The loss of macular ganglion cells begins from the early stages of disease and correlates with brain atrophy in multiple sclerosis patients

The macular retinal ganglion cell layer as a biomarker for diagnosis and prognosis in multiple sclerosis: A deep learning approach

PURPOSE

The macular ganglion cell layer (mGCL) is a strong potential biomarker of axonal degeneration in multiple sclerosis (MS). For this reason, this study aims to develop a computer-aided method to facilitate diagnosis and prognosis in MS.

METHODS

This paper combines a cross-sectional study of 72 MS patients and 30 healthy control subjects for diagnosis and a 10-year longitudinal study of the same MS patients for the prediction of disability progression, during which the mGCL was measured using optical coherence tomography (OCT). Deep neural networks were used as an automatic classifier.

RESULTS

For MS diagnosis, greatest accuracy (90.3%) was achieved using 17 features as inputs. The neural network architecture comprised the input layer, two hidden layers and the output layer with softmax activation. For the prediction of disability progression 8 years later, accuracy of 81.9% was achieved with a neural network comprising two hidden layers and 400 epochs.

CONCLUSION

We present evidence that by applying deep learning techniques to clinical and mGCL thickness data it is possible to identify MS and predict the course of the disease. This approach potentially constitutes a non-invasive, low-cost, easy-to-implement and effective method.

Optical coherence tomography as a potential surrogate marker of dopaminergic modulation across the life span

The retina has been considered a "window to the brain" and shares similar innervation by the dopaminergic system with the cortex in terms of an unequal distribution of D1 and D2 receptors. Here, we provide a comprehensive overview that Optical Coherence Tomography (OCT), a non-invasive imaging technique, which provides an "in vivo" representation of the retina, shows promise to be used as a surrogate marker of dopaminergic neuromodulation in cognition. Overall, most evidence supports reduced retinal thickness in individuals with dopaminergic dysregulation (e.g., patients with Parkinson's Disease, non-demented older adults) and with poor cognitive functioning. By using the theoretical framework of metacontrol, we derive hypotheses that retinal thinning associated to decreased dopamine (DA) levels affecting D1 families, might lead to a decrease in the signal-to-noise ratio (SNR) affecting cognitive persistence (depending on D1-modulated DA activity) but not cognitive flexibility (depending on D2-modulated DA activity). We argue that the use of OCT parameters might not only be an insightful for cognitive neuroscience research, but also a potentially effective tool for individualized medicine with a focus on cognition. As our society progressively ages in the forthcoming years and decades, the preservation of cognitive abilities and promoting healthy aging will hold of crucial significance. OCT has the potential to function as a swift, non-invasive, and economical method for promptly recognizing individuals with a heightened vulnerability to cognitive deterioration throughout all stages of life.

Retinal changes in multiple sclerosis: An optical coherence tomography and angiography study

BACKGROUND

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system with neuroaxonal damage. It is the principal driver of non-traumatic disability in young adults. Visual symptoms are common and optic neuritis (ON) may be the revealing feature in up to 30% of cases. Structural optical coherence tomography (OCT) represents a biomarker of central nervous system neurodegeneration in MS. OCT-angiography (OCT-A) is a noninvasive tool allowing the study of retinal vasculature and the detection of microvascular damage in neuro-retinal diseases. In this study, we aimed to assess structural and microvascular retinal changes in patients with MS with and without ON and to correlate the findings with visual function and MS disability.

METHODS

We conducted a cross-sectional study including patients diagnosed with MS according to the 2017 McDonald criteria. All patients underwent complete neurological examination with evaluation of the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS) and an ophthalmological examination including OCT and OCT-A. Patients were compared with age- and sex-matched healthy subjects. The primary endpoints were assessment of retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL+), and ganglion cell complex (GCL++) thicknesses on OCT. Vascular densities in the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) were assessed on OCT-A, as well as central avascular zone (CAZ) parameters, lacunarity and fractal dimension.

RESULTS

A total of 160 MS eyes with and without a previous history of ON and 64 age- and gender-matched healthy eyes were analyzed. Among 160 eyes with MS, 69 had a history of ON. We observed a decrease in RNFL and GCL++ thickness in all 12 quadrants in MS patients when compared to healthy controls. Multivariate analysis by linear regression noted a significant correlation for temporal GCL++ and inferonasal RNFL thickness that were decreased in the MS group. A greater decrease in retinal layers thickness was identified in MS patients with a history of ON. On OCT-A, vascular density in (SCP) was significantly reduced in the MS group (P<0.002). A significant correlation between RNFL thickness and retinal vascular density was found but only in less than half of the hourly quadrants. A significant correlation was noted between visual acuity and CC density (P<0.0001). We also noted an inverse correlation between EDSS scores and CC density (P=0.02 and r=-0.275) and between MSSS and RNFL/GCL++ thicknesses.

CONCLUSIONS

RNFL and GCL++ layers were thinner in MS patients with a history of ON and were reversely correlated with disease severity. Moreover, retinal vascular changes were observed in MS even in eyes without ON, and CC was reversely correlated with visual function and current disability. Thus, structural OCT coupled with OCT-A could represent a noninvasive and dynamic biomarker of MS severity and progression.

[Importance of fluorescein angiography for differentiating between early papilledema and papillitis]

BACKGROUND

Optic disc swelling poses a diagnostic challenge due to its multiple underlying pathological causes. This study aimed to investigate the use of fluorescein angiography (FLA) in combination with optical coherence tomography (OCT) as a diagnostic tool for differentiating between papilledema and papillitis in cases of optic disc swelling.

MATERIAL AND METHODS

A total of 12 patients were included in the study in whom both FLA and OCT of the optic disc were performed to evaluate the optic disc swelling in cases of papilledema (7 patients, 14 eyes) and papillitis (5 patients, 7 eyes). The fluorescence behavior of the optic disc during late phase FLA was examined in relation to papillary thickness measured by OCT.

RESULTS AND DISCUSSION

In the papilledema group OCT revealed a mean papillary thickness of 873 µm. In 6 patients FLA detected a ring-shaped papillary hyperfluorescence with papillary thicknesses ranging from 611 µm to 972 µm. Another patient with chronic and marked papilledema exhibited bilateral panpapillary leakage in FLA and papillary thicknesses of 1287 µm (right eye) and 1526 µm (left eye). In the papillitis group FLA showed panpapillary leakage in all cases. The mean papillary thickness was 865 µm (range 632-1195 µm).

CONCLUSION

In acute optic disc swelling and a papillary prominence less than 1000 µm in OCT, a difference in FLA was noticeable between papilledema and papillitis. While acute and mild papilledema exhibited a ring-shaped hyperfluorescence, papillitis showed a panpapillary leakage in late phase FLA in the examined cases. This difference could not be seen in the case of papilledema with chronic and severe swelling.

Peering further into the mind's eye: combining visual evoked potential and optical coherence tomography measures enhances insight into the variance in cognitive functioning in multiple sclerosis

BACKGROUND

Spectral Optical Coherence Tomography (OCT) and Visual Evoked Potentials (VEPs) have both emerged as potentially useful biomarkers of cognitive decline in people with multiple sclerosis (PwMS). Their combined use may provide additional predictive value for identifying disease impact, progression, and remyelination capacity above-and-beyond what is captured using either approach alone.

OBJECTIVE

We examined the relationship between OCT/VEP measures and cognitive functioning in 205 PwMS. OCT measures included Retinal Nerve Fiber Layer Volume (RNFLV), Papillo-Macular Bundle Volume (PBMV), and Macular Volume (MV). VEP measures included latency of the P100, and inter-ocular latency. Cognitive performance was evaluated across seven separate domains of performance, and for overall cognition, using the NeuroTrax computerized testing battery.

RESULTS

Both OCT and VEP measures were significantly correlated with cognitive performance across several domains. Linear regression models that controlled for the influence of visual acuity revealed (1) that reduced MV was significantly predictive of poorer visual-spatial functioning, and (2) that delayed VEP latency was significantly predictive of performance in global cognitive functioning and visual-spatial functioning, after controlling for multiple comparisons. Among PwMS with normal visual acuity, PwMS with a combination of both relatively low MV and delayed VEP latency tended to have poorer performance in the domains of global, executive, and visual-spatial functioning compared to PwMS with both high MV and normal VEP latency.

CONCLUSION

Approaches that combine the use of OCT and VEP measures can enhance insight into underlying factors that contribute to variance in cognitive functioning in PwMS.

Structural and Metabolic Retinal Changes Associated With Mild Cognitive Impairment in Type 2 Diabetes

Type 2 diabetes is associated with cognitive impairment and a twofold increased risk of dementia compared with age-matched individuals without diabetes. Given that the eye and the brain share similar embryologic origin and anatomical features, the retina offers a unique window to the brain. In this study, we wanted to determine whether there was a difference in retinal imaging-based neuronal and vascular markers in individuals with type 2 diabetes with or without mild cognitive impairment (MCI). We included 134 persons with type 2 diabetes. Based on neuropsychological tests, the prevalence of MCI was 28%. We performed seven-field color fundus photos, optical coherence tomography (OCT), OCT-angiography (OCT-A), and retinal oximetry to analyze retinal markers. In a multivariable cluster analysis, persons with MCI had a significantly thinner macular retinal nerve fiber layer and macular ganglion cell layer, and less venular oxygen saturation in the nasal quadrant compared with those without MCI. There were no differences in retinal vessel density, fractal dimension, width, tortuosity, or OCT-A markers. People with type 2 diabetes and MCI demonstrate alterations in retinal structure and metabolism, suggesting noninvasive retinal markers may be useful to detect people with type 2 diabetes at risk for cognitive dysfunction.

ARTICLE HIGHLIGHTS

Type 2 diabetes is associated with mild cognitive impairment (MCI). Therefore, retinal and cerebral neurodegeneration may run in parallel. To assess whether there was a difference in retinal structure, vessel, and metabolic parameters in individuals with MCI. We found those with MCI had a thinner macular retinal nerve fiber layer, macular ganglion cell layer, and less venular oxygen saturation. We suggest noninvasive retinal markers may be useful to detect those at risk of cognitive dysfunction.

Evaluation of multiple sclerosis severity using a new OCT tool

PURPOSE

To assess the ability of a new posterior pole protocol to detect areas with significant differences in retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness in patients with multiple sclerosis versus healthy control subjects; in addition, to assess the correlation between RNFL and GCL thickness, disease duration, and the Expanded Disability Status Scale (EDSS).

METHODS

We analyzed 66 eyes of healthy control subjects and 100 eyes of remitting-relapsing multiple sclerosis (RR-MS) patients. Double analysis based on first clinical symptom onset (CSO) and conversion to clinically definite MS (CDMS) was performed. The RR-MS group was divided into subgroups by CSO and CDMS year: CSO-1 (≤ 5 years) and CSO-2 (≥ 6 years), and CDMS-1 (≤ 5 years) and CDMS-2 (≥ 6 years).

RESULTS

Significant differences in RNFL and GCL thickness were found between the RR-MS group and the healthy controls and between the CSO and CDMS subgroups and in both layers. Moderate to strong correlations were found between RNFL and GCL thickness and CSO and CDMS. Furthermore, we observed a strong correlation with EDSS 1 year after the OCT examination.

CONCLUSIONS

The posterior pole protocol is a useful tool for assessing MS and can reveal differences even in early stages of the disease. RNFL thickness shows a strong correlation with disability status, while GCL thickness correlates better with disease duration.

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

BACKGROUND

Retinal degeneration leading to optical coherence tomography (OCT) changes is frequent in patients with multiple sclerosis (PwMS).

OBJECTIVE

To investigate associations among OCT changes, MRI measurements of global and regional brain volume loss, and physical and cognitive impairment in PwMS.

METHODS

95 PwMS and 52 healthy controls underwent OCT and MRI examinations. Mean peripapillary retinal nerve fiber layer (pRNFL) thickness and ganglion cell/inner plexiform layer (GCIPL) volume were measured. In PwMS disability was quantified with the Expanded Disability Status Scale (EDSS) and Symbol Digit Modalities Test (SDMT). Associations between OCT, MRI, and clinical measures were investigated with multivariable regression models.

RESULTS

In PwMS, pRNFL and GCIPL were associated with the volume of whole brain (p < 0.04), total gray matter (p < 0.002), thalamus (p ≤ 0.04), and cerebral cortex (p ≤ 0.003) -both globally and regionally-, but not white matter. pRNFL and GCIPL were also inversely associated with T2-lesion volume (T2LV), especially in the optic radiations (p < 0.0001). The brain volumes associated with EDSS and SDMT significantly overlapped with those correlating with pRNFL and GCIPL.

CONCLUSIONS

In PwMS, pRNFL and GCIPL reflect the integrity of clinically-relevant gray matter structures, underling the value of OCT measures as markers of neurodegeneration and disability in multiple sclerosis.

Swept-Source Optical Coherence Tomography Thresholds in Differentiating Clinical Outcomes in a Real-World Cohort of Treatment-Naïve Multiple Sclerosis Patients

This study aimed to determine whether peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell–inner plexiform layer (GCIPL) thickness thresholds for single-time-point swept-source optical coherence tomography (SS-OCT) measures can differentiate the clinical outcomes of treatment-naïve people with multiple sclerosis (pwMS). A total of 275 patients with the clinically isolated syndrome (n = 23), benign MS (n = 8), relapsing–remitting MS (n = 185), secondary progressive MS (n = 28), primary progressive MS (n = 31), and with no history of optic neuritis were included. The mean Expanded Disability Status Scale (EDSS) score was 3.0 ± 1.6. The cut-off values of pRNFL (87 µm and 88 µm) and GCIPL (70 µm) thicknesses have been adopted from previous studies using spectral-domain OCT. PwMS with pRNFL ≤87 µm and ≤88 µm had a longer disease duration, more advanced disability, and more frequently progressive MS variants compared to those with greater pRNFL thicknesses. In distinguishing pwMS with disability greater than or equal to the mean EDSS score (EDSS ≥ 3) from those with less severe disability, GCIPL thickness <70 µm had the highest sensitivity, while pRNFL thickness ≤87 µm had the greatest specificity. The optimal cut-off values differentiating patients with EDSS ≥ 3 from those with less severe disability was 63 µm for GCIPL thickness and 93.5 µm for pRNFL thickness. In conclusion, pRNFL and GCIPL thickness thresholds for single-time-point SS-OCT measurements may be helpful in differentiating the disability status of treatment-naïve pwMS.

Changes in Retinal Thickness and Brain Volume during 6.8-Year Escalating Therapy for Multiple Sclerosis

Background. Different disease-modifying therapies (DMT) for multiple sclerosis (MS) have disparate effects on disability outcomes. Sweden has a leading position globally in initiating high-efficacy DMT instead of escalating DMT from 1st-line to high-efficacy DMT. With optical coherence tomography (OCT), retinal changes can be measured at a few micrometer level. OCT has been increasingly applied in diagnosing MS and monitoring disease course and therapeutic effect. Objective. We investigate the effects of 1st-line versus high-efficacy DMT for MS on retinal and brain atrophy and on functional outcomes during 6.8 years of escalating DMT. Materials and Methods. In this prospective longitudinal observational study, 18 MS patients were followed up for 6.8 years. Twelve of the patients were untreated at baseline. All patients underwent 1st-line DMT for median duration of 2.4 years and then switched to high-efficacy DMT for a median duration of 2.9 years. Findings from neurological examinations, MRI, and OCT measures were registered 2-4 times per year. Results. Ganglion cell-inner plexiform layer (GCIPL) thickness was significantly reduced during 1st-line DMT (73.75 μm, $p<0.01$ ) compared to baseline (76.38 μm). During high-efficacy DMT, thickness reduction was slower (73.27 μm, $p<0.05$ ), and MRI contrast-loading lesions vanished ( $p<0.01$ ). However, brain parenchymal fraction (BPF) decreased during high-efficacy DMT compared to 1st-line DMT. Estimated models showed similar results. Conclusion. GCIPL decline was most profound during 1st-line DMT and diminished during high-efficacy DMT. MRI contrast lesions vanished during high-efficacy DMT. However, brain atrophy continued regardless of high-efficacy DMT.

Macular ganglion cell-inner plexiform layer defect patterns in multiple sclerosis patients without optic neuritis: A Spectral-Domain-Optical Coherence Tomography Cross-Sectional, Case-Control, Pilot Study

PURPOSE

Spectral-domain optical coherence tomography (SD-OCT) was used to evaluate, in patients with multiple sclerosis without a history of optic neuritis (MSNON), the proportion of the different macular ganglion cell-inner plexiform layer complex (mGCIP) defect patterns. The results were compared with those of healthy controls (HCs).

METHODS

In this cross-sectional case-control study, 34 eyes of 34 individuals, 17 with MSNON and 17 HCs, were evaluated. All participants underwent mGCIP thickness measurement using SD-OCT (Zeiss Cirrus HD-OCT 4000, macular cube protocol). The mGCIP defect patterns were classified in nine types (minimal, inner, outer, diffuse mild, diffuse severe inferior confined, inferior dominant, superior confined, and superior dominant), according to the shape derived by the deviation map of the instrument, and the proportion of each type was assessed.

RESULTS

A mGCIP defect pattern was detected in 70.5% of MSNON eyes, with an inner type as the most frequent pattern (47%), followed by the outer type (11.7%) and the inferior confined type (11.7%). No defect was found in Hcs.

CONCLUSIONS

A significant thinning of the mGCIP with the frequent presence of an inner defect was seen in MSNON patients. The presence of this defect may serve as a biomarker of subclinical optic nerve involvement in MS patients.

Retinal thinning in progressive supranuclear palsy: differences with healthy controls and correlation with clinical variables

Background

Available evidence reports conflicting data on retinal thickness in progressive supranuclear palsy (PSP). In studies including healthy controls, PSP showed either the thinning of the retinal nerve fiber layer, macular ganglion cell, inner nuclear, or outer retina layer.

Objectives

The goals of the present study were to describe retinal layer thickness in a large cohort of PSP compared to healthy controls and in PSP phenotypes using spectral-domain optical coherence tomography (SD-OCT). The additional objective was to verify the relationship between retinal layers thickness and clinical variables in PSP.

Methods

Using a cross-sectional design, we examined retinal structure in 27 PSP patients and 27 controls using standard SD-OCT. Motor and cognitive impairment in PSP was rated with the PSP rating scale and the Montreal Cognitive Assessment battery (MoCA), respectively. Eyes with poor image quality or confounding diseases were excluded. SD-OCT measures of PSP and controls were compared with parametric testing, and correlations between retinal layer thicknesses and disease severity were evaluated.

Results

PSP showed significant thinning of the inner retinal layer (IRL), ganglion cell layer (GCL), inner plexiform layer (IPL), and the outer plexiform layer (OPL) compared to healthy controls. PSP phenotypes showed similar retinal layer thicknesses. Retinal layer thickness correlated with MoCA visuospatial subscore (p < 0.001).

Conclusions

We demonstrated PSP patients disclosed thinner IRL, GCL, IPL, and OPL compared to healthy controls. Furthermore, we found a significant correlation between visuospatial abilities and retinal layers suggesting the existence of a mutual relationship between posterior cognitive function and retinal structure.

Associations of Alcohol Consumption and Smoking With Disease Risk and Neurodegeneration in Individuals With Multiple Sclerosis in the United Kingdom

IMPORTANCE

Understanding the effects of modifiable risk factors on risk for multiple sclerosis (MS) and associated neurodegeneration is important to guide clinical counseling.

OBJECTIVE

To investigate associations of alcohol use, smoking, and obesity with odds of MS diagnosis and macular ganglion cell layer and inner plexiform layer (mGCIPL) thickness.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study analyzed data from the community-based UK Biobank study on health behaviors and retinal thickness (measured by optical coherence tomography in both eyes) in individuals aged 40 to 69 years examined from December 1, 2009, to December 31, 2010. Risk factors were identified with multivariable logistic regression analyses. To adjust for intereye correlations, multivariable generalized estimating equations were used to explore associations of alcohol use and smoking with mGCIPL thickness. Finally, interaction models explored whether the correlations of alcohol and smoking with mGCIPL thickness differed for individuals with MS. Data were analyzed from February 1 to July 1, 2021.

EXPOSURES

Smoking status (never, previous, or current), alcohol intake (never or special occasions only [low], once per month to ≤4 times per week [moderate], or daily/almost daily [high]), and body mass index.

MAIN OUTCOMES AND MEASURES

Multiple sclerosis case status and mGCIPL thickness.

RESULTS

A total of 71 981 individuals (38 685 women [53.7%] and 33 296 men [46.3%]; mean [SD] age, 56.7 [8.0] years) were included in the analysis (20 065 healthy control individuals, 51 737 control individuals with comorbidities, and 179 individuals with MS). Modifiable risk factors significantly associated with MS case status were current smoking (odds ratio [OR], 3.05 [95% CI, 1.95-4.64]), moderate alcohol intake (OR, 0.62 [95% CI, 0.43-0.91]), and obesity (OR, 1.72 [95% CI, 1.15-2.56]) compared with healthy control individuals. Compared with the control individuals with comorbidities, only smoking was associated with case status (OR, 2.30 [95% CI, 1.48-3.51]). High alcohol intake was associated with a thinner mGCIPL in individuals with MS (adjusted β = -3.09 [95% CI, -5.70 to -0.48] μm; P = .02). In the alcohol interaction model, high alcohol intake was associated with thinner mGCIPL in control individuals (β = -0.93 [95% CI, -1.07 to -0.79] μm; P < .001), but there was no statistically significant association in individuals with MS (β = -2.27 [95% CI, -4.76 to 0.22] μm; P = .07). Smoking was not associated with mGCIPL thickness in MS. However, smoking was associated with greater mGCIPL thickness in control individuals (β = 0.89 [95% CI, 0.74-1.05 μm]; P < .001).

CONCLUSIONS AND RELEVANCE

These findings suggest that high alcohol intake was associated with retinal features indicative of more severe neurodegeneration, whereas smoking was associated with higher odds of being diagnosed with MS.

Optical Coherence Tomography in the Differential Diagnosis of Patients with Multiple Sclerosis and Patients with MRI Nonspecific White Matter Lesions

In the differential diagnosis of nonspecific white matter lesions (NSWMLs) detected on magnetic resonance imaging (MRI), multiple sclerosis (MS) should be taken into consideration. Optical coherence tomography (OCT) is a promising tool applied in the differential diagnostic process of MS. We tested whether OCT may be useful in distinguishing between MS and NSWMLs patients. In patients with MS (n = 41) and NSWMLs (n = 19), the following OCT parameters were measured: thickness of the peripapillary Retinal Nerve Fibre Layer (pRNFL) in superior, inferior, nasal, and temporal segments; thickness of the ganglion cell-inner plexiform layer (GCIPL); thickness of macular RNFL (mRNFL); and macular volume (MV). In MS patients, GCIPL was significantly lower than in NSWMLs patients (p = 0.024). Additionally, in MS patients, mRNFL was significantly lower than in NSWMLs patients (p = 0.030). The average segmental pRNFL and MV did not differ between MS and NSWMLs patients (p > 0.05). GCIPL and macular RNFL thinning significantly influenced the risk of MS (18.6% [95% CI 2.7%, 25.3%]; 27.4% [95% CI 4.5%, 62.3%]), and reduced GCIPL thickness appeared to be the best predictor of MS. We conclude that OCT may be helpful in the differential diagnosis of MS and NSWMLs patients in real-world settings.

Association of Retinal Layer Thickness With Cognition in Patients With Multiple Sclerosis

Objective

Retinal layer thickness (RLT) measured by optical coherence tomography (OCT) is considered a noninvasive, cost-efficient marker of neurodegeneration in multiple sclerosis (MS). We aimed to investigate associations of RLT with cognitive performance and its potential as indicator of cognitive status in patients with MS by performing generalized estimating equation (GEE) analyses.

Methods

In this cross-sectional study, patients with at least mild signs of cognitive impairment were examined by OCT as well as by the Brief International Cognitive Assessment for MS and tests assessing attention and executive functions (Trail Making Test [TMT] A and B). Associations of these factors were investigated using GEE models controlling for demographic and disease-related factors and correcting for multiple testing.

Results

A total of 64 patients entered the study. In the final sample (n = 50 [n = 14 excluded due to missing data or drop-outs]; n = 44 relapsing-remitting MS and n = 6 secondary progressive MS, mean Expanded Disability Status Scale score = 2.59 [SD = 1.17], disease duration [median] = 7.34 [interquartile range = 12.1]), 36.0% were cognitively impaired. RLT of the macular retinal nerve fiber layer was associated with performance in TMT-B (β = −0.259). Analyses focusing on the upper and lower tertile of RLT additionally revealed associations between macular ganglion cell-inner plexiform layer and TMT-B and verbal short-term memory and learning, respectively.

Conclusion

In patients with MS, at less advanced disease stages, RLT was especially associated with cognitive flexibility promoting OCT as a potential marker advocating further extensive neuropsychological examination.

Bruch's membrane opening-minimum rim width: An alternative OCT biomarker study for multiple sclerosis

PURPOSE

Bruch's membrane opening-minimum rim width (BMO-MRW) and RNFL measured using anatomic positioning system (APS-RNFL) are novel OCT methods and remained unexplored in MS patients.To investigate the novel parameters of spectral-domain OCT as an alternative biomarker in patients with multiple sclerosis (MS).

METHODS

Retrospective cohort study; participants consisted of relapsing-remitting MS (RRMS) patients and healthy controls (HC). Eyes were classified according to the presence of MS and previous optic neuritis (ON). Measurements of standard peripapillary RNFL (S-RNFL), BMO-MRW, and APS-RNFL were performed.

RESULT

A total of 244 eyes of 122 participants (MS-patients: 63, HC: 59) were included in the study. Fifty-one eyes had a history of previous ON. In almost all measured parameters, neuroretinal rim thicknesses were observed the thinnest in eyes with ON history between all subgroups. S-RNFL and APS-RNFL techniques showed the difference in neuroretinal rim thickness in all three subjects (ON+, ON-, and HC). However, BMO-MRW, on the other hand, could not distinguish between ON(-) patients and HC. The relationship between OCT parameters and EDSS were observed only in eyes with an ON history in all three techniques. A meaningful model with 78% accuracy was obtained by using only the OCT parameters as risk factors. In the ROC analysis, no parameters were found to have acceptable high sensitivity and specificity. BMO-MRW was statistically weaker in every aspect than other RNFL techniques.

CONCLUSION

The novel APS-RNFL technique appears to be a bit more reliable alternative to S-RNFL technique to support therapeutic decision-making in MS. BMO-MRW has not been found as a successful alternative to S-RNFL.

Magnetic resonance imaging and optical coherence tomography correlations in multiple sclerosis beyond anatomical landmarks

OBJECTIVE

To investigate multiple sclerosis (MS) optical coherence tomography (OCT) cross-sectional correlations with central nervous system (CNS) magnetic resonance imaging (MRI).

MATERIAL AND METHODS

Peripapillary retinal nerve fiber layer (pRNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner (INL) and outer nuclear layer (ONL) of 54 relapsing remitting (RRMS) and 38 progressive (PMS, 9 primary and 29 secondary) patients were measured. With less than 3 months brain parenchymal fraction (BPF), spinal cord (SC), total gray matter (GM) and white matter volumes were calculated. Demographical and clinical data was compared according to the history of optic neuritis (HON). Relationships between OCT and MRI data were assessed using multivariable linear regression models, adjusting for age, gender and disease duration, taking into account HON and disease subtype.

RESULTS

Cerebellum (p = 0.008), pRNFL (p = 0.001), GCL (p = 0.001) and IPL (p = 0.001) were thinner, while INL was thicker (p = 0.02) if HON. SC correlated better with nasal pRNFL sectors in eyes with HON (all eyes: average pRNFL p = 0.035 η² = 0.213; N-pRNFL p = 0.04 η² = 0.36, NI-pRNFL p = 0.0001 η² = 0.484. RRMS eyes: N-pRNFL p = 0.034 η² = 0.348; NI-pRNFL p = 0.013 η² = 0.441), while it correlates with PMB (p = 0.032 η² = 0.144), GCL (p = 0.03 η² = 0.147) and IPL (p = 0.028 η² = 0.151) in eyes without HON regardless of the disease subtype. INL presented no microcystic macular oedema and was inversely associated with BPF (p = 0.029 η² = 0.363) and cerebellum (p = 0.015 η² = 0.428) in PMS eyes without HON.

CONCLUSIONS

OCT data correlates with different CNS compartments, even with no anatomical or functional linkage, serving as useful neurodegeneration and inflammation surrogate marker.

Early diagnosis of multiple sclerosis by OCT analysis using Cohen's d method and a neural network as classifier

BACKGROUND

The consequences of inflammation, demyelination, axonal degeneration and neuronal loss in the central nervous system, typical of the development of multiple sclerosis (MS), are manifested in thinning of the retina and optic nerve. The purpose of this work is to diagnose early-stage MS patients based on analysis of retinal layer thickness obtained by swept-source optical coherence tomography (SS-OCT).

METHOD

OCT (Triton® SS-OCT device -Topcon, Tokyo, Japan-) recordings were obtained from 48 control subjects and 48 recently diagnosed MS patients. The following thicknesses were measured on a 45 × 60 grid: retinal nerve fibre layer (RNFL), ganglion cell layer (GCL+), GCL++, retinal thickness and choroid. Using Cohen's d effect size, it was determined the regions and layers with greatest capacity to discriminate between control subjects and patients. Points exceeding the threshold set were used as inputs for an automatic classifier: support vector machine and feed-forward neural network.

RESULTS

In MS at clinical onset the layer with greatest discriminant capacity is GCL++ [AUC = 0.83] which exhibits a horseshoe-like macular topographic distribution. It is followed by retina, GCL+ and RNFL; choroidal thicknesses do not provide discriminatory capacity. Using a neural network as a classifier between controls and MS patients, obtains sensitivity of 0.98 and specificity of 0.98.

CONCLUSIONS

This work suggest that OCT may serve as an important complementary role to other clinical tests, particularly regarding neurodegeneration. It is possible to characterise structural alterations in retina and diagnose early-stage MS with high degree of accuracy using OCT and artificial neural networks.

OCT parameters of the optic nerve head and the retina as surrogate markers of brain volume in a normal population, a pilot study

The relationship between optical coherence tomography (OCT) measurements of the retinal structures has been described for various neurological diseases including Multiple Sclerosis (MS), Alzheimer's disease (AD) and Parkinson's disease (PD). Brain volume changes, both globally and by area, are associated with some of these same diseases, yet the correlation of OCT and disease is not fully elucidated. Our study looked at normal subjects, at the correlation of OCT measurements and brain volumes, both globally and for specific regions including the pericalcarine grey matter, entorhinal grey matter, and cerebellar volume using a retrospective, cross-sectional cohort study design. Thickness of the retinal nerve fiber layer (RNFL) as measured by OCT, correlated with volume of the pericalcarine grey matter, when adjusted for age and gender. Similarly, thickness of the ganglion cell layer-inner plexiform layer complex may be associated with both entorhinal grey matter volumes and total cerebellar volumes, although our pilot study did not reach statistical significance. This suggests that both eye and brain volumes follow a similar trajectory and understanding the inter-relationship of these structures will aid in the analysis of changes seen in disease. Further studies are needed to longitudinally demonstrate these relationships.

Effect of age and sex on neurodevelopment and neurodegeneration in the healthy eye: Longitudinal functional and structural study in the Long-Evans rat

The processes involved in neurodevelopment and aging have not yet been fully discovered. This is especially challenging in premorbid or borderline situations of neurodegenerative diseases such as Alzheimer's or glaucoma. The retina, as part of the central nervous system, can be considered the easiest and most accessible neural structure that can be analyzed using non-invasive methods. Animal studies of neuroretinal tissue in situations of health and under controlled conditions allow the earliest sex- and aging-induced changes to be analyzed so as to differentiate them from the first signs occurring in manifested disease. This study evaluates differences by age and sex based on intraocular pressure (IOP) and neuroretinal function and structure in healthy young and adult rats before decline due to senescence. For this purpose, eighty-five healthy Long-Evans rats (31 males and 54 females) were analyzed in this 6-month longitudinal study running from childhood to adulthood. IOP was measured by tonometer (Tonolab; Tiolat Oy Helsinki, Finland), neuroretinal function was recorded by flash scotopic and light-adapted photopic negative response electroretinography (ERG) (Roland consult® RETIanimal ERG, Germany) at 4, 16 and 28 weeks of age; and structure was evaluated by in vivo optical coherence tomography (OCT) (Spectralis, Heidelberg® Engineering, Germany). Analyzing both sexes together, IOP was below 20 mmHg throughout the study; retina (R), retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thicknesses measured by OCT decreased over time; an increase in ERG signal was recorded at week 16; and no differences were found between right and left eyes. However, analyzing differences by sex revealed that males had higher IOP (even reaching ocular hypertension [>20 mmHg] by the end of the study [7 months of age]), exhibited greater neuroretinal thickness but higher structural percentage loss, and had worse dark- and light-adapted function as measured by ERG than females. This study concludes that age and sex influenced neurodevelopment and neurodegeneration. Different structural and functional degenerative patterns were observed by sex; these occurred earlier and more intensely in males than in age-matched females.

Protective effects of 4-aminopyridine in experimental optic neuritis and multiple sclerosis

Chronic disability in multiple sclerosis is linked to neuroaxonal degeneration. 4-aminopyridine (4-AP) is used and licensed as a symptomatic treatment to ameliorate ambulatory disability in multiple sclerosis. The presumed mode of action is via blockade of axonal voltage gated potassium channels, thereby enhancing conduction in demyelinated axons. In this study, we provide evidence that in addition to those symptomatic effects, 4-AP can prevent neuroaxonal loss in the CNS. Using in vivo optical coherence tomography imaging, visual function testing and histologic assessment, we observed a reduction in retinal neurodegeneration with 4-AP in models of experimental optic neuritis and optic nerve crush. These effects were not related to an anti-inflammatory mode of action or a direct impact on retinal ganglion cells. Rather, histology and in vitro experiments indicated 4-AP stabilization of myelin and oligodendrocyte precursor cells associated with increased nuclear translocation of the nuclear factor of activated T cells. In experimental optic neuritis, 4-AP potentiated the effects of immunomodulatory treatment with fingolimod. As extended release 4-AP is already licensed for symptomatic multiple sclerosis treatment, we performed a retrospective, multicentre optical coherence tomography study to longitudinally compare retinal neurodegeneration between 52 patients on continuous 4-AP therapy and 51 matched controls. In line with the experimental data, during concurrent 4-AP therapy, degeneration of the macular retinal nerve fibre layer was reduced over 2 years. These results indicate disease-modifying effects of 4-AP beyond symptomatic therapy and provide support for the design of a prospective clinical study using visual function and retinal structure as outcome parameters.

Asymptomatic optic nerve lesions: An underestimated cause of silent retinal atrophy in MS

OBJECTIVE

To evaluate the frequency of asymptomatic optic nerve lesions and their role in the asymptomatic retinal neuroaxonal loss observed in multiple sclerosis (MS).

METHODS

We included patients with remitting-relapsing MS in the VWIMS study (Analysis of Neurodegenerative Process Within Visual Ways In Multiple Sclerosis) (ClinicalTrials.gov Identifier: 03656055). Included patients underwent optical coherence tomography (OCT), optic nerve and brain MRI, and low-contrast visual acuity measurement. In eyes of patients with MS without optic neuritis (MS-NON), an optic nerve lesion on MRI (3D double inversion recovery [DIR] sequence) was considered as an asymptomatic lesion. We considered the following OCT/MRI measures: peripapillary retinal nerve fiber layer thickness, macular ganglion cell + inner plexiform layer (mGCIPL) volumes, optic nerve lesion length, T2 lesion burden, and fractional anisotropy within optic radiations.

RESULTS

An optic nerve lesion was detected in half of MS-NON eyes. Compared to optic nerves without any lesion and independently of the optic radiation lesions, the asymptomatic lesions were associated with thinner inner retinal layers (p < 0.0001) and a lower contrast visual acuity (p ≤ 0.003). Within eyes with asymptomatic optic nerve lesions, optic nerve lesion length was the only MRI measure significantly associated with retinal neuroaxonal loss (p < 0.03). Intereye mGCIPL thickness difference (IETD) was lower in patients with bilateral optic nerve DIR hypersignal compared to patients with unilateral hypersignal (p = 0.0317). For the diagnosis of history of optic neuritis, sensitivity of 3D DIR and of mGCIPL IETD were 84.9% and 63.5%, respectively.

CONCLUSIONS

Asymptomatic optic nerve lesions are an underestimated and preponderant cause of retinal neuroaxonal loss in MS. 3D DIR sequence may be more sensitive than IETD measured by OCT for the detection of optic nerve lesions.

Serum neurofilament light chain and optical coherence tomography measures in MS: A longitudinal study

OBJECTIVE

To study the association between serum neurofilament light chain (sNfL) and multiple optical coherence tomography (OCT) measures in patients with MS and healthy controls (HCs).

METHODS

In this prospective study, 110 patients with MS were recruited, together with 52 age- and sex-matched HCs. Clinical evaluation and spectral domain OCT and sNfL were obtained at baseline and after 5.5 years of follow-up. Nested linear mixed models were used to assess differences between MS vs HC and associations between sNfL and OCT measures. Partial correlation coefficients are reported, and p values were adjusted for the false discovery rate.

RESULTS

At baseline, peripapillary retinal nerve fiber layer thickness (pRNFLT) and macular ganglion cell and inner plexiform layer thickness (mGCIP) were significantly lower in MS than HC both in MS-associated optic neuritis (MSON) (p = 0.007, p = 0.001) and nonaffected MSON (n-MSON) eyes (p = 0.003, p = 0.018), along with total macular volume (TMV) in n-MSON eyes (p = 0.011). At follow-up, MS showed significantly lower pRNFLT, mGCIP, and TMV both in MSON and n-MSON eyes (p < 0.001) compared with HC. In MS n-MSON eyes, sNfL was significantly associated with baseline pRNFLT and mGCIP (q = 0.019). No significant associations were found in MSON eyes.

CONCLUSIONS

This study confirms the ability of sNfL to detect neurodegeneration in MS and advocates for the inclusion of sNfL and OCT measures in clinical trials.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that sNfL levels were associated with MS neurodegeneration measured by OCT.

Retinal thickness as a potential biomarker of neurodegeneration and a predictor of early cognitive impairment in patients with multiple sclerosis

OBJECTIVES

The purpose of this research is to predict the cognitive impairment and to determine its correlation with retinal thickness, mainly (RFNL and GCIPL) in cases of multiple sclerosis.

METHODS

60 multiple sclerosis patients and 30 age and sex-matched healthy controls were included in this study. Cognitive functions were evaluated in all study participants by the Montreal Cognitive Assessment (MoCA). OCT imaging was done to determine the thickness. The correlation between the cognitive domains of MoCA and the thickness of the retinal nerve fiber layers was analyzed by Spearman correlation. ROC curve was constructed to determine the cut-off points for retinal thickness, and a binary logistic regression was performed to determine the independent predictive capacity of established cut-off points.

RESULTS

Impaired cognition was found in 26 MS patients (43.3%). Cognitively impaired patients were significantly older (P < 0.05), had significantly longer disease duration (P < 0.05), had higher average EDSS scores (4.3 ± 1.22 vs 3.1 ± 1.45, P < 0.001), and occurred more in progressive types of MS (P < 0.001). A significant positive correlation was found between cognitive function and RNFL thickness and GCIPL (P < 0.001). The retinal thickness (RNFL and GCIPL) cut-off points established for the prediction of cognitive impairment in MS patients were 79 μm and 76 μm, respectively.

CONCLUSION

The clear correlation between cognitive impairment and atrophy of inner retinal layers (RNFL and GCIPL) proposes that OCT is valuable in evaluating the neurodegeneration and prediction of early cognitive impairment in MS.

ABBREVIATIONS

EDSS: Expanded Disability Status Scale; HCs: Healthy controls; GCIPL: Ganglion cell-inner plexiform layer; ILM: Internal limiting membrane; INL:  Inner nuclear layer; MoCA: Montreal Cognitive Assessment; MS: Multiple sclerosis; PPMS: Primary progressive multiple sclerosis; RNFL:  Retinal nerve fiber layer; RRMS: Relapsing-remitting multiple sclerosis; SD: Standard deviations; SPMS: Secondary progressive multiple sclerosis; SPSS: Statistical Package for the Social Sciences.

Detecting neurodegenerative pathology in multiple sclerosis before irreversible brain tissue loss sets in

Background

Multiple sclerosis (MS) is a complex chronic inflammatory and degenerative disorder of the central nervous system. Accelerated brain volume loss, or also termed atrophy, is currently emerging as a popular imaging marker of neurodegeneration in affected patients, but, unfortunately, can only be reliably interpreted at the time when irreversible tissue damage likely has already occurred. Timing of treatment decisions based on brain atrophy may therefore be viewed as suboptimal.

Main body

This Narrative Review focuses on alternative techniques with the potential of detecting neurodegenerative events in the brain of subjects with MS prior to the atrophic stage. First, metabolic and molecular imaging provide the opportunity to identify early subcellular changes associated with energy dysfunction, which is an assumed core mechanism of axonal degeneration in MS. Second, cerebral hypoperfusion has been observed throughout the entire clinical spectrum of the disorder but it remains an open question whether this serves as an alternative marker of reduced metabolic activity, or exists as an independent contributing process, mediated by endothelin-1 hyperexpression. Third, both metabolic and perfusion alterations may lead to repercussions at the level of network performance and structural connectivity, respectively assessable by functional and diffusion tensor imaging. Fourth and finally, elevated body fluid levels of neurofilaments are gaining interest as a biochemical mirror of axonal damage in a wide range of neurological conditions, with early rises in patients with MS appearing to be predictive of future brain atrophy.

Conclusions

Recent findings from the fields of advanced neuroradiology and neurochemistry provide the promising prospect of demonstrating degenerative brain pathology in patients with MS before atrophy has installed. Although the overall level of evidence on the presented topic is still preliminary, this Review may pave the way for further longitudinal and multimodal studies exploring the relationships between the abovementioned measures, possibly leading to novel insights in early disease mechanisms and therapeutic intervention strategies.

Anatomically constrained tractography facilitates biologically plausible fiber reconstruction of the optic radiation in multiple sclerosis

Diffusion-weighted magnetic resonance imaging (dMRI) enables the microstructural characterization and reconstruction of white matter pathways in vivo non-invasively. However, dMRI only provides information on the orientation of potential fibers but not on their anatomical plausibility. To that end, recent methodological advances facilitate the effective use of anatomical priors in the process of fiber reconstruction, thus improving the accuracy of the results. Here, we investigated the potential of anatomically constrained tracking (ACT), a modular addition to the tractography software package MRtrix3, to accurately reconstruct the optic radiation, a commonly affected pathway in multiple sclerosis (MS). Diffusion MRI data were acquired from 28 MS patients and 22 age- and sex-matched healthy controls. For each participant, the optic radiation was segmented based on the fiber reconstruction obtained using ACT. When implementing ACT in MS, it proved essential to incorporate lesion maps to avoid incorrect reconstructions due to tissue-type misclassifications in lesional areas. The ACT-based results were compared with those obtained using two commonly used probabilistic fiber tracking procedures, based on FSL (FMRIB Software Library) and MRtrix3 without ACT. All three procedures enabled a reliable localization of the optic radiation in both MS patients and controls. However, for FSL and MRtrix3 without ACT it was necessary to place an additional waypoint halfway between the lateral geniculate nucleus and the primary visual cortex to filter out anatomically implausible tracks. In the case of ACT, the results with and without an additional waypoint were virtually identical, presumably because the employed anatomical constraints already prevented the occurrence of the most implausible tracks. Irrespective of the employed tractography procedure, increased diffusivity and decreased anisotropy were found in the optic radiation of the MS patients compared to the controls.

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Anatomical constraints improve tractography of the optic radiation in MS.

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In MS, lesion mapping is essential to implement sensible anatomical constraints.

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Patients showed increased diffusivity and decreased anisotropy in the OR.

Retinal degeneration is associated with brain volume reduction and prognosis in radiologically isolated syndrome

Background:

The extent of neurodegeneration in the earliest stages of central nervous system (CNS) demyelination is not known. Optical coherence tomography (OCT) is a powerful tool to study neurodegeneration in demyelinating disorders.

Objectives:

To study neuroaxonal loss in the retina of individuals with radiologically isolated syndrome (RIS) and investigate whether OCT measurements are associated with brain volumetrics and clinical conversion to multiple sclerosis (MS).

Methods:

Subjects fulfilling the Okuda criteria for RIS ( n = 15 patients, 30 eyes) and age- and sex-matched healthy controls (HC) underwent spectral-domain OCT and magnetic resonance imaging for volumetric measurement of brain structures.

Results:

Macular ganglion cell-inner plexiform layer (mGCIPL), macular retinal nerve fiber layer (mRNFL), and temporal peripapillary RNFL (pRNFL) thickness; normalized total brain volume (nTBV); and normalized thalamic volume (nTV) were reduced in RIS compared to HC. mGCIPL, mRNFL, and pRNFL measurements were associated with nTBV, nTV, and normalized gray and white matter volumes in the RIS group. pRNFL was thinner in individuals with RIS who converted to MS in 5 years.

Conclusions:

Retinal neurodegeneration can be detected in the papillomacular region in the earliest stages of CNS demyelination and reflects global disease processes in the brain. OCT can be potentially useful for predicting prognosis in RIS.

Multifocal visual evoked potentials and contrast sensitivity correlate with ganglion cell-inner plexiform layer thickness in multiple sclerosis

OBJECTIVE

To examine the relationship between optical coherence tomography (OCT) macular ganglion cell-inner plexiform layer thickness (GCIPLT), peripapillary retinal nerve fiber layer thickness (RNFLT) and visual function in relapsing-remitting multiple sclerosis (RRMS).

METHODS

Cirrus OCT, VERIS 60-sector multifocal visual evoked potential (mfVEP) and Pelli-Robson contrast sensitivity (CS) were obtained for 53 eyes with last optic neuritis (ON) > 6 months and 105 non-ON eyes in 90 patients. One eye (43 ON, 73 non-ON) was used for correlations when both had the same history. Global (G, 60 sectors) and central 5.6° (C, 24 sectors) mfVEP amplitude and latency were calculated as mean logSNR and median latency.

RESULTS

Eyes showing abnormal mfVEP (amplitude or latency) vs OCT (GCIPLT or RNFLT) was 77% vs 69% (p = 0.33) in ON, 45% vs 22% (p < 0.0005) in non-ON. In ON and non-ON, mfVEP measures and CS correlated with GCIPLT and RNFLT (r = -0.24 to 0.78, p = 0.03-0.0001). In ON, mfVEP amplitude (C,G) correlated better with GCIPLT (r = 0.78, 0.76) than RNFLT (r = 0.43, 0.58; p < 0.001, 0.01).

CONCLUSIONS

MfVEP measures and CS correlated well with GCIPLT and RNFLT in ON and non-ON. MfVEP amplitudes were more highly correlated with GCIPLT than RNFLT in ON. MfVEP detected significantly more defects than OCT in non-ON.

SIGNIFICANCE

GCIPLT, mfVEP and CS provide useful measures of optic nerve integrity in RRMS.

Discriminative power of intra-retinal layers in early multiple sclerosis using 3D OCT imaging

OBJECTIVE

To evaluate volumetric changes and discriminative power of intra-retinal layers in early-stage multiple sclerosis (MS) using a 3D optical coherence tomography (OCT) imaging method based on an in-house segmentation algorithm.

METHODS

3D analysis of intra-retinal layers was performed in 71 patients with early-stage MS (mean disease duration 2.2 ± 3.5 years) at baseline and 40 healthy controls (HCs). All patients underwent a follow-up OCT scan within 23 ± 9 months. Patients with a clinical episode of optic neuritis (ON) more than 6 months prior to study entrance were compared with patients who never experienced clinical symptoms of an ON episode (NON).

RESULTS

Significantly decreased total retinal volume (TRV), macular retinal nerve fiber layer (mRNFL) and ganglion cell-inner plexiform layer (GCIPL) volumes were detected in ON patients compared to NON patients (all p values < 0.05) at baseline. Each parameter on its own allowed identification of prior clinical ON based on a discriminative model (ROC analysis). Over time, TRV decreased in both ON (p = 0.013) and NON patients (p = 0.002), whereas mRNFL volume (p = 0.028) decreased only in ON and GCIPL volume (p = 0.003) decreased only in NON patients.

CONCLUSION

Our 3D-OCT data demonstrated that TRV, mRNFL and GCIPL allow discrimination between ON and NON patients in a cross-sectional analysis. However, the subsequent retinal atrophy pattern diverges in the initial phase of MS: Prior ON promotes sustained axonal thinning over time indicated by mRNFL loss, whereas longitudinal measurement of GCIPL volume better depicts continuous retrograde neurodegeneration in NON patients in early-stage MS.

Searching for neurodegeneration in multiple sclerosis at clinical onset: Diagnostic value of biomarkers

BACKGROUND

Neurodegeneration occurs during the early stages of multiple sclerosis. It is an essential, devastating part of the pathophysiology. Tools for measuring the degree of neurodegeneration could improve diagnostics and patient characterization.

OBJECTIVE

This study aimed to determine the diagnostic value of biomarkers of degeneration in patients with recent clinical onset of suspected multiple sclerosis, and to evaluate these biomarkers for characterizing disease course.

METHODS

This cross-sectional study included 271 patients with clinical features of suspected multiple sclerosis onset and was the baseline of a prospective study. After diagnostic investigations, the patients were classified into the following disease groups: patients with clinically isolated syndrome (n = 4) or early relapsing remitting multiple sclerosis (early RRMS; n = 93); patients with relapsing remitting multiple sclerosis with disease durations ≥2 years (established RRMS; n = 39); patients without multiple sclerosis, but showing symptoms (symptomatic controls; n = 89); and patients diagnosed with other diseases (n = 46). In addition, we included healthy controls (n = 51) and patients with progressive multiple sclerosis (n = 23). We analyzed six biomarkers of neurodegeneration: cerebrospinal fluid neurofilament light chain levels; cerebral spinal fluid glial fibrillary acidic protein; cerebral spinal fluid tau; retinal nerve fiber layer thickness; macula volume; and the brain parenchymal fraction.

RESULTS

Except for increased cerebral spinal fluid neurofilament light chain levels, median 670 ng/L (IQR 400-2110), we could not find signs of early degeneration in the early disease group with recent clinical onset. However, the intrathecal immunoglobin G production and cerebral spinal fluid neurofilament light chain levels showed diagnostic value. Moreover, elevated levels of cerebral spinal fluid glial fibrillary acidic protein, thin retinal nerve fiber layers, and low brain parenchymal fractions were associated with progressive disease, but not with the other phenotypes. Thin retinal nerve fiber layers and low brain parenchymal fractions, which indicated neurodegeneration, were associated with longer disease duration.

CONCLUSIONS

In clinically suspected multiple sclerosis, intrathecal immunoglobin G production and neurofilament light chain levels had diagnostic value. Therefore, these biomarkers could be included in diagnostic work-ups for multiple sclerosis. We found that the thickness of the retinal nerve fiber layer and the brain parenchymal fraction were not different between individuals that were healthy, symptomatic, or newly diagnosed with multiple sclerosis. This finding suggested that neurodegeneration had not reached a significant magnitude in patients with a recent clinical onset of multiple sclerosis.

The Temporal Retinal Nerve Fiber Layer Thickness Is the Most Important Optical Coherence Tomography Estimate in Multiple Sclerosis

BACKGROUND

Reduced peripapillary retinal nerve fiber layer (pRNFL) and combined ganglion cell and inner plexiform layer (GCIP) thicknesses as measured by optical coherence tomography (OCT) have been observed in multiple sclerosis (MS) patients. The purpose was to determine the most associative OCT measure to level of cognitive and physical disability in MS.

METHODS

Data were collected from 546 MS patients and 175 healthy controls (HCs). We compared the average pRNFL, temporal pRNFL (T-pRNFL), overall inner ganglion cell/inner plexiform layer (GCIP), and the overall ganglion cell complex (GCC) including macular RNFL and GCIP thicknesses measurements in differentiating MS subtypes from HCs. The association between OCT measures, Expanded Disability Status Scale (EDSS), and Symbol Digit Modalities Test (SDMT) were assessed using generalized estimating equations models.

RESULTS

Both peripapillary and macular OCT measurements could differentiate all MS subtypes from HCs. The SDMT score was significantly associated with reduced thickness of all OCT measures, mostly in average pRNFL (0.14 µm, P = 0.001) and T-pRNFL (0.17 µm, P < 0.001). The EDSS score was significantly associated with reduced inner retinal layer thickness. The largest reduction was seen in T-pRNFL (-1.52 μm, P < 0.001) and inner GCC (-1.78 μm, P < 0.001).

CONCLUSION

The T-pRNFL is highly sensitive and associated with level of both cognitive and physical disability.