Association between visual parameters and neuroimaging features of idiopathic intracranial hypertension

Idiopathic Intracranial Hypertension: Incidental Discovery Versus Symptomatic Presentation

BACKGROUND

We aim to compare the clinical characteristics, disease course and visual outcomes between Canadian patients with idiopathic intracranial hypertension (IIH) who were incidentally discovered and those who sought care due to symptoms of IIH.

METHODS

Retrospective chart review of consecutive IIH patients conducted at tertiary neuro-ophthalmology clinics. Patients were divided into Group 1 (incidentally discovered disease) and Group 2 (patients seeking medical care due to symptoms of intracranial hypertension).

RESULTS

One hundred eighty-six patients were included in the study; of which, 75 (40.3%; Group-1) were incidentally discovered and 111 presented due to symptoms of IIH (Group-2). There were no differences in proportion of females (P = 0.101), age (P = 0.450), body mass index (P = 0.386), MRI findings of empty or partially empty sella (P = 0.41), and sella grade (P = 0.704). Group-1 patients were less likely to have experienced headache (P = 0.001), transient visual obscurations (P < 0.001), and diplopia (P = 0.026) at presentation. Group-1 patients were less likely to receive medical (P < 0.001) and surgical (P = 0.004) treatment. There was no difference in proportion of patients who lost weight between the groups (P = 0.848). At baseline, Group-1 patients exhibited better visual acuity (P = 0.001), Humphrey mean deviation (P < 0.001) and retinal nerve fiber layer thickness (P < 0.001). Group-1 patients continued to have better visual acuity (P = 0.002) and Humphrey mean deviation (P < 0.001) at final follow-up.

CONCLUSIONS

A significant portion of IIH patients were incidentally discovered. This group exhibited a favorable prognosis and only a minority of these patients required treatment. The way in which patients enter the medical system may be a valuable way to risk stratify IIH patients.

Change in contrast sensitivity and OCT parameters in idiopathic intracranial hypertension

Background:

Deterioration in peripheral contrast sensitivity (CS) can be an indicator to detect progressive deterioration of visual function in patients with idiopathic intracranial hypertension (IIH).

Objectives:

The aim of this study was to evaluate the changes in central and peripheral CS and optical coherence tomography (OCT) parameters and in patients with IIH.

Design and Methods:

In this pilot observational study, data of 20 eyes of 10 ‘treatment-naïve’ IIH patients were analyzed. Detailed ocular examination was performed including CS assessment using both Pelli–Robson (PR) test and Spaeth–Richman Contrast Sensitivity Test (SPARCS) along with the OCT for macular and optic nerve head (ONH) parameters. A comparative analysis was done for CS and OCT parameters from baseline to a follow-up visit > 12 months (range: 18–24 months).

Results:

The study population had a female preponderance (80%, n = 8), and mean age at diagnosis was 31.9 ± 10.3 years. Mean follow-up period was 21.2 months (range: 15–24 months). At presentation, 6/6 visual acuity was noted in 75% eyes ( n = 15) while all eyes had 6/6 vision at the last follow-up. Average PR score increased from 1.96 ± 0.36 to 2.30 at the last visit (Wilcoxon test: V = 0.0, p ⩽ 0.001) while average SPARCS score (total) increased from 71.85 ± 9.10 to 77.55 ± 6.20 (Paired t-test: t = −2.3, p = 0.035). Change in SPARCS score was significant in average total score ( p = 0.035), and quadrant-wise score in superonasal ( p = 0.014), inferonasal ( p = 0.001), and inferotemporal ( p = 0.021) quadrants. Same trend in SPARCS scores was observed when eyes with and without recurrence were analyzed. Statistically significant difference in retinal nerve fiber layer (RNFL) thickness ( p = 0.007) and macular thickness (MT) in nasal quadrant ( p = 0.006) was seen between the eyes with recurrence and without recurrence.

Conclusion:

Peripheral CS showed significant difference in all eyes over time. It showed significant change in eyes with recurrence, even in the presence of intact visual acuity and preserved central CS. Changes in RNFL thickness and nasal MT could differentiate eyes which developed recurrence from normal eyes.

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.

Association between Optical Coherence Tomography Measurements and Clinical Parameters in Idiopathic Intracranial Hypertension

Purpose

To correlate optical coherence tomography (OCT) measurements with clinical parameters in idiopathic intracranial hypertension (IIH).

Methods

A cross-sectional study was conducted with 22 patients with IIH and 11 controls. All participants underwent comprehensive ophthalmological examination followed by spectral-domain OCT (SD-OCT) and standard automated perimetry using the 30–2 program of the Humphrey visual field analyzer. Correlations between ganglion cell complex (GCC) thickness and retinal nerve fiber layer (RNFL) thickness, as measured by SD-OCT, and clinical parameters were assessed using generalized estimating equations.

Result

The mean age of the participants was 35.0 ± 10.83 years. The groups were similar regarding age, but were significantly different regarding sex and visual acuity (p=0.001 and p=0.038, respectively). The GCC was significantly thinner in the IIH group, with a mean of 90.535 ± 9.766 μm compared to 98.119 ± 6.988 μm for the controls (p=0.023). There was a significant association between GCC thickness and optic disc pallor (p=0.016) and between edema and visual acuity (p=0.037). No significant difference was found in RNFL thickness between patients and controls.

Conclusion

The GCC was thinner in the patients with IIH compared to the controls, and there was an association between GCC and optic disc pallor. This might suggest a role for OCT parameters when the structural changes that occur in IIH are investigated, possibly guiding clinical decision making.

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.

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.

Idiopathic Intracranial Hypertension: Review of Clinical Syndrome, Imaging Findings, and Treatment

Idiopathic intracranial hypertension (IIH) is a syndrome of unknown cause that is increasing in frequency. Patients who are typically women of childbearing age and obese present with headaches and may also present with visual changes that may become chronic. The purpose of this review is to describe the possible mechanisms for this disease and also to illustrate the ever increasing role of imaging in the diagnosis of this disorder. In addition, the various methods of treatment including medical and surgical will be reviewed. The fact that idiopathic intracranial hypertension has undergone many name changes over the years serves as a reminder that the underlying mechanism is still not well understood. Although there are only several possible mechanisms that can cause increased intracranial pressure, it is still not certain which of these mechanisms is involved. The role of imaging has significantly changed in the evaluation of patients with possible IIH. First, it is involved in ruling out secondary causes of increased intracranial pressure. In addition, there is now ample evidence that the previously held belief that imaging of patients with IIH should be normal is incorrect but rather that there are several subtle findings that radiologists need to look for. These findings include a partially empty sella, flattening of the posterior globe, cupping of optic disks and distension of the optic nerve sheaths. In addition, the role of intracranial venography is playing an ever increasing role due to the finding that a very high percentage of patients have dural venous sinus stenoses. It is becoming clear that there is potentially true morbidity associated with idiopathic intracranial hypertension. The earlier the disease can be diagnosed, the earlier treatment can be started to minimalize permanent visual changes including blindness. Treatment varies from institution to institution due to the fact that multiple specialists with different perspectives treat these patients. Knowledge of subtle imaging features associated with idiopathic intracranial hypertension can help radiologists establish the diagnosis earlier and potentially prevent complications of this disorder. However imaging has not as of yet been shown to be beneficial in managing patients with idiopathic intracranial hypertension.

Contrast-Enhanced 3D-FLAIR Imaging of the Optic Nerve and Optic Nerve Head: Novel Neuroimaging Findings of Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

The sensitivity of contrast-enhanced 3D-FLAIR has not been assessed in patients with idiopathic intracranial hypertension. The purpose of this study was to evaluate whether hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR imaging is associated with papilledema in patients with idiopathic intracranial hypertension.

MATERIALS AND METHODS

A retrospective review was conducted from 2012 to 2015 of patients with clinically diagnosed idiopathic intracranial hypertension and age- and sex-matched controls who had MR imaging with contrast-enhanced 3D-FLAIR. Two neuroradiologists graded each optic nerve/optic nerve head on a scale of 0-3. This grade was then correlated with the Frisén Scale, an ophthalmologic scale used for grading papilledema from 0 (normal) to 5 (severe edema). To estimate the correlation between the MR imaging and Frisén scores, we calculated the Kendall τ coefficient.

RESULTS

Forty-six patients (3 men, 43 women) with idiopathic intracranial hypertension and 61 controls (5 men, 56 women) with normal findings on MR imaging were included in this study. For both eyes, there was moderate correlation between the 2 scales (right eye: τ = 0.47; 95% CI, 0.31-0.57; left eye: τ = 0.38; 95% CI, 0.24-0.49). Interreader reliability for MR imaging scores showed high interreader reliability (right eye: κ = 0.76; 95% CI, 0.55-0.88; left eye: κ = 0.87; 95% CI, 0.78-0.94). Contrast-enhanced 3D-FLAIR imaging correlates with the Frisén Scale for moderate-to-severe papilledema and less so for mild papilledema.

CONCLUSIONS

Hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR is sensitive for the detection of papilledema in patients with idiopathic intracranial hypertension, which may be useful when prompt diagnosis is crucial.

The Significance and Reliability of Imaging Findings in Pseudotumor Cerebri

The 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.

Characterization of Retinal Ganglion Cell and Optic Nerve Phenotypes Caused by Sustained Intracranial Pressure Elevation in Mice

Elevated intracranial pressure (ICP) can result in multiple neurologic sequelae including vision loss. Inducible models of ICP elevation are lacking in model organisms, which limits our understanding of the mechanism by which increased ICP impacts the visual system. We adapted a mouse model for the sustained elevation of ICP and tested the hypothesis that elevated ICP impacts the optic nerve and retinal ganglion cells (RGCs). ICP was elevated and maintained for 2 weeks, and resulted in multiple anatomic changes that are consistent with human disease including papilledema, loss of physiologic cupping, and engorgement of the optic nerve head. Elevated ICP caused a loss of RGC somas in the retina and RGC axons within the optic nerve, as well as a reduction in both RGC electrical function and contrast sensitivity. Elevated ICP also caused increased hypoxia-inducible factor (HIF)-1 alpha expression in the ganglion cell layer. These experiments confirm that sustained ICP elevation can be achieved in mice and causes phenotypes that preferentially impact RGCs and are similar to those seen in human disease. With this model, it is possible to model human diseases of elevated ICP such as Idiopathic Intracranial Hypertension and Spaceflight Associated Neuro-ocular Syndrome.

The Optic Canal Size Is Associated With the Severity of Papilledema and Poor Visual Function in Idiopathic Intracranial Hypertension

BACKGROUND

To determine whether the size of the bony optic canal is associated with the severity of papilledema and poor visual function in idiopathic intracranial hypertension (IIH).

METHODS

We performed a retrospective review of definite patients with IIH with requisite brain magnetic resonance imaging allowing for optic canal measurement. Clinical characteristics and automated (Humphrey) visual field results were reviewed; papilledema was graded according to the modified Frisén scale. Cross-sectional area of the optic canals was measured independently by 2 readers and averaged for each canal. Logistic regression modeling was applied.

RESULTS

Sixty-nine patients with IIH were included (mean age: 33; 91% women; 65% black). Controlling for age, sex, body mass index, race, and cerebrospinal fluid (CSF) opening pressure, each mm increase in canal size was associated with a 0.50 dB reduction in Humphrey visual field mean deviation (P = 0.006); this was likely mediated by the increased odds of Grade 4-5 papilledema or optic atrophy in patients with larger canals (odds ratio: 1.30 [95% CI: 1.10-1.55; P = 0.003] for Grade 4-5 papilledema or atrophy vs grade <4 papilledema per mm increase in canal size).

CONCLUSIONS

Poor visual function and severe papilledema or optic atrophy were associated with a larger optic canal. Potential mechanisms include alteration of local CSF flow or bony remodeling at the optic canals.

Effect of venous stenting on intracranial pressure in idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is characterised by an increased intracranial pressure (ICP) in the absence of any central nervous system disease or structural abnormality and by normal CSF composition. Management becomes complicated once surgical intervention is required. Venous sinus stenosis has been suggested as a possible aetiology for IIH. Venous sinus stenting has emerged as a possible interventional option. Evidence for venous sinus stenting is based on elimination of the venous pressure gradient and clinical response. There have been no studies demonstrating the immediate effect of venous stenting on ICP.

METHODS

Patients with a potential or already known diagnosis of IIH were investigated according to departmental protocol. ICP monitoring was performed for 24 h. When high pressures were confirmed, CT venogram and catheter venography were performed to look for venous stenosis to demonstrate a pressure gradient. If positive, venous stenting would be performed and ICP monitoring would continue for a further 24 h after deployment of the venous stent.

RESULTS

Ten patients underwent venous sinus stenting with concomitant ICP monitoring. Nine out of ten patients displayed an immediate reduction in their ICP that was maintained at 24 h. The average reduction in mean ICP and pulsatility was significant (p = 0.003). Six out of ten patients reported a symptomatic improvement within the first 2 weeks.

CONCLUSIONS

Venous sinus stenting results in an immediate reduction in ICP. This physiological response to venous stenting has not previously been reported. Venous stenting could offer an alternative treatment option in correctly selected patients with IIH.

The diagnostic challenge of evaluating papilledema in the pediatric patient

Pseudopapilledema is a fairly common finding in ophthalmic practice, and in many cases, the diagnosis is straightforward. However, an accurate diagnosis can challenge the most seasoned clinicians, and missing true papilledema can result in life-threatening or vision-threatening consequences. In this review, we describe the clinical findings and a diagnostic algorithm to distinguish pseudopapilledema and papilledema in the pediatric patients. We also describe the clinical evaluation once a diagnosis of papilledema has been established.

Morphometric MRI changes in intracranial hypertension due to cerebral venous thrombosis: a retrospective imaging study

AIM

To evaluate whether some magnetic resonance imaging (MRI) signs suggesting idiopathic intracranial hypertension (IIH) could also be found in intracranial hypertension (IH) due to cerebral venous thrombosis (CVT) and to assess their possible contribution to diagnosing this disorder.

MATERIALS AND METHODS

Thirty-one patients with IH due to CVT were evaluated prospectively using MRI. A group of 33 age- and sex-matched healthy volunteers served as controls. The optic nerve and sheath, pituitary gland, and ventricles were assessed. The prevalence of each imaging feature was compared between the two groups.

RESULTS

Optic nerve sheath (ONS) dilatation and decreased pituitary gland height were the most valid signs suggesting IH in CVT patients: sensitivity 70.97% and 87.1%, respectively; specificity 96.97% and 72.73%, respectively; area under the curve 0.840 and 0.809, respectively. The MRI finding that showed the strongest association with IH in CVT patients was ONS dilatation (odds ratio 78.5).

CONCLUSIONS

The combination of T1-weighted volumetric MRI and magnetic resonance venography could be helpful for diagnosing IH with CVT. Abnormalities of the ONS and the pituitary gland were reliable diagnostic signs for IH due to CVT.

Neuroimaging Features of Idiopathic Intracranial Hypertension Persist After Resolution of Papilloedema

Papilloedema is a key clinical finding in the diagnosis of idiopathic intracranial hypertension (IIH). However, newly proposed criteria allow diagnosis without papilloedema only if certain neuroimaging features are present. It is currently unclear if these findings persist upon resolution of papilloedema and IIH. A retrospective chart review identified three groups of patients (six per group) who had received orbital imaging within 4 weeks of fundoscopic examination: (1) IIH patients without active papilloedema, (2) IIH patients with active papilloedema, and (3) patients with no history of IIH or papilloedema. All magnetic resonance imaging (MRI) scans were graded by a neuroradiologist who was blinded to clinical status. Neuroimaging features were compared by using the Kruskal-Wallis one-way analysis of variance. Measurements of sellar and optic nerve configuration showed a statistical trend with papilloedema status. For the control group versus the active papilloedema group, the values were 0.0597 and 0.0621, respectively. For the control group versus the resolved papilloedema group, the values were 0.0485 and 0.0512, respectively. However, globe and sellar p values for the resolved papilloedema group versus the active papilloedema group were 1.000 and 0.6023, respectively, and not significant. Sellar and globe configuration suggest that a statistical trend for persistence after papilloedema has resolved and intracranial pressure (ICP) has normalised. Careful clinical correlation and fundus examination are essential because some of these neuroimaging features can be seen in normal patients and those with resolved IIH, and their presence on MRI may not necessarily indicate active disease or elevated ICP.

MRI in the Evaluation of Acute Visual Syndromes

Acute visual symptom emergencies occur commonly and present a challenge to both clinical and radiologic facets. Although most patients with visual complaints routinely require clinical evaluation with direct ophthalmologic evaluation, imaging is rarely necessary. However, there are highly morbid conditions where the prompt recognition and management of an acute visual syndrome (AVS) requires an astute physician to probe further. Suspicious symptomatology including abrupt visual loss, diplopia, ophthalmoplegia, and proptosis/exophthalmos require further investigation with advanced imaging modalities such as magnetic resonance imaging and magnetic resonance angiography. This review will discuss a variety of AVSs including orbital apex syndrome, cavernous sinus thrombosis, cavernous carotid fistula, acute hypertensive encephalopathy (posterior reversible encephalopathy syndrome), optic neuritis, pituitary apoplexy including hemorrhage into an existing adenoma, and idiopathic intracranial hypertension. A discussion of each entity will focus on the clinical presentation, management and prognosis when necessary and finally, neuroimaging with emphasis on magnetic resonance imaging. The primary purpose of this review is to provide an organized approach to the differential diagnosis and typical imaging patterns for AVSs. We have provided a template for radiologists and specialists to assist in early intervention in order to decrease morbidity and provide value-based patient care through imaging.

Correlation between papilledema grade and diffusion-weighted magnetic resonance imaging in idiopathic intracranial hypertension

BACKGROUND

To explore the relationship between diffusion-weighted magnetic resonance imaging (DWI) hyperintensity of the optic nerve head (ONH) and papilledema grade in patients with idiopathic intracranial hypertension (IIH).

METHODS

A retrospective chart review was conducted of patients with definitively diagnosed IIH by clinical examination and visual field (VF) analysis who underwent orbital magnetic resonance imaging (MRI) within 4 weeks of diagnosis. A neuroradiologist masked to the diagnosis assessed the results of DWI for each eye independently and graded the signal intensity of the ONH into none, mild, and prominent categories. DWI grading was compared with papilledema grade and visual field mean deviation (VFMD) by Spearman rank correlation analysis and t-tests.

RESULTS

Forty-two patients were included in the study. A statistically significant difference (P = 0.0195) was found between papilledema grade and patients with prominent DWI findings (n = 16; mean papilledema grade 3.75 ± 1.25) vs mild or no ONH hyperintensity (n = 26; mean papilledema grade 2.79 ± 1.24) at the time of initial diagnosis. DWI hyperintensity of the ONH at diagnosis was also found to be significantly correlated with the degree of papilledema at follow-up (ρ = 0.39, P = 0.0183) but not with VFMD.

CONCLUSIONS

We found a significant correlation between the severity of papilledema and ONH hyperintensity on DWI in patients with IIH but not with VF loss or other visual parameters. These findings may offer insight into the pathophysiology of papilledema in IIH and provide a surrogate marker for the presence and severity of papilledema.

Neuro-Ophthalmology Annual Review

PURPOSE

The purpose of this review was to update the practicing ophthalmologist on the English language neuro-ophthalmology literature from the past year.

DESIGN

A review of English language literature from August 1, 2013, to August 1, 2014, was conducted.

METHODS

The author searched PubMed from August 1, 2013, to August 1, 2014, limited to English language publications including original articles, review articles, and case reports and excluding letters to the editor, unpublished work, and abstracts. The following topics were searched: pupillary abnormalities, eye movement dysfunction, neuromuscular diseases, optic neuropathies, optic neuritis, demyelinating diseases including multiple sclerosis, lesions of the optic chiasm and posterior primary visual pathways, elevated intracranial pressure, tumors and aneurysms affecting the visual pathways, vascular diseases, higher visual function, and neuroimaging advances. The focus of this review is on clinically relevant literature in the past year for the practicing ophthalmologist. The aim was to highlight remarkable and interesting literature rather than exhaustively including all new neuro-ophthalmological publications of the year.

RESULTS

Initially, more than 11,000 articles were identified. One hundred were selected that met criteria specified above.

CONCLUSIONS

This review updates the comprehensive ophthalmologist on neuro-ophthalmic topics.

Novel Magnetic Resonance Imaging Findings in Children With Intracranial Hypertension

BACKGROUND

Increased intracranial hypertension is defined as elevated intracranial pressure with absence of hydrocephalus, vascular or structural abnormalities, and normal cerebrospinal fluid content. Magnetic resonance imaging abnormalities of the optic nerve and sheath that have been described in adults include increased nerve tortuosity, flattening in posterior aspect of globe, intraocular protrusion of the optic nerve, and enlarged optic nerve sheath.

PURPOSE

We evaluated accuracy of those proposed markers on magnetic resonance imaging in children with increased intracranial hypertension that are described in adults.

MATERIALS AND METHODS

Eleven patients between 3 and 15 years of age with intracranial hypertension were selected for re-evaluation of magnetic resonance imaging that had been previously described as normal to determine the presence of: (1) increased tortuosity and elongation of the optic nerve; (2) enlargement of the optic nerve sheath on axial and coronal T2 so called by us "target sign" and postcontrast T1 sequences; (3) flattening in posterior aspect of the globe; and (4) intraocular protrusion of the optic nerve head.

RESULTS

Of the 11 patients, tortuosity of the optic nerve (10/11, 90.9%) and enlarged optic nerve sheath--target sign (7/11, 63.6%)--were the most common findings. Flattening in the posterior aspect of globe (5/11, 45.5%) and intraocular protrusion (3/11, 27.3%) were also detected as a novel magnetic resonance imaging findings.

CONCLUSION

Magnetic resonance imaging findings of the optic nerve and sheath include valuable signs of intracranial hypertension not only in adults but also in children. This is the first detailed analysis of the magnetic resonance imaging findings in children with increased intracranial hypertension.

Association between idiopathic intracranial hypertension and sigmoid sinus dehiscence/diverticulum with pulsatile tinnitus: a retrospective imaging study

INTRODUCTION

The mechanism of occurrence of sigmoid sinus dehiscence/diverticulum (SSDD) in pulsatile tinnitus (PT) patients remains under debate. Its association with idiopathic intracranial hypertension (IIH) lacks evidence, which is important for therapeutic planning and improving the clinical outcome. This study aimed to evaluate the association between SSDD and IIH by comparing the prevalence of several established imaging features of IIH between PT patients with SSDD and healthy volunteers.

METHODS

Thirty-three unilateral PT patients with SSDD identified on CT images and 33 age- and sex-matched healthy volunteers underwent T1-weighted volumetric magnetic resonance imaging (MRI). The optic nerve, pituitary gland, transverse sinus, and ventricles were assessed. The prevalence of established IIH imaging features was compared between the two groups. Furthermore, the PT patients were divided into two subgroups: PT patients with dehiscence only and PT patients with diverticulum. The same statistical analysis was performed on each pathophysiologic entity respectively.

RESULTS

The PT patients with SSDD showed a significantly higher prevalence of empty sella (P < 0.001), flattened posterior sclera (P = 0.001), vertical tortuosity of the optic nerve (P = 0.001), protrusion of the optic nerve (P = 0.006), transverse sinus stenosis (P = 0.011), and distension of the optic nerve sheath (P = 0.000). There were no significant differences between the PT and control groups in the maximum widths of the third and fourth ventricles and the lateral ventricle size. In contrast to controls, the imaging findings persisted in both of pathophysiologic entities, except for transverse sinus stenosis.

CONCLUSIONS

Several IIH imaging features occur more frequently in PT patients with SSDD than in healthy individuals, which suggests a potential correlation between SSDD with PT and IIH.

Elevated intracranial pressure causes optic nerve and retinal ganglion cell degeneration in mice

The purpose of this study was to develop a novel experimental system for the modulation and measurement of intracranial pressure (ICP), and to use this system to assess the impact of elevated ICP on the optic nerve and retinal ganglion cells (RGCs) in CD1 mice. This system involved surgical implantation of an infusion cannula and a radiowave based pressure monitoring probe through the skull and into the subarachnoid space. The infusion cannula was used to increase ICP, which was measured by the probe and transmitted to a nearby receiver. The system provided robust and consistent ICP waveforms, was well tolerated, and was stable over time. ICP was elevated to approximately 30 mmHg for one week, after which we assessed changes in optic nerve structure with transmission electron microscopy in cross section and RGC numbers with antibody staining in retinal flat mounts. ICP elevation resulted in optic nerve axonal loss and disorganization, as well as RGC soma loss. We conclude that the controlled manipulation of ICP in active, awake mice is possible, despite their small size. Furthermore, ICP elevation results in visual system phenotypes of optic nerve and RGC degeneration, suggesting that this model can be used to study the impact of ICP on the visual system. Potentially, this model can also be used to study the relationship between ICP and IOP, as well diseases impacted by ICP variation such as glaucoma, idiopathic intracranial hypertension, and the spaceflight-related visual impairment intracranial pressure syndrome.