MR imaging of papilledema and visual pathways: effects of increased intracranial pressure and pathophysiologic mechanisms

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.

Nontraumatic Pediatric Head and Neck Emergencies: Resource for On-Call Radiologists

The vast array of acute nontraumatic diseases encountered in the head and neck of pediatric patients can be intimidating for radiologists in training in a fast-paced emergency setting. Although there is some overlap of pediatric and adult diseases, congenital lesions and developmental variants are much more common in the pediatric population. Furthermore, the relative incidences of numerous infections and neoplasms differ between pediatric and adult populations. Young patients and/or those with developmental delays may have clinical histories that are difficult to elicit or nonspecific presentations, underscoring the importance of imaging in facilitating accurate and timely diagnoses. It is essential that radiologists caring for children be well versed in pediatric nontraumatic head and neck emergency imaging. The authors provide an on-call resource for radiology trainees, organized by anatomic location and highlighting key points, pearls, pitfalls, and mimics of many acute nontraumatic diseases in the pediatric head and neck. ©RSNA, 2024 Supplemental material is available for this article.

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.

Diagnostic dilemma of papilledema and pseudopapilledema

BACKGROUND

Papilledema is the optic disc swelling caused by increased intracranial pressure (ICP) that can damage the optic nerve and cause subsequent vision loss. Pseudopapilledema refers to optic disc elevation without peripapillary fluid that can arise from several optic disc disorders, with optic disc drusen (ODD) being the most frequent cause. Occasionally, pseudopapilledema patients are mistakenly diagnosed as papilledema, leading to the possibility of unneeded procedures. We aim to thoroughly examine the most current evidence on papilledema and pseudopapilledema causes and several methods for distinguishing between both conditions.

METHODS

An extensive literature search was conducted on electronic databases including PubMed and google scholar using keywords that were relevant to the assessed pathologies. Data were collected and then summarized in comprehensive form.

RESULTS

Various techniques are employed to distinguish between papilledema and pseudopapilledema. These techniques include Fundus fluorescein angiography, optical coherence tomography, ultrasonography, and magnetic resonance imaging. Lumbar puncture and other invasive procedures may be needed if results are suspicious.

CONCLUSION

Papilledema is a sight-threatening condition that may lead to visual affection. Many disc conditions may mimic papilledema. Accordingly, differentiation between papilledema and pseudopailledema is crucial and can be conducted through many modalities.

The Pseudotumor Cerebri Syndrome

Pseudotumor cerebri syndrome is a syndrome of increased cerebrospinal fluid pressure without ventriculomegaly, mass lesion, or meningeal abnormality. It is either primary (idiopathic intracranial hypertension, IIH) or secondary. A secondary cause is unlikely when adhering to the diagnostic criteria. Permanent visual loss occurs if undetected or untreated, and the associated headaches may be debilitating. Fulminant disease may result in blindness despite aggressive treatment. This study addresses the diagnosis and management of IIH including new insights into the pathobiology of IIH, updates in therapeutics and causes of overdiagnosis.

Foundations of the Diagnosis and Management of Idiopathic Intracranial Hypertension and Pulsatile Tinnitus

Venous sinus stenosis has garnered increasing academic attention as a potential etiology of idiopathic intracranial hypertension (IIH) and pulsatile tinnitus (PT). The complex anatomy of the cerebral venous sinuses and veins plays a crucial role in the pathophysiology of these conditions. Venous sinus stenosis, often found in the superior sagittal or transverse sinus, can lead to elevated intracranial pressure (ICP) and characteristic IIH symptoms. Stenosis, variations in dural venous anatomy, and flow dominance patterns contribute to aberrant flow and subsequent PT. Accurate imaging plays a vital role in diagnosis, and magnetic resonance (MR) venography is particularly useful for detecting stenosis. Management strategies for IIH and PT focus on treating the underlying disease, weight management, medical interventions, and, in severe cases, surgical or endovascular procedures. Recently, venous sinus stenting has gained interest as a minimally invasive treatment option for IIH and PT. Stenting addresses venous sinus stenosis, breaking the feedback loop between elevated ICP and stenosis, thus reducing ICP and promoting cerebrospinal fluid outflow. The correction and resolution of flow aberrances can also mitigate or resolve PT symptoms. While venous sinus stenting remains an emerging field, initial results are promising. Further research is needed to refine patient selection criteria and evaluate the long-term efficacy of stenting as compared to traditional treatments.

Transorbital point-of-care ultrasound versus fundoscopic papilledema to support treatment indication for potentially elevated intracranial pressure in children

PURPOSE

To compare transorbital point-of-care ultrasound techniques -optic nerve sheath diameter (US-ONSD) and optic disc elevation (US-ODE)- with fundoscopic papilledema to detect potentially raised intracranial pressure (ICP) with treatment indication in children.

METHODS

In a prospective study, 72 symptomatic children were included, 50 with later proven disease associated with raised ICP (e.g. pseudotumour cerebri, brain tumour, hydrocephalus) and 22 with pathology excluded. Bilateral US-ONSD and US-ODE were quantified by US using a 12-MHz-linear-array transducer. This was compared to fundoscopic optic disc findings (existence of papilledema) and, in 28 cases, invasively measured ICP values.

RESULTS

The sensitivity and specificity of a cut-off value of US-ONSD (5.73 mm) to detect treatment indication for diseases associated with increased ICP was 92% and 86.4%, respectively, compared to US-ODE (0.43 mm) with sensitivity: 72%, specificity: 77.3%. Fundoscopic papilledema had a sensitivity of 46% and a specificity of 100% in this context. Repeatability and observer-reliability of US-ODE examination was eminent (Cronbach's α = 0.978-0.989). Papilledema was detected fundoscopically only when US-ODE was > 0.67 mm; a US-ODE > 0.43 mm had a positive predictive value of 90% for potentially increased ICP.

CONCLUSION

In our cohort, transorbital point-of-care US-ONSD and US-ODE detected potentially elevated ICP requiring treatment in children more reliably than fundoscopy. US-ONSD and US-ODE indicated the decrease in ICP after treatment earlier and more reliably than fundoscopy. The established cut-off values for US-ONSD and US-ODE and a newly developed US-based grading of ODE can be used as an ideal first-line screening tool to detect or exclude conditions with potentially elevated ICP in children.

Normative body mass-adjusted reference ranges of magnetic resonance imaging signs commonly used in diagnosing idiopathic intracranial hypertension in a healthy standard population

Patients with chronic daily headaches (CDH) are often a diagnostic challenge and frequently undergo neuroimaging. One common underlying cause of CDH is idiopathic intracranial hypertension (IIH). However, certain neuroimaging abnormalities that suggest IIH, such as optic nerve sheath diameters (ONSD), pituitary gland height, and venous sinus diameter, require interpretation due to the absence of established normative values. Notably, intracranial pressure is known to varies with age, sex and weight, further complicating the determination of objectively abnormal findings within a specific patient group. This study aims to assist clinical neuroradiologists in differentiating neuroimaging results in CDH by providing weight-adjusted normative values for imaging characteristics of IIH. In addition to age and BMI we here assessed 1924 population-based T1-weighted MRI datasets of healthy participants for relevant MRI aspects of IIH. Association to BMI was analyzed using linear/logistic regression controlled for age and stratified for sex. ONSD was 4.3 mm [2.8; 5.9]/4.6 mm [3.6; 5.7] and diameter of transverse sinus was 4.67 mm [1.6; 6.5]/4.45 mm [3.0; 7.9]. Height of pituitary gland was 5.1 mm [2.2;8.1]/4.6 mm [1.9;7.1] for female and male respectively. Values generally varied with BMI with regression slopes spanning 0.0001 to 0.05 and were therefor presented as normative values stratified by BMI. Protrusion of ocular papilla, empty sella and transverse sinus occlusion were rare in total. Our data show an association between BMI and commonly used MRI features for diagnosing IIH. We provide categorized normative BMI values for ONSD, pituitary gland height, and transverse sinus diameter. This distinction helps objectively identify potential IIH indicators compared to regular population norms, enhancing diagnostic accuracy for suspected IIH patients. Notably, optic nerve head protrusion, empty sella, and transverse sinus occlusion are rare in healthy individuals, solidifying their importance as imaging markers regardless of BMI.

Leukemic Optic Neuropathy in Pediatric Patients: A Case Series

PURPOSE

To characterize the presentation, clinical course, and treatment of a series of children with leukemic optic neuropathy.

METHODS

Patients with leukemia who were treated at a tertiary children's hospital for optic nerve infiltration were included (n = 11). Demographic information, cancer history, ophthalmologic examination findings, treatment, and outcomes were retrospectively collected.

RESULTS

Mean age was 10.0 ± 4.8 years, and 63.6% were male and 36.4% were female. The most common underlying oncologic diagnosis was B-precursor acute lymphoblastic leukemia (n = 7, 63.6%). Notably, the majority presented with optic nerve infiltration during presumed remission (n = 9, 81.8%), but 2 patients (18.2%) presented with optic nerve infiltration at their initial leukemia diagnosis. Cerebrospinal fluid was positive for leukemic cells in 36.4% of patients. Magnetic resonance imaging demonstrated optic nerve enhancement and/or enlargement in only 8 patients (72.7%). In addition to other leukemia-directed treatment, 8 patients (72.7%) received emergent local radiation within 1.5 ± 1.2 days of initial ophthalmology examination.

CONCLUSIONS

The largely negative cerebrospinal fluid results and variable magnetic resonance imaging findings in this study emphasize the importance of clinical context for this diagnosis. Clinicians should consider optic nerve infiltration in patients with leukemia and visual or ocular complaints, because urgent treatment is required to preserve vision and manage systemic disease. [J Pediatr Ophthalmol Strabismus. 2024;61(1):67-72.].

Influence of sex and disease etiology on the development of papilledema and optic nerve sheath extension in the setting of intracranial pressure elevation in children

Introduction

Dilatation of the optic nerve sheath diameter and swelling of the optic disc are known phenomena associated with intracranial pressure elevation.

Research question

Do sex and disease etiology have an impact on the development of optic disc elevation and optic nerve sheath extension in children in the setting of ICP elevation? Fundoscopic papilledema and point-of-care-ultrasound techniques-optic nerve sheath diameter (US-ONSD) and optic disc elevation (US-ODE) - were compared in this regard.

Material and methods

72 children were included in this prospective study; 50 with proven pathology (e.g. pseudotumor cerebri, tumor), 22 with pathology excluded. Bilateral US-ONSD and US-ODE were quantified by US using a 12-MHz-linear-array-transducer. This was compared with fundoscopic optic disc findings and in 28 patients with invasive ICP values, stratified for sex and etiology.

Results

In patients with proven disease, significant more girls (69%) had fundoscopic papilledema compared with boys (37%, p < 0.05). Girls had also larger US-ODE values (0.86 ± 0.36 mm vs. 0.65 ± 0.40 mm in boys). 80% of tumor patients had initial papilledema (100% girls, 79% boys), compared with 50% in pseudotumor cerebri (PTC) (83% girls, 30% boys). US-ONSD had no sex- and no etiology-specificity.

Discussion and conclusion

Presence of papilledema appears to be influenced by sex and etiology, whereas US-ONSD is not. Girls seem more likely to develop papilledema under similar conditions. Male sex and PTC appear as risk factors for being undetected by fundoscopic findings. US-ONSD and US-ODE seem useful tools to identify pathologies with potentially increased ICP requiring treatment in children regardless of sex and etiology.

Interthalamic Adhesion: Can it be used to Diagnose Idiopathic Intracranial Hypertension?

OBJECTIVE

This retrospective study aimed at determining the dimension of the interthalamic adhesion (ITA) in patients with the idiopathic intracranial hypertension (IIH) for assisting in preoperative radiologic diagnosis.

METHODS

The study universe consisted of magnetic resonance images of 20 patients with IIH (age: 22.70 ± 4.04 years, sex: 14 females and 6 males) and 20 normal subjects (age 22.30± 2.94 years, sex: 14 females and 6 males). To determine the morphology of ITA, its height (vertical diameter) and width (horizontal diameter) were measured on the coronal and axial planes, respectively.

RESULTS

The height and width of ITA in IIH were measured as 2.58 ± 0.71 mm (range: 1.40-4.20 mm) and 2.73 ± 0.77 mm (range: 1.70-4.40 mm), respectively. Its height and width in controls were measured as 4.99 ± 1.04 mm (range: 2.70-6.30 mm) and 4.92 ± 1.11 mm (range: 2.60-6.50 mm), respectively. ITA height and width in IIH was significantly smaller compared with controls (P < 0.001). For an arbitrary cutoff of 3.85 mm, the sensitivity of the height of ITA was 85% with 95% specificity. For an arbitrary cutoff of 4.45 mm, the sensitivity of the width of ITA was 75% with 100% specificity.

CONCLUSIONS

The height and width of ITA are approximately 50% smaller in IIH than controls; therefore alterations in the dimension of ITA may be a valuable radiologic sign for the diagnosis of IIH.

Non-Invasive Intracranial Pressure Monitoring

(1) Background: Intracranial pressure (ICP) monitoring plays a key role in the treatment of patients in intensive care units, as well as during long-term surgeries and interventions. The gold standard is invasive measurement and monitoring via ventricular drainage or a parenchymal probe. In recent decades, numerous methods for non-invasive measurement have been evaluated but none have become established in routine clinical practice. The aim of this study was to reflect on the current state of research and shed light on relevant techniques for future clinical application. (2) Methods: We performed a PubMed search for “non-invasive AND ICP AND (measurement OR monitoring)” and identified 306 results. On the basis of these search results, we conducted an in-depth source analysis to identify additional methods. Studies were analyzed for design, patient type (e.g., infants, adults, and shunt patients), statistical evaluation (correlation, accuracy, and reliability), number of included measurements, and statistical assessment of accuracy and reliability. (3) Results: MRI-ICP and two-depth Doppler showed the most potential (and were the most complex methods). Tympanic membrane temperature, diffuse correlation spectroscopy, natural resonance frequency, and retinal vein approaches were also promising. (4) Conclusions: To date, no convincing evidence supports the use of a particular method for non-invasive intracranial pressure measurement. However, many new approaches are under development.

Perioptic cerebro-spinal fluid transudation: case report of an unusual finding of optic hydrops in idiopathic intracranial hypertension

Background

Idiopathic intracranial hypertension (IIH) has well-described imaging findings, typically reversible with the adequate treatment. We hereby report a case of IIH with a peculiar imaging finding, that to our knowledge and by the research conducted, has never been described before—cerebro-spinal fluid (CSF) transudation across the optic nerve sheath.

Case presentation

A 15-year-old girl with a 2-week history of occipital headache, nausea and vomiting, diplopia, blurred vision and tinnitus in her right ear, was admitted in the neuropediatric department and after extensive diagnostic work-up was diagnosed with IIH. The MRI showed typical signs of idiopathic intracranial hypertension, including enlargement of the perioptic CSF spaces associated with a peculiar finding described as a blurred hyperintensity T2/FLAIR of the perioptic fat, which was likely related to transudation of CSF. The adequate medical therapy (including corticosteroids and acetazolamide) for 2 weeks didn’t revert the signs and symptoms and so a lumboperitoneal shunt was placed with complete resolution of the clinical picture and the imaging findings described.

Conclusions

The documentation of CSF transudation around the optic nerve in the setting of hydrops has never been reported before and should be recognized by the neuroradiologist. It seems to be reversible, like the other findings of IIH and its physiopathology is not clear.

Transorbital Ultrasonography Used to Detect Papilledema, in a Patient With Intracranial Hypertension

Intracranial hypertension (IH) is an important cause of secondary brain injury, and it is often associated with poor outcomes; due to that monitoring of intracranial pressure (ICP) is essential for the management of neurocritical patients. Although invasive methods have been the gold standard for ICP monitoring, recent non-invasive ultrasonography techniques have been used to estimate ICP. Among the most used methods are the measurement of the diameter of the optic nerve sheath and transorbital ultrasonography to evaluate papilledema. This presented case is of a patient with refractory IH due to subarachnoid hemorrhage, measured through an intraventricular catheter. A transorbital sonogram was performed and showed the presence of papilledema.

Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) values of optic nerve head in Papilledema

Background

Papilledema is optic disc pathology characterized by swelling of the optic disc occurring secondary to elevated intracranial pressure (ICP), and it was proposed that elevated ICP is transferred along the subarachnoid space to the optic nerve (ON) leading to metabolic process interruptions and MRI changes within ON head. This study aimed to rule out if DWI and ADC map can be used as a diagnostic tool for detection of papilledema and if ADC values can be helpful in papilledema grading.

Result

ADC value was significantly lower in papilledema cases group (A) in comparison with control group (B).

Conclusion

Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) map can be utilized as a diagnostic tool for diagnosis of papilledema, and ADC values can be helpful in diagnosis of papilledema grade.

Clinical profile and ophthalmological manifestations of idiopathic intracranial hypertension in adults at a tertiary care center in India: A cross-sectional study

Purpose

Our aim was to describe the clinical profile of patients with idiopathic intracranial hypertension (IIH), assess ophthalmological manifestations, and correlate grade of papilledema with optic nerve sheath diameter (ONSD) and cerebrospinal fluid (CSF) opening pressure.

Methods

This was a prospective cross-sectional study. Patients between 18 and 60 years, diagnosed with IIH using modified Dandy criteria were included. Demographic details, ocular symptoms and signs were noted and papilledema graded. Ocular investigations such as B-scan ONSD and perimetry findings were noted for analysis.

Results

The study included 32 patients of mean age 35.25(±9.57) years with a predominantly female population (96.9%). Mean BMI was 28.12(±5.32) kg/m². Common presenting complaint was headache (87.5%). The most common gynecological disorder was dysmenorrhea (15.6%). Vitamin D deficiency (46.9%) was a biochemical abnormality seen. Most patients had BCVA 6/6 (62.5%). Lateral rectus palsy was present in 12.5%. Papilledema was present in 81.3% eyes with 31.3% Grade I. There was visual field loss in 53.1%, with 20.3% Grade I. Mean CSF opening pressure was 376.3(±191.51) mmH₂O. MRI showed empty sella (34.4%) and tortuous optic nerve (18.8%). MRV showed transverse sinus stenosis (52.4%) as common abnormality. There was significant correlation between grade of papilledema and B-scan ONSD. No correlation was seen between CSF opening pressure and ONSD, grade of papilledema and grade of visual field defect and CSF opening pressure with BMI.

Conclusion

Clinical profile of patients with IIH was an overweight female of child-bearing age with headache. Visual field examinations are essential in management and follow-up. B-scan ONSD is useful to quantify raised ICP.

Optic Nerve Atrophy in Syndromic Craniosynostosis

BACKGROUND

Numerous children born with syndromic craniosynostosis will develop visual impairments. Based on the hypothesis that elevations in intracranial pressure might have greater impacts on vision than development, this review sought to ascertain the prevalence of optic nerve atrophy in syndromic craniosynostosis and to look for potential predictive factors.

METHODS

A retrospective chart review of all children with syndromic craniosynostosis treated at a single center.

RESULTS

Of 442 patients with syndromic craniosynostosis, complete ophthalmologic records were available for 253. Although no instances of optic nerve atrophy were noted among those with Saethre-Chotzen or Muenke syndromes, an overall 14.7% prevalence was noted among those with Apert (7.8%), Crouzon (27.9%), and Pfeiffer syndromes (23.1%), with initial diagnoses occurring at a mean age of 10 years. The presence of a Chiari malformation was found to significantly correlate with the subsequent diagnosis of optic nerve atrophy (Odds ratio 3.544, p = 0.002); however, the timing of the first cranial vault procedure, presence of a venticuloperitoneal shunt, degree of brachycephaly, number of vault expansions, and diagnosis of sleep apnea, did not show significant associations.

CONCLUSIONS

A substantial percentage of children with Apert, Crouzon, and Pfeiffer syndrome were found to develop optic nerve atrophy, with a prevalence likely to trend higher with longer follow up. Chiari malformations were the only significant potential predictor for optic nerve atrophy. With the goal of preventing visual losses, more frequent monitoring for raised intracranial pressure with ophthalmologic evaluations and MRI measurements of optic nerve sheath diameters should be considered.

Cerebral Venous Outflow Implications in Idiopathic Intracranial Hypertension-From Physiopathology to Treatment

In this review, we provide an update on the pathogenesis, diagnosis, and management of adults with idiopathic intracranial hypertension (IIH) and implications of the cerebral venous system, highlighting the progress made during the past decade with regard to mechanisms of the venous outflow pathway and its connection with the cerebral glymphatic and lymphatic network in genesis of IIH. Early diagnosis and treatment are crucial for favorable visual outcomes and to avoid vision loss, but there is also a risk of overdiagnosis and misdiagnosis in many patients with IIH. We also present details about treatment of intracranial hypertension, which is possible in most cases with a combination of weight loss and drug treatments, but also in selected cases with surgical interventions such as optic nerve sheath fenestration, cerebral spinal fluid (CSF) diversion, or dural venous sinus stenting for some patients with cerebral venous sinus stenosis, after careful analysis of mechanisms of intracranial hypertension, patient clinical profile, and method risks.

Subarachnoid space of the optic nerve sheath and intracranial hypertension: a macroscopic, light and electron microscopic study

PURPOSE

The optic nerve (ON) is an extension of the central nervous system via the optic canal to the orbital cavity. It is accompanied by meninges whose arachnoid layer is in continuity with that of the chiasmatic cistern. This arachnoid layer is extended along the ON, delimiting a subarachnoid space (SAS) around the ON. Not all forms of chronic intracranial hypertension (ICH) present papilledema. The latter is sometimes asymmetric, unilateral, or absent. The radiological signs of optic nerve sheath (ONS) dilation, in magnetic resonance imaging, are inconsistent or difficult to interpret. The objective of this study was to analyze the anatomy, the constitution, and the variability of the SAS around the ON in its intraorbital segment to improve the understanding of the pathophysiologic mechanism of asymmetric or unilateral or absent papilledema in certain ICH.

METHODS

The study was carried out on nine cadaveric specimens. In four embalmed specimens, macroscopic analysis of the SAS of the ONS were performed, with description about density of the arachnoid trabecular meshwork in three distinct areas (bulbar segment, mid-orbital segment and the precanal segment). In three other embalmed specimens, after staining of SAS by methylene blue (MB), we performed macroscopic analysis of MB progression in the SAS of the ONS. Then, in two non-embalmed specimens, light and electron microscopy (EM) analysis were also done.

RESULTS

On the macroscopic level, after staining of SAS, we found in all cases that MB progressed on 16 mm average throughout the SAS of the ONS without reaching the papilla. In four embalmed specimens, in the SAS of the ONS, the density of the arachnoid trabecular meshwork showed inter-individual variability (100%) and intra-individual variability with bilateral variability (50%) and/or variability within the same ONS (88%). On the microscopic level, the arachnoid trabeculae of the ONS are composed of dense connective tissue. The EM perfectly depicted its composition which is mainly of collagen fibers of parallel orientation.

CONCLUSION

The variability of the SAS around the ONS probably impacts the symmetrical or asymmetrical nature of papilledema in ICH.

Utility of Neuroimaging in the Management of Chronic and Acute Headache

Imaging plays an important role in identifying the cause of the much less common secondary headaches. Such headaches may be caused by a variety of pathologic conditions which can be categorized as intracranial and extracranial. Idiopathic intracranial hypertension imaging findings include "empty sella," orbital changes, and dural venous sinus narrowing. Intracranial hypotension (ICH) is frequently caused by CSF leaks. Imaging findings include loss of the CSF spaces, downward displacement of the brain, as well as dural thickening and enhancement. Severe cases of ICH may result in subdural hematomas. A variety of intracranial and skull base tumors may cause headaches due to dural involvement. Extracranial tumors and lesions that frequently present with headaches include a variety of sinonasal tumors as well as mucoceles. Neurovascular compression disorders causing headaches include trigeminal and glossopharyngeal neuralgia. Imaging findings include displacement and atrophy of the cranial nerve caused by an adjacent arterial or venous structure.

Advances in the Understanding of the Complex Role of Venous Sinus Stenosis in Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is a disorder characterized by elevated intracranial pressure (ICP) that predominantly affects young obese women. IIH is a diagnosis of exclusion. That is, if increased ICP is suspected, magnetic resonance imaging and magnetic resonance venography of the brain are recommended to exclude secondary causes. Imaging findings, such as empty sella, orbital findings, meningocele, and encephalocele, are not diagnostic of ICP, nor does their absence exclude ICP either. Therefore, venous manometry is recommended as the gold standard for evaluation, regardless of previous anatomic imaging results. Venous manometry is an invasive examination that is frequently applied to derive physiologic information concerning the nature of the pressure gradient. However, the pathogenesis of IIH has not been fully elucidated. The presence of venous sinus stenosis in a subset of patients has provided some support for the potential mechanisms underlying this condition. Hence, this review provides an up‐to‐date discussion on the potential pathogenic mechanisms of IIH with a special focus on venous sinus stenosis.

Vogt-Koyanagi-Harada disease – A diagnostic pitfall for neurologists

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VKH is an idiopathic autoimmune disease presenting with uveomeningeal syndrome.

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Granulomatous uveitis and serious retinal detachments are the most common findings of VKH.

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VKH can masquerade as IIH by presenting with severe headache and optic disc edema.

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The characteristic retinal finding of VKH can be easily missed by direct funduscopy.

Papilledema: A Review of the Pathophysiology, Imaging Findings, and Mimics

Increased intracranial pressure is the most common cause of papilledema. Multiple etiologies such as cerebral edema, hydrocephalus, space occupying lesions, infection, and idiopathic intracranial hypertension among others should be considered. Imaging plays a critical role in the detection of pathologies that can cause papilledema. MRI with contrast and CE-MRV, in particular, are key for the diagnosis of idiopathic intracranial hypertension. This review will focus in common and infrequent causes of papilledema, the role of imaging in patients with papilledema as well as its potential mimickers.

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.

Management of ventriculomegaly in pediatric patients with syndromic craniosynostosis: a single center experience

INTRODUCTION

Management of ventriculomegaly in pediatric patients with syndromic craniosynostosis (SC) requires understanding the underlying mechanisms that cause increased intracranial pressure (ICP) and the role of cerebrospinal fluid (CSF) in cranial vault expansion in order to select the best treatment option for each individual patient.

METHODS

A total of 33 pediatric patients with SC requiring craniofacial surgery were retrospectively evaluated. Cases of nonsyndromic craniosynostosis and shunt-induced craniosynostosis were excluded. Six syndrome-based categories were distinguished: Crouzon syndrome, Pfeiffer syndrome, Apert syndrome, cloverleaf skull syndrome, and others (Muenke syndrome, Sensenbrenner syndrome, unclassified). All of the patients were treated surgically for their cranial deformity between 2010 and 2016. The presence of ventriculomegaly and ventriculoperitoneal (VP) shunt requirement with its impact in cranial vault expansion were analyzed. Clinical and neuroimaging studies covering the time from presentation through the follow-up period were revised. The mean postoperative follow-up was 6 years and 3 months. A systematic review of the literature was conducted through a PubMed search.

RESULTS

Of the total of 33 patients with SC, 18 (54.5%) developed ventriculomegaly and 13 (39.4%) required ventriculoperitoneal (VP) shunt placement. Six patients (18.2%) required shunt placement previous to craniofacial surgery. Seven patients (21.2%) required a shunt after craniofacial surgery. Seven fixed pressure ventriculoperitoneal shunts and six programmable valves were placed as first choice. All patients improved their clinical symptoms after shunt placement. Aesthetic results seemed to be better in patients with programmable shunts.

CONCLUSIONS

Unless clear criteria for overt hydrocephalus are present, it is recommended to perform craniofacial surgery as a first step in the management of patients with SC in order to preserve the expansive effect of CSF for cranial vault expansion. In our experience, the use of externally programmable valves allows for the treatment of hydrocephalus while maintaining the expansive effect of CSF for the remodeling of the cranial vault. Prospective evaluations are needed to determine causality.

Evaluation of 2D FLAIR hyperintensity of the optic nerve and optic nerve head and visual parameters in idiopathic intracranial hypertension

BACKGROUND AND PURPOSE

T2/FLAIR hyperintensity of the optic nerve/optic nerve head has been described as a sensitive finding in idiopathic intracranial hypertension using post-contrast 3D-T2/FLAIR imaging. The purpose of this study is to assess whether hyperintensity on non-enhanced 2D-T2/FLAIR imaging occurs more likely in diseased patients than controls and to evaluate the relationship between FLAIR signal and visual parameters MATERIALS AND METHODS: A retrospective case-control study was performed of patients with idiopathic intracranial hypertension and controls who underwent orbital MRI. Three neuroradiologists reviewed the FLAIR images, subjectively evaluating for hyperintense signal within the optic nerves/optic nerve heads using a 5-point Likert Scale. Quantitative assessment of optic nerve signal using regions of interests was performed. Clinical parameters were extracted. The diagnostic performance was evaluated, and Spearman correlation calculated to assess the relationship between FLAIR signal and visual outcomes.

RESULTS

The sensitivity of abnormal FLAIR signal within the optic nerves and optic nerve heads in patients with idiopathic intracranial hypertension ranged from 25-54% and 4-29%, respectively, with specificities ranging from 67-92% and 83-100%. Quantitative assessment revealed a significant difference in CNR between cases and controls in the left posterior optic nerve (p=.002). A positive linear relationship existed between abnormal optic nerve head signal and papilledema grade (OD: p=.02, OS: p=.008) but not with other visual parameters.

CONCLUSION

T2/FLAIR hyperintensity in the optic nerve/optic nerve head may support the diagnosis of idiopathic intracranial hypertension but its absence should not dissuade it. If present, abnormal signal in the optic nerve head correlates with papilledema.

Optic Disc Edema and Posterior Globe Flattening Secondary to Ocular Hypotony: Case Report and Discussion Regarding Pathophysiology and Clinical Findings

ABSTRACT

We describe a case of a young female patient presenting with ocular hypotension (4 mm Hg) secondary to cyclodialysis, and optic disc edema (ODE) after a blunt trauma in the right eye (right eye). MRI showed posterior globe flattening of the right eye, drawing our attention to the pathophysiology behind these findings. The combination of ODE and posterior globe flattening, as observed in the present case of ocular hypotony, is known from other conditions such as intracranial hypertension and space-flight neuro-ocular syndrome, pointing to a common pathophysiological mechanism, possibly resulting from axoplasmic stasis at the level of the lamina cribrosa due to a high translaminar pressure difference.

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.

Advances in magnetic resonance imaging of orbital disease

Magnetic resonance imaging (MRI) is increasingly used by the orbital surgeon to aid in the diagnosis, surgical planning, and monitoring of orbital disease. MRI provides superior soft tissue detail compared with computed tomography or ultrasound, and advancing techniques enhance its ability to highlight abnormal orbital pathology. Diffusion-weighted imaging is a specialized technique that uses water molecule diffusion patterns in tissue to generate contrast signals and can help distinguish malignant from benign lesions. Steady-state free precession sequences such as Constructive Interference in Steady-State (CISS) and Fast Imaging Employing Steady-state Acquisition (FIESTA) generate highly detailed, 3-dimensional reconstructed images and are particularly useful in distinguishing structures adjacent to cerebral spinal fluid. Magnetic resonance angiography can be used to characterize vascular lesions within the orbit. New developments in magnetic field strength as well as the use of orbital surface coils achieve increasingly improved imaging resolution.

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.

Neuroimaging in Children with Ophthalmological Complaints: A Review

Pediatric patients are commonly referred to imaging following abnormal ophthalmological examinations. Common indications include papilledema, altered vision, strabismus, nystagmus, anisocoria, proptosis, coloboma, and leukocoria. Magnetic resonance imaging (MRI) of the brain and orbits (with or without contrast material administration) is typically the imaging modality of choice. However, a cranial CT scan is sometimes initially performed, particularly when MRI is not readily available. Familiarity with the various ophthalmological conditions may assist the radiologist in formulating differential diagnoses and proper MRI protocols afterward. Although MRI of the brain and orbits usually suffices, further refinements are sometimes warranted to enable suitable assessment and accurate diagnosis. For example, the assessment of children with sudden onset anisocoria associated with Horner syndrome will require imaging of the entire oculosympathetic pathway, including the brain, orbits, neck, and chest. Dedicated orbital scans should cover the area between the hard palate and approximately 1 cm above the orbits in the axial plane and extend from the lens to the midpons in the coronal plane. Fat-suppressed T2-weighted fast spin echo sequences should enable proper assessment of the globes, optic nerves, and perioptic subarachnoid spaces. Contrast material should be given judiciously, ideally according to clinical circumstances and precontrast scans. In this review, we discuss the major indications for imaging following abnormal ophthalmological examinations.

MRI findings as markers of idiopathic intracranial hypertension

PURPOSE OF REVIEW

Negative findings on neuroimaging are part of the diagnostic criteria for idiopathic intracranial hypertension (IIH), a syndrome characterized by increased intracranial pressure (ICP). Some positive neuroimaging findings are associated with increased ICP, but their role in diagnosis of IIH has not been established. We provide an overview of these findings and their relevance for diagnosis of raised intracranial pressure.

RECENT FINDINGS

MRI acquisition techniques have significantly improved in the last few decades leading to better characterization of the intracranial changes associated with IIH, including empty sella turcica, optic nerve tortuosity, distension of the optic nerve sheath, posterior globe flattening, slit-like ventricles, and venous sinus stenosis. These may be MRI biomarkers of increased ICP. Prevalence difference between people with and without increased ICP, and reversibility of these MRI findings following treatment of increased ICP inform evaluation of their diagnostic potential.

SUMMARY

MRI and magnetic resonance venography findings are important tools in the diagnosis of IIH. Empty sella turcica, optic nerve protrusion, distension of the optic nerve sheath, optic nerve tortuosity, posterior globe flattening, and transverse sinus stenosis have been found to be the most promising diagnostic markers for IIH, although absence of these findings does not rule out the diagnosis.

Numerical Investigation on the Role of Mechanical Factors Contributing to Globe Flattening in States of Elevated Intracranial Pressure

Flattening of the posterior eye globe in the magnetic resonance (MR) images is a sign associated with elevated intracranial pressure (ICP), often seen in people with idiopathic intracranial hypertension (IIH). The exact underlying mechanisms of globe flattening (GF) are not fully known but mechanical factors are believed to play a role. In the present study, we investigated the effects of material properties and pressure loads on GF. For this purpose, we used a generic finite element model to investigate the deformation of the posterior eyeball. The degree of GF in numerical models and the significance of different mechanical factors on GF were characterized using an automated angle-slope technique and a statistical measure. From the numerical models, we found that ICP had the most important role in GF. We also showed that the angle-slope graphs pertaining to MR images from five people with high ICP can be represented numerically by manipulating the parameters of the finite element model. This numerical study suggests that GF observed in IIH patients can be accounted for by the forces caused by elevation of ICP from its normal level, while material properties of ocular tissues, such as sclera (SC), peripapillary sclera (PSC), and optic nerve (ON), would impact its severity.

Acute Visual Loss Secondary to Arnold Chiari Type I Malformation Completely Resolving After Decompressive Posterior Fossa Surgery

We describe the case of a 22-year-old woman of southeast-Asian origin, presenting with unilateral sudden visual loss after a self-healing hearing loss a week before. Ophthalmological examination showed visual acuity of light perception in the left eye, mild RAPD, normal ocular motility and an elevated optic disc with indistinct margins. Neurological examination showed no acute pathology and brain CT-MRI imaging revealed a small-almost subclinical-herniation of the cerebellar tonsils. As investigation eliminated every other infectious or inflammatory cause of papillitis, neurosurgical intervention was proposed. The patient underwent an uncomplicated occipital craniotomy with posterior fossa decompression and had a favorable revolution with regression of papilledema and a fully recovering visual acuity that reached 20/20. Chiari malformation type I refers to an abnormality of the posterior fossa that has a smaller volume than normal, leading to the herniation of cerebellar tonsils, at least 5 mm below the foramen magnum. The occurrence of papilledema associated with Chiari malformation type 1 is rare. Chiari malformation has, until today, mainly been studied among children populations, usually with a poor visual acuity recovery. The originality of our case report consists in the description of an adult patient case showing unilateral, unusual ophthalmological findings and complete recovery after surgical treatment.

The impact of hypertonic saline on cerebrovascular reactivity and compensatory reserve in traumatic brain injury: an exploratory analysis

Background

Intravenous hypertonic saline is utilized commonly in critical care for treatment of acute or refractory elevations of intracranial pressure (ICP) in traumatic brain injury (TBI) patients. Though there is a clear understanding of the general physiological effects of a hypertonic saline solution over long periods of time, smaller epoch effects of hypertonic saline (HTS) have not been thoroughly analyzed. The aim of this study was to perform a direct evaluation of the high-frequency response of HTS on the cerebrovascular physiological responses in TBI.

Methods

We retrospectively reviewed our prospectively maintained adult TBI database for those with archived high-frequency cerebral physiology and available HTS treatment information. We evaluated different epochs of physiology around HTS bolus dosing, comparing pre- with post-HTS. We assessed for changes in slow fluctuations in ICP, pulse amplitude of ICP (AMP), cerebral perfusion pressure (CPP), mean arterial pressure (MAP), cerebrovascular reactivity (as measured through pressure reactivity index (PRx)), and cerebral compensatory reserve (correlation (R) between AMP (A) and ICP (P)). Comparisons of mean measures and percentage time above clinically relevant thresholds for the physiological parameters were compared pre- and post-HTS using descriptive statistics and Mann-Whitney U testing. We assessed for subgroups of physiological responses using latent profile analysis (LPA).

Results

Fifteen patients underwent 69 distinct bolus infusions of hypertonic saline. Apart from the well-documented decrease in ICP, there was also a reduction in AMP. The analysis of cerebrovascular reactivity response to HTS solution had two main effects. For patients with grossly impaired cerebrovascular reactivity pre-HTS (PRx > + 0.30), HTS bolus led to improved reactivity. However, for those with intact cerebrovascular reactivity pre-HTS (PRx < 0), HTS bolus demonstrated a trend towards more impaired reactivity. This indicates that HTS has different impacts, dependent on pre-bolus cerebrovascular status. There was no significant change in metrics of cerebral compensatory reserve. LPA failed to demonstrate any subgroups of physiological responses to HTS administration.

Conclusions

The direct decrease in ICP and AMP confirms that a bolus dose of a HTS solution is an effective therapeutic agent for intracranial hypertension. However, in patients with intact autoregulation, hypertonic saline may impair cerebral hemodynamics. These findings regarding cerebrovascular reactivity remain preliminary and require further investigation.

Electronic supplementary material

The online version of this article (10.1007/s00701-020-04579-0) contains supplementary material, which is available to authorized users.

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.

Bilateral Proptosis in a Child-A Rare Manifestation of Ventriculoperitoneal Shunt Obstruction

Ventriculoperitoneal shunt (VPS) obstruction may have a myriad of presentations. We reported a case of an 11-year-old girl presenting with acute, bilateral proptosis secondary to VPS obstruction. While neuroimaging was interpreted as unremarkable, fundoscopy revealed bilateral papilledema and lumbar puncture showed elevated intracranial pressure. Neurosurgical exploration demonstrated VPS valve obstruction and a new VPS was inserted. Postoperatively, she developed a recurrent extradural hematoma, which was initially evacuated and later managed conservatively. To our knowledge, this is the first report of bilateral proptosis secondary to VPS obstruction. This case highlights the value of key clinical findings and limitations of neuroimaging.

Magnetic Resonance Imaging of Idiopathic Intracranial Hypertension: Before and After Treatment

BACKGROUND

This study aimed to identify the reversibility of MRI findings indicative of increased intracranial hypertension in idiopathic intracranial hypertension (IIH) patients after treatment.

METHODS

This retrospective, observational study included demographic and clinical data from 10 patients with IIH and 10 controls. Brain MRI findings in IIH patients were recorded twice: once when patients had papilledema and again after resolution of papilledema. Neuroradiologists graded MRI findings in both groups based on an imaging grading scale.

RESULTS

After resolution of papilledema, all patients showed improvement in 2 or more of the MRI characteristics of IIH. This was especially the case for the height of the midsagittal pituitary gland and optic nerve sheath thickness (ONST), which were significantly different in all pairwise group comparisons. Sellar configuration, globe configuration, and horizontal orbital optic nerve tortuosity were different between the IIH pre-treatment group and controls, but not between controls and the IIH post-treatment group. We found no difference in optic nerve head hyperintensity or optic nerve thickness among the 3 groups.

CONCLUSIONS

We demonstrated that several morphometric MRI characteristics in IIH are reversible to a certain extent after treatment. Enlarged subarachnoid spaces filled with cerebrospinal fluid seem to remain reduced, and the ONST and height of the pituitary gland are not fully normalized after treatment.

Effect of 5 different cervical collars on optic nerve sheath diameter: A randomized crossover trial

BACKGROUND

There is considerable evidence that prolonged use of cervical collars potentially cause detrimental effects including increase in optic nerve sheath diameter (ONSD) among healthy volunteers. Different types of cervical collars immobilize cervical spine variably well and may presumably differently influence the venous compression and hence the intracranial pressure. We therefore aimed to evaluate the influence of cervical spine immobilization with 5 different types of cervical collars on ONSD measured noninvasively by ultrasound on healthy volunteers.

METHODS

We conducted a randomized crossover trial including 60 adult healthy volunteers. Control assessment of the optic nerve sheath thickness was performed in both sagittal and transverse planes. Patient was placed supine on a transport stretcher, cervical collar was placed, and ONSD measurement was performed after 5 and 20 minutes. During the next days, the procedure was repeated with random allocation of participants and random cervical collar.

RESULTS

Sixty healthy volunteers were included in our study. ONSD left diameter [mm] for the baseline was 3.8 [interquartile range (IQR): 3.65-3.93)] mm. Using AMBU after 5 min, ONSD was changed up to 4.505 (IQR 4.285-4.61; P < .001) mm. The largest change at 5 minutes and 20 minutes was using Philly 4.73 (IQR: 4.49-4.895; P < .001) and 4.925 (IQR: 4.65-5.06; P < .001), respectively. Necklite reported the lower change in ONSD: 3.92 (IQR: 3.795-4; P = 1.0) mm in 5 minutes and 3.995 (IQR: 3.875 - 4.1; P = 1.0) mm in 20 minutes. ONSD right diameter [mm] for the baseline was 3.8 (IQR 3.675-3.9) mm. Using AMBU after 5 minutes, ONSD was changed up to 4.5 (IQR 4.21-4.6) mm. The largest change at 5 minutes and 20 minutes was using Philly 4.705 (IQR 4.455-4.9) and 4.93 (IQR 4.645-5.075), respectively. Necklite reported the lower change in ONSD -33.9 (IQR 3.795-3.99) mm in 5 minutes and 3.995 (IQR 3.86-4.09) mm in 20 minutes.

CONCLUSION

We report significant increase of ONSD from the baseline after cervical collar placement among healthy volunteers at 5 minutes and 20 minutes interval. In addition, no significant difference was noted between ONSD measurements at 5 and 20 minutes. Clinicians should take proactive steps to assess the actual need of cervical collar case by case basis. Nonetheless, when needed, Necklite moldable neck brace seems to be a reasonable option.Registration: ClinicalTrials database (www.clinicaltrials.gov, NCT03609879).

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.

Evaluation of optic nerve head changes with optic coherence tomography in patients with idiopathic intracranial hypertension

In the case of mild papilledema, fundoscopy findings may sometimes be insufficient, leading to false and misleading indices in the diagnosis of early-stage idiopathic intracranial hypertension (IIH). This study aims to evaluate these patients through optic coherence tomography (OCT). The study included 54 individuals diagnosed with IIH and 48 healthy individuals in the control group. All patients underwent neurological and ophthalmologic examinations. Opening pressure values of patients' cerebrospinal fluid (CSF) were recorded. We measured the thickness of the retinal nerve fiber layer (RNFL) and the ganglion cell complex, cup volume, and the optical disc area, as well as the neuroretinal rim in both groups. A total of 108 eyes from the patient group and 96 eyes from the control group were evaluated. It was found that the mean value of the RNFL thickness of the IIH patients was greater than the control group in the following eight segments: superior nasal, superior temporal, inferior nasal, inferior temporal, nasal superior, nasal inferior, temporal superior, and temporal inferior (p < 0.01 for all). In contrast to the control group, the disc and rim area values of the patient group were higher (p < 0.01), while the cup volume was smaller (p < 0.01) than in the control group. In the patient group, a positive correlation was observed between the papilledema grade and the RNFL thickness (r = 0.64, p < 0.01), CSF opening pressure (r = 0.59, p < 0.01), disc area (r = 0.68, p < 0.01), and rim area (r = 0.70, p < 0.01). Furthermore, RNFL thickness, CSF opening pressure (r = 0.61, p < 0.01), disc area (r = 0.71, p < 0.01), and rim area (r = 0.71, p < 0.01) values were determined to be positively correlated to each other. OCT is believed to contribute to the diagnosis of IIH, by providing reliable data on optical cup volume, optical disc and rim area, and a greater RNFL thickness.

Venous Manometry as an Adjunct for Diagnosis and Multimodal Management of Intracranial Hypertension due to Meningioma Compressing Sigmoid Sinus

Intracranial venous hypertension is a rare presentation of meningiomas in the transverse-sigmoid sinus region. We describe a case of a young patient presenting with intracranial hypertension due to a meningioma causing compression of the dominant sigmoid sinus. We were able to document the cerebral venous pressure gradient across the lesion confirming our hypothesis that compression of the sigmoid sinus from the meningioma was the cause of intracranial hypertension. The patient is a 17-year-old male who presented with intracranial hypertension due to meningioma at the right dominant sigmoid sinus, which was treated by a Simpson grade IV surgical resection followed by stereotactic radiosurgery. Following treatment, his papilledema resolved and he remains symptom-free at 18 months. In conclusion, venous manometry is a useful adjunct to diagnose intracranial hypertension in non-idiopathic causes of intracranial hypertension. A multimodal management approach of intracranial hypertension due to outflow obstruction from the dominant sinus led to an excellent recovery on follow up.

Brain Physiological Response and Adaptation During Spaceflight

More than half of astronauts returning from long-duration missions on the International Space Station present with neuro-ocular structural and/or functional changes, including optic disc edema, optic nerve sheath distension, globe flattening, choroidal folds, or hyperopic shifts. This spaceflight-associated neuro-ocular syndrome (SANS) represents a major risk to future exploration class human spaceflight missions, including Mars missions. Although the exact pathophysiology of SANS is unknown, evidence thus far suggests that an increase in intracranial pressure (ICP) relative to the upright position on Earth, which is due to the loss of hydrostatic pressure gradients in space, may play a leading role. This review focuses on brain physiology in the spaceflight environment, specifically on how spaceflight may affect ICP and related indicators of cranial compliance, potential factors related to the development of SANS, and findings from spaceflight as well as ground-based spaceflight analog research studies.

Papilloedema: diffusion-weighted imaging of optic nerve head

AIM

To establish the correlation between clinical grading of papilloedema and diffusion abnormalities of optic nerve head (ONH) on diffusion-weighted imaging (DWI).

MATERIALS AND METHODS

Brain magnetic resonance imaging (MRI), including readout segmented echo planar imaging-based DWI, was performed in 32 patients with papilloedema and the same number of age- and sex-matched controls. Clinical grading of papilloedema was done according to the modified Frisén scale. Two neuroradiologists independently evaluated the MRI for ONH hyperintensity and apparent diffusion coefficient (ADC) value of ONH. The comparison between papilloedema clinical grade and qualitative grade of ONH hyperintensity and its presence between cases and control groups were done using the Chi-square test and Fisher's exact test, respectively. The comparison between mean ADC value of ONH among different grades and between cases and controls were done using analysis of variance (ANOVA)-F-test and Student's t-test, respectively. Receiver operating characteristic (ROC) analysis was done to calculate a cut-off ADC value between the case and control groups.

RESULTS

Significant correlation between ONH hyperintensity and mean ADC value of ONH with clinical grades of papilloedema and between cases and control groups were found. ONH hyperintensity was found to be a highly sensitive (87.5% for both) and specific (specificity 97.1% and 98.6% for two observers) sign of papilloedema. A mean cut-off ONH ADC value was found to have high sensitivity (96.83%) and specificity (95.31%) to distinguish between the cases and controls.

CONCLUSIONS

Diffusion parameters of ONH have significant correlation with clinical grading of papilloedema and can serve as a surrogate marker for intracranial pressure.

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.