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

Non-arteritic anterior ischemic optic neuropathy secondary to idiopathic intracranial hypertension

Purpose

Patients with increased intracranial pressure and underlying hypertensive emergency may present with optic disc edema. Papilledema in this setting may be a predisposing risk factor for superimposed non-arteritic anterior ischemic optic neuropathy (NAION). We highlight the role of neuroimaging including diffusion-weighted imaging in magnetic resonance imaging that can help to differentiate visual loss from NAION versus papilledema in fulminant IIH with and without hypertension.

Observations

A 46-year-old female presented with acute vision loss in the right eye and transient right hemiparesis. Neuro-ophthalmic examination revealed optic disc edema in both eyes. Magnetic resonance imaging (MRI) of the brain with diffusion-weighted imaging (DWI) sequences showed restricted diffusion in the optic nerve head of the affected eye. Lumbar puncture revealed an elevated opening pressure of 34.8 cm H2O confirming increased intracranial pressure. Additionally, literature searches were conducted in the PubMed, Google Scholar and Embase databases to uncover previous cases of patients with ischemic optic neuropathy and restricted diffusion on MRI.

Conclusions and importance

We highlight the shared pathophysiology between optic disc edema related visual loss in NAION and papilledema in IIH. We review the overlapping clinical and radiographic findings in these two conditions which may occur simultaneously. The presence of restricted diffusion in the optic nerve head versus in the optic nerve parenchyma may support a diagnosis of superimposed NAION and might influence the decision to perform surgery in cases of IIH with fulminant visual loss. Although restricted diffusion on MRI DWI sequences is often used to define cytotoxic edema related to ischemic infarction in the brain, this radiographic finding alone should not be used to determine the indication for surgery for papilledema related visual loss in fulminant IIH.

High diagnostic accuracy of T2FLAIR at 3 T in the detection of optic nerve head edema in acute optic neuritis

OBJECTIVES

Optic nerve head edema (ONHE) detected by fundoscopy is observed in one-third of patients presenting optic neuritis (ON). While ONHE is an important semiological feature, the correlation between ONHE and optic nerve head MRI abnormalities (ONHMA), sometimes called "optic nerve head swelling," remains unknown. Our study aimed to assess the diagnostic accuracy of T2 fluid-attenuated inversion recovery (FLAIR) MRI sequence in detecting ONHE in patients with acute ON.

METHODS

In the present single-center study, data were extracted from two prospective cohort studies that consecutively included adults with a first episode of acute ON treated between 2015 and 2020. Two experienced readers blinded to study data independently analyzed imaging. A senior neuroradiologist resolved any discrepancies. The primary judgment criterion of ONHMA was assessed as optic nerve head high signal intensity on gadolinium-enhanced T2FLAIR MRI sequence. Its diagnostic accuracy was evaluated with both the gold standard of ONHE on fundus photography (FP) and peripapillary retinal nerve fiber layer thickening on optic coherence tomography (OCT).

RESULTS

A total of 102 patients were included, providing 110 affected and 94 unaffected optic nerves. Agreement was high between the different modalities: 92% between MRI and FP (k = 0.77, 95% CI: 0.67-0.88) and 93% between MRI and OCT (k = 0.77, 95% CI: 0.67-0.87). MRI sensitivity was 0.84 (95% CI: 0.70-0.93) and specificity was 0.94 (95% CI: 0.89-0.97) when compared with the FP.

CONCLUSION

Optic nerve head high T2FLAIR signal intensity corresponds indeed to the optic nerve head edema diagnosed by the ophthalmologists. MRI is a sensitive tool for detecting ONHE in patients presenting acute ON.

CLINICAL RELEVANCE STATEMENT

In patients with optic neuritis the high T2FLAIR (fluid-attenuated inversion recovery) signal intensity of the optic nerve head corresponds indeed to optic nerve head edema, which is a useful feature in optic neuritis etiological evaluation and treatment.

KEY POINTS

Optic nerve head edema is a prominent clinical feature of acute optic neuritis and is usually diagnosed during dilated or non-dilated eye fundus examination. Agreement was high between magnetic resonance imaging, fundus photography, and optical coherence tomography. Optic nerve head high T2 fluid attenuation inversion recovery signal intensity is a promising detection tool for optic nerve head edema in patients presenting acute optic neuritis.

Enhancement of optic nerve sheath on MRI in idiopathic intracranial hypertension(IIH)

OBJECTIVE

Optic nerve sheath(ONS) enhancement in idiopathic intracranial hypertension (IIH) patients has been reported in recent years. In this retrospective observation, we analyzed the clinical characteristics of IIH patients with enhancement of ONS.

METHODS

Eighty-two patients with clinically diagnosed IIH from January 2017 to December 2019 were under observation. Then, based on the presence of contrast-enhancement (CE) in ONS on orbital magnetic resonance image (MRI), the IIH patients were divided into CE-ONS group and no-CE(NCE)-ONS group. Six months follow-up information was also included in the observation study. By comparing clinical data of the two groups of IIH patients, we tried to evaluate whether there is clinical heterogeneity in CE-ONS patients.

RESULT

12 patients were included in CE-ONS group, 10 females and 2 males. 70 patients were included in NCE-ONS group, 56 women and 14 men. We found that patients with CE-ONS had a longer course of disease (median disease duration before diagnosis, 5 months vs. 3months, P<0.01) and more likely had the sign of distension of the perioptic subarachnoid space (DPSS) (58.33 % vs. 24.29 %, P = 0.034). But no significant differences were found in demographic characteristics, clinical symptoms, degree of visual impairment, papilledema, opening pressure(OP) on lumbar puncture and clinical outcomes.

CONCLUSION

As a rare sign on MRI, ONS enhancement can occur in patients with IIH. IIH patients with CE-ONS may have a longer course of disease and more prone to DPSS, but there is no significant difference in clinical manifestations, OP, and clinical outcomes compared with IIH patients without CE-ONS.

Large rhabdoid meningioma presenting prominent hyperintensity in the optic nerve: An indicator of visual disturbance on constructive interference steady-state sequence?

BACKGROUND

Rhabdoid meningiomas (RMs) are a rare type of malignant meningioma. Here, we report a case of intracranial RM presenting with visual disturbance and prominent hyperintensity in the optic nerve (ON).

CASE DESCRIPTION

A 20-year-old female presented with a 1-year history of headache. At presentation, her visual acuity (VA) was 20/50 on the right side and 20/40 on the left, with an intraocular pressure of 17 mmHg on both sides. Cerebral magnetic resonance imaging revealed a broad-based tumor in the right frontal convexity. It measured 82 mm × 65 mm × 70 mm in diameter, accompanied by cystic components, and was inhomogeneously enhanced. The intraorbital ONs demonstrated prominent intramedullary hyperintensity on the constructive interference steady-state sequence. Gross total tumor resection was performed and the pathology was consistent with RM. Immediately after surgery, her VA and IOP were 20/17 and 10 mmHg, respectively, with a remarkable resolution of the intramedullary hyperintensity.

CONCLUSION

Prominent hyperintensity in the ON identified in patients with chronic intracranial hypertension may be an indicator of visual disturbance. It can rapidly resolve after resolution of intracranial hypertension with functional recovery.

Evolution of MRI Findings in Patients with Idiopathic Intracranial Hypertension after Venous Sinus Stenting

BACKGROUND AND PURPOSE

The correlation between imaging findings and clinical status in patients with idiopathic intracranial hypertension is unclear. We aimed to examine the evolution of idiopathic intracranial hypertension-related MR imaging findings in patients treated with venous sinus stent placement.

MATERIALS AND METHODS

Thirteen patients with idiopathic intracranial hypertension (median age, 26.9 years) were assessed for changes in the CSF opening pressure, transstenotic pressure gradient, and symptoms after venous sinus stent placement. Optic nerve sheath diameter, posterior globe flattening and/or optic nerve protrusion, empty sella, the Meckel cave, tonsillar ectopia, the ventricles, the occipital emissary vein, and subcutaneous fat were evaluated on MR imaging before and 6 months after venous sinus stent placement. Data are expressed as percentages, medians, or correlation coefficients (r) with P values.

RESULTS

Although all patients showed significant reductions of the CSF opening pressure (31 versus 21 cm H₂O; P = .005) and transstenotic pressure gradient (22.5 versus 1.5 mm Hg; P = .002) and substantial improvement of clinical symptoms 6 months after venous sinus stent placement, a concomitant reduction was observed only for posterior globe involvement (61.5% versus 15.4%; P = .001), optic nerve sheath diameter (6.8  versus 6.1 mm; P < .001), and subcutaneous neck fat (8.9  versus 7.4 mm; P = .001). Strong correlations were observed between decreasing optic nerve sheath diameters and improving nausea/emesis (right optic nerve sheath diameter, r =  0.592, P = .033; left optic nerve sheath diameter, r = 0.718, P = .006), improvement of posterior globe involvement and decreasing papilledema (r = 0.775, P = .003), and decreasing occipital emissary vein diameter and decreasing headache frequency (r = 0.74, P = .035). Decreasing transstenotic pressure gradient at 6 months strongly correlated with decreasing empty sella (r = 0.625, P = .022) and regressing cerebellar ectopia (r = 0.662, P = .019).

CONCLUSIONS

Most imaging findings persist long after normalization of intracranial pressure and clinical improvement. However, MR imaging findings related to the optic nerve may reflect treatment success.

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.

Combined accuracy of optic nerve sheath diameter, strain ratio, and shear wave elastography of the optic nerve in patients with idiopathic intracranial hypertension

PURPOSE

This study assessed the combined accuracy of optic nerve sheath diameter (ONSD), strain ratio (SR), and shear wave elastography (SWE) of the optic nerve (ON) in patients with idiopathic intracranial hypertension (IIH).

METHODS

This prospective study was carried out on both ONs of 34 consecutive patients diagnosed with IIH and 16 age- and sex-matched healthy volunteers. All of the study participants were women. The ONSD, SR, and SWE of the ON were measured. The severity of papilledema of IIH patients was sub-classified into mild papilledema and moderate/severe papilledema.

RESULTS

The mean ONSD (5.6±1.1 mm), SR (0.7±0.1), and SWE (30.1±16.7 kPa) of the IIH patients were significantly different (P=0.001) from the ONSD (4.1±0.5 mm), SR (0.9±0.1), and SWE (8.2±3.4 kPa) of controls. The cutoff values of ONSD, SR, and SWE of the ON for differentiating IIH patients from controls were 5.45 mm, 0.8, and 10.3 kPa with areas under the curve (AUCs) of 0.91, 0.86, and 0.96 and accuracy values of 91%, 81%, and 93%, respectively. Combined SWE and ONSD and combined SWE, ONSD, and SR for differentiating IIH patients from controls revealed AUCs of 0.98 and 0.99 and accuracy values of 96% and 96%, respectively. ONSD, SR, and SWE showed significant differences between mild and moderate/severe papilledema (P=0.001). Papilledema was correlated with SWE (r=0.8, P=0.001), ONSD (r=0.4, P=0.001), and SR (r=-0.4, P=0.001).

CONCLUSION

The combination of ONSD, SR, and SWE may be helpful for diagnosing IIH, and a good indicator of the degree of papilledema.

Technical Improvements in Head and Neck MR Imaging: At the Cutting Edge

Head and neck MR imaging is technically challenging because of magnetic field inhomogeneity, respiratory and swallowing motion, and necessity of high-resolution imaging to trace key anatomic structures. These challenges have been answered by advances in MR imaging technology, including isovolumetric three-dimensional imaging, robust fat-water separation techniques, and novel deep learning-based reconstruction algorithms. New applications of MR imaging have been advanced and functional imaging has been improved. Improvements in acquisition and reconstruction technique facilitate novel applications of morphologic and functional imaging. This results in opportunities to improve diagnosis, staging, and treatment selection through application of advanced MR imaging techniques.

An update on idiopathic intracranial hypertension in adults: a look at pathophysiology, diagnostic approach and management

Idiopathic intracranial hypertension is a neurological syndrome determined by a rise in intracranial pressure without a detectable cause. Course and prognosis may be changeable, requiring a multidisciplinary approach for its diagnosis and management. Although its precise pathogenesis is still unknown, many studies have been carried out to define the possible causal and associated factors, such as retinoids, steroid hormones, body mass index and recent weight gains, cytokines and adipokines levels. The clinical presentation can be variable including chronic headache, disturbance of vision, diplopia and tinnitus. Even if papilloedema is considered the most specific sign, it could not be observed in more than 5% of patients during the evaluation of the fundus oculi. Neuroradiological signs acquire greater importance in patients who do not present papilloedema and may suggest the diagnosis of idiopathic intracranial hypertension. Other assessments can be useful in the diagnostic process, such as optical coherence tomography, visual evoked potentials, ocular ultrasonography and fundus fluorescein angiography and autofluorescence. Nonetheless, cerebrospinal fluid pressure measurement is required to establish a definite diagnosis. Management may be different, since surgical procedures or lumbar punctures are often required when symptoms develop rapidly leading to a loss of visual function. Apart from these cases, patients can be treated with a pharmacological approach and low-calorie diet, but they also need to be monitored over time since relapses years later are not uncommon.