Optical coherence tomography reflects clinically relevant gray matter damage in patients with multiple sclerosis

Optical coherence tomography and angiography in multiple sclerosis: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Anterior visual pathway involvement is common in multiple sclerosis (MS) and optical coherence tomography (OCT) can be utilized to examine the integrity of the ganglion cell axons (peri-papillary retinal nerve fiber layer; pRNFL) and cell bodies (ganglion cell & inner plexiform layer; GCIPL). OCT angiography (OCTA) can be used to investigate the retinal microvasculature. In this systematic review and meta-analysis, we synthesized OCT and OCTA findings in MS.

METHODS

We identified studies that performed OCT and OCTA in people with MS and included data permitting at least one of the following comparisons: 1) MS optic neuritis (MS-ON) vs healthy-control (HC) eyes; 2) MS non-ON (MS-NON) vs HC eyes; and 3) MS-ON vs MS-NON eyes.

RESULTS

The OCT meta-analysis included 170 studies and 8542 HC, 5529 MS-ON, and 14,822 MS-NON eyes. MS-ON and MS-NON eyes had lower pRNFL and GCIPL thickness compared to HC. There was no difference in inner nuclear layer (INL) thickness between HC and MS; INL was thicker in MS-ON compared to MS-NON eyes. The OCTA meta-analysis included 24 studies and 1344 HC, 505 MS-ON, and 1168 MS-NON eyes. MS-ON and MS-NON eyes had lower peripapillary vessel density and macular superficial vessel density compared to HC. We also summarized 12 studies evaluating the diagnostic yield of inter-eye differences in OCT measurements for detecting unilateral optic nerve involvement.

CONCLUSIONS

OCT allows for reliable quantification of retinal neuro-axonal damage in MS. In our review, we highlight studies demonstrating that OCT can establish robust thresholds for detecting unilateral optic nerve involvement.

The relationship between optical coherence tomography and magnetic resonance imaging measurements in people with multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Several studies show that optical coherence tomography (OCT) metrics e with cognition, disability, and brain structure in people with multiple sclerosis (PwMS). This review the correlation between OCT parameters and magnetic resonance imaging (MRI) measurements in PwMS.

METHODS

A comprehensive search of PubMed/MEDLINE, Embase, Scopus, and Web of Science was performed, including studies published in English up to November 29, 2024 to identify studies reporting quantitative data on the correlation between baseline OCT parameters and MRI measurements in PwMS. The meta-analysis was performed using R software version 4.4.0.

RESULTS

From 4931 studies, 68 studies on 6168 PwMS (67.4 % female) were included. The most significant correlations were found between peripapillary retinal nerve fiber layer (pRNFL) thickness and lower T1 lesion volume r = -0.42 (95 % CI: -0.52 to -0.31, p-value <0.001, I2 = 24 %), greater thalamic volume r = 0.39 (95 % CI: 0.17 to 0.61, p-value <0.001, I2 = 81 %), and lower T2 lesion volume r = -0.37 (95 % CI: -0.54 to -0.21, p-value <0.001, I2 = 85 %), respectively. Additionally, lower macular ganglion cell-inner plexiform layer (mGCIPL) thickness showed the most significant correlations with positive and lower thalamic volume r = 0.37 (95 % CI: 0.1 to 0.64, p-value = 0.008, I2 = 88 %), and positive and lower grey matter volume (GMV) 0.33 (95 % CI: 0.15 to 0.52, p-value <0.001, I2 = 81 %), respectively.

CONCLUSION

pRNFL and mGCIPL thickness are correlated with MRI measurements, suggesting that OCT can serve as a non-invasive, cost-effective, and complementary tool to MRI for enhancing the exploring of brain structural changes in PwMS.

Biomarker combinations from different modalities predict early disability accumulation in multiple sclerosis

Objective

Establishing biomarkers to predict multiple sclerosis (MS) disability accrual has been challenging using a single biomarker approach, likely due to the complex interplay of neuroinflammation and neurodegeneration. Here, we aimed to investigate the prognostic value of single and multimodal biomarker combinations to predict four-year disability progression in patients with MS.

Methods

In total, 111 MS patients were followed up for four years to track disability accumulation based on the Expanded Disability Status Scale (EDSS). Three clinically relevant modalities (MRI, OCT and blood serum) served as sources of potential predictors for disease worsening. Two key measures from each modality were determined and related to subsequent disability progression: lesion volume (LV), gray matter volume (GMV), retinal nerve fiber layer, ganglion cell-inner plexiform layer, serum neurofilament light chain (sNfL) and serum glial fibrillary acidic protein. First, receiver operator characteristic (ROC) analyses were performed to identify the discriminative power of individual biomarkers and their combinations. Second, we applied structural equation modeling (SEM) to the single biomarkers in order to determine their causal inter-relationships.

Results

Baseline GMV on its own allowed identification of subsequent EDSS progression based on ROC analysis. All other individual baseline biomarkers were unable to discriminate between progressive and non-progressive patients on their own. When comparing all possible biomarker combinations, the tripartite combination of MRI, OCT and blood biomarkers achieved the highest discriminative accuracy. Finally, predictive causal modeling identified that LV mediates significant parts of the effect of GMV and sNfL on disability progression.

Conclusion

Multimodal biomarkers, i.e. different major surrogates for pathology derived from MRI, OCT and blood, inform about different parts of the disease pathology leading to clinical progression.

NLRX1 limits inflammatory neurodegeneration in the anterior visual pathway

Chronic innate immune activation in the central nervous system (CNS) significantly contributes to neurodegeneration in progressive multiple sclerosis (MS). Using multiple experimental autoimmune encephalomyelitis (EAE) models, we discovered that NLRX1 protects neurons in the anterior visual pathway from inflammatory neurodegeneration. We quantified retinal ganglion cell (RGC) density and optic nerve axonal degeneration, gliosis, and T-cell infiltration in Nlrx1-/- and wild-type (WT) EAE mice and found increased RGC loss and axonal injury in Nlrx1-/- mice compared to WT mice in both active immunization EAE and spontaneous opticospinal encephalomyelitis (OSE) models. To minimize the effects of Nlrx1-/- on peripheral lymphocyte priming during EAE, we performed adoptive transfer experiments, in which activated myelin-specific T cells were transferred into lymphocyte-deficient Rag-/- or Nlrx1-/-Rag-/- mice. In this model, we found more severe microgliosis and astrogliosis in the optic nerve of Nlrx1-/-Rag-/- mice compared to Rag-/- mice, suggesting a regulatory role of NLRX1 in innate immune cells. Transcriptome analysis in primary astrocytes activated with LPS and IFNγ demonstrated that NLRX1 suppresses NF-κB activation and regulates mitochondrial oxidative phosphorylation in inflammatory reactive astrocytes. The novel pharmacologic NLRX1 activators NX-13 and LABP-66 decreased LPS-mediated gene expression of inflammatory cytokines and chemokines in mixed glial cultures. Moreover, treating EAE mice with oral LABP-66, compared to vehicle, after the onset of paralysis resulted in less anterior visual pathway neurodegeneration. These data suggest that pharmacologic NLRX1 activators have the potential to limit inflammatory neurodegeneration. This study highlights that NLRX1 could serve as a promising target for neuroprotection in progressive MS and other neurodegenerative diseases. Further studies are needed to better understand the cell-specific mechanisms underlying the neuroprotective role of NLRX1 in response to inflammation in the CNS.

Dynamics-aware deep predictive adaptive scanning optical coherence tomography

Conventional scanned optical coherence tomography (OCT) suffers from the frame rate/resolution tradeoff, whereby increasing image resolution leads to decreases in the maximum achievable frame rate. To overcome this limitation, we propose two variants of machine learning (ML)-based adaptive scanning approaches: one using a ConvLSTM-based sequential prediction model and another leveraging a temporal attention unit (TAU)-based parallel prediction model for scene dynamics prediction. These models are integrated with a kinodynamic path planner based on the clustered traveling salesperson problem to create two versions of ML-based adaptive scanning pipelines. Through experimental validation with novel deterministic phantoms based on a digital light processing board, our techniques achieved mean frame rate speed-ups of up to 40% compared to conventional raster scanning and the probabilistic adaptive scanning method without compromising image quality. Furthermore, these techniques reduced scene-dependent manual tuning of system parameters to demonstrate better generalizability across scenes of varying types, including those of intrasurgical relevance. In a real-time surgical tool tracking experiment, our technique achieved an average speed-up factor of over 3.2× compared to conventional scanning methods, without compromising image quality.

Correlations Between Disability Score, Optical Coherence Tomography and Microperimetry in Patients with Multiple Sclerosis

Purpose

To characterize ocular motility disturbances through Microperimetry (MP) in patients with Multiple Sclerosis (MS) trying to detect those capable of influencing the disability to improve the accuracy of assessing visual impact in EDSS scale. MP results were compare with some structural parameters obtained by OCT.

Patients and Methods

Cross-sectional analytical and correlational case-control study approved by Ethical Committee. A total of 82 eyes (41 patients) and 30 healthy eyes (15 subjects) were enrolled after informed consent. All participants underwent ophthalmological evaluation with MP and OCT. Variables included MS disease duration, Expanded Disability Status Scale (EDSS) score; in OCT: central macular thickness (CMT), ganglion cell-inner plexiform layer thickness (GCIPL), and peripapillary retinal nerve fiber layer thickness (pRNFL); and in MP: test duration, reaction time, average macular threshold (AT), and 4 fixation stability indexes (P1, P2, BCEA63, BCEA95).

Results

MS group showed a significant decrease in GCIPL (p < 0.001) and pRNFL thickness (p < 0.001) compared to the control group. Furthermore, patients demonstrated a longer examination (p < 0.001) and reaction (p < 0.001) times, reduced AT (p < 0.001), more unstable fixation indexes (P1 p <0.004, P2 p = 0.018, BCEA63 p = 0.005 and BCEA95 p = 0.007), measured by MP. In addition, patients with a history of ON (n=16) demonstrated longer examination times in MP (p = 0.049) compared to MS patients without ON, but they were not correlations with OCT measurements, EDSS score correlated with the CMT (p = 0.023, r = -0.25), MP duration (p = 0.043, r = 0.22), and fixation indexes (P1 p = 0.049, r = -0.22, BCEA63 p = 0.041, r = 0.23, BCEA95 p = 0.049, r = 0.22).

Conclusion

Our study emphasizes the complementary utility of MP and OCT in assessing MS patients. Additionally, it highlights that using MP for objective measurements of oculomotor dysfunction could improves accuracy in disability assessment on the EDSS scale.

Retinal layer thinning for monitoring disease-modifying treatment in relapsing multiple sclerosis-Evidence for applying a rebaselining concept

BACKGROUND

Employing a rebaselining concept may reduce noise in retinal layer thinning measured by optical coherence tomography (OCT).

METHODS

From an ongoing prospective observational study, we included patients with relapsing multiple sclerosis (RMS), who had OCT scans at disease-modifying treatment (DMT) start (baseline), 6-12 months after baseline (rebaseline), and ⩾12 months after rebaseline. Mean annualized percent loss (aL) rates (%/year) were calculated both from baseline and rebaseline for peripapillary-retinal-nerve-fiber-layer (aLpRNFLbaseline/aLpRNFLrebaseline) and macular-ganglion-cell-plus-inner-plexiform-layer (aLGCIPLbaseline/aLGCIPLrebaseline) by mixed-effects linear regression models.

RESULTS

We included 173 RMS patients (mean age 31.7 years (SD 8.8), 72.8% female, median disease duration 15 months (12-94) median baseline-to-last-follow-up-interval 37 months (18-71); 56.6% moderately effective DMT (M-DMT), 43.4% highly effective DMT (HE-DMT)). Both mean aLpRNFLbaseline and aLGCIPLbaseline significantly increased in association with relapse (0.51% and 0.26% per relapse, p < 0.001, respectively) and disability worsening (1.10% and 0.48%, p < 0.001, respectively) before baseline, but not with DMT class. Contrarily, neither aLpRNFLrebaseline nor aLGCIPLrebaseline was dependent on relapse or disability worsening before baseline, while HE-DMT significantly lowered aLpRNFLrebaseline (by 0.31%, p < 0.001) and aLGCIPLrebaseline (0.25%, p < 0.001) compared with M-DMT.

CONCLUSIONS

Applying a rebaselining concept significantly improves differentiation of DMT effects on retinal layer thinning by avoiding carry-over confounding from previous disease activity.

Novel and Emerging Treatments to Target Pathophysiological Mechanisms in Various Phenotypes of Multiple Sclerosis

The objective is to comprehensively review novel pharmacotherapies used in multiple sclerosis (MS) and the possibilities they may carry for therapeutic improvement. Specifically, we discuss pathophysiological mechanisms worth targeting in MS, ranging from well known targets, such as autoinflammation and demyelination, to more novel and advanced targets, such as neuroaxonal damage and repair. To set the stage, a brief overview of clinical MS phenotypes is provided, followed by a comprehensive recapitulation of both clinical and paraclinical outcomes available to assess the effectiveness of treatments in achieving these targets. Finally, we discuss various promising novel and emerging treatments, including their respective hypothesized modes of action and currently available evidence from clinical trials. SIGNIFICANCE STATEMENT: This comprehensive review discusses pathophysiological mechanisms worth targeting in multiple sclerosis. Various promising novel and emerging treatments, including their respective hypothesized modes of action and currently available evidence from clinical trials, are reviewed.

Optic chiasm involvement in multiple sclerosis, aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein-associated disease

BACKGROUND

Optic neuritis (ON) is a common feature of inflammatory demyelinating diseases (IDDs) such as multiple sclerosis (MS), aquaporin 4-antibody neuromyelitis optica spectrum disorder (AQP4 + NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). However, the involvement of the optic chiasm (OC) in IDD has not been fully investigated.

AIMS

To examine OC differences in non-acute IDD patients with (ON+) and without ON (ON-) using magnetisation transfer ratio (MTR), to compare differences between MS, AQP4 + NMOSD and MOGAD and understand their associations with other neuro-ophthalmological markers.

METHODS

Twenty-eight relapsing-remitting multiple sclerosis (RRMS), 24 AQP4 + NMOSD, 28 MOGAD patients and 32 healthy controls (HCs) underwent clinical evaluation, MRI and optical coherence tomography (OCT) scan. Multivariable linear regression models were applied.

RESULTS

ON + IDD patients showed lower OC MTR than HCs (28.87 ± 4.58 vs 31.65 ± 4.93; p = 0.004). When compared with HCs, lower OC MTR was found in ON + AQP4 + NMOSD (28.55 ± 4.18 vs 31.65 ± 4.93; p = 0.020) and MOGAD (28.73 ± 4.99 vs 31.65 ± 4.93; p = 0.007) and in ON- AQP4 + NMOSD (28.37 ± 7.27 vs 31.65 ± 4.93; p = 0.035). ON+ RRMS had lower MTR than ON- RRMS (28.87 ± 4.58 vs 30.99 ± 4.76; p = 0.038). Lower OC MTR was associated with higher number of ON (regression coefficient (RC) = -1.15, 95% confidence interval (CI) = -1.819 to -0.490, p = 0.001), worse visual acuity (RC = -0.026, 95% CI = -0.041 to -0.011, p = 0.001) and lower peripapillary retinal nerve fibre layer (pRNFL) thickness (RC = 1.129, 95% CI = 0.199 to 2.059, p = 0.018) when considering the whole IDD group.

CONCLUSION

OC microstructural damage indicates prior ON in IDD and is linked to reduced vision and thinner pRNFL.

Non-invasive in vivo imaging of brain and retinal microglia in neurodegenerative diseases

Microglia play crucial roles in immune responses and contribute to fundamental biological processes within the central nervous system (CNS). In neurodegenerative diseases, microglia undergo functional changes and can have both protective and pathogenic roles. Microglia in the retina, as an extension of the CNS, have also been shown to be affected in many neurological diseases. While our understanding of how microglia contribute to pathological conditions is incomplete, non-invasive in vivo imaging of brain and retinal microglia in living subjects could provide valuable insights into their role in the neurodegenerative diseases and open new avenues for diagnostic biomarkers. This mini-review provides an overview of the current brain and retinal imaging tools for studying microglia in vivo. We focus on microglia targets, the advantages and limitations of in vivo microglia imaging approaches, and applications for evaluating the pathogenesis of neurological conditions, such as Alzheimer's disease and multiple sclerosis.

Optical coherence tomography versus other biomarkers: Associations with physical and cognitive disability in multiple sclerosis

BACKGROUND

Optical coherence tomography (OCT) is a biomarker of neuroaxonal loss in multiple sclerosis (MS).

OBJECTIVE

The objective was to assess the relative role of OCT, next to magnetic resonance imaging (MRI) and serum markers of disability in MS.

METHODS

A total of 100 patients and 52 controls underwent OCT to determine peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell-inner plexiform layers (GCIPL). Serum neurofilament light chain (sNfL), total lesion volume (TLV), and brain parenchymal fraction (BPF) were also assessed. The associations of OCT with disability were examined in linear regression models with correction for age, vision, and education.

RESULTS

In patients, pRNFL was associated with the Symbol Digit Modalities Test (SDMT; p = 0.030). In the multivariate analysis including sNfL and MRI measures, pRNFL (β = 0.19, p = 0.044) and TLV (β = -0.24, p = 0.023) were the only markers associated with the SDMT. pRNFL (p < 0.001) and GCIPL (p < 0.001) showed associations with the Expanded Disability Status Scale (EDSS). In the multivariate analysis, GCIPL showed the strongest association with the EDSS (β = -0.32, p < 0.001) followed by sNfL (β = 0.18, p = 0.024).

CONCLUSION

The associations of OCT measures with cognitive and physical disability were independent of serum and brain MRI markers of neuroaxonal loss. OCT can be an important tool for stratification in MS, while longitudinal studies using combinations of biomarkers are warranted.