH over a 10-year period was conducted. Children who underwent ICP monitoring (ICPM) were selected. We considered 2 LP-OP values-last LP (lLP) and the mean LP (mLP) for analysis. ICPM and LP-OP were compared. Follow-up till last clinic visit was also considered for long-term outcome.

RESULTS

Eleven children (male 3; female 8) were included in the study. Mean delay between LP and ICPM was 112.8 days (17-257 days). There was lack of correlation between LP-OP and ICP in 9 children. ICP monitoring refuted the diagnosis of IIH in 80% of children and prevented exposure to unnecessary medical and surgical intervention. There was 1complication with ICPM. In 90% of children, there was no progression of symptoms following a decision based on ICP monitoring on long-term follow-up (mean, 36.5 months).

CONCLUSION

When the diagnosis of IIH is in doubt, LP may be unreliable and formal ICP monitoring is advised.

Intracranial pressure based decision making: Prediction of suspected increased intracranial pressure with machine learning

Background

Repeated invasive intracranial pressure (ICP) monitoring is desirable because many neurosurgical pathologies are associated with elevated ICP. On the other hand, it could become a risk for children to repeat sedation, anesthesia, or radiation exposure. As a non-invasive method, measurements of optic nerve sheath diameter (ONSD) has been revealed to accurately predict increased ICP. However, no studies have indicated a relationship among age, brain, and ventricular parameters in normal children, nor a prediction of increased ICP with artificial intelligence.

Methods and findings

This study enrolled 400 normal children for control and 75 children with signs of increased ICP between 2009 and 2019. Measurements of the parameters including ONSD on CT were obtained. A supervised machine learning was applied to predict suspected increased ICP based on CT measurements. A linear correlation was shown between ln(age) and mean ONSD (mONSD) in normal children, revealing mONSD = 0.36ln(age)+2.26 (R² = 0.60). This study revealed a linear correlation of mONSD measured on CT with ln(age) and the width of the brain, not the width of the ventricles in 400 normal children based on the univariate analyses. Additionally, the multivariate analyses revealed minimum bicaudate nuclei distance was also associated with mONSD. The results of the group comparison between control and suspected increased ICP revealed a statistical significance in mONSD and the width of the ventricles. The study indicated that supervised machine learning application could be applied to predict suspected increased ICP in children, with an accuracy of 94% for training, 91% for test.

Conclusions

This study clarified three issues regarding ONSD and ICP. Mean ONSD measured on CT was correlated with ln(age) and the width of the brain, not the width of the ventricles in 400 normal children based on the univariate analyses. The multivariate analyses revealed minimum bicaudate nuclei distance was also associated with mONSD. Mean ONSD and the width of ventricles were statistically significant in children with signs of elevated ICP. Finally, the study showed that machine learning could be used to predict children with suspected increased ICP.

Neurofibromatosis 1-associated optic pathway gliomas

BACKGROUND

Optic Pathway Gliomas (OPG) are the most common brain tumor in Neurofibromatosis 1 patients (NF1). They are found along the optic pathway and may involve the optic nerves, chiasm, retro-chiasmatic structures, and the optic radiations. NF1 associate OPG (NF1-OPG) have variable presentation, disease course and response to treatment. The optimal management is patient-specific and should be tailored by a multidisciplinary team. Age, sex, histology, and molecular markers may be important factors in the individualized decision-making process. Chemotherapy is the first-line treatment in cases of progressive tumors, and visual preservation is the main goal of treatment.

PURPOSE

In this paper we will review the disease, practical management, and recent advances of NF1-OPG.

Early Detection of Central Nervous System Relapse of Pediatric Leukemia with Measurement of Optic Nerve Sheath Diameter on MRI

BACKGROUND

Leukemia is the most common pediatric malignancy. Central Nervous System (CNS) is the most frequently involved extramedullary location at diagnosis and at relapse.

OBJECTIVE

To determine if Magnetic Resonance Imaging (MRI) findings of optic nerves should contribute to early detection of CNS relapse in pediatric leukemia.

METHODS

Twenty patients (10 boys, 10 girls; mean age 8,3 years, range 4-16 years) with proven CNS relapse of leukemia followed up between 2009 and 2017 in our institution were included. Orbital MRI exams performed before and during CNS relapse were reviewed retrospectively. Forty optic nerves with Optic Nerve Sheaths (ONS) and Optic Nerve Heads (ONH) were evaluated on fat-suppressed T2-weighted TSE axial MR images. ONS diameter was measured from the point 10 mm posterior to the globe. ONS distension and ONH configuration were graded as 0, 1 and 2.

RESULTS

Before CNS relapse, right mean ONS diameter was 4.52 mm and left was 4.61 mm which were 5.68 mm and 5.66 mm respectively during CNS relapse showing a mean increase of 25% on right and 22% on left. During CNS relapse, ONS showed grade 0 distension in 15%, grade 1 in 60%, grade 2 in 25% and ONH demonstrated grade 0 configuration in 70%, grade 1 in 25% and grade 2 in 5% of the patients.

CONCLUSION

MRI findings of optic nerves may contribute to diagnose CNS relapse by demonstrating elevated intracranial pressure in children with leukemia.

Correlation between the total number of features of paediatric pseudotumour cerebri syndrome and cerebrospinal fluid pressure

PURPOSE

Accurate diagnosis of pseudotumour cerebri syndrome (PTCS) in children is challenging. We aimed to see if the clinical and radiological assessment that is carried out before lumbar puncture could predict subsequently recorded CSF pressures, and thus whether it could be used to increase diagnostic certainty of paediatric PTCS.

METHODS

We used internationally recognised diagnostic criteria to derive a list of clinical, brain neuroimaging and venography features that were accepted to be associated with a diagnosis of PTCS. We performed a retrospective cohort study of children referred to our centre with suspected PTCS, identifying the presence or absence of those features for each child at initial presentation. The sum total scores of the features that were present were correlated with the child's recorded CSF pressure.

RESULTS

The sum total scores were significantly positively correlated with recorded CSF pressures. The positive correlation was seen when clinical and brain neuroimaging features were included alone, and the correlation was slightly stronger when venography features were included in addition.

CONCLUSION

Calculating the sum total of clinical, brain neuroimaging and venography features (where venography is performed) present at initial presentation can help in the management of children under investigation for PTCS. Children with high scores are more likely to have severely raised CSF pressures and thus may warrant more urgent LP investigations. By contrast, in children with subtle abnormalities in optic disc appearance such that disc oedema cannot be ruled out, a low score may add further reassurance and less urgency to proceed to LP.

Partial empty sella syndrome, GH deficiency and transient central adrenal insufficiency in a patient with NF1

PURPOSE

To describe the case of a 9-year-old male patient with neurofibromatosis type 1 (NF1), partial empty sella (PES), transient central adrenal insufficiency (CAI) and growth hormone (GH) deficiency (GHD) treated with recombinant GH (rGH).

METHODS

The diagnosis of GHD was established upon peak GH response <10 ng/mL following glucagon and clonidine stimulation tests. CAI was diagnosed when peak cortisol response was <18 μg/dL following 1 μg Synacthen test (ST) with normal ACTH levels.

RESULTS

The diagnosis of NF1 was made at the age of 1.5 year. The patient first attended our Department at the age of 4.5 years. He presented with short stature (height: 95 cm < 3rd percentile), macrocephaly, frontal bossing, café-au-lait spots and bilateral proptosis. His growth rate (GR) initially was 5.3 cm/year. Brain/pituitary MRI showed T2-hyperintensities typical for NF1 and PES with reduced pituitary gland height (3 mm). The pituitary function tests revealed GHD. During follow-up his imaging findings remained unchanged, while his GR decelerated. He was started on rGH at the age of 8.5 years. Within the following year he grew 8.7 cm in height and could preserve a normal GR thereafter. At the age of 10.3 years, he was diagnosed with CAI (maximum cortisol response post-1 μg ST: 13.1 μg/dL). Ηe received hydrocortisone for 1 year. A repeat 1 μg ST off hydrocortisone showed normal cortisol response. During follow-up, brain MRI findings remained stable, while his pituitary demonstrated normal size and signal intensity.

CONCLUSION

Empty sella and hypopituitarism may occur in the context of NF1. Short stature may be associated with GHD in the absence of intrasellar masses in affected individuals. Lifelong endocrine follow-up is recommended for all NF1 patients.

Validation of Noninvasive Absolute Intracranial Pressure Measurements in Traumatic Brain Injury and Intracranial Hemorrhage

BACKGROUND

Increased intracranial pressure (ICP) causes secondary damage in traumatic brain injury (TBI), and intracranial hemorrhage (ICH). Current methods of ICP monitoring require surgery and carry risks of complications.

OBJECTIVE

To validate a new instrument for noninvasive ICP measurement by comparing values obtained from noninvasive measurements to those from commercial implantable devices through this pilot study.

METHODS

The ophthalmic artery (OA) served as a natural ICP sensor. ICP measurements obtained using noninvasive, self-calibrating device utilizing Doppler ultrasound to evaluate OA flow were compared to standard implantable ICP measurement probes.

RESULTS

A total of 78 simultaneous, paired, invasive, and noninvasive ICP measurements were obtained in 11 ICU patients over a 17-mo period with the diagnosis of TBI, SAH, or ICH. A total of 24 paired data points were initially excluded because of questions about data independence. Analysis of variance was performed first on the 54 remaining data points and then on the entire set of 78 data points. There was no difference between the 2 groups nor was there any correlation between type of sensor and the patient (F[10, 43] = 1.516, P = .167), or the accuracy and precision of noninvasive ICP measurements (F[1, 43] = 0.511, P = .479). Accuracy was [-1.130; 0.539] mm Hg (CL = 95%). Patient-specific calibration was not needed. Standard deviation (precision) was [1.632; 2.396] mm Hg (CL = 95%). No adverse events were encountered.

CONCLUSION

This pilot study revealed no significant differences between invasive and noninvasive ICP measurements (P < .05), suggesting that noninvasive ICP measurements obtained by this method are comparable and reliable.

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.

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.

Magnetic Resonance Imaging Findings in Pediatric Pseudotumor Cerebri Syndrome

BACKGROUND

Revised diagnostic criteria for pseudotumor cerebri syndrome require three of four neuroimaging findings in the absence of papilledema. We examined the sensitivity and specificity of three or more of four of these magnetic resonance imaging (MRI) findings for pseudotumor cerebri syndrome in children.

METHODS

As part of clinical care, patients in whom there was suspicion for pseudotumor cerebri syndrome underwent neurological and fundoscopic examinations, lumbar puncture, MRI, or magnetic resonance venogram. For this retrospective study, we used this information to classify 119 subjects into definite (n = 66) or probable pseudotumor cerebri syndrome (n = 12), elevated opening pressure without papilledema (n = 23), or controls who had normal opening pressure without papilledema (n = 24). A neuroradiologist, unaware of the clinical findings or original MRI report, reviewed MRIs for pituitary gland flattening, flattening of the posterior sclera, optic nerve sheath distention, and transverse venous sinus stenosis.

RESULTS

The presence of three or more MRI findings has a sensitivity of 62% (95% confidence interval: 47% to 75%) and a specificity of 95% (95% confidence interval: 77% to 100%), compared with controls. Two of three (transverse venous sinus stenosis, pituitary gland flattening, flattening of the posterior sclera) had a similar sensitivity and specificity. Transverse venous sinus stenosis alone had a slightly higher sensitivity (74%, 95% confidence interval: 60% to 85%) and specificity (100%, 95% confidence interval: 80% to 100%).

CONCLUSIONS

In children, three of four of the proposed neuroimaging criteria and transverse venous sinus stenosis alone have a moderate sensitivity and robust specificity for pseudotumor cerebri syndrome. MRIs should be reviewed for these criteria, and their presence should raise suspicion for pseudotumor cerebri syndrome in children, particularly if the presence of papilledema is uncertain.

Determination of cerebral edema with serial measurement of optic nerve sheath diameter during treatment in children with diabetic ketoacidosis: a longitudinal study

Background Cerebral edema is a fatal complication that can occur in children with diabetic ketoacidosis (DKA). Its clinical signs are generally not explicit, and subclinical cerebral edema can occur. This study is one of the few longitudinal studies conducted to identify cerebral edema in patients with DKA by measuring the optic nerve sheath diameter (ONSD). The aim of this study was to investigate cerebral edema in children with DKA with serial measurement of ONSD, which is an early and reliable indicator of cerebral edema, and to monitor changes in ONSD during therapy. Methods The study was conducted by measuring ONSD ultrasonographically at baseline and during the course of therapy in patients with DKA. All participants were diagnosed and received therapy at our unit between May 2016 and June 2017. The study was registered with the Clinical Trials database, with a study number of NCT02937441. Measurements were obtained while the patients were in the supine position with their eyes closed, and axial transbulbar images of both eyes were obtained with a 6-15-MHz linear probe. Results The ONSD values of children with DKA changed during the treatment, reaching the highest values at 12-16 h of therapy, and the greatest ONSD was observed in children who had moderate and severe DKA. Conclusions During treatment of children with DKA, it is possible to predict cerebral edema by measuring ONSD, and this may contribute to clinical management, especially fluid treatment.

Clinico-radiological correlation of magnetic resonance imaging findings in patients with idiopathic intracranial hypertension

PURPOSE

Although several studies have reported imaging findings associated with idiopathic intracranial hypertension (IIH), less is known about the correlation between imaging findings and IIH-related symptoms or signs. Our study aimed to determine if clinical features of IIH are correlated with magnetic resonance imaging (MRI) features.

METHODS

A retrospective chart review was conducted on consecutive patients presenting at the neuro-ophthalmology department over the last 15 years. All patients diagnosed with IIH were identified and those with available MRI were included in the final analysis. All MRI images were reviewed by a neuroradiologist blinded to the presenting symptoms and signs. Statistical analysis was performed to determine the correlation between the MRI findings with each clinical symptom or sign.

RESULTS

Thirty-one out of 88 patients with the initial diagnosis of IIH had MRI available and were included in the study. Significant correlations were observed between colour vision and amount of perineural fluid around the optic nerve on MRI (r = - 0.382; p = 0.004), disc assessment and intraocular optic nerve protrusion (r = 0.364; p = 0.004), disc assessment and perineural fluid around the optic nerve (r = 0.276; p = 0.033) and disc assessment and venous sinus stenosis (r = 0.351; p = 0.009).

CONCLUSION

Our study highlights correlations between imaging and clinical findings of IIH. MRI findings in IIH may be useful in ruling out ominous causes of intracranial pressure and risk stratifying ophthalmologic intervention and management of patients with headaches possibly due to IIH.

Pediatric optic nerve and optic nerve sheath diameter on magnetic resonance imaging

BACKGROUND

The normal values of optic nerve diameter and optic nerve sheath diameter might be beneficial in defining an abnormality such as optic nerve hypoplasia, or enlarged subarachnoid space, reflecting the state of increased intracranial pressure.

OBJECTIVE

To study the normal optic nerve diameter and optic nerve sheath diameter on magnetic resonance imaging (MRI) in the early years of postnatal visual development from MRI of the brain.

MATERIALS AND METHODS

MRI of the brain in patients ages 4 years and younger were gathered. Forty-two studies with normal intracranial findings and a lack of history of increased intracranial pressure were retrospectively reviewed by two reviewers using axial T2-weighted images. Measurements were performed in transverse diameter perpendicular to the optic nerve at 3 mm behind the globe.

RESULTS

The mean optic nerve diameter of the 77 optic nerves were 2.5 mm (95% confidence interval [CI] 2.4-2.6). The mean optic nerve sheath diameter values of the 79 optic nerve sheath complexes were 5.0 mm (95% CI 4.9-5.1). The mean±standard deviation optic nerve diameter and optic nerve sheath diameter stratified by each age groups were, respectively, 0 to <1 year: 2.3±0.40 and 4.81±0.37; 1 to <2 years: 2.6±0.2 and 5.0±0.4; 2 to <3 years: 2.4±0.3 and 4.9±0.6, and 3 to <4 years: 2.9±0.4 and 5.2±0.60 mm.

CONCLUSION

Seventy-four of the 77 measurements (96%) were of the measurements were above the threshold of 2 mm for optic nerve diameter. Seventy-seven of the 79 measurements (97%) were of the measurements were below the threshold of 6 mm for optic nerve sheath diameter.

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.

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.

Electronic Medical Record Context Signatures Improve Diagnostic Classification Using Medical Image Computing

Composite models that combine medical imaging with electronic medical records (EMR) improve predictive power when compared to traditional models that use imaging alone. The digitization of EMR provides potential access to a wealth of medical information, but presents new challenges in algorithm design and inference. Previous studies, such as Phenome Wide Association Study (PheWAS), have shown that EMR data can be used to investigate the relationship between genotypes and clinical conditions. Here, we introduce Phenome-Disease Association Study to extend the statistical capabilities of the PheWAS software through a custom Python package, which creates diagnostic EMR signatures to capture system-wide co-morbidities for a disease population within a given time interval. We investigate the effect of integrating these EMR signatures with radiological data to improve diagnostic classification in disease domains known to have confounding factors because of variable and complex clinical presentation. Specifically, we focus on two studies: First, a study of four major optic nerve related conditions; and second, a study of diabetes. Addition of EMR signature vectors to radiologically derived structural metrics improves the area under the curve (AUC) for diagnostic classification using elastic net regression, for diseases of the optic nerve. For glaucoma, the AUC improves from 0.71 to 0.83, for intrinsic optic nerve disease it increases from 0.72 to 0.91, for optic nerve edema it increases from 0.95 to 0.96, and for thyroid eye disease from 0.79 to 0.89. The EMR signatures recapitulate known comorbidities with diabetes, such as abnormal glucose, but do not significantly modulate image-derived features. In summary, EMR signatures present a scalable and readily applicable.

Measurement of the Optic Nerve Sheath Diameter with Magnetic Resonance Imaging and Its Association with Eyeball Diameter in Healthy Adults

BACKGROUND AND PURPOSE

The optic nerve sheath diameter (ONSD) is an indirect marker of the intracranial pressure, but the normal range of ONSD as measured using magnetic resonance imaging (MRI) and its associations with clinical parameters and the eyeball transverse diameter (ETD) remain unclear.

METHODS

We included 314 healthy adults who underwent brain MRI examinations for health screening between June 2014 and September 2017. The ONSD and ETD of each eye were calculated using time-of-flight magnetic resonance angiography. Linear regression analyses were performed to assess the relationships between ONSD and variables including age, sex, height, weight, body mass index (BMI), mean arterial blood pressure (MABP), intraocular pressure (IOP), and ETD. We further investigated a normative value for the ONSD/ETD ratio and its associated factors.

RESULTS

The mean ONSD and ETD were 4.71 mm [95% confidence interval (CI), 4.66-4.75 mm] and 21.24 mm (95% CI, 21.13-21.35 mm), respectively. Multiple linear regression analysis showed that ONSD was only associated with ETD (p<0.001), with it being independent of age, sex, height, weight, BMI, MABP, and IOP. The ONSD/ETD ratio had a mean value of 0.22 (95% CI, 0.22-0.22), and was not correlated with age, sex, height, weight, BMI, MABP, or IOP.

CONCLUSIONS

This study determined the normative value of MRI-based ONSD in healthy Korean adults. There was a strong correlation between the ETD and ONSD, which can be presented as the ONSD/ETD ratio. This parameter needs to be investigated further in disease populations.

Radiological Correlates of Raised Intracranial Pressure in Children: A Review

Radiological assessment of the head is a routine part of the management of traumatic brain injury. This assessment can help to determine the requirement for invasive intracranial pressure (ICP) monitoring. The radiological correlates of elevated ICP have been widely studied in adults but far fewer specific pediatric studies have been conducted. There is, however, growing evidence that there are important differences in the radiological presentations of elevated ICP between children and adults; a reflection of the anatomical and physiological differences, as well as a difference in the pathophysiology of brain injury in children. Here in, we review the radiological parameters that correspond with increased ICP in children that have been described in the literature. We then describe the future directions of this work and our recommendations in order to develop non-invasive and radiological markers of raised ICP in children.

Optic Nerve Measurement on MRI in the Pediatric Population: Normative Values and Correlations

BACKGROUND AND PURPOSE

Few articles in the literature have looked at the diameter of the optic nerve on MR imaging, especially in children, in whom observations are subjective and no normative data exist. The aim of this study was to establish a data base for optic nerve diameter measurements on MR imaging in the pediatric population.

MATERIALS AND METHODS

This was a retrospective study on the MR imaging of pediatric subjects (younger than 18 years of age) at the Department of Diagnostic Radiology at the American University of Beirut Medical Center, Beirut, Lebanon. The optic nerve measurements were obtained by 3 raters on axial and coronal sections at 3 mm (retrobulbar) and 7 mm (intraorbital) posterior to the lamina cribrosa.

RESULTS

Of 211 scans of patients (422 optic nerves), 377 optic nerves were measured and included. Ninety-four patients were female (45%) and the median age at MR imaging was 8.6 years (interquartile range, 3.9-13.3 years). Optic nerves were divided into 5 age groups: 0-6 months (n = 18), 6 months-2 years (n = 44), 2-6 years (n = 86), 6-12 years (n = 120), and 12-18 years (n = 109). An increase in optic nerve diameter was observed with age, especially in the first 2 years of life. Measurements did not differ with eye laterality or sex.

CONCLUSIONS

We report normative values of optic nerve diameter measured on MR imaging in children from birth to 18 years of age. A rapid increase in optic nerve diameter was demonstrated during the first 2 years of life, followed by a slower increase. This was independent of sex or eye laterality.

MRI measurements of the normal pediatric optic nerve pathway

The purpose of this work is to establish a reference scale of optic nerve pathway measurements in pediatric patients according to age using MRI. Optic nerve pathway measurements were retrospectively analyzed using an orbits equivalent sequence on brain MRI scans of 137 pediatric patients (72 male, 65 female, average age = 7.7 years, standard deviation  = 5.3). The examinations were performed on a 1.5-T or 3-T Siemens MR system using routine imaging protocols. Measurements include diameters of the orbital optic nerves (OON), prechiasmatic optic nerves (PON), optic tracts (OT), and optic chiasm (OC). Measurements were performed manually by 2 neuroradiologists, using post-processing software. Patients were stratified into five age groups for measurement analyses: (I) 0-1.49 years, (II) 1.5-2.99 years, (III) 3-5.99 years, (IV) 6-11.99 years, and (V) 12-18 years. The observed value range of OON mean diameter was 2.7 mm (Interquartile range (IQR) = 2.4-2.9), PON was 3.2 mm (IQR  =  3.05-3.5), OT 2.6 mm (IQR = 2-2.9). A strong positive correlation was established between age and mean diameter of OON (r = 0.73, p < .001), PON (r = 0.59, p < .001), and OT (r = 0.72, p < .001). A significant difference in mean OON diameters was found between age groups I-II (d = 0.3, p = .01), II-III (d = 0.5, p < .001), III-IV (d = 0.5, p < .001) followed by a plateau between IV-V (d = 0.l0, p = .19). OON/OT ratio maintained a steady mean value 1 (IQR = 0.93-1.1) regardless of age (p = .7). The diameter of optic pathways was found to increase as a function of age with consistent positive correlation between nerve and tract for all ages.

Isolated optic nerve gliomas: a multicenter historical cohort study

OBJECTIVE Isolated optic nerve gliomas (IONGs) constitute a rare subgroup of optic pathway gliomas (OPGs). Due to the rarity of this condition and the difficulty in differentiating IONGs from other types of OPGs in most clinical series, little is known about these tumors. Currently, due to lack of evidence, they are managed the same as any other OPG. METHODS The authors conducted a multicenter retrospective cohort study aimed at determining the natural history of IONGs. Included were patients with clear-cut glioma of the optic nerve without posterior (chiasmatic/hypothalamic) involvement. At least 1 year of follow-up, 2 MRI studies, and 2 neuro-ophthalmological examinations were required for inclusion. RESULTS Thirty-six patients with 39 tumors were included in this study. Age at diagnosis ranged between 6 months and 16 years (average 6 years). The mean follow-up time was 5.6 years. Twenty-five patients had neurofibromatosis Type 1. During the follow-up period, 59% of the tumors progressed, 23% remained stable, and 18% (all with neurofibromatosis Type 1) displayed some degree of spontaneous regression. Fifty-one percent of the patients presented with visual decline, of whom 90% experienced further deterioration. Nine patients were treated with chemotherapy, 5 of whom improved visually. Ten patients underwent operation, and no local or distal recurrence was noted. CONCLUSIONS Isolated optic nerve gliomas are highly dynamic tumors. Radiological progression and visual deterioration occur in greater percentages than in the general population of patients with OPGs. Response to chemotherapy may be better in this group, and its use should be considered early in the course of the disease.

Pulsatile Dynamics of the Optic Nerve Sheath and Intracranial Pressure: An Exploratory In Vivo Investigation

BACKGROUND

Raised intracranial pressure (ICP) may lead to increased stiffness of the optic nerve sheath (ONS).

OBJECTIVE

To develop a method for analyzing ONS dynamics from transorbital ultrasound and investigate a potential difference between patients with raised ICP vs normal ICP.

METHODS

We retrospectively analyzed data from 16 patients (≤12 years old) for whom ultrasound image sequences of the ONS had been acquired from both eyes just before invasive measurement of ICP. Eight patients had an ICP ≥20 mm Hg. The transverse motion on each side of the ONS was estimated from ultrasound, and Fourier analysis was used to extract the magnitude of the displacement corresponding to the heart rate. By calculating the normalized absolute difference between the displacements on each side of the ONS, a measure of ONS deformation was obtained. This parameter was referred to as the deformability index. According to our hypothesis, because deformability is inversely related to stiffness, we expected this parameter to be lower for ICP ≥20 mm Hg compared with ICP <20 mm Hg. The one-sided Mann-Whitney U test was used for statistical comparison.

RESULTS

The deformability index was significantly lower in the group with ICP ≥20 mm Hg (median value 0.11 vs 0.24; P = .002).

CONCLUSION

We present a method for assessment of ONS pulsatile dynamics using transorbital ultrasound imaging. A significant difference was noted between the patient groups, indicating that deformability of the ONS may be relevant as a noninvasive marker of raised ICP. The clinical implications are promising and should be investigated in future clinical studies.

ABBREVIATIONS

AUC, area under curveICP, intracranial pressureONS, optic nerve sheathONSD, optic nerve sheath diameterROC, receiver operating characteristic.