Trans-Synaptic Degeneration Following Acute Optic Neuritis in Multiple Sclerosis.

OBJECTIVE: To explore longitudinal changes in brain volumetric measures and retinal layer thicknesses following acute optic neuritis (AON) in people with multiple sclerosis (PwMS), to investigate the process of trans-synaptic degeneration, and determine its clinical relevance. METHODS: PwMS were recruited within 40 days of AON onset (n = 49), and underwent baseline retinal optical coherence tomography and brain magnetic resonance imaging followed by longitudinal tracking for up to 5 years. A comparator cohort of PwMS without a recent episode of AON were similarly tracked (n = 73). Mixed-effects linear regression models were used. RESULTS: Accelerated atrophy of the occipital gray matter (GM), calcarine GM, and thalamus was seen in the AON cohort, as compared with the non-AON cohort (-0.76% vs -0.22% per year [p = 0.01] for occipital GM, -1.83% vs -0.32% per year [p = 0.008] for calcarine GM, -1.17% vs -0.67% per year [p = 0.02] for thalamus), whereas rates of whole-brain, cortical GM, non-occipital cortical GM atrophy, and T2 lesion accumulation did not differ significantly between the cohorts. In the AON cohort, greater AON-induced reduction in ganglion cell+inner plexiform layer thickness over the first year was associated with faster rates of whole-brain (r = 0.32, p = 0.04), white matter (r = 0.32, p = 0.04), and thalamic (r = 0.36, p = 0.02) atrophy over the study period. Significant relationships were identified between faster atrophy of the subcortical GM and thalamus, with worse visual function outcomes after AON. INTERPRETATION: These results provide in-vivo evidence for anterograde trans-synaptic degeneration following AON in PwMS, and suggest that trans-synaptic degeneration may be related to clinically-relevant visual outcomes. ANN NEUROL 2023;93:76-87.

Visual Pathway Involvement in NMDA Receptor Encephalitis: A Clinical, Optical Coherence Tomography, and 18-Fluorodeoxyglucose PET/CT Approach.

BACKGROUND: Anti-NMDA receptor (NMDAR) encephalitis patients have been reported to exhibit visual dysfunction without retinal thinning. The objective of our study was to examine the involvement of the visual pathway structure and function in anti-NMDAR encephalitis by assessing postrecovery visual function and retinal structure, and acute-phase occipital cortex function. METHODS: In this cross-sectional study, patients diagnosed with anti-NMDAR encephalitis per consensus criteria underwent postrecovery visual acuity (VA) testing and optical coherence tomography (OCT) with automated retinal layer segmentation. Clinical data and acute-phase brain 18F-fluorodeoxyglucose (FDG) PET/CT (performed within 90 days of symptom onset, assessed qualitatively and semi-quantitatively) were retrospectively analyzed. VA and OCT measures were compared between anti-NMDAR and age, sex, and race-matched healthy controls (HC). When available, FDG-PET/CT metabolism patterns were analyzed for correlations with VA, and OCT measures. RESULTS: A total of 16 anti-NMDAR (32 eyes) and 32 HC (64 eyes) were included in the study. Anti-NMDAR exhibited lower low-contrast VA (2.5% contrast: -4.4 letters [95% CI; -8.5 to -0.3]; P = 0.04, 1.25% contrast: -6.8 letters [95%CI; -12 to -1.7]; P = 0.01) compared with HC, but no differences were found on OCT-derived retinal layer thicknesses. Acute-phase FDG-PET/CT medial occipital cortex metabolism did not correlate with follow-up low-contrast VA or ganglion cell/inner plexiform layer thickness (GCIPL) (n = 7, 2.5% contrast: r = -0.31; P = 0.50, 1.25% contrast: r = -0.34; P = 0.45, GCIPL: r = -0.04; P = 0.94). CONCLUSIONS: Although the visual system seems to be involved in anti-NMDAR encephalitis, no retinal structural or occipital cortex functional abnormalities seem to be responsible for the visual dysfunction. When detected acutely, occipital lobe hypometabolism in anti-NMDAR encephalitis does not seem to associate with subsequent retrograde trans-synaptic degenerative phenomena, potentially reflecting reversible neuronal/synaptic dysfunction in the acute phase of the illness rather than neuronal degeneration.

Socioeconomic disparity is associated with faster retinal neurodegeneration in multiple sclerosis.

Disease course in multiple sclerosis is notably heterogeneous, and few prognostic indicators have been consistently associated with multiple sclerosis severity. In the general population, socioeconomic disparity is associated with multimorbidity and may contribute to worse disease outcomes in multiple sclerosis. Herein, we assessed whether indicators of socioeconomic status are associated with disease progression in patients with multiple sclerosis using highly sensitive imaging tools such as optical coherence tomography, and determined whether differential multiple sclerosis management or comorbidity mediate any observed socioeconomic status-associated effects. We included 789 participants with longitudinal optical coherence tomography and low contrast letter acuity (at 1.25 and 2.5%) in whom neighbourhood- (derived via nine-digit postal codes) and participant-level socioeconomic status indicators were available ≤10 years of multiple sclerosis symptom onset. Sensitivity analyses included participants with socioeconomic status indicators available ≤3years of symptom onset (n = 552). Neighbourhood-level indicators included state and national area deprivation indices, median household income and the Agency for Healthcare Research and Quality (AHRQ) Socioeconomic Status Index. Participant-level indicators included education level. Biannual optical coherence tomography scans were segmented to quantify thickness of the composite macular ganglion cell+inner plexiform (GCIPL) layer. We assessed the association between socioeconomic status indicators and GCIPL atrophy or low contrast letter acuity loss using mixed models adjusting for demographic (including race and ethnicity) and disease-related characteristics. We also assessed socioeconomic status indicators in relation to multiple sclerosis therapy changes and comorbidity risk using survival analysis. More disadvantaged neighbourhood-level and patient-level socioeconomic status indicators were associated with faster retinal atrophy. Differences in rate of GCIPL atrophy for individuals in the top quartile (most disadvantaged) relative to the bottom quartile (least) for state area deprivation indices were -0.12 µm/year faster [95% confidence interval (CI): -0.19, -0.04; P = 0.003], for national area deprivation indices were -0.08 µm/year faster (95% CI: -0.15, -0.005; P = 0.02), for household income were -0.11 µm/year faster (95% CI: -0.19, -0.03; P = 0.008), for AHRQ Socioeconomic Status Index were -0.12 µm/year faster (95% CI: -0.19, -0.04) and for education level were -0.17 µm/year faster (95% CI: -0.26, -0.08; P = 0.0002). Similar associations were observed for socioeconomic status indicators and low contrast letter acuity loss. Lower socioeconomic status was associated with higher risk of incident comorbidity during follow-up. Low socioeconomic status individuals had faster rates of therapy escalation, suggesting the association between socioeconomic status and GCIPL atrophy may not be explained by differential contemporaneous multiple sclerosis therapy management. In conclusion, socioeconomic disparity is associated with faster retinal neurodegeneration in multiple sclerosis. As low socioeconomic status was associated with a higher risk of incident comorbidities that may adversely affect multiple sclerosis outcomes, comorbidity prevention may mitigate some of the unfavourable socioeconomic status-associated consequences.

Effects of Myopia on Rates of Change in Optical Coherence Tomography Measured Retinal Layer Thicknesses in People with Multiple Sclerosis and Healthy Controls.

PURPOSE: To quantify the associations of myopia with longitudinal changes in retinal layer thicknesses in people with multiple sclerosis (PwMS) and healthy controls (HC). METHODS: A cohort of PwMS and HC with recorded refractive error (RE) prospectively scanned on Cirrus HD-OCT at the Johns Hopkins MS Center was assessed for inclusion. Exclusion criteria included OCT follow-up < 6 months, ocular comorbidities, incidental OCT pathologies, and inadequate scan quality. Eyes were classified as having high myopia (HM) (RE≤ -6 diopters), low myopia (LM) (RE> -6 and ≤ -3 diopters), or no myopia (NM) (RE> -3 and ≤ +2.75). Linear mixed-effects regression models were used in analyses. RESULTS: A total of 213 PwMS (eyes: 67 HM, 98 LM, 207 NM) and 80 HC (eyes: 26 HM, 37 LM, 93 NM) were included. Baseline average ganglion cell/inner plexiform (GCIPL) and peri-papillary retinal nerve fiber layer (pRNFL) thicknesses were lower in MS HM compared with MS NM (diff: -3.2 µm, 95% CI: -5.5 to -0.8, p = 0.008 and -5.3 µm, 95% CI: -9.0 to -1.7, p = 0.004, respectively), and similarly in HC HM, as compared with HC NM. Baseline superior, inferior, and nasal pRNFL thicknesses were lower in HM compared with NM, while temporal pRNFL thickness was higher, both in MS and HC (MS: 7.1 µm, 95% CI: 2.7-11.6, p = 0.002; HC: 4.7 µm, 95% CI: -0.3 to 9.7, p = 0.07). No longitudinal differences in rates of GCIPL change were noted between HM and LM vs. NM, either in MS or HC. CONCLUSION: Cross-sectional differences in average GCIPL and pRNFL thicknesses are commonly seen in people with HM as compared to reference normative values from people with NM and can lead to false attribution of pathology if RE is not taken into account. However, our study suggests that longitudinal changes in average GCIPL thickness in PwMS with myopia are similar in magnitude to PwMS with NM, and therefore are appropriate for monitoring disease-related pathology.

Effects of Ibudilast on Retinal Atrophy in Progressive Multiple Sclerosis Subtypes: Post Hoc Analyses of the SPRINT-MS Trial.

BACKGROUND AND OBJECTIVES: Ganglion cell + inner plexiform layer (GCIPL) thinning, measured by optical coherence tomography (OCT), reflects global neurodegeneration in multiple sclerosis (MS). Atrophy of the inner (INL) and outer nuclear layer (ONL) may also be prominent in progressive MS (PMS). The phase 2, SPRINT-MS trial found reduced brain atrophy with ibudilast therapy in PMS. In this post hoc analysis of the SPRINT-MS trial, we investigate (1) retinal atrophy (2) differences in response by subtype and (3) associations between OCT and MRI measures of neurodegeneration. METHODS: In the multicenter, double-blind SPRINT-MS trial, participants with secondary progressive MS (SPMS) or primary progressive MS (PPMS) were randomized to ibudilast or placebo. OCT and MRI data were collected every 24 weeks for 96 weeks. Extensive OCT quality control and algorithmic segmentation produced consistent results across Cirrus HD-OCT and Spectralis devices. Primary endpoints were GCIPL, INL, and ONL atrophy, assessed by linear mixed-effects regression. Secondary endpoints were associations of OCT measures, brain parenchymal fraction, and cortical thickness, assessed by partial Pearson correlations. RESULTS: One hundred thirty-four PPMS and 121 SPMS participants were included. GCIPL atrophy was 79% slower in the ibudilast (-0.07 ± 0.23 µm/y) vs placebo group (-0.32 ± 0.20 µm/y, p = 0.003). This effect predominated in the PPMS cohort (ibudilast: -0.08 ± 0.29 µm/y vs placebo: -0.60 ± 0.29 µm/y, a decrease of 87%, p < 0.001) and was not detected in the SPMS cohort (ibudilast: -0.21 ± 0.28 µm/y vs placebo: -0.14 ± 0.27 µm/y, p = 0.55). GCIPL, INL, and ONL atrophy rates correlated with whole brain atrophy rates across the cohort (r = 0.27, r = 0.26, and r = 0.20, respectively; p < 0.001). Power calculations from these data show future trials of similar size and design have ≥80% power to detect GCIPL atrophy effect sizes of approximately 40%. DISCUSSION: Ibudilast treatment decreased GCIPL atrophy in PMS, driven by the PPMS cohort, with no effect seen in SPMS. Modulated atrophy of retinal layers may be detectable in sample sizes smaller than the SPRINT-MS trial and correlate with whole brain atrophy in PMS, further highlighting their utility as outcomes in PMS. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that ibudilast reduces composite ganglion cell + inner plexiform layer atrophy, without reduction of inner or outer nuclear layer atrophy, in patients with primary progressive MS but not those with secondary progressive MS.

Modulation of Retinal Atrophy With Rituximab in Multiple Sclerosis.

OBJECTIVE: To investigate the effects of rituximab on retinal atrophy in patients with relapsing-remitting multiple sclerosis (RRMS), we performed serial optical coherence tomography (OCT) scans among a cohort of patients with RRMS on rituximab and compared rates of ganglion cell + inner plexiform layer (GCIPL) atrophy to those observed among age- and sex-matched glatiramer acetate (GA)-and natalizumab-treated patients with RRMS and healthy controls (HCs). METHODS: In this observational study, patients with RRMS treated with a single disease-modifying therapy and HCs were followed with serial OCT for a median duration of 2.8 years. Participants with uncontrolled hypertension, diabetes mellitus, or glaucoma, and eyes with optic neuritis ≤6 months prior to baseline OCT, or during follow-up, were excluded. Statistical analyses were performed using linear mixed-effects regression. RESULTS: During the overall follow-up period, rates of GCIPL atrophy were -0.28 ± 0.11 µm/y among rituximab-treated patients with RRMS (n = 35). This was similar to GA-treated (n = 49; -0.33 ± 0.05 µm/y; p = 0.69) and natalizumab-treated patients (n = 88; -0.17 ± 0.10 µm/y; p = 0.13) and faster than HCs (n = 78; -0.15 ± 0.03 µm/y; p = 0.006). Rituximab-treated patients exhibited 0.55 ± 0.23 µm/y faster rates of GCIPL atrophy during the first 12 months of treatment, relative to afterwards (n = 25; p = 0.02), during which period GCIPL atrophy rates were -0.14 ± 0.13 µm/y. CONCLUSIONS: Retinal atrophy in RRMS is modulated by rituximab. Greater attenuation of retinal atrophy may occur after 12 months of rituximab treatment, following which time GCIPL atrophy rates are similar to those observed among natalizumab-treated patients with RRMS and HCs. Our findings raise the possibility that the neuroprotective therapeutic response with rituximab in RRMS may take up to 12 months, which should be confirmed by larger studies. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence on the difference in rate of change of the GCIPL thickness in patients with RRMS comparing rituximab to other disease-modifying therapies.

Optical Coherence Tomography and Optical Coherence Tomography Angiography Findings After Optic Neuritis in Multiple Sclerosis.

Background: In people with multiple sclerosis (MS), optic neuritis (ON) results in inner retinal layer thinning, and reduced density of the retinal microvasculature. Objective: To compare inter-eye differences (IEDs) in macular optical coherence tomography (OCT) and OCT angiography (OCTA) measures in MS patients with a history of unilateral ON (MS ON) vs. MS patients with no history of ON (MS non-ON), and to assess how these measures correlate with visual function outcomes after ON. Methods: In this cross-sectional study, people with MS underwent OCT and OCTA. Superficial vascular plexus (SVP) density of each eye was quantified using a deep neural network. IEDs were calculated with respect to the ON eye in MS ON patients, and with respect to the right eye in MS non-ON patients. Statistical analyses used mixed-effect regression models accounting for intra-subject correlations. Results: We included 43 MS ON patients (with 92 discrete OCT/OCTA visits) and 14 MS non-ON patients (with 24 OCT/OCTA visits). Across the cohorts, mean IED in SVP density was -2.69% (SD 3.23) in MS ON patients, as compared to 0.17% (SD 2.39) in MS non-ON patients (p = 0.002). When the MS ON patients were further stratified according to time from ON and compared to MS non-ON patients with multiple cross-sectional analyses, we identified that IED in SVP density was significantly increased in MS ON patients at 1-3 years (p = < 0.001) and >3 years post-ON (p < 0.001), but not at <3 months (p = 0.21) or 3-12 months post-ON (p = 0.07), while IED in ganglion cell + inner plexiform layer (GCIPL) thickness was significantly increased in MS ON patients at all time points post-ON (p ≦ 0.01 for all). IED in SVP density and IED in GCIPL thickness demonstrated significant relationships with IEDs in 100% contrast, 2.5% contrast, and 1.25% contrast letter acuity in MS ON patients (p < 0.001 for all). Conclusions: Our findings suggest that increased IED in SVP density can be detected after ON in MS using OCTA, and detectable changes in SVP density after ON may occur after changes in GCIPL thickness. IED in SVP density and IED in GCIPL thickness correlate well with visual function outcomes in MS ON patients.