Optic Nerve Sheath Distention Research Articles

Quantitative ultrasound image assessment of the optic nerve subarachnoid space during 90-day head-down tilt bed rest

The elevation in the optic nerve sheath (ONS) pressure (ONSP) due to microgravity-induced headward fluid shift is the primary hypothesized contributor to SANS. This longitudinal study aims to quantify the axial plane of the optic nerve subarachnoid space area (ONSSA), which is filled with cerebrospinal fluid (CSF) and expands with elevated ONSP during and after head-down tilt (HDT) bed rest (BR). 36 healthy male volunteers (72 eyes) underwent a 90-day strict 6° HDT BR. Without obtaining the pre-HDT data, measurements were performed on days 30, 60, and 90 during HDT and at 6 recovery time points extended to 180-days (R + 180) in a supine position. Portable B-scan ultrasound was performed using the 12 MHz linear array probe binocularly. The measurements of the ONS and the calculation of the ONSSA were performed with ImageJ 1.51 analysis software by two experienced observers in a masked manner. Compared to R + 180, the ONSSA on HDT30, HDT60, and HDT90 exhibited a consistently significant distention of 0.44 mm2 (95% CI: 0.13 to 0.76 mm2, P = 0.001), 0.45 mm2 (95% CI: 0.15 to 0.75 mm2, P = 0.001), and 0.46 mm2 (95% CI: 0.15 to 0.76 mm2, P < 0.001), respectively, and recovered immediately after HDT on R + 2. Such small changes in the ONSSA were below the lateral resolution limit of ultrasound (0.4 mm) and may not be clinically relevant, possibly due to ONS hysteresis causing persistent ONS distension. Future research can explore advanced quantitative portable ultrasound-based techniques and establish comparisons containing the pre-HDT measurements to deepen our understanding of SANS.

NCMP-18. ENDOVASCULAR TREATMENT OF SYMPTOMATIC TUMORAL VENOUS SINUS STENOSIS: COMPARATIVE ANALYSIS OF CORONARY BALLOON-MOUNTED STENTS AND CONVENTIONAL TECHNIQUES

Abstract Meningiomas may lead to symptomatic papilledema due to elevated intracranial pressure (ICP) from venous sinus compression. While venous sinus stenting has proven effective for treating elevated intracranial pressure, evidence for its application in tumoral-induced stenosis and acquired intracranial hypertension is limited. This study presents an institutional series of symptomatic tumoral venous sinus stenosis cases and compares the technical considerations of endovascular treatment using a coronary balloon-mounted stent to conventional venous sinus stenting. Three patients with meningioma-induced, bilateral papilledema received treatment with venous sinus stenting between 2019-2022. Presentation, stenosis severity, venous manometry, ophthalmologic findings, procedural techniques, and post-operative outcomes were retrospectively analyzed. Three patients (mean age: 59 years, 2 out of 3 male) presented with worsening blurry vision, diplopia, and persistent headaches. Bilateral papilledema was observed (median optic nerve sheath distension=0.48mm). Pre-procedure measurements showed elevated ICP with opening pressures ranging from 37-38 cmH2O. Imaging revealed extra-axial parieto-occipital lesions with significant mass effect, and MR venograms confirmed severe stenosis of the superior sagittal sinus (SSS). Venous angiography (DSV) demonstrated median venous sinus pressures of 32-mmHg proximal to the stenosis with a 4-mmHg pressure gradient across the stenosis. During the procedure, balloon-mounted Onyx coronary stents or a self-expanding PrecisePro carotid stent were deployed successfully. Post-stenting, papilledema resolved completely in two patients, while one patient experienced partial symptom resolution. Proximal SSS pressures decreased by a mean of 46.8%, and trans-stenotic pressure gradients were reduced to ≤1 mmHg. Stent patency without complications was maintained throughout the 2 to 5-month follow-up in all patients. Adjacent meningiomas were subsequently monitored for observation or stereotactic radiosurgery. Small extra-axial lesions causing symptomatic venous sinus compression can be endovascularly treated using balloon-mounted cardiac stents. Non-surgical meningioma patients, symptomatic for intracranial hypertension and lesions proximal to venous sinuses, should be assessed with DSV for potential management with endovascular interventions.

Optic Nerve Sheath Diameter as a Predictor of Raised Intracranial Pressure Findings on Orbital Ultrasound

BACKGROUND&#x0D; Several studies have found an association between raised intracranial pressure (ICP) and optic nerve sheath diameter (ONSD) in conditions with severe head injury and intracranial bleeding. Idiopathic intracranial hypertension is also a cause of elevated ICP. Because the meninges and subarachnoid space around the optic nerve are continuous, a rise in ICP can be detected with an increase in ONSD. The objectives of this study were to correlate Optic Nerve Sheath Diameter (ONSD) with features suggestive of raised intracranial pressure on CT / MRI of the Brain and describe the features suggestive of raised intracranial pressure on CT/MRI Brain in clinically suspected patients.&#x0D; METHODS&#x0D; This was a case control study carried out in the Department of Radio-diagnosis at MGMCRI for suspected raised intracranial pressure evaluation. All these patients were subjected to ultrasound examination of the eye and the optic sheath diameter was measured while the patients were in supine posture. ONSD was measured on Mind ray DC8, and/or GE S7 Expert using High frequency linear probe on the closed upper eyelid with adequate aqueous gel as a coupling agent. ONSD was also measured in Philips 1.5T MRI and Ge optima 128 slice CT. Patients were followed up on whether they were treated surgically or medically and if they developed clinical signs of raised ICP such as headache, vomiting, raised blood pressure, double vision, confusion or loss of consciousness.&#x0D; RESULTS&#x0D; The raised ICP was observed in 30.67 % of study patients and the optic nerve sheath distension was observed in 37.33% of patients. The diagnostic accuracy of determining the optic nerve sheath diameter was equal such as area under curve, sensitivity and specificity as 0.833, 66.67% and 100 % respectively in both methods.&#x0D; CONCLUSIONS&#x0D; ONSD has emerged as an interesting option for measuring intracranial hypertension in brain-injured states, owing to its simplicity, non-invasive nature, and accessibility.

Impact of rater experience and referral question on detecting magnetic resonance imaging features of idiopathic intracranial hypertension.

In idiopathic intracranial hypertension (IIH), magnetic resonance imaging (MRI) features are promising diagnostic markers, but the impact of rater experience and the specific referral question is unknown. From the Vienna Idiopathic Intracranial Hypertension database, patients were included with definitive IIH and routine cranial MRI performed during diagnostic work-up. Frequencies of partial empty sella (ES), optic nerve sheath distension (ONSD), optic nerve tortuosity (ONT), posterior globe flattening (PGF) and transverse sinus stenosis (TSS) were compared in three settings: (i) real-world rating, (ii) junior neuroradiologist without special IIH training and (iii) senior neuroradiologist with experience in IIH imaging (gold standard). Magnetic resonance imaging scans of 84 IIH patients (88% female, mean age 33.5 years) were evaluated. By gold standard, ONSD was the most frequent (64.3%) followed by TSS (60.0%), ONT (46.4%), ES (44.4%) and PGF (23.8%). Compared to the gold standard, IIH features were described significantly less frequently in routine MRI reports (ONSD 28.6%, ONT 13.1%, PGF 4.8%, TSS 42.9%, p < 0.01 respectively) except for ES (42.9%, p = 0.9). A specific referral question regarding IIH increased detection rates in routine reports, but rates remained significantly lower than by gold standard. In contrast, a rating by a neuroradiologist without special training produced significantly higher frequencies of ONSD (81.0%, p < 0.01) and ONT (60.7%, p < 0.01) but not of ES (47.6%), PGF (29.8%) and TSS (68.1%). Idiopathic intracranial hypertension MRI features are underestimated in routine MRI reports and partly overcalled by less experienced neuroradiologists, driven by features less well known or methodologically difficult. Reevaluation of MRI scans by an experienced rater (and to a lesser degree a specific referral question) improves diagnostic accuracy.

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

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. General anesthesia and positive pressure ventilation might result in changes in optic sheath diameter (OSD) observed on clinical brain MRI. Retrospective. 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. 1.5T or 3.0T volumetric T2 images. T2 images were obtained from different vendors. 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. Chi-square test; Mann-Whitney Test; Spearman's test and ROCs; Interclass correlation coefficient, P = 0.05. 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. 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. 4 Technical Efficacy: 5.

Pre-operative MRI Findings in Idiopathic Intracranial Hypertension (IIH) Patients Who Underwent Optic Nerve Sheath Fenestration (ONSF) with Postoperative Visual Improvement: Observational Findings

Background: Optic nerve sheath fenestration (ONSF) is commonly used in idiopathic intracranial hypertension (IIH) with visual deterioration and visual improvement is observed post operatively in these patients.&#x0D; Objective: Retrospective evaluation of MRI observations in IIH patients who underwent optic nerve sheath fenestration (ONSF) with postoperative visual improvement.&#x0D; Materials and method: Optic nerve sheath fenestration (ONSF) was done in twenty four (24) patients with IIH having severe visual impairment. Post operatively all patients improved in their visual functions. The recorded pre operative MRI (of brain and orbit) of patients were reviewed and evaluated retrospectively.&#x0D; Results: Total number of MRI studied was 24. Male female ratio was 1:11. Posterior globe flattening was found in all 24 (100%) cases. Other findings were horizontal tortuosity of optic nerve (92%), optic nerve head protrusion (87.5%), optic nerve sheath distension (87%), and vertical buckling (62.5%). Ventricular size was normal in 92% cases and slit ventricle was found only in 8% cases. On magnetic resonance venogram (MRV) one sided transverse sinus abnormality was found in 25% cases. There was empty sella in 79% cases, more marked in three cases.&#x0D; Conclusion: The MRI findings in IIH patients with positive post ONSF result are of variable degree and prevalence except posterior globe flattening which was found in all cases.&#x0D; Delta Med Col J. Jul 2020 8(1): 21-27

Contributed Session I: A Multi-Modal Visual Assessment System For Monitoring Spaceflight Associated Neuro-Ocular Syndrome (SANS) During Long Duration Spaceflight

Spaceflight Associated Neuro-Ocular Syndrome (SANS) refers to a unique collection of neuro-ophthalmic clinical and imaging findings that are observed in astronauts during long duration spaceflight. These findings include optic disc edema, posterior globe flattening, retinal nerve layer fiber thickening, optic nerve sheath distension, and hyperopic shift. SANS currently serves as a large barrier to deep space exploration; however, the exact pathophysiology is still being investigated. While in-flight imaging exists on the International Space Station, there are limitations to constant monitoring. To efficiently document the subtle changes that occur in SANS, NASA has funded the development of a head-mounted display, multi-modal visual assessment system; this novel device integrates visual acuity, visual field, contrast sensitivity, and metamorphopsia data (indirect indications) with known terrestrial neuro-ophthalmic imaging (direct indications) from astronauts and terrestrial analogs. By mapping these two indications, this visual assessment device will provide rapid in-flight monitoring of SANS symptoms and provide tools for the terrestrial development of countermeasures. We are in the process of beginning a pilot study of this multi-modal visual assessment device in healthy subjects to investigate the validity and reliability of this novel technology. This foundational study will compare the system with standard vision assessments utilized in clinical practice.

Atypical idiopathic intracranial hypertension presenting as cyclic vomiting syndrome: a case report

BackgroundIdiopathic intracranial hypertension is a disorder of increased intracranial pressure in the absence of cerebrospinal outflow obstruction, mass lesion, or other underlying cause. It is a rare phenomenon in prepubertal children and is most typically found in women of childbearing age. The classic presentation consists of headaches, nausea, vomiting, and visual changes; however, children present more atypically. We report a case of idiopathic intracranial hypertension in an otherwise healthy, 4-year-old child with atypical symptoms resembling those of cyclic vomiting syndrome.Case presentationA 4-year-old Caucasian, otherwise healthy, male child presented to our emergency department with episodic intermittent early-morning vomiting occurring once every 1–3 weeks without interepisodic symptoms, starting 10 months prior. With outpatient metabolic, autoimmune, endocrine, allergy, and gastroenterology work-up all unremarkable, he was initially diagnosed with cyclic vomiting syndrome. Discovery of mild optic nerve sheath distension on magnetic resonance imaging of the brain 10 months after symptom onset led to inpatient admission and a lumbar puncture notable for an opening pressure of 47 mmHg, with normal cell count and protein levels. He had no changes in visual acuity or optic disc edema on dilated fundoscopic examination. The patient was started on acetazolamide, with resolution of episodic emesis at his last follow-up visit 12 weeks after discharge.ConclusionsIdiopathic intracranial hypertension presents atypically in prepubescent children, with about one-fourth presenting asymptomatically, and only 13–52% presenting with “classic” symptoms. With a prevalence of only 0.6–0.7 per 100,000, much remains unknown regarding the underlying pathophysiology in this demographic. Cyclic vomiting syndrome, however, has a much higher prevalence in this age group, with a prevalence of 0.4–1.9 per 100. It is thought to be an idiopathic, periodic disorder of childhood, often linked to neurological conditions such as abdominal migraines, epilepsy, mitochondrial disorders, and structural lesions such as chiari malformation and posterior fossa tumors. While cyclic vomiting syndrome is thought to have a benign course, untreated idiopathic intracranial hypertension can have long-term detrimental effects, such as visual loss or even blindness. We present a case of idiopathic intracranial hypertension presenting with symptoms resembling cyclic vomiting syndrome in a 4-year-old child, diagnosed 10 months after initial onset of symptoms. We aim to demonstrate the need for a high level of clinical suspicion and the need for further investigation into underlying pathophysiology in this vulnerable population.

Potential Involvement of the Ocular Glymphatic System in Optic Disc Edema in Astronauts.

INTRODUCTION: A significant proportion of the astronauts who spend extended periods in microgravity develop ophthalmic abnormalities, including optic disc edema, optic nerve sheath distention, globe flattening, chorioretinal folds, hyperopic refractive error shifts, and nerve fiber layer infarcts. A constellation of these neuro-ophthalmic findings has been termed spaceflight-associated neuro-ocular syndrome. An increased understanding of factors contributing to this syndrome is one of the top priorities for ESA and NASA because the length of missions is expected to increase substantially in the future. As discussed in the present article, the very recent discovery of an ocular glymphatic clearance system can potentially help to unlock mechanisms underlying microgravity-induced optic disc edema. Observations pertaining to the ocular glymphatic pathway provide supporting evidence for the hypothesis, originally proposed by our group, suggesting that the glymphatic outflow from the eye into the optic nerve may be impeded under prolonged microgravity conditions, leading to optic disc edema.Wostyn P, De Winne F, Stern C, Mader TH, Gibson CR, De Deyn PP. Potential involvement of the ocular glymphatic system in optic disc edema in astronauts. Aerosp Med Hum Perform. 2020; 91(12):975977.

Quantitative magnetic resonance image assessment of the optic nerve and surrounding sheath after spaceflight

A subset of long-duration spaceflight astronauts have experienced ophthalmic abnormalities, collectively termed spaceflight-associated neuro-ocular syndrome (SANS). Little is understood about the pathophysiology of SANS; however, microgravity-induced alterations in intracranial pressure (ICP) due to headward fluid shifts is the primary hypothesized contributor. In particular, potential changes in optic nerve (ON) tortuosity and ON sheath (ONS) distension may indicate altered cerebrospinal fluid dynamics during weightlessness. The present longitudinal study aims to provide a quantitative analysis of ON and ONS cross-sectional areas, and ON deviation, an indication of tortuosity, before and after spaceflight. Ten astronauts undergoing ~6-month missions on the International Space Station (ISS) underwent high-resolution magnetic resonance imaging (MRI) preflight and at five recovery time points extending to 1 year after return from the ISS. The mean changes in ON deviation, ON cross-sectional area, and ONS cross-sectional area immediately post flight were −0.14 mm (95% CI: −0.36 to 0.08, Bonferroni-adjusted P = 1.00), 0.13 mm2 (95% CI −0.66 to 0.91, Bonferroni-adjusted P = 1.00), and −0.22 mm2 (95% CI: −1.78 to 1.34, Bonferroni-adjusted P = 1.00), respectively, and remained consistent during the recovery period. Terrestrially, ONS distension is associated with increased ICP; therefore, these results suggest that, on average, ICP was not pathologically elevated immediately after spaceflight. However, a subject diagnosed with optic disc edema (Frisen Grade 1, right eye) displayed increased ONS area post flight, although this increase is relatively small compared to clinical populations with increased ICP. Advanced quantitative MRI-based assessment of the ON and ONS could help our understanding of SANS and the role of ICP.

Retinal and Optic Nerve Deformations Due to Orbital Versus Intracranial Venous Hypertension.

Abnormal forces around the optic nerve head (ONH) due to orbital diseases, intracranial hypertension (IH), glaucoma, and space travel, are associated with alterations of the ONH shape. Elevated cerebral and ophthalmic venous pressure can contribute to stress and strain on the ONH and peripapillary retina. We hypothesize that IH and elevated ophthalmic venous pressure without IH cause different ONH and retinal changes. We compared MRI and spectral domain optical coherence tomography (SDOCT) findings in patients with cavernous sinus arteriovenous shunts (CSAVSs), where orbital venous pressure is known to be elevated, with patients with intracranial dural venous sinus thrombosis and secondary IH. We also compared the results to those obtained in the Idiopathic IH (IIH) Treatment Trial. Among 18 patients with dural venous sinus thrombosis, the MRI/magnetic resonance venography displayed partial empty sella (61%) and optic nerve sheath distension (67%). None exhibited ophthalmic vein dilation or signs of orbital congestion. SDOCT of these eyes and IIH eyes showed a similar frequency of abnormal thickening of the mean retinal nerve fiber layer, anterior displacement of the basement membrane opening, peripapillary wrinkles, retinal folds (RF), and choroidal folds (CF). Among 21 patients with CSAVSs, MRI showed ipsilateral dilated superior ophthalmic vein (76%) and orbital congestion (52%) without distension of the optic nerve sheath or globe distortion. SDOCT showed CF (19%), one with overlying RF, and no ONH deformations. SDOCT findings for dural venous sinus thrombosis are similar to those seen with IIH but distinct from changes due to local ophthalmic venous hypertension. These data support the concept that IH even if due to a vascular cause and local orbital venous hypertension cause different stresses and strains on the ONH.

Migraine or idiopathic intracranial hypertension: Magnetic resonance venography and magnetic resonance imaging findings.

Idiopathic intracranial hypertension (IIH) is a disease characterised by increased cerebral pressure without a mass or hydrocephalus. We aimed to differentiate migraine and IIH patients based on imaging findings. Patients with IIH (n = 32), migraine patients (n = 34) and control subjects (n = 33) were evaluated. Routine magnetic resonance imaging, contrast-enhanced 3D magnetic resonance venography and/or T1-weighted 3D gradient-recalled echo were taken with a 1.5 T magnetic resonance scanner. Optic-nerve sheath distention, flattened posterior globe and the height of the pituitary gland were evaluated in the three groups. Transverse sinuses (TS) were evaluated with respect to score of attenuation/stenosis and distribution. Pearson chi-square, Fisher's exact test and chi-square trend statistical analyses were used for comparisons between the groups. A p-value of <0.05 was considered statistically significant. Decreased pituitary gland height, optic-nerve sheath distention and flattened posterior globe were found to be statistically significant (p < 0.001) in IIH patients. Bilateral TS stenosis was also more common in IIH patients than in the control group and migraine group (p = 0.02). Decreased pituitary gland height, optic-nerve sheath distention, flattened posterior globe, bilateral stenosis and discontinuity in TS are significant findings in differentiating IIH cases from healthy individuals and migraine patients. Bilateral TS stenosis may be the cause rather than the result of increased intracranial pressure. The increase in intracranial pressure, which is considered to be responsible for the pathophysiology of IIH, is not involved in the pathophysiology of migraine.

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.

The effect of CSF drain on the optic nerve in idiopathic intracranial hypertension

BackgroundElevation of intracranial pressure in idiopathic intracranial hypertension induces an edema of the prelaminar section of the optic nerve (papilledema). Beside the commonly observed optic nerve sheath distention, information on a potential pathology of the retrolaminar section of the optic nerve and the short-term effect of normalization of intracranial pressure on these abnormalities remains scarce.MethodsIn this exploratory study 8 patients diagnosed with idiopathic intracranial hypertension underwent a MRI scan (T2 mapping) as well as a diffusion tensor imaging analysis (fractional anisotropy and mean diffusivity). In addition, the clinical presentation of headache and its accompanying symptoms were assessed. Intracranial pressure was then normalized by lumbar puncture and the initial parameters (MRI and clinical features) were re-assessed within 26 h.ResultsAfter normalization of CSF pressure, the morphometric MRI scans of the optic nerve and optic nerve sheath remained unchanged. In the diffusion tensor imaging, the fractional anisotropy value was reduced suggesting a tissue decompression of the optic nerve after lumbar puncture. In line with these finding, headache and most of the accompanying symptoms also improved or remitted within that short time frame.ConclusionThe findings support the hypothesis that the elevation of intracranial pressure induces a microstructural compression of the optic nerve impairing axoplasmic flow and thereby causing the prelaminar papilledema. The microstructural compression of the optic nerve as well as the clinical symptoms improve within hours of normalization of intracranial pressure.

Magnetic Resonance Imaging Findings in Pediatric Pseudotumor Cerebri Syndrome

BackgroundRevised 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. MethodsAs 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. ResultsThe 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%). ConclusionsIn 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.

The escape of retrobulbar cerebrospinal fluid in the astronaut's eye: mission impossible?

Ophthalmic abnormalities including unilateral and bilateral optic disc edema, optic nerve sheath distention, globe flattening, choroidal folds, and hyperopic shifts have been observed in astronauts during and after long-duration spaceflight. An increased understanding of factors contributing to this syndrome, termed spaceflight-associated neuro-ocular syndrome, is currently a top priority for the ESA and NASA, especially since this medical obstacle could impact the visual health of astronauts as well as the success of future missions, including continued trips to the International Space Station, a return to the moon, or a future human mission to Mars. Currently, the exact mechanisms causing this neuro-ocular syndrome are not fully understood. In the present paper, we propose a hypothetical framework by which optic disc edema in astronauts may result, at least partly, from the forcing of perioptic cerebrospinal fluid into the optic nerve and optic disc along perivascular spaces surrounding the central retinal vessels, related to long-standing microgravity fluid shifts and variations in optic nerve sheath anatomy and compliance. Although this hypothesis remains speculative at the present time, future research in this area of investigation could not only provide exciting new insights into the mechanisms underlying microgravity-induced optic disc swelling but also offer opportunities to develop countermeasure strategies.

Clinical Features of Pediatric Idiopathic Intracranial Hypertension and Applicability of New ICHD-3 Criteria.

Idiopathic intracranial hypertension (IIH) is characterized by intracranial pressure >28 cmH2O in the absence of identifiable causes. Aim of this paper is to describe the clinical phenotype of pediatric IIH and to analyze the applicability of ICHD-3 criteria in comparison to the ICHD-2. We conducted a retrospective analysis of full clinical data of pediatric patients diagnosed with IIH between January 2007 and June 2018. Diagnostic evaluation included neuroimaging (all patients) and ultrasound-based optic nerve sheath diameter measurement (9 patients). Diagnosis of IIH was verified according to both ICHD-2 and ICHD-3 criteria for headache attributed to IIH, to verify the degree of concordance. We identified 41 subjects with suspected IIH; 14 were excluded due a diagnosis of secondary IH or lack of data. We therefore selected 27 subjects (age 4–15 years, mean 11). All patients presented with headache and bilateral papilloedema. Headache was daily in 22% cases, with diffuse gravative pain in 41%. In 4%, pain was exacerbated by cough, stress or tension. The most common presentation symptoms, in addition to headache, were blurred vision or diplopia (70%), vomiting (33%), and dizziness (15%). Twenty patients (74%) were obese. In 6 patients (22%) neuroimaging showed empty sella. Optic nerve sheath distension was detected in 6 out of 9 patients. Regarding the applicability of the ICHD-2 criteria, 18/27 (71%) patients have criterion A; 24/27 (89%) criterion B; 27/27 (100%) criterion C; 27/27 (100%) criterion D. When the ICHD-3 criteria were used, 27/27 (100%) fitted criterion A; 24/27 (89%) criterion B; 27/27 (100%) criterion C; and 27/27 (100%) criterion D. Our study suggests that, as compared with the ICHD-2, the new ICHD-3 criteria for headache attributed to IIH are better satisfied by pediatric patients with IIH. This is mainly due to the fact that qualitative headache characteristics are no longer considered in ICHD-3. Although the risk of under-rating the symptom of headache in IIH should not be disregarded, in pediatric population headache characteristics are usually less defined than in adults and obtaining a precise description of them is often very difficult.

The Significance and Reliability of Imaging Findings in Pseudotumor Cerebri

ABSTRACTThe objective of our study was to provide a comparative assessment of previously reported magnetic resonance imaging (MRI) parameters in primary and secondary pseudotumor cerebri (PTC) patients, to examine their diagnostic contribution, and to evaluate their association with symptoms, neuro-ophthalmological findings, laboratory results, and cerebrospinal fluid characteristics.Twenty-eight consecutive patients with PTC were included in the study. Age- and sex-matched 20 individuals with normal neurologic examination served as the control group. Modified Dandy Criteria were used for the diagnosis of PTC. Orbital and cranial MRI and MR venography of all patients and controls were assessed by three radiologists.According to our study, posterior flattening of the globe (64% sensitive, 100% specific), optic nerve sheath distention (46% sensitive, 100% specific), vertical tortuosity of the optic nerve (30% sensitive, 95% specific), and partial empty sella (43% sensitive, 100% specific) emerged as particularly valuable markers for a diagnosis of PTC.

Morphometric and volumetric MRI changes in idiopathic intracranial hypertension

We aimed at validating established imaging features of idiopathic intracranial hypertension (IIH) by using state-of-the-art MR imaging together with advanced post-processing techniques and correlated imaging findings to clinical scores. Twenty-five IIH patients as well as age-, sex- and body mass index (BMI)-matched controls underwent high-resolution T1w and T2w MR imaging in a 1.5 T scanner, followed by assessment of optic nerve sheaths, pituitary gland, ventricles and Meckel's cave. Imaging findings were correlated with cerebrospinal fluid (CSF) opening pressures and clinical symptom scores of visual disturbances (visual field defects or enlarged blind spot), headache, tinnitus (pulsatile and non-pulsatile) and vertigo. CSF as well as ventricle volumes were determined by using an automated MRI volumetry algorithm. So-called 'empty sella' and optic nerve sheath distension were identified as reliable imaging signs in IIH. Posterior globe flattening turned out as a highly specific but not very sensitive sign. No abnormalities of the lateral ventricles were observed. These morphometric results could be confirmed using MR volumetry (VBM). Clinical symptoms did not correlate with an increase in lumbar opening pressure. Our study results indicate that lateral ventricle size is not affected in IIH. In contrast, abnormalities of the pituitary gland and optic nerve sheath were reliable diagnostic signs for IIH.

Imaging features of idiopathic intracranial hypertension, including a new finding: widening of the foramen ovale

Idiopathic intracranial hypertension (IIH) is a clinical disorder of unknown etiology manifesting with increased intracranial pressure in the absence of hydrocephalus, an underlying mass lesion, and demonstrating normal cerebrospinal fluid composition. IIH may exhibit several non-specific imaging findings including: an empty sella, posterior globe flattening, tortuosity of the optic nerve, and optic nerve sheath distention. To introduce widening of the foramen ovale as a new imaging marker for IIH. IIH is a syndrome which may exhibit several previously described non-specific imaging findings including: an empty sella, posterior globe flattening, tortuosity of the optic nerve, and optic nerve sheath distention. We hypothesize that chronically elevated cerebrospinal fluid pressure can lead to osseous erosions and we propose widening of the foramen ovale as a new imaging marker for IIH. Average foramen ovale sizes were increased in patients with IIH compared to controls (30.03 ± 7.00 mm(2) vs. 24.21 ± 5.97 mm(2), P < 0.001). For a cut-off value of 30 mm(2), the sensitivity of FO area to detect IIH was 50%, with 81% specificity. Classic findings were significantly more common in patients with IIH compared to controls including: empty sella (65.9% vs. 0%), posterior globe flattening (65.9% vs. 4.5%), vertical tortuosity of the optic nerve (54.5% vs. 9.1%), and optic nerve sheath distention (52.3% vs. 11.4%, all P values < 0.001). Our study confirms the association of several classic imaging findings with IIH and supports widening of the foramen ovale as an additional imaging marker which may be incorporated into the evaluation of patients suspected to have this condition.