Optical coherence tomography for detection of asymptomatic optic nerve lesions in clinically isolated syndrome

Diagnostic Value of Inter-Eye Difference Metrics on OCT for Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis

BACKGROUND AND OBJECTIVES

The 2022 International Consortium for Optic Neuritis diagnostic criteria for optic neuritis (ON) include optical coherence tomography (OCT). The diagnostic value of intereye difference (IED) metrics is high for ON in patients with multiple sclerosis and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders, but unknown in myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON).

METHODS

A multicenter validation study was conducted on the published IED cutoff values (>4% or >4 μm in the macular ganglion cell and inner plexiform layer [mGCIP] or >5% or >5 μm in the peripapillary retinal nerve fiber layer [pRNFL]) in individuals with MOG-ON and age-matched and sex-matched healthy controls (HCs). Structural data were acquired with Spectralis spectral-domain OCT >6 months after ON. We calculated sensitivity, specificity, and receiver operating characteristics for both intereye percentage (IEPD) and absolute difference (IEAD).

RESULTS

A total of 66 individuals were included (MOG-ON N = 33; HCs N = 33). ON was unilateral in 20 and bilateral in 13 subjects. In the pooled analysis, the mGCIP IEPD was most sensitive (92%), followed by the mGCIP IEAD (88%) and pRNFL (84%). The same pattern was found for the specificity (mGCIP IEPD 82%, IEAD 82%; pRNFL IEPD 82%, IEAD 79%).In subgroup analyses, the diagnostic sensitivity was higher in subjects with unilateral ON (>99% for all metrics) compared with bilateral ON (61%-78%).

DISCUSSION

In individuals with MOG-ON, the diagnostic accuracy of OCT-based IED metrics for ON was high, especially of mGCIP IEPD.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the intereye difference on OCT can distinguish between those with MOG and normal controls.

Current and future role of MRI in the diagnosis and prognosis of multiple sclerosis

In the majority of cases, multiple sclerosis (MS) is characterized by reversible episodes of neurological dysfunction, often followed by irreversible clinical disability. Accurate diagnostic criteria and prognostic markers are critical to enable early diagnosis and correctly identify patients with MS at increased risk of disease progression. The 2017 McDonald diagnostic criteria, which include magnetic resonance imaging (MRI) as a fundamental paraclinical tool, show high sensitivity and accuracy for the diagnosis of MS allowing early diagnosis and treatment. However, their inappropriate application, especially in the context of atypical clinical presentations, may increase the risk of misdiagnosis. To further improve the diagnostic process, novel imaging markers are emerging, but rigorous validation and standardization is still needed before they can be incorporated into clinical practice. This Series article discusses the current role of MRI in the diagnosis and prognosis of MS, while examining promising MRI markers, which could serve as reliable predictors of subsequent disease progression, helping to optimize the management of individual patients with MS. We also explore the potential of new technologies, such as artificial intelligence and automated quantification tools, to support clinicians in the management of patients. Yet, to ensure consistency and improvement in the use of MRI in MS diagnosis and patient follow-up, it is essential that standardized brain and spinal cord MRI protocols are applied, and that interpretation of results is performed by qualified (neuro)radiologists in all countries.

Trans-Synaptic Degeneration in the Visual Pathway in Patients With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

BACKGROUND AND OBJECTIVES

We aimed to assess the presence of retinal neurodegeneration independent of optic neuritis (ON) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and to investigate the development of trans-synaptic anterograde degeneration in these patients after ON.

METHODS

Cross-sectional, retrospective study of 34 adult patients with MOGAD and 23 healthy controls (HC). Clinical, optical coherence tomography (OCT), and MRI data were collected. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell inner plexiform layer (GCIPL) were obtained using Heidelberg Spectralis. FreeSurfer7 was used to obtain the lateral geniculate nucleus (LGN), occipital volume fractions (to total estimated intracranial volume), and occipital cortical thickness. For the anterior visual pathway, the analysis was conducted using eyes, classified based on the history of ON (Eye-ON and Eye-NON) and compared with Eye-HC. The analysis of OCT and brain volumetric measures was conducted comparing MOGAD-ON, MOGAD-NON, and HC groups. The analysis of covariance with a Bonferroni-adjusted post hoc test was used to test differences between groups and linear regression analysis to evaluate OCT/MRI associations; age and sex were considered as covariates.

RESULTS

24 (70.5%) patients had a prior ON. Median pRNFL and GCIPL thickness (um) was significantly reduced in Eye-ON vs EyeNON and HC (pRNFL: 69.4 (17.3), 89.6 (13.7), 98.2 (11.7), p < 0.001; GCIPL: 55.8 (8.7), 67.39 (8.7), 72.6 (4.5), p < 0.001). pRNFL and GCIPL thickness had a negative correlation with the number of ON episodes (p = 0.025 and p = 0.031, respectively). LGN volume fraction was significantly lower in patients with MOGAD-ON than in HC (0.33 (0.05) vs 0.39 (0.04), p = 0.002). The occipital cortical thickness was lower in MOGAD-ON compared with MOGAD-NON and HC (p = 0.010). In patients with MOGAD-ON, pRNFL correlated with LGN volume (p = 0.006), occipital thickness (p = 0.002), and the medial occipital cortex (p = 0.002), but not the lateral occipital lobe.

DISCUSSION

Compared with HC, MOGAD-ON exhibits reduced retinal thickness, primarily influenced by the presence and the number of prior ON episodes. Moreover, MOGAD-ON demonstrates significant atrophy in the retinal, subcortical, and cortical regions of the visual pathway, distinguishing them from MOGAD-NON and HC. These findings suggest that in patients with MOGAD neurodegeneration is tightly correlated with damage to the involved pathway.

Consensus statement of the Spanish Society of Neurology on the treatment of multiple sclerosis and holistic patient management in 2023

The last consensus statement of the Spanish Society of Neurology's Demyelinating Diseases Study Group on the treatment of multiple sclerosis (MS) was issued in 2016. Although many of the positions taken remain valid, there have been significant changes in the management and treatment of MS, both due to the approval of new drugs with different action mechanisms and due to the evolution of previously fixed concepts. This has enabled new approaches to specific situations such as pregnancy and vaccination, and the inclusion of new variables in clinical decision-making, such as the early use of high-efficacy disease-modifying therapies (DMT), consideration of the patient's perspective, and the use of such novel technologies as remote monitoring. In the light of these changes, this updated consensus statement, developed according to the Delphi method, seeks to reflect the new paradigm in the management of patients with MS, based on the available scientific evidence and the clinical expertise of the participants. The most significant recommendations are that immunomodulatory DMT be started in patients with radiologically isolated syndrome with persistent radiological activity, that patient perspectives be considered, and that the term "lines of therapy" no longer be used in the classification of DMTs (> 90% consensus). Following diagnosis of MS, the first DMT should be selected according to the presence/absence of factors of poor prognosis (whether epidemiological, clinical, radiological, or biomarkers) for the occurrence of new relapses or progression of disability; high-efficacy DMTs may be considered from disease onset.

Optic nerve topography in multiple sclerosis diagnostic criteria: Existing knowledge and future directions

Current diagnostic criteria for multiple sclerosis (MS) do not consider the optic nerve as a typical topography for establishing the diagnosis. Recent studies have proved the utility of optic nerve magnetic resonance imaging, optical coherence tomography and visual evoked potentials in detecting optic nerve lesions during the early stages of MS. In addition, emerging evidence supports the inclusion of optic nerve topography as a fifth region to fulfil the dissemination in space criteria. Anticipating a modification in the McDonald criteria, it is crucial for neurologists to familiarize with the diagnostic properties of each test in detecting optic nerve lesions and understand how to incorporate them into the MS diagnostic process. Therefore, the objective of this article is to review the existing evidence supporting the use of these tests in the diagnostic process of MS and provide a practical algorithm that can serve as a valuable guide for clinical practice.

Adding the Optic Nerve in Multiple Sclerosis Diagnostic Criteria: A Longitudinal, Prospective, Multicenter Study

BACKGROUND AND OBJECTIVES

The optic nerve is not one of the areas of the CNS that can be used to demonstrate dissemination in space (DIS) within the 2017 McDonald criteria for the diagnosis of multiple sclerosis (MS). Objectives were (1) to assess whether optic nerve-MRI (ON-MRI), optical coherence tomography (OCT), and visual evoked potentials (VEP) detect optic nerve involvement in clinically isolated syndrome (CIS) and (2) to evaluate the contribution of the optic nerve topography to the current diagnostic criteria in a prospective, multicenter cohort.

METHODS

MAGNIMS centers were invited to provide prospective data on patients with CIS who underwent a visual assessment with at least 2 of 3 investigations (ON-MRI, OCT, or VEP) within 6 months of onset. Modified DIS criteria were constructed by adding the optic nerve topography, defined by each investigation separately and any combination of them, as the fifth area of the CNS. A risk assessment analysis and the performance of the different DIS criteria were analyzed using the diagnosis of MS according to the 2017 McDonald criteria as the primary outcome and new T2 lesions and/or a second relapse as the secondary outcome.

RESULTS

We included 157 patients with CIS from 5 MAGNIMS centers; 60/157 (38.2%) patients presented with optic neuritis. Optic nerve involvement on ON-MRI was found in 40.2% patients at study entry and in 72.5% of those with optic neuritis.At follow-up (mean 27.9 months, SD 14.5), 111/157 patients (70.7%) were diagnosed with MS according to the 2017 McDonald criteria. Fulfilling either 2017 DIS or any modified DIS criteria conferred a similar high risk for reaching primary and secondary outcomes. The modified DIS criteria had higher sensitivity (92.5% [with ON-MRI] vs 88.2%), but slightly lower specificity (80.0% [with GCIPL IEA ≥4 μm] vs 82.2%), with overall similar accuracy (86.6% [with ON-MRI] vs 86.5%) than 2017 DIS criteria. Consistent results were found for secondary outcomes.

DISCUSSION

In patients with CIS, the presence of an optic nerve lesion defined by MRI, OCT, or VEP is frequently detected, especially when presenting with optic neuritis. Our study supports the addition of the optic nerve as a fifth topography to fulfill DIS criteria.

Radiologically isolated syndrome

Individuals can be deemed to have radiologically isolated syndrome (RIS) if they have incidental demyelinating-appearing lesions in their brain or spinal cord that are highly suggestive of multiple sclerosis but their clinical history does not include symptoms consistent with multiple sclerosis. Data from international longitudinal cohorts indicate that around half of people with RIS will develop relapsing or progressive symptoms of multiple sclerosis within 10 years, suggesting that in some individuals, RIS is a presymptomatic stage of multiple sclerosis. Risk factors for progression from RIS to clinical multiple sclerosis include younger age (ie, <35 years), male sex, CSF-restricted oligoclonal bands, spinal cord or infratentorial lesions, and gadolinium-enhancing lesions. Other imaging, biological, genetic, and digital biomarkers that might be of value in identifying individuals who are at the highest risk of developing multiple sclerosis need further investigation. Two 2-year randomised clinical trials showed the efficacy of approved multiple sclerosis immunomodulatory medications in preventing the clinical conversion to multiple sclerosis in some individuals with RIS. If substantiated in longer-term studies, these data have the potential to transform our approach to care for the people with RIS who are at the greatest risk of diagnosis with multiple sclerosis.

Subclinical damage to the contralateral eye in unilateral optic neuritis: A longitudinal study

BACKGROUND

Early detection of subclinical injuries can lead to a correct diagnosis and help control the advancement of the condition. This study aims to investigate the presence of subclinical damage and silent progression to the contralateral eye's visual function and structure in patients experiencing their first episode of unilateral optic neuritis (ON).

METHODS

Fifty patients with first-onset unilateral ON were enrolled in this study. Based on etiology, they were classified as having neuromyelitis optica spectrum disorder-related ON (NMOSD-ON), myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON), idiopathic ON (IDON), or multiple sclerosis-related ON (MS-ON). These cases were followed up for one year to determine whether there was any silent progression of visual function and structure in the contralateral non-ON (NON) eye. A gender- and age-matched healthy control (HC) group was included to compare the differences in visual function and structure between the patients with NON eyes and the HC group.

RESULTS

Within two weeks of onset, best-corrected visual acuity (BCVA; P = 0.008), mean deviation (MD) of the visual field (VF) (P = 0.001), and peripapillary retinal nerve fiber layer (pRNFL; P = 0.019) thickness were significantly worse in the NMOSD-NON patients than those in the HC group, while there were no differences in the pRNFL and the ganglion cell-inner plexiform layer (GCIPL) thicknesses and quadrant thicknesses (P > 0.05) of the groups. IDON-NON only showed subclinical damage in VF (P = 0.001) and temporal pRNFL (P = 0.042), while the BCVA, VF, and optic nerve structure (pRNFL, GCIPL) of the MOG-NON patients showed no subclinical damage (P > 0.05). In addition, the one-year follow-up of each NON eye type showed that there was no silent progression in NMOSD-NON, MOG-NON, or IDON-NON. A pairwise comparison of the different types of NON eyes revealed no statistical differences (P > 0.05).

CONCLUSION

Among the patients with unilateral ON, NMOSD-NON and IDON-NON resulted in subclinical damage to the visual function and structure of the contralateral eye within two weeks of onset, whereas MOG-NON did not show any subclinical damage to visual function or structure. Furthermore, these subclinical damages did not show any silent progression during the one-year follow-up period.

Diagnostic Performance of Adding the Optic Nerve Region Assessed by Optical Coherence Tomography to the Diagnostic Criteria for Multiple Sclerosis

BACKGROUND AND OBJECTIVES

The optic nerve has been recommended as an additional region for demonstrating dissemination in space (DIS) in diagnostic criteria for multiple sclerosis (MS). The aim of this study was to investigate whether adding the optic nerve region as determined by optical coherence tomography (OCT) as part of the DIS criteria improves the 2017 diagnostic criteria.

METHODS

From a prospective observational study, we included patients with a first demyelinating event who had complete information to assess DIS and a spectral domain OCT scan obtained within 180 days. Modified DIS criteria (DIS + OCT) were constructed by adding the optic nerve to the current DIS regions based on validated thresholds for OCT intereye differences. Time to second clinical attack was the primary endpoint.

RESULTS

We analyzed 267 patients with MS (mean age 31.3 years [SD 8.1], 69% female) during a median observation period of 59 months (range: 13-98). Adding the optic nerve as a fifth region improved the diagnostic performance by increasing accuracy (DIS + OCT 81.2% vs DIS 65.6%) and sensitivity (DIS + OCT 84.2% vs DIS 77.9%) without lowering specificity (DIS + OCT 52.2% vs DIS 52.2%). Fulfilling DIS + OCT criteria (≥2 of 5 DIS + OCT regions involved) indicated a similar risk of a second clinical attack (hazard ratio [HR] 3.6, CI 1.4-14.5) compared with a 2.5-fold increased risk when fulfilling DIS criteria (HR 2.5, CI 1.2-11.8). When the analysis was conducted according to topography of the first demyelinating event, DIS + OCT criteria performed similarly in both optic neuritis and nonoptic neuritis.

DISCUSSION

Addition of the optic nerve, assessed by OCT, as a fifth region in the current DIS criteria improves diagnostic performance by increasing sensitivity without lowering specificity.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that adding the optic nerve as determined by OCT as a fifth DIS criterion to the 2017 McDonald criteria improves diagnostic accuracy.

Utility of optical coherence tomography in patients of central immune mediated demyelinating diseases - A prospective study

Optical coherence tomography (OCT) is a non-invasive tool to measure thickness of various layers of retina. Recently, retinal nerve fibre layer (RNFL) and ganglion cell and inner plexiform layer (GCIP) thinning has been observed in OCT in patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), This study compared OCT profile, along with visual acuity (VA), color vision (CV), contrast saturation (CS) and visual evoked potentials (VEP) in two main cohorts of MS and NMOSD and with controls, during acute episode of optic neuritis (ON), at 3 and 6 months. We found that changes of ON were present in 75% of MS eyes and in 45% of NMOSD patients. Of these, subclinical involvement was present in 56.25% of MS eyes and only in 5% of NMOSD eyes suggesting frequent subclinical involvement in the former. Mean RNFL was 95.23 ± 15.53 in MS and 66.14 ± 43.73 in NMOSD after 6 months of ON episode. Thinning of NQ and IQ was observed in NMOSD eyes in the immediate period after ON attack. At 6 months relative sparing of RNFL in TQ was observed in NMOSD ON eyes and MS ON showed predilection for involvement of TQ.

Improved detection of multiple sclerosis lesions with T2-prepared double inversion recovery at 3T

BACKGROUND AND PURPOSE

Double inversion recovery (DIR) imaging is used in multiple sclerosis (MS) clinical protocols to improve the detection of cortical and juxtacortical gray matter lesions by nulling confounding signals originating from the cerebrospinal fluid and white matter. Achieving a high isotropic spatial resolution, to depict the neocortex and its typically small lesions, is challenged by the reduced signal-to-noise ratio (SNR) determined by multiple tissue signal nulling. Here, we evaluate both conventional and optimized DIR implementations to improve tissue contrast (TC), SNR, and MS lesion conspicuity.

METHODS

DIR images were obtained from MS patients and healthy controls using both conventional and prototype implementations featuring a T2-preparation module (T2P), to improve SNR and TC, as well as an image reconstruction routine with iterative denoising (ID). We obtained quantitative measures of SNR and TC, and evaluated the visibility of MS cortical, cervical cord, and optic nerve lesions in the different DIR images.

RESULTS

DIR implementations adopting T2P and ID enabled improving the SNR and TC of conventional DIR. In MS patients, 34% of cortical, optic nerve, and cervical cord lesions were visible only in DIR images acquired with T2P, and not in conventional DIR images. In the studied cases, image reconstruction with ID did not improve lesion conspicuity.

CONCLUSIONS

DIR with T2P should be preferred to conventional DIR imaging in protocols studying MS patients, as it improves SNR and TC and determines an improvement in cortical, optic nerve, and cervical cord lesion conspicuity.

A prospective longitudinal study on prognostic factors of visual recovery and structural change after a first episode of optic neuritis

BACKGROUND

To determine the role of OCT in predicting the final visual and structural outcome, and evaluate the correlation between functional eye outcome and retinal changes, in patients with first episode of optic neuritis (ON).

METHODS

In this prospective study, consecutive adult patients with acute ON underwent ophthalmological evaluation at baseline and 1 and 12 months, including OCT measurements of peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell and innerplexiform layer, and innernuclear layer thicknesses, high- and low-contrast visual acuity, visual field assessment, and baseline brain MRI. Univariate and multivariate linear regressions were used to assess predictive factors of outcome. Correlations between 12-month visual function and retinal structure were estimated by Spearman coefficients. Two groups of patients were analysed, with or without multiple sclerosis (MS).

RESULTS

Among 116 patients, 79 (68.1%) had MS, and 37 (31.9%) had ON not related to MS (including 19 idiopathic (i.e isolated) ON, and 13 and 5 with myelin oligodendrocyte glycoprotein and aquaporin-4 antibodies, respectively). We found no independent predictive factor of visual and retinal outcome. Analysis of the relationship between the visual field test (mean deviation) and pRNFL thickness demonstrated a threshold of 75.4 μm and 66.4 μm, below which the mean deviation was worse, for patients with MS (p=0.007) and without MS (p<0.001), respectively.

CONCLUSIONS

We found that inner retinal layer measurements during the first month are not predictive of final outcome. The critical threshold of axonal integrity, below which visual function is damaged, is different between patients with and without MS.

Dynamics of Retinal Vessel Loss After Acute Optic Neuritis in Patients With Relapsing Multiple Sclerosis

Background and Objectives

Rarefication of the retinal vasculature as measured by optical coherence tomography angiography (OCT-A) is a novel finding in patients with multiple sclerosis (MS). This study aimed to analyze longitudinal dynamics of the retinal vasculature following an acute inflammatory relapse including acute optic neuritis (ON) and to search for associations with alterations of the retinal architecture and visual function.

Methods

This prospective longitudinal cohort study included patients with relapsing-remitting MS or clinically isolated syndrome having an acute ON (n = 20) or a non-ON relapse (n = 33). Patients underwent examinations at baseline and after 7, 14, 28, 90, and 180 days with OCT, OCT-A, and assessment of the high- (HCVA) and low-contrast visual acuity (LCVA).

Results

Retinal vessel loss of the superficial vascular complex (SVC) evolves early after ON and reaches a plateau between 90 and 180 days (relative vessel loss 15% ± 8% [mean ± SD]). In addition, an 18% ± 18% intraindividual increase of the foveal avascular zone (FAZ) is evident within 180 days after acute ON. Both SVC thinning and FAZ enlargement were associated with worse HCVA and LCVA. Rarefication of the SVC evolved simultaneously to thinning of the common ganglion cell and inner plexiform layer (GCIP) after ON. No alterations of the deep vascular complex were seen in eyes with ON, and no alterations of the retinal vasculature were recognized in patients having acute non-ON relapses.

Discussion

Rarefication of the SVC and growing of the FAZ evolve rapidly after ON and are linked to persistent visual disability. ON-related SVC thinning might be closely linked to GCIP atrophy and might occur due to an altered local metabolic activity within inner retinal layers.

Low Contrast Visual Evoked Potentials for Early Detection of Optic Neuritis

Optic neuritis (ON) detection is important for the early diagnosis and management of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). However, the conventional high-contrast visual evoked potential (VEP) used for ON detection lacks sensitivity for identifying ON presenting as mild or unremarkable visual disturbance, which is common in first-episode ON. Therefore, this study aimed to investigate whether a change in contrast or check size improves the sensitivity of VEP to first-ever ON. In total, 60 patients with the demyelinating disease (29 MS and 31 idiopathic patients with ON) without ON or with first-ever ON at least 6 months prior and 32 healthy controls underwent neuro-ophthalmic evaluations. VEPs were induced using three pattern-reversal checkerboard stimuli having, respectively, 10% contrast with a check size of 32' (LC32 VEP), 100% contrast with a check size of 32' (HC32 VEP; conventional VEP), and 100% contrast with a check size of 16' (HC16 VEP). The receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) were calculated to determine the most appropriate VEP method for detecting optic nerve involvement. The optimal cut-off point was determined using the Youden index (J-index). The McNemar test was used to determine whether dichotomous proportions were equivalent. In comparison with first-ever ON eyes (n = 39) and healthy eyes (n = 64), LC32 VEP showed the highest AUC for discriminating ON (0.750, p < 0.001; 0.730 for HC32 VEP, p < 0.001; 0.702 for HC16 VEP, p = 0.001). In the first-ever ON group, LC32 VEP and conventional HC32 VEP were abnormal in 76.9 and 43.6%, respectively (McNemar, p < 0.001), and combining these tests did not improve sensitivity. These indicate that LC32 VEP is the most sensitive method for detecting first-ever ON. Visual evoked potential with 10% contrast stimuli was superior to conventional VEP for detecting first-ever ON. Thus, adding these LC stimuli might be helpful in identifying optic nerve involvement in ON with mild or unremarkable visual impairment.

Retinal imaging with optical coherence tomography in multiple sclerosis: novel aspects

Optical coherence tomography (OCT) is of increasing interest in the clinical assessment of multiple sclerosis (MS) patients beyond the scope of clinical studies. In this narrative review, we discuss novel changes of OCT parameters during acute optic neuritis and the disease course of MS patients. OCT images document the changes of retinal layers during an episode of acute optic neuritis and can therefore provide valuable insights into the pathophysiology. Moreover, MS patients show progredient thinning of retinal layers throughout the disease. The thinning is accelerated through relapses as well as disease progression without relapse. The OCT parameters are also associated with clinical outcome parameters, including disability, cognitive function, and brain atrophy. The impact of disease-modifying therapies on OCT parameters is the subject of ongoing research and depends on the agent used. Additional data are still necessary before OCT parameters can be implemented in the clinical standard of care of MS patients.

Optic Nerve Lesion Length at the Acute Phase of Optic Neuritis Is Predictive of Retinal Neuronal Loss

Background and Objectives

Acute optic neuritis (ON) is a classical presenting symptom of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and anti–MOG-associated disorders. The resulting visual impairment is variable and can be severe. Clinicians are in need of predictive biomarkers to optimize the management of acute ON. In this longitudinal study (IRMANO, NCT03651662), we evaluated the ability of optic nerve lesion length measured on MRI at the acute phase of ON to predict retinal neuro-axonal loss and visual impairment at a chronic stage.

Methods

We conducted a longitudinal study (IRMANO, NCT03651662) of patients who presented a clinical episode of ON (≤8 weeks). All patients underwent a retinal optical coherence tomography (OCT) and a brain/optic nerve MRI, including 3D double-inversion recovery (DIR) sequence at the acute phase of ON and 12 months later. Primary outcomes were optic nerve DIR hypersignal lesion length, macular ganglion cell–inner plexiform layer (GCIPL) volume measured on OCT, and low-contrast monocular visual acuity (LCMVA).

Results

The study group included 51 patients (33 women, mean age of 32.4 years ± 7.9). We recruited patients with a clinically isolated syndrome (n = 20), a relapsing-remitting MS (n = 23), an isolated ON (n = 6), and a first clinical episode of NMOSD (n = 2). Optic nerve DIR hypersignal was observed in all but 1 symptomatic optic nerves. At inclusion, the mean optic nerve lesion length (in mm) was 12.35 ± 5.98. The mean GCIPL volume (in mm³) significantly decreased between inclusion (1.90 ± 0.18) and M₁₂ (1.67 ± 0.21; p < 0.0001). Optic nerve lesion length at inclusion was significantly associated with GCIPL thinning (estimate ± SD; −0.012 ± 0.004; p = 0.0016) and LCMVA at M₁₂ (0.016 ± 0.003; p < 0.001). Optic nerve lesion length significantly increased at M₁₂ (15.76 ± 8.70; p = 0.0007). The increase in optic nerve lesion length was significantly associated with the GCIPL thinning between inclusion and M₁₂ (−0.012 ± 0.003; p = 0.0011).

Discussion

At the acute phase of ON, optic nerve lesion length is an imaging biomarker predictive of retinal neuro-axonal loss and chronic visual impairment, which can help to stratify future therapeutic strategies in acute ON.

Classification of Evidence

This study provides Class I evidence that optic nerve lesion length measured on MRI during the acute phase of a first episode of ON is associated with long-term retinal neuro-axonal loss and visual impairment.

Retinal inter-eye difference and atrophy progression in multiple sclerosis diagnostics

BACKGROUND

The visual system could be included in the diagnostic criteria for multiple sclerosis (MS) to demonstrate dissemination in space (DIS) and dissemination in time (DIT).

OBJECTIVE

To investigate the diagnostic value of retinal asymmetry in MS.

METHODS

A prospective, longitudinal study in individuals with MS (n=151) and healthy controls (n=27). Optical coherence tomography (OCT) was performed at 0, 2 and 4 years. Macular ganglion cell and inner plexiform layer (mGCIPL) thickness was determined as well as measures for retinal asymmetry: the inter-eye percentage difference (IEPD) and inter-eye absolute difference (IEAD). Receiver operator characteristics curves were plotted and the area under the curve (AUC) was calculated for group comparisons of the mGCIPL, IEPD, IEAD and atrophy rates.

RESULTS

The diagnostic accuracy of both the IEPD and IEAD for differentiating bilateral and unilateral MS optic neuritis was high and stable over time (AUCs 0.88-0.93). The IEPD slightly outperformed the IEAD. Atrophy rates showed low discriminatory abilities for differentiating MS from controls (AUC 0.49-0.58).

CONCLUSION

The inter-eye differences of the mGCIPL have value for demonstration of DIS but in individuals with longstanding MS not for DIT. This may be considered as a test to detect DIS in future diagnostic criteria. Validation in a large prospective study in people presenting with symptoms suggestive of MS is required.

Subclinical anterior optic pathway involvement in early multiple sclerosis and clinically isolated syndromes

Optical coherence tomography (OCT) is gaining increasing relevance in the assessment of patients with multiple sclerosis. Converging evidence point to the view that neuro-retinal changes, in eyes without acute optic neuritis, reflect inflammatory and neurodegenerative processes taking place throughout the CNS. The present study aims at exploring the usefulness of OCT as a marker of inflammation and disease burden in the earliest phases of the disease. Thus, a cohort of 150 consecutive patients underwent clinical, neurophysiological and brain MRI assessment as well as lumbar puncture as part of their diagnostic workup for a neurological episode suggestive of inflammatory CNS disorder; among those 32 patients had another previous misdiagnosed episode. For the present study, patients also received a visual pathway assessment (OCT, visual evoked potentials, visual acuity), measurement of CSF inflammatory markers (17 cytokines-chemokines, extracellular vesicles of myeloid origin), and dosage of plasma neurofilaments. Subclinical optic nerve involvement is frequently found in clinically isolated syndromes by visual evoked potentials (19.2%). OCT reveals ganglion cell layer asymmetries in 6.8% of patients; retinal fibre layer asymmetries, despite being more frequent (17.8%), display poor specificity. The presence of subclinical involvement is associated with a greater disease burden. Second, ganglion cell layer thinning reflects the severity of disease involvement even beyond the anterior optic pathway. In fact, the ganglion cell layer in eyes without evidence of subclinical optic involvement is correlated with Expanded Disability Status Scale, low contrast visual acuity, disease duration, brain lesion load, presence of gadolinium enhancing lesions, abnormalities along motor and somatosensory evoked potentials, and frequency of CSF-specific oligoclonal bands. Third, the inner nuclear layer thickens in a post-acute (1.1-3.7 months) phase after a relapse, and this phenomenon is counteracted by steroid treatment. Likewise, a longitudinal analysis on 65 patients shows that this swelling is transient and returns to normal values after 1 year follow-up. Notwithstanding, the clinical, MRI, serological and CSF markers of disease activity considered in the study are strictly associated with one another, but none of them are associated with the inner nuclear layer. Our findings challenge the current hypothesis that the inner nuclear layer is an acute phase marker of inflammatory activity. The present study suggests that instrumental evidence of subclinical optic nerve involvement is associated with a greater disease burden in clinically isolated syndrome. Neuro-retinal changes are present since the earliest phases of the disease and yield important information regarding the neurodegenerative and inflammatory processes occurring in the CNS.

Beyond McDonald: updated perspectives on MRI diagnosis of multiple sclerosis

INTRODUCTION

Magnetic resonance imaging (MRI) is an essential paraclinical test to establish an accurate and early diagnosis of multiple sclerosis (MS), which is based on the application of the McDonald criteria.

AREAS COVERED

The objective of this article is to analyze, based on publicly available database since the publication of the 2017 McDonald diagnostic criteria, the clinical impact of these criteria, to discuss the potential inclusion within these criteria of the optic nerve to demonstrate dissemination in space, and to guide the acquisition and interpretation of MRI scans for diagnostic purposes. Finally, the authors will review emerging MRI features that could improve the specificity of MRI in the diagnosis of MS and consequently minimize the misdiagnosis of this disease.

EXPERT OPINION

Although the optic nerve has not been included as one of the topographies required to demonstrate demyelinating lesion disseminated in space in the 2017 McDonald criteria, new studies seem to show some improvement in the sensitivity of these criteria when this topography is considered. New radiological findings such as the central vein sign and iron rims, should be considered within the typical MRI features of this disease with the objective of minimizing MRI-based diagnostic errors.

Artificial intelligence extension of the OSCAR-IB criteria

Artificial intelligence (AI)-based diagnostic algorithms have achieved ambitious aims through automated image pattern recognition. For neurological disorders, this includes neurodegeneration and inflammation. Scalable imaging technology for big data in neurology is optical coherence tomography (OCT). We highlight that OCT changes observed in the retina, as a window to the brain, are small, requiring rigorous quality control pipelines. There are existing tools for this purpose. Firstly, there are human-led validated consensus quality control criteria (OSCAR-IB) for OCT. Secondly, these criteria are embedded into OCT reporting guidelines (APOSTEL). The use of the described annotation of failed OCT scans advances machine learning. This is illustrated through the present review of the advantages and disadvantages of AI-based applications to OCT data. The neurological conditions reviewed here for the use of big data include Alzheimer disease, stroke, multiple sclerosis (MS), Parkinson disease, and epilepsy. It is noted that while big data is relevant for AI, ownership is complex. For this reason, we also reached out to involve representatives from patient organizations and the public domain in addition to clinical and research centers. The evidence reviewed can be grouped in a five-point expansion of the OSCAR-IB criteria to embrace AI (OSCAR-AI). The review concludes by specific recommendations on how this can be achieved practically and in compliance with existing guidelines.

Retinal asymmetry in multiple sclerosis

The diagnosis of multiple sclerosis is based on a combination of clinical and paraclinical tests. The potential contribution of retinal optical coherence tomography (OCT) has been recognized. We tested the feasibility of OCT measures of retinal asymmetry as a diagnostic test for multiple sclerosis at the community level. In this community-based study of 72 120 subjects, we examined the diagnostic potential of the inter-eye difference of inner retinal OCT data for multiple sclerosis using the UK Biobank data collected at 22 sites between 2007 and 2010. OCT reporting and quality control guidelines were followed. The inter-eye percentage difference (IEPD) and inter-eye absolute difference (IEAD) were calculated for the macular retinal nerve fibre layer (RNFL), ganglion cell inner plexiform layer (GCIPL) complex and ganglion cell complex. Area under the receiver operating characteristic curve (AUROC) comparisons were followed by univariate and multivariable comparisons accounting for a large range of diseases and co-morbidities. Cut-off levels were optimized by ROC and the Youden index. The prevalence of multiple sclerosis was 0.0023 [95% confidence interval (CI) 0.00229–0.00231]. Overall the discriminatory power of diagnosing multiple sclerosis with the IEPD AUROC curve (0.71, 95% CI 0.67–0.76) and IEAD (0.71, 95% CI 0.67–0.75) for the macular GCIPL complex were significantly higher if compared to the macular ganglion cell complex IEPD AUROC curve (0.64, 95% CI 0.59–0.69, P = 0.0017); IEAD AUROC curve (0.63, 95% CI 0.58–0.68, P < 0.0001) and macular RNFL IEPD AUROC curve (0.59, 95% CI 0.54–0.63, P < 0.0001); IEAD AUROC curve (0.55, 95% CI 0.50–0.59, P < 0.0001). Screening sensitivity levels for the macular GCIPL complex IEPD (4% cut-off) were 51.7% and for the IEAD (4 μm cut-off) 43.5%. Specificity levels were 82.8% and 86.8%, respectively. The number of co-morbidities was important. There was a stepwise decrease of the AUROC curve from 0.72 in control subjects to 0.66 in more than nine co-morbidities or presence of neuromyelitis optica spectrum disease. In the multivariable analyses greater age, diabetes mellitus, other eye disease and a non-white ethnic background were relevant confounders. For most interactions, the effect sizes were large (partial ω² > 0.14) with narrow confidence intervals. In conclusion, the OCT macular GCIPL complex IEPD and IEAD may be considered as supportive measurements for multiple sclerosis diagnostic criteria in a young patient without relevant co-morbidity. The metric does not allow separation of multiple sclerosis from neuromyelitis optica. Retinal OCT imaging is accurate, rapid, non-invasive, widely available and may therefore help to reduce need for invasive and more costly procedures. To be viable, higher sensitivity and specificity levels are needed.

Advances in ophthalmic structural and functional measures in multiple sclerosis: do the potential ocular biomarkers meet the unmet needs?

PURPOSE OF REVIEW

Multiple sclerosis is a heterogeneous disorder. Biomarkers to monitor disease activities are highly desirable especially because of the recent shift toward personalized medicine that coincides with the expansion of disease-modifying therapy. The visual system is highly involved in multiple sclerosis, and the rapid advancement of ophthalmic techniques has boosted the development of potential ocular biomarkers for multiple sclerosis management.

RECENT FINDINGS

Recent studies have found that the rapid thinning of the peripapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer (GCIPL) occurs in the progressive stage. Furthermore, the inter-eye thickness difference of the GCIPL could be used in identifying unilateral optic neuritis to facilitate the early diagnosis of multiple sclerosis. Moreover, the retinal microvascular alterations measured as vessel density were found to be related to the disability and visual function, although a standardized protocol to measure retinal microvascular alterations has not been well established. Additionally, aberrant ocular motility, such as fixation microsaccades, can be used to measure disability objectively.

SUMMARY

The fast expansion of potential ocular biomarkers measured as retinal microstructural, microvascular, and ocular motility changes may facilitate the diagnosis and management of multiple sclerosis.

Recent advances and future directions on the use of optical coherence tomography in neuro-ophthalmology

Optical coherence tomography (OCT) is a noninvasive imaging technique used to qualitatively and quantitatively analyze various layers of the retina. OCT of the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) is particularly useful in neuro-ophthalmology for the evaluation of patients with optic neuropathies and retrochiasmal visual pathway disorders. OCT allows for an objective quantification of edema and atrophy of the RNFL and GCIPL, which may be evident before obvious clinical signs and visual dysfunction develop. Enhanced depth imaging OCT allows for visualization of deep structures of the optic nerve and has emerged as the gold standard for the detection of optic disc drusen. In the evaluation of compressive optic neuropathies, OCT RNFL and GCIPL thicknesses have been established as the most important visual prognostic factor. There is increasing evidence that inclusion of OCT as part of the diagnostic criteria for multiple sclerosis (MS) increases its sensitivity. Moreover, OCT of the RNFL and GCIPL may be helpful in the early detection and monitoring the treatment of conditions such as MS and Alzheimer's disease. OCT is an important aspect of the neuro-ophthalmologic assessment and its use is likely to increase moving forward.