Diffusion tensor imaging metrics associated with future disability in multiple sclerosis.

The relationship between brain diffusion microstructural changes and disability in multiple sclerosis (MS) remains poorly understood. We aimed to explore the predictive value of microstructural properties in white (WM) and grey matter (GM), and identify areas associated with mid-term disability in MS patients. We studied 185 patients (71% female; 86% RRMS) with the Expanded Disability Status Scale (EDSS), timed 25-foot walk (T25FW), nine-hole peg test (9HPT), and Symbol Digit Modalities Test (SDMT) at two time-points. We used Lasso regression to analyse the predictive value of baseline WM fractional anisotropy and GM mean diffusivity, and to identify areas related to each outcome at 4.1 years follow-up. Motor performance was associated with WM (T25FW: RMSE = 0.524, R2 = 0.304; 9HPT dominant hand: RMSE = 0.662, R2 = 0.062; 9HPT non-dominant hand: RMSE = 0.649, R2 = 0.139), and SDMT with GM diffusion metrics (RMSE = 0.772, R2 = 0.186). Cingulum, longitudinal fasciculus, optic radiation, forceps minor and frontal aslant were the WM tracts most closely linked to motor dysfunction, and temporal and frontal cortex were relevant for cognition. Regional specificity related to clinical outcomes provide valuable information that can be used to develop more accurate predictive models that could improve therapeutic strategies.

Color vision impairment in multiple sclerosis points to retinal ganglion cell damage.

Multiple Sclerosis (MS) results in color vision impairment regardless of optic neuritis (ON). The exact location of injury remains undefined. The objective of this study is to identify the region leading to dyschromatopsia in MS patients' NON-eyes. We evaluated Spearman correlations between color vision and measures of different regions in the afferent visual pathway in 106 MS patients. Regions with significant correlations were included in logistic regression models to assess their independent role in dyschromatopsia. We evaluated color vision with Hardy-Rand-Rittler plates and retinal damage using Optical Coherence Tomography. We ran SIENAX to measure Normalized Brain Parenchymal Volume (NBPV), FIRST for thalamus volume and Freesurfer for visual cortex areas. We found moderate, significant correlations between color vision and macular retinal nerve fiber layer (rho = 0.289, p = 0.003), ganglion cell complex (GCC = GCIP) (rho = 0.353, p < 0.001), thalamus (rho = 0.361, p < 0.001), and lesion volume within the optic radiations (rho = -0.230, p = 0.030). Only GCC thickness remained significant (p = 0.023) in the logistic regression model. In the final model including lesion load and NBPV as markers of diffuse neuroaxonal damage, GCC remained associated with dyschromatopsia [OR = 0.88 95 % CI (0.80-0.97) p = 0.016]. This association remained significant when we also added sex, age, and disease duration as covariates in the regression model. Dyschromatopsia in NON-eyes is due to damage of retinal ganglion cells (RGC) in MS. Color vision can serve as a marker of RGC damage in MS.

A Population Approach to Characterize Interferon Beta-1b Effect on Contrast Enhancing Lesions in Patients With Relapsing Remitting Multiple Sclerosis.

In patients with relapsing-remitting multiple sclerosis (RRMS), interferon beta-1b (IFNß-1b) reduces the occurrence of contrast enhancing lesions (CELs) on magnetic resonance imaging (MRI). Questions remain on the stability of IFNß-1b effect over time and its action beyond the reduction of CELs. In this study, we described the IFNß-1b effect by a mixed effects model, quantifying the interpatient variability associated with its parameters. Using a negative binomial distribution model as a natural history model, the effect of IFNß-1b was evaluated using different mathematical functions of time. IFNß-1b produced a decrease in the expected CEL numbers, inhibiting the formation of new CELs but did not promote the resolution of the already-formed ones. Based on the final selected model, simulations were carried out to optimize the combined IFNß-1b-corticosteroid therapy as a proof-of-concept. In summary, we provide evidence on the dynamics of CELs under IFNß-1b treatment that can be used to monitor the effects of therapies in MS.

Neuromyelitis optica and multiple sclerosis: Seeing differences through optical coherence tomography.

Neuromyelitis optica (NMO) is an inflammatory autoimmune disease of the central nervous system that preferentially targets the optic nerves and spinal cord. The clinical presentation may suggest multiple sclerosis (MS), but a highly specific serum autoantibody against the astrocytic water channel aquaporin-4 present in up to 80% of NMO patients enables distinction from MS. Optic neuritis may occur in either condition resulting in neuro-anatomical retinal changes. Optical coherence tomography (OCT) has become a useful tool for analyzing retinal damage both in MS and NMO. Numerous studies showed that optic neuritis in NMO typically results in more severe retinal nerve fiber layer (RNFL) and ganglion cell layer thinning and more frequent development of microcystic macular edema than in MS. Furthermore, while patients' RNFL thinning also occurs in the absence of optic neuritis in MS, subclinical damage seems to be rare in NMO. Thus, OCT might be useful in differentiating NMO from MS and serve as an outcome parameter in clinical studies.

Quality control for retinal OCT in multiple sclerosis: validation of the OSCAR-IB criteria.

BACKGROUND: Retinal optical coherence tomography (OCT) permits quantification of retinal layer atrophy relevant to assessment of neurodegeneration in multiple sclerosis (MS). Measurement artefacts may limit the use of OCT to MS research. OBJECTIVE: An expert task force convened with the aim to provide guidance on the use of validated quality control (QC) criteria for the use of OCT in MS research and clinical trials. METHODS: A prospective multi-centre (n = 13) study. Peripapillary ring scan QC rating of an OCT training set (n = 50) was followed by a test set (n = 50). Inter-rater agreement was calculated using kappa statistics. Results were discussed at a round table after the assessment had taken place. RESULTS: The inter-rater QC agreement was substantial (kappa = 0.7). Disagreement was found highest for judging signal strength (kappa = 0.40). Future steps to resolve these issues were discussed. CONCLUSION: Substantial agreement for QC assessment was achieved with aid of the OSCAR-IB criteria. The task force has developed a website for free online training and QC certification. The criteria may prove useful for future research and trials in MS using OCT as a secondary outcome measure in a multi-centre setting.

The visual pathway as a model to understand brain damage in multiple sclerosis.

Patients with multiple sclerosis (MS) almost always experience effects in the visual pathway; and thus, visual dysfunction is not only common but also highly relevant. The visual pathway represents a model of acute focal central nervous system (CNS) damage, through acute optic neuritis and retinal periphlebitis, as well as a model of chronic, diffuse CNS damage through chronic retinopathy and optic neuropathy. The optic pathway can be accurately evaluated in detail, due to the availability of highly sensitive imaging techniques (e.g. magnetic resonance imaging or optical coherent tomography) or electrophysiological tests (multifocal visual evoked potentials or electroretinography). These techniques allow the interactions between the different processes at play to be evaluated, such as inflammation, demyelination, axonal damage and neurodegeneration. Moreover, these features mean that the visual pathway can be used as a model to test new neuroprotective or regenerative therapies.

A Web platform for the interactive visualization and analysis of the 3D fractal dimension of MRI data.

This study presents a Web platform (http://3dfd.ujaen.es) for computing and analyzing the 3D fractal dimension (3DFD) from volumetric data in an efficient, visual and interactive way. The Web platform is specially designed for working with magnetic resonance images (MRIs) of the brain. The program estimates the 3DFD by calculating the 3D box-counting of the entire volume of the brain, and also of its 3D skeleton. All of this is done in a graphical, fast and optimized way by using novel technologies like CUDA and WebGL. The usefulness of the Web platform presented is demonstrated by its application in a case study where an analysis and characterization of groups of 3D MR images is performed for three neurodegenerative diseases: Multiple Sclerosis, Intrauterine Growth Restriction and Alzheimer's disease. To the best of our knowledge, this is the first Web platform that allows the users to calculate, visualize, analyze and compare the 3DFD from MRI images in the cloud.

Recomendaciones para la utilización clínica del estudio de potenciales evocados motores en la esclerosis múltiple / Recommendations for the clinical use of motor evoked potentials in multiple sclerosis

Objetivo: Establecer una guía clínica para la utilización clínica del estudio de potenciales evocados motores (PEM) en el diagnóstico y el seguimiento de la esclerosis múltiple (EM). Disponer de unas recomendaciones para la utilización clínica de los PEM contribuye a racionalizar y optimizar los recursos en el proceso diagnóstico y de seguimiento en los pacientes con EM. Método: Hemos llevado a cabo una extensa revisión de la literatura médica y puesto en común nuestros propios datos para consensuar recomendaciones para el uso clínico de los PEM en el estudio de la EM. Resultados: Los PEM contribuyen, junto con la resonancia magnética medular o cerebral, al diagnóstico y evaluación de los pacientes cuyo inicio clínico es un síndrome medular, que presentan hallazgos de neuroimagen poco específicos o que presentan criterios clínicos de EM con neuroimagen cerebral normal. Conclusiones: Es aconsejable realizar un estudio de potenciales evocados multimodales en pacientes con sospecha de EM para documentar la afectación de la vía motora como apoyo al diagnóstico de diseminación en espacio (AU)

Objective: To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. Method: We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. Results: MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. Conclusions: Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space (AU)

[Recommendations for the clinical use of motor evoked potentials in multiple sclerosis]. / Recomendaciones para la utilización clínica del estudio de potenciales evocados motores en la esclerosis múltiple.

OBJECTIVE: To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. METHOD: We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. RESULTS: MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. CONCLUSIONS: Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space.

Guía de uso adecuado de modelos animales para el desarrollo de terapias en esclerosis múltiple / Guidelines on the appropriate use of animal models for developing therapies in multiple sclerosis

Introducción. La búsqueda de terapias efectivas para la esclerosis múltiple (EM) y la definición de ventanas terapéuticas apropiadas, así como el establecimiento de mejores biomarcadores diagnósticos y pronósticos, continúan siendo un reto para investigadores tanto básicos como clínicos. El desarrollo y el método de evaluación de los estudios preclínicos en modelos animales podrían subyacer al hecho de que terapias eficaces en modelos animales fracasen en su aplicación clínica. Objetivo. Unificar la metodología en la aplicación de los modelos experimentales para la EM mediante la elaboración, por parte de grupos españoles expertos pertenecientes a la Red Española de Esclerosis Múltiple, de una guía de recomendaciones para los estudios preclínicos. Desarrollo. Se ha realizado una valoración detallada de los modelos experimentales adecuados y su aplicación en función del objetivo perseguido, incorporando estándares y criterios de calidad imprescindibles en un estudio preclínico. Conclusiones. El éxito traslacional en el avance terapéutico de la EM conlleva la adquisición de compromisos metodológicos en los modelos experimentales, de manera que se optimice la bondad y adecuación del modelo al estudio perseguido. Las recomendaciones establecidas en esta guía podrían ayudar a generar datos preclínicos de utilidad en la práctica clínica (AU)

Introduction. The advance in the achievement of effective therapies for multiple sclerosis (MS), the definition of appropriate therapeutic windows and to establish better diagnostic and prognostic biomarkers have become a challenging task for both researchers and clinicians. Some pitfalls in clinical trials might be related to lack of adequacy of the preclinical studies in MS experimental animal models Aim. To standardize the methodological protocols of experimental models by developing a set of guidelines for preclinical studies by groups of experts from REEM (Spanish Network for MS). Development. A guide with recommendations for the application of MS models including a detailed assessment of appropriate experimental models taking into account the objective of the study that has been presented. Standards and quality criteria necessary in a preclinical study have been included. Conclusions. Standardized animal models of MS are essential to increase the success of the preclinical findings in order to transfer them to the clinical practice (AU)

Analysis of relapses in anti-NMDAR encephalitis.

OBJECTIVE: The clinical characteristics of patients with relapsing anti-NMDA receptor (NMDAR) encephalitis are not well-defined. In this study, we report the clinical profile and outcome of relapses in a series of anti-NMDAR encephalitis. METHODS: We did a retrospective review of relapses that occurred in 25 patients with anti-NMDAR encephalitis. Relapses were defined as any new psychiatric or neurologic syndrome, not explained by other causes, which improved after immunotherapy or, less frequently, spontaneously. RESULTS: A total of 13 relapses were identified in 6 patients. Four of them had several, 2 to 4, relapses. There was a median delay of 2 years (range 0.5 to 13 years) for the first relapse. Median relapse rate was 0.52 relapses/patient-year. Relapse risk was higher in patients who did not receive immunotherapy in the first episode (p = 0.009). Most cases (53%) presented partial syndromes of the typical anti-NMDAR encephalitis. Main symptoms of relapses were speech dysfunction (61%), psychiatric (54%), consciousness-attention disturbance (38%), and seizures (31%). Three relapses (23%) presented with isolated atypical symptoms suggestive of brainstem-cerebellar involvement. An ovarian teratoma was detected at relapse in only 1 patient (17%). Relapses did not add residual deficit to that caused by the first episode. CONCLUSIONS: Relapses in anti-NMDAR encephalitis are common (24%). They may occur many years after the initial episode. Relapses may present with partial aspects or with isolated symptoms of the full-blown syndrome. Immunotherapy at first episode reduces the risk of relapses.

[HLA-DRB1 typing in Caucasians patients with neuromyelitis optica]. / HLA-DRB1 en pacientes caucasicos con neuromielitis optica.

INTRODUCTION: The existence of antibodies to aquaporin-4 (AQP-4-ab) has identified neuromyelitis optica (NMO) and multiple sclerosis (MS) as different diseases. Although HLA-DRB1 alleles contribute to MS risk, recent studies suggest that HLA back-ground differs between patients with NMO or MS in non-Caucasians populations. Our study was aimed to analyze HLA-DRB1 distribution in Caucasians NMO patients. SUBJECTS AND METHODS: We recruited a cohort of 22 NMO patients (73% were AQP-4-ab positive), 228 MS patients and 225 healthy controls from Spain and we genotyped the HLA-DRB1 locus. Then, we performed a pool analysis using reported data from 45 NMO patients (53% were AQP-4-ab positive), 156 MS patients and 310 healthy controls from Caucasian French population. RESULTS: In the Spanish cohort, NMO was associated with increased frequency of DRB1*10 allele compared with MS (odds ratio, OR = 15.1; 95% confidence interval, 95% CI = 3.26-69.84; p = 0.012). In the pooled analysis, by comparison with healthy controls, NMO was associated with increased frequency of DRB1*03 allele (OR = 2.27; 95% CI = 1.44-3.58; p < 0.0008) which was related to AQP-4-ab seropositivity (OR = 2.74; 95% CI = 1.58-4.77; p < 0.0008). By contrast, MS was associated with increased frequency of DRB1*15 allele (OR = 2.09; 95% CI = 1.62-2.68; p < 0.0008) and decreased frequency of DRB1*07 allele (OR = 0.58; 95% CI = 0.44-0.78; p < 0.0008). CONCLUSIONS: Caucasian patients with NMO and MS have a different HLA-DRB1 allelic distribution. DRB1*03 allele seems to contribute to NMO seropositivity. Multicenter collaborative efforts are needed to adequately address the genetic contribution to NMO susceptibility.

Triiodothyronine administration ameliorates the demyelination/remyelination ratio in a non-human primate model of multiple sclerosis by correcting tissue hypothyroidism.

Remyelination failure is a key landmark in chronic progression of multiple sclerosis (MS), the most diffuse demyelinating disease in human, but the reasons for this are still unknown. It has been shown that thyroid hormone administration in the rodent models of acute and chronic demyelinating diseases improved their clinical course, pathology and remyelination. In the present study, we translated this therapeutic attempt to experimental allergic encephalomyelitis (EAE) in the non-human primate Callithrix Jacchus (marmoset). We report that short protocols of triiodothyronine treatment shifts the demyelination/remyelination balance toward remyelination, as assessed by morphology, immunohistochemistry and molecular biology, and improves the clinical course of the disease. We also found that severely ill animals display hypothyroidism and severe alteration of deiodinase and thyroid hormone receptor mRNAs expression in the spinal cord, which was completely corrected by thyroid hormone treatment. We therefore suggest that thyroid hormone treatment improves myelin sheath morphology in marmoset EAE, by correcting the dysfunction of thyroid hormone cellular effectors.

UJA-3DFD: a program to compute the 3D fractal dimension from MRI data.

This work presents a computer program for computing the 3D fractal dimension (3DFD) from magnetic-resonance images of the brain. The program is based on an algorithm that calculates the 3D box counting of the entire volume of the brain, and also of its 3D skeletonization. The validity and accuracy of the software has been confirmed using solids with well-known 3DFD values. The usefulness of the program developed is demonstrated by its successful characterization of several neurodegenerative diseases.

Preclinical studies of methylthioadenosine for the treatment of multiple sclerosis.

BACKGROUND: Methylthioadenosine (MTA) is a natural metabolite with immunomodulatory properties. MTA improves the clinical course and pathology of the animal model of multiple sclerosis, even when therapy is started after disease onset. OBJECTIVE: Our aim was to compare the efficacy of MTA in ameliorating experimental autoimmune encephalomyelitis (EAE) compared with first line approved therapies, to develop an oral formulation of MTA and to assess its pharmacokinetic profile. METHODS: EAE was induced in C57BL/6 mice by immunization with MOG(35-55) peptide in Freund's Adjuvant. Animals were treated with MTA, interferon-beta or glatiramer acetate starting the day of immunization and the clinical score was collected blind. Pharmacokinetic studies were performed in Sprague Dawley rats by administering MTA by intraperitoneal injection and orally, and collecting blood at different intervals. MTA levels were measured by high-performance liquid chromatography. RESULTS: We found that MTA ameliorated EAE in a dose-response manner. Moreover, the highest dose of MTA (60 mg/kg) was more efficacious than mouse interferon-beta or glatiramer acetate. We developed a salt of MTA for oral administration, with similar dose-response effect in the EAE model. Combination therapy assays between MTA and interferon-beta or glatiramer acetate were more effective than the individual therapies. Finally, oral MTA half-life was 20 min, with a C(max) of 80 mg/L and without signs of obvious toxicity (animal death, behavioural changes, liver enzymes). CONCLUSIONS: In the EAE model MTA is more efficacious than first line therapies for multiple sclerosis, with a dose- response effect and higher efficacy when combined with interferon-beta or glatiramer acetate. Oral MTA was also effective in the animal model of multiple sclerosis.

Abnormalities in brain synchronization are correlated with cognitive impairment in multiple sclerosis.

BACKGROUND: Cognitive functions are supported by brain networks and they are highly dependent on the integrity of long white matter tracts that mediate the information flow between such distant cortical areas. Brain damage in multiple sclerosis (MS) may produce cognitive impairment by preferentially damaging these tracts, thereby impairing brain synchrony. Auditory amplitude modulation following responses (AMFR), are oscillatory steady-state responses to rhythmic auditory stimuli that indirectly measure brain synchrony. OBJECTIVE: To study the effect of MS lesions in brain synchrony and its relationship with cognitive function. METHODS: We assessed the correlation between cognitive performance, as assessed with the brief repeatable battery-neuropsychology (BRB-N), and the AMFR in a group of 27 MS patients and 22 healthy controls. RESULTS: The maximal AMFR frequency - but not the amplitude - in the 30-60 Hz range was lower in patients with cognitive impairment than in patients with no cognitive impairment or the healthy controls (39.79 Hz, 43.85 Hz, and 43.84 Hz, respectively, P < 0.05). Indeed, the frequency of the AMFR was negatively correlated with the scores obtained in verbal memory, attention, and executive function. The multiple regression analysis indicates that the AMFR was the best predictor of the BRB-N scores after controlling for potential confounding factors such as age, education, disability, and years of disease evolution. CONCLUSIONS: These results suggest that the loss of synchronization in different central nervous system (CNS) pathways caused by demyelinating lesions might involve both the slowing of brain oscillatory activity and less efficient cognitive processing.

Fatigue in multiple sclerosis is associated with the disruption of frontal and parietal pathways.

BACKGROUND: Fatigue is one of the most frequent and disturbing symptoms in multiple sclerosis (MS), directly affecting the patient's quality of life. However, many questions remain unclear regarding the anatomic brain correlate of MS-related fatigue. OBJECTIVE: To assess the relationship between fatigue and white matter lesion location and gray matter atrophy. METHODS: In this study, 60 patients with MS were evaluated with the Modified Fatigue Impact Scale and magnetic resonance imaging. Location of white matter lesion was analyzed using a voxel-by-voxel lesion probability mapping approach and gray matter atrophy degree and location using an optimized voxel-based morphometry method. RESULTS: We found a correlation between lesion load and fatigue score (T2 lesion load: r=0.415, P=0.001; T1 lesion load r=0.328, P=0.011). Moreover, fatigue correlated with lesions in the right parietotemporal (periatrial area, juxtaventricular white matter deep in the parietal lobe and callosal forceps) and left frontal (middle-anterior corpus callosum, anterior cingulum and centrum semiovale of the superior and middle frontal gyri) white matter regions (P<0.001 in all cases). Finally, fatigue score significantly correlated with gray matter atrophy in frontal regions, specifically, the left superior frontal gyrus and bilateral middle frontal gyri (P<0.001 in all cases). CONCLUSION: Our results suggest that the symptom of fatigue is associated with a disruption of brain networks involved in cognitive/attentional processes.

Memantine induces reversible neurologic impairment in patients with MS.

BACKGROUND: Cognitive dysfunction is very common in multiple sclerosis (MS) and it severely impairs patients' quality of life. Thus, we explored whether memantine might improve cognitive performance in patients with MS. METHODS: We conducted a pilot trial with memantine (30 mg/day) in patients with MS with cognitive impairment. The trial was designed as a 1-year, randomized, double-blind, crossover study comparing memantine against a placebo in 60 patients with MS and cognitive impairment. Cognitive impairment was defined as the performance 1.5 standard deviations below the normative data in at least two tests of two cognitive domains in the Brief Repeatable Battery-Neuropsychology. The primary endpoint was improvement of verbal memory and the secondary endpoints were safety and improvements in the other cognitive domains, disability and quality of life. The trial was registered at www.clinicaltrials.org: NCT00638833. RESULTS: Although 19 patients had been included, the trial was halted after nine patients reported a worsening of their neurologic symptoms that deteriorated their quality of life. Seven of the nine patients in the memantine arm had blurred vision, fatigue, severe headache, increased muscle weakness, walking difficulties, or unstable gait. Only two patients in the placebo group reported neurologic symptoms and in both cases they were related with changes in their disease-modifying therapy. The adverse events only occurred on reaching the maximum dose (30 mg/day). After stopping medication, the patients reverted to their baseline disability within a few days. CONCLUSIONS: Memantine at a dose of 30 mg/day may induce transient worsening of neurologic symptoms of multiple sclerosis.

Memory decline evolves independently of disease activity in MS.

BACKGROUND: The natural history of cognitive impairment in multiple sclerosis (MS) and its relationship with disease activity is not well known. In this study, we evaluate a prospective cohort of 44 MS patients who were followed every 3 months for 2 years. Cognitive evaluation was done at baseline and by the end of the study using the Brief Repeatable Battery-Neuropsychology. Clinical evaluation included assessment of new relapses and changes in disability (Extended Disability Status Scale (EDSS)) confirmed at 6 months. RESULTS: We found that verbal memory performance deteriorates after 2 years in patients with MS. These changes were observed in stable and active patients both in terms of relapses and disability progression, even at the beginning of the disease, and in patients with or without cognitive impairment at study entry. Attention and executive functions measured with the symbol digit modality test (SDMT) declined after 2 years in patients with confirmed disability progression. Furthermore, SDMT performance correlated with the EDSS change. CONCLUSIONS: Our findings indicate that verbal memory steadily declines in patients with MS from the beginning of the disease and independently of other parameters of disease activity.

Retinal nerve fiber layer atrophy is associated with physical and cognitive disability in multiple sclerosis.

BACKGROUND: Studying axonal loss in the retina is a promising biomarker for multiple sclerosis (MS). Our aim was to compare optical coherence tomography (OCT) and Heidelberg retinal tomography (HRT) techniques to measure the thickness of the retinal nerve fiber layer (RNFL) in patients with MS, and to explore the relationship between changes in the RNFL thickness with physical and cognitive disability. We studied 52 patients with MS and 18 proportionally matched controls by performing neurological examination, neuropsychological evaluation using the Brief Repetitive Battery-Neuropsychology and RNFL thickness measurement using OCT and HRT. RESULTS: We found that both OCT and HRT could define a reduction in the thickness of the RNFL in patients with MS compared with controls, although both measurements were weakly correlated, suggesting that they might measure different aspects of the tissue changes in MS. The degree of RNFL atrophy was correlated with cognitive disability, mainly with the symbol digit modality test (r=0.754, P<0.001). Moreover, temporal quadrant RNFL atrophy measured with OCT was associated with physical disability. CONCLUSION: In summary, both OCT and HRT are able to detect thinning of the RNFL, but OCT seems to be the most sensitive technique to identify changes associated with MS evolution.