Assessing structure and function of the afferent visual pathway in multiple sclerosis and associated optic neuritis

Analysis of the initial orbital MRI in aquaporin-4 antibody-positive optic neuritis (AQP4-ON): lesion location and lesion length can be predictive of visual prognosis

PURPOSE

Despite mounting evidence indicating that aquaporin-4 antibody-positive optic neuritis (AQP4-ON) presents a less favorable prognosis than other types of optic neuritis, there exists substantial heterogeneity in the prognostic outcomes within the AQP4-ON cohort. Considering the persistent debate over the role of MRI in assessing the prognosis of optic neuritis, we aim to investigate the correlation between the MRI appearance and long-term visual prognosis in AQP4-ON patients.

METHODS

We retrospectively reviewed the ophthalmological and imaging data of AQP4-ON patients admitted to our Neuro-ophthalmology Department from January 2015 to March 2018, with consecutive follow-up visits for a minimum of 3 years.

RESULTS

A total of 51 AQP4-ON patients (59 eyes) meeting the criteria were enrolled in this research. After assessing the initial orbital MR images of each patient at the first onset, we observed the involvement of the canalicular segment (p < 0.001), intracranial segment (p = 0.004), optic chiasm (p = 0.009), and the presence of LEON (p = 0.002) were significantly different between recovery group and impairment group. For quantitative measurement, the length of the lesions is significantly higher in the impairment group (20.1 ± 9.3 mm) than in the recovery group (12.5 ± 5.3 mm) (p = 0.001).

CONCLUSION

AQP4-ON patients with involvement of canalicular, intracranial segment and optic chiasm of the optic nerve, and the longer range of lesions threaten worse vision prognoses. Timely MR examination during the initial acute phase can not only exclude the intracranial or orbital mass lesions but also indicate visual prognosis in the long term.

Tissue Hypoxia and Associated Innate Immune Factors in Experimental Autoimmune Optic Neuritis

Visual loss in acute optic neuritis is typically attributed to axonal conduction block due to inflammatory demyelination, but the mechanisms remain unclear. Recent research has highlighted tissue hypoxia as an important cause of neurological deficits and tissue damage in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) and, here, we examine whether the optic nerves are hypoxic in experimental optic neuritis induced in Dark Agouti rats. At both the first and second peaks of disease expression, inflamed optic nerves labelled significantly for tissue hypoxia (namely, positive for hypoxia inducible factor-1α (HIF1α) and intravenously administered pimonidazole). Acutely inflamed nerves were also labelled significantly for innate markers of oxidative and nitrative stress and damage, including superoxide, nitric oxide and 3-nitrotyrosine. The density and diameter of capillaries were also increased. We conclude that in acute optic neuritis, the optic nerves are hypoxic and come under oxidative and nitrative stress and damage. Tissue hypoxia can cause mitochondrial failure and thus explains visual loss due to axonal conduction block. Tissue hypoxia can also induce a damaging oxidative and nitrative environment. The findings indicate that treatment to prevent tissue hypoxia in acute optic neuritis may help to restore vision and protect from damaging reactive oxygen and nitrogen species.

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.

A 4D transcriptomic map for the evolution of multiple sclerosis-like lesions in the marmoset brain

Single-time-point histopathological studies on postmortem multiple sclerosis (MS) tissue fail to capture lesion evolution dynamics, posing challenges for therapy development targeting development and repair of focal inflammatory demyelination. To close this gap, we studied experimental autoimmune encephalitis (EAE) in the common marmoset, the most faithful animal model of these processes. Using MRI-informed RNA profiling, we analyzed ~600,000 single-nucleus and ~55,000 spatial transcriptomes, comparing them against EAE inoculation status, longitudinal radiological signals, and histopathological features. We categorized 5 groups of microenvironments pertinent to neural function, immune and glial responses, tissue destruction and repair, and regulatory network at brain borders. Exploring perilesional microenvironment diversity, we uncovered central roles of EAE-associated astrocytes, oligodendrocyte precursor cells, and ependyma in lesion formation and resolution. We pinpointed imaging and molecular features capturing the pathological trajectory of WM, offering potential for assessing treatment outcomes using marmoset as a platform.

Altered neural intrinsic oscillations in patients with multiple sclerosis: effects of cortical thickness

Objective

To investigate the effects of cortical thickness on the identification accuracy of fractional amplitude of low-frequency fluctuation (fALFF) in patients with multiple sclerosis (MS).

Methods

Resting-state functional magnetic resonance imaging data were collected from 31 remitting MS, 20 acute MS, and 42 healthy controls (HCs). After preprocessing, we first calculated two-dimensional fALFF (2d-fALFF) maps using the DPABISurf toolkit, and 2d-fALFF per unit thickness was obtained by dividing 2d-fALFF by cortical thickness. Then, between-group comparison, clinical correlation, and classification analyses were performed in 2d-fALFF and 2d-fALFF per unit thickness maps. Finally, we also examined whether the effect of cortical thickness on 2d-fALFF maps was affected by the subfrequency band.

Results

In contrast with 2d-fALFF, more changed regions in 2d-fALFF per unit thickness maps were detected in MS patients, such as increased region of the right inferior frontal cortex and faded regions of the right paracentral lobule, middle cingulate cortex, and right medial temporal cortex. There was a significant positive correlation between the disease duration and the 2d-fALFF values in the left early visual cortex in remitting MS patients (r = 0.517, Bonferroni-corrected, p = 0.008 × 4 < 0.05). In contrast with 2d-fALFF, we detected a positive correlation between the 2d-fALFF per unit thickness of the right ventral stream visual cortex and the modified Fatigue Impact Scale (MFIS) scores (r = 0.555, Bonferroni-corrected, p = 0.017 × 4 > 0.05). For detecting MS patients, 2d-fALFF and 2d- fALFF per unit thickness both performed remarkably well in support vector machine (SVM) analysis, especially in the remitting phase (AUC = 86, 83%). Compared with 2d-fALFF, the SVM model of 2d-fALFF per unit thickness had significantly higher classification performance in distinguishing between remitting and acute MS. More changed regions and more clinically relevant 2d-fALFF per unit thickness maps in the subfrequency band were also detected in MS patients.

Conclusion

By dividing the functional value by the cortical thickness, the identification accuracy of fALFF in MS patients was detected to be potentially influenced by cortical thickness. Additionally, 2d-fALFF per unit thickness is a potential diagnostic marker that can be utilized to distinguish between acute and remitting MS patients. Notably, we observed similar variations in the subfrequency band.

Multiple sclerosis progression: time for a new mechanism-driven framework

Traditionally, multiple sclerosis has been categorised by distinct clinical descriptors-relapsing-remitting, secondary progressive, and primary progressive-for patient care, research, and regulatory approval of medications. Accumulating evidence suggests that the clinical course of multiple sclerosis is better considered as a continuum, with contributions from concurrent pathophysiological processes that vary across individuals and over time. The apparent evolution to a progressive course reflects a partial shift from predominantly localised acute injury to widespread inflammation and neurodegeneration, coupled with failure of compensatory mechanisms, such as neuroplasticity and remyelination. Ageing increases neural susceptibility to injury and decreases resilience. These observations encourage a new consideration of the course of multiple sclerosis as a spectrum defined by the relative contributions of overlapping pathological and reparative or compensatory processes. New understanding of key mechanisms underlying progression and measures to quantify progressive pathology will potentially have important and beneficial implications for clinical care, treatment targets, and regulatory decision-making.

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

Background and Objectives

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

Methods

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

Results

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

Discussion

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

Classification of Evidence

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

Evaluation of Retinal Structure and Optic Nerve Function Changes in Multiple Sclerosis: Longitudinal Study with 1-Year Follow-Up

Background

Multiple sclerosis (MS) is an autoimmune disease characterized by inflammation and demyelination of the central nervous system which often involves the optic nerve even though only 20% of the patients experience optic neuritis (ON).

Objective

This study aims to compare the retinal structure and optic nerve function between patients with MS and healthy controls (HCs), evaluate optic nerve alterations in MS over 1-year follow-up, and analyze its correlations with disease duration, number of relapses, degree of disability, and different subtypes.

Methods

This is a prospective cohort study involving 58 eyes of MS patients. Optic nerve function was evaluated with best-corrected visual acuity (BCVA), contrast sensitivity, and P100 latency, while the retinal structure was evaluated from the GCIPL and RNFL thickness measured with optical coherence tomography (OCT) and fundus photography.

Results

The MS group had lower BCVA (p=0.001), contrast sensitivity (p < 0.001), mean GCIPL thickness (p < 0.001), and mean RNFL thickness (p < 0.001) than HC. At 6 and 12 months of observations, GCIPL and RNFL (nasal quadrant) of MS patients decreased significantly (p=0.007 and p=0.004, respectively). Disease duration and the number of relapses correlated with delayed P100 latency (r = −0.61, p < 0.001 and r = −0.46, p=0.02). GCIPL and RNFL in the SPMS subtype were thinner than in RRMS.

Conclusions

The retinal structure and optic nerve function of MS patients are worse than those of normal individuals. GCIPL and RNFL thinning occurs at 6 and 12 months but do not correlate with disease duration, the number of relapses, and degree of disability.

Neuroprotective Effects of Fingolimod Supplement on the Retina and Optic Nerve in the Mouse Model of Experimental Autoimmune Encephalomyelitis

Favorable effects exerted by long-term administration of fingolimod therapy in multiple sclerosis (MS) patients have been reported, but sporadic side effects, such as reversible macular edema, also have been recorded. The present study aimed to determine whether fingolimod therapy is beneficial to the visual system in experimental autoimmune encephalomyelitis (EAE) mice. A decrease in demyelination and axon loss in the optic nerve as well as cellular infiltration, especially the recruited macrophages, was observed in EAE with fingolimod treatment. Fingolimod administration diminished hypergliosis of macroglia, including astrocytes and Müller cells in the retina and optic nerve in EAE. Microglia were hyperactivated in the retina and optic nerve in the EAE mice compared to controls, which could be alleviated by fingolimod treatment. Moreover, apoptosis of retinal ganglion cells (RGC) and oligodendrocytes in the optic nerve was significantly reduced with fingolimod treatment compared to that in the untreated EAE mice. These results suggested that fingolimod exerts neuroprotective and anti-inflammatory effects on the retina and optic nerve in a mouse model of EAE. Considering the paradox of favorable and side effects of fingolimod on visual system, we speculate that side effects including macular oedema caused by fingolimod during MS treatment is tendency to be vasogenic rather than hypergliosis in optic nerve and retina which warrants further neuroophthalmological investigation.

Radiomic analysis of the optic nerve at the first episode of acute optic neuritis: an indicator of optic nerve pathology and a predictor of visual recovery?

OBJECTIVE

Retinal nerve fiber layer thickness (RNFL) is a biomarker of neuroaxonal loss and index of visual function in multiple sclerosis (MS). We aimed to assess the correlation between radiomic features and RNFL, visual acuity (VA) at patients' presentation, visual outcome (VO), and clinical diagnosis.

METHODS

We reviewed imaging and clinical data of 25 patients with a first episode of optic neuritis (ON) (14 females, 11 males; 5 bilateral ON; 7 left ON; 13 right ON). All patients underwent a complete ophthalmological assessment, including visual acuity and RNFL, neurological evaluation, orbits MRI. Segmentation of the optic nerves was performed through 3D slicer open software to get radiomics analysis. All patients underwent a complete neuro-ophthalmological follow-up at 6 months to assess the VO, classified as: complete recovery, partial recovery, deficit persistence/relapse, or visual worsening and were diagnosed as MS or clinically isolated syndrome.

RESULTS

We observed significant correlations between radiomic features and RNFL and between radiomic features and VA. Regression model analysis identified 1 radiomic feature with significant association with VO (Gray Level non-uniformity Normalized, p = 0.004) and 6 radiomic features with significant correlation with diagnosis (High Gray Level Zone Emphasis, p < 0.001; Entropy, p < 0.001, for T1 segmentation; Mean Absolute Deviation, p < 0.001; Coarseness < 0.001; Small Area Low Gray Level Emphasis, p < 0.001; Contrast, p = 0.008, for STIR segmentation).

CONCLUSION

Orbits MRI analysis at the first episode of ON has the potential to assess the visual function and VO in ON patients, and predict MS development.

Volume of Lateral Geniculate Nucleus in Patients with Glaucoma in 7Tesla MRI

The aim of the study was to assess the volume of the lateral geniculate nucleus (LGN) in patients with open-angle glaucoma in 7Tesla MRI and to evaluate its relation to RNFL thickness and VF indices. Material and methods. The studied group consisted of 20 open-angle glaucoma patients with bilaterally the same stage of glaucoma (11 with early glaucoma and nine with advanced glaucoma) and nine healthy volunteers from the Department of Diagnostics and Microsurgery of Glaucoma, Medical University of Lublin, Poland. Circumpapillary RNFL-thickness measurements were performed using OCT in all patients and visual fields were performed in the glaucoma group. A 7Tesla MRI was performed to assess the volume of both lateral geniculate bodies. Results. The LGN volume varied significantly between groups from 122.1 ± 14.4 mm³ (right LGN) and 101.6 ± 13.3 mm³ (left LGN) in the control group to 80.2 ± 17.7 mm³ (right LGN) and 71.8 ± 14.2 mm³ (left LGN) in the advanced glaucoma group (right LGN p = 0.003, left LGN p = 0.018). However, volume values from early glaucoma: right LGN = 120.2 ± 26.5 mm³ and left LGN = 103.2 ± 28.0 mm³ differed significantly only from values from the advanced group (right LGN p = 0.006, left LGN p = 0.012), but not from controls (right LGN p = 0.998, left LGN p = 0.986). There were no significant correlations between visual field indices (MD (mean deviation) and VFI (visual field index)) and LGN volumes in both glaucoma groups. Significant correlations between mean RNFL (retinal nerve fiber layers) thickness and corresponding and contralateral LGN were observed for the control group (corresponding LGN: p = 0.064; contralateral LGN: p = 0.031) and early glaucoma (corresponding LGN: p = 0.017; contralateral LGN: p = 0.008), but not advanced glaucoma (corresponding LGN: p = 0.496; contralateral LGN: p = 0.258). Conclusions. The LGN volume decreases in the course of glaucoma. These changes are correlated with RNFL thickness in early stages of glaucoma and are not correlated with visual field indices.

The Evaluation of Optic Nerves Using 7 Tesla "Silent" Zero Echo Time Imaging in Patients with Leber's Hereditary Optic Neuropathy with or without Idebenone Treatment

Magnetic Resonance Imaging (MRI) of the Optic Nerve is difficult due to the fine extended nature of the structure, strong local magnetic field distortions induced by anatomy, and large motion artefacts associated with eye movement. To address these problems we used a Zero Echo Time (ZTE) MRI sequence with an Adiabatic SPectral Inversion Recovery (ASPIR) fat suppression pulse which also imbues the images with Magnetisation Transfer contrast. We investigated an application of the sequence for imaging the optic nerve in subjects with Leber's hereditary optic neuropathy (LHON). Of particular note is the sequence's near-silent operation, which can enhance image quality of the optic nerve by reducing the occurrence of involuntary saccades induced during Magnetic Resonance (MR) scanning.

Optical coherence tomography: a window to the optic nerve in clinically isolated syndrome

In this study, we aimed to evaluate the association of asymptomatic optic nerve demyelinating lesion in patients presenting a clinically isolated syndrome with the asymptomatic retinal neuro-axonal loss previously reported at clinically isolated syndrome. We prospectively recruited 66 patients presenting a clinically isolated syndrome and 66 healthy control subjects matched according to age and gender. All patients underwent brain magnetic resonance imaging including 3D-double inversion recovery (DIR) sequence, optical coherence tomography examination and visual function evaluation, at 2.5-4.5 months after CIS. Evaluation criteria were presence and length of optic nerve DIR hypersignal, retinal layers (including ganglion cell inner plexiform layer and inner nuclear layer) thickness/volume, and low contrast monocular vision acuity (number of letters correctly identified). All clinically isolated syndrome eyes with past history of optic neuritis (CIS-ON) presented an optic nerve DIR hypersignal. We observed asymptomatic optic nerve DIR hypersignal in 22.2% of clinically isolated syndrome eyes without optic neuritis (CIS-NON). In comparison with healthy control, GCIPL volume (in mm3) was significantly lower in CIS-ON eyes [β (95% confidence interval, CI) = -0.121 (-0.168 to -0.074); P < 0.0001], and to a lesser extent in CIS-NON [β (95% CI) = -0.023 (-0.039 to -0.008); P = 0.004]. In comparison to healthy controls, eyes with asymptomatic optic nerve DIR hypersignal presented significantly lower macular ganglion cell inner plexiform layer volume [β (95% CI) = -0.043 (-0.068 to -0.019); P = 0.001], and eyes without did not [β (95% CI) = -0.016 (-0.034 to 0.003); P = 0.083]. Among CIS-NON, macular ganglion cell inner plexiform layer volume decrease was associated with asymptomatic optic nerve DIR hypersignal independently of optic radiations T2 lesions and primary visual cortex volumes (P = 0.012). Symptomatic optic nerve DIR hypersignal were significantly longer (13.8 ± 6.7 mm) than asymptomatic optic nerve hypersignal (10.0 ± 5.5 mm; P = 0.047). Length of optic nerve DIR hypersignal was significantly associated with thinner inner retinal layers (P ≤ 0.001), thicker inner nuclear layer (P = 0.017) and lower low contrast monocular vision acuity (P < 0.05). Compared to healthy control, low contrast monocular vision acuity was significantly lower in CIS-ON eyes (P < 0.0001) and CIS-NON eyes with (P = 0.03) or without asymptomatic optic nerve DIR hypersignal (P = 0.0005). Asymptomatic demyelinating optic nerve DIR hypersignal at the earliest clinical stage of multiple sclerosis is frequent and associated with asymptomatic retinal neuro-axonal loss reported at clinically isolated syndrome stage. Length of optic nerve DIR hypersignal is a biomarker of retinal neuro-axonal loss and visual disability at clinically isolated syndrome stage. Visual disability of clinically isolated syndrome eyes without clinical and subclinical optic nerve involvement might be due to missed optic nerve lesions on MRI. At the earliest clinical stage of multiple sclerosis, our results support considering optical coherence tomography as a window to the optic nerve rather than to the brain.

Visual evoked potentials after panretinal photocoagulation in patients with proliferative diabetic retinopathy

Purpose

To evaluate the changes of latency and amplitudes of pattern-reversal visual evoked potentials (PRVEP) in patients with proliferative diabetic retinopathy after panretinal photocoagulation (PRP).

Methods

PRVEP was recorded in 21 eyes of 21 patients with proliferative diabetic retinopathy prior to, 1 week after every sessions of laser therapy and 1.5 months after the final treatment. Results were compared between pre and post laser treatment sessions in the study group and paired t-test was used for statistical analysis.

Results

The P100 amplitude showed a significant difference among all treatment sessions with a decreasing trend in the study group after PRP (P<0.001). Also, P100 latency evaluation showed a significant increase after PRP in the study group in all post-PRP sessions (P<0.05). However, 1.5 months after laser treatment, an increase in amplitudes (P<0.001) and a decrease in latencies (P<0.001) of PRVEP were observed and the magnitudes of the parameters approximately returned to their baseline values.

Conclusion

Although decreasing changes in the amplitude and increasing changes in the latency of PRVEP were observed after laser treatment in proliferative diabetic retinopathy patients, one and a half months after the completion of laser therapy, partial recovery of these parameters values was observed.

Effect of Treating Acute Optic Neuritis With Bioequivalent Oral vs Intravenous Corticosteroids: A Randomized Clinical Trial

Importance

Intravenous (IV) administration of corticosteroids is the standard of care in the treatment of acute optic neuritis. However, it is uncertain whether a bioequivalent dose of corticosteroid administered orally, which may be more cost-efficient and convenient for patients, is as effective as IV administration in the treatment of acute optic neuritis.

Objective

To determine whether recovery of vision following treatment of acute optic neuritis with a high-dose IV corticosteroid is superior to that with a bioequivalent dose of an oral corticosteroid.

Design, Setting, and Participants

This single-blind (participants unblinded) randomized clinical trial with 6-month follow-up was conducted at a single tertiary care center in London, Ontario, Canada. Participants were enrolled from March 2012 to May 2015, with the last participant's final visit occurring November 2015. Patients 18 to 64 years of age presenting within 14 days of acute optic neuritis onset, without any recovery at time of randomization and without history of optic neuritis in the same eye, were screened. Inclusion criteria included best-corrected visual acuity (BCVA) of 20/40 or worse and corticosteroids deemed required by treating physician. In total, 89 participants were screened; 64 were eligible, but 9 declined to participate. Thus, 55 participants were enrolled and randomized. Primary analysis was unadjusted and according to the intention-to-treat principle.

Interventions

Participants were randomized 1:1 to the IV methylprednisolone sodium succinate (1000-mg) or oral prednisone (1250-mg) group.

Main Outcomes and Measures

Primary outcome was recovery of the latency of the P100 component of the visual evoked potential at 6 months. Secondary outcomes were the P100 latency at 1 month and BCVA as assessed with Early Treatment Diabetic Retinopathy Study letter scores on the alphabet chart and scores on low-contrast letters at 1 and 6 months.

Results

Of 55 randomized participants, the final analyzed cohort comprised 23 participants in the IV and 22 in the oral treatment groups. The mean (SD) age of the cohort was 34.6 (9.5) years, and there were 28 women (62.2%). At 6 months' recovery, P100 latency in the IV group improved by 62.9 milliseconds (from a mean [SD] of 181.9 [53.6] to 119.0 [16.5] milliseconds), and the oral group improved by 66.7 milliseconds (from a mean [SD] of 200.5 [67.2] to 133.8 [31.5] milliseconds), with no significant difference between groups (P = .07). Similarly, no significant group difference was found in the mean P100 latency recovery at 1 month. For BCVA, recovery between the groups did not reach statistical significance at 1 month or 6 months. In addition, improvements in low-contrast (1.25% and 2.5%) BCVA were not significantly different between treatment groups at 1 or 6 months' recovery.

Conclusions and Relevance

This study finds that bioequivalent doses of oral corticosteroids may be used as an alternative to IV corticosteroids to treat acute optic neuritis.

Trial Registration

clinicaltrials.gov Identifier: NCT01524250.

Color vision testing versus pattern visual evoked potentials and optical coherence tomography parameters in subclinical optic nerve involvement in multiple sclerosis

Acute idiopathic demyelinating optic neuritis is frequently the initial manifestation of multiple sclerosis (MS). We aimed to discuss the value of color vision testing to detect possible optic nerve involvement in patients with MS who had no history of optic neuritis. We evaluated color vision with Farnsworth-Munsell 100 (FM-100) hue test. Total error scores (TES), partial error scores for the red-green axis (RGS) and blue-yellow axis (BYS) were calculated. Topographic optic disc parameters (RNFL, RA, DA, CV, RV, and vertical C/D ratio), total macular volume (TMV), central macular thickness (CMT), and retinal ganglion cell layer (RGCL) were determined using spectral domain optical coherence tomography (SD-OCT). Choroidal thickness (CT) was measured using enhanced depth imaging optical coherence tomography (EDI-OCT). Pattern visual evoked potentials (PVEP) were also performed. Twenty-eight patients with RRMS (56 eyes) and 25 healthy controls (50 eyes) were included. P100 latencies were significantly delayed and P100 amplitudes were significantly reduced in the patient group compared with the controls (p ≤ 0.05). Statistically significant thinning was found in temporal quadrant in the patient group compared with the controls (p = 0.002). TES RGS, and BYS were all increased in the patient group but this was not statistically significant. We found no correlation between TES, RGS, BYS, and P100 latencies or OCT parameters. In our investigation as to whether color vision testing could be a simple biomarker for showing neurodegeneration of the anterior visual pathway regardless of optic neuritis, PVEP and OCT-assessed RNFL thickness seemed to be a more valuable biomarker than color vision testing.

Evoked potentials in diagnosis of visual dysfunction in amateur boxers

OBJECTIVE

Injuries with varying degrees of temporary or permanent visual dysfunction are common in boxing. This study presents clinical diagnostic information regarding the functional integrity of the visual system in elite amateur boxers. The objective of this study was to assess the presence of normal or abnormal pattern visual evoked potentials (VEP). VEP in boxers were analyzed in relation to the nonathletic group and years of boxing activity.

METHODS

Clinical examination involved 31 boxers (21 male and 10 female) and 31 controls homogeneous in terms of age and gender. Pattern-reversal VEP elicited by checkerboard stimuli with large (LC) and small checks (SC) under monocular condition were applied. The latency and amplitude of N75, P100 and N135 components of the VEP waveform were analyzed. Absolute values and interocular differences of P100 latency and N75-P100 amplitude were used in determining VEP abnormalities.

RESULTS

Individual analysis showed prolonged P100 latency in both eyes in one male boxer. Interocular P100 latency differences beyond 8 ms were observed in three male boxers. The N75-P100 amplitude of four boxers exceeded the normal range in both eyes for the LC stimulation and one boxer for the SC stimulation. Interocular N75-P100 amplitude differences beyond the normal range in two cases for both the LC and the SC stimulation were confirmed. There was a positive correlation between years of boxing activity and N75 latency in SC (R = 0.480, p < 0.05) and N75-P100 amplitude in LC (R = -0.370, p < 0.05).

CONCLUSION

Long-term boxing training may cause impairments in neural conductivity in the visual pathway. VEP seem to be a valuable tool in the neurophysiological diagnosis of visual function in contact sports. They can be recommended as a systematical examination for boxers during training processes for the indication and reduction in the incidence of vision-threatening injuries.

Visual cortex neural activity alteration in cervical spondylotic myelopathy patients: a resting-state fMRI study

PURPOSE

We sought to investigate visual cortex neural activity and functional connectivity (FC) alterations in cervical spondylotic myelopathy (CSM) patients using resting-state fMRI (rs-fMRI) and to explore the relationships of these alterations with visual disorder.

METHODS

Twenty-seven CSM patients and 11 healthy controls were recruited as the study and control groups. The amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) values were calculated to represent neural activity, seed-based correlation analysis (SCA) was performed to analyze the FC of visual cortex, and the outcomes were compared between groups. The preoperative best-corrected visual acuity (pre-BCVA) and postoperative BCVA (post-BCVA) of study groups were measured. Correlation analyses of the ALFF/ReHo values with the preoperative and postoperative BCVAs were performed. Correlations of the bilateral BCVAs with the ipsilateral and contralateral visual cortex neural activities were performed.

RESULTS

The ALFF/ReHo values were decreased in the occipital lobe and increased in the cerebellar posterior lobe in the study group (P < 0.05). Increased FC was demonstrated between Brodmann's area 17 and posterior cingulate lobe (P < 0.05). Postoperatively, the BCVAs were ameliorated in 22 oculi dexter (ODs) and 20 oculi sinister (OSs) in the study group. Positive correlations between neural activity in the visual cortex and the preoperative and postoperative BCVAs were detected in the study group. The bilateral BCVAs were positively correlated with either the ipsilateral or contralateral visual cortex neural activity.

CONCLUSION

Both ALFF/ReHo value changes and positive correlations of these changes with BCVA were demonstrated in CSM. The FC between the visual cortex and posterior cingulate lobe was also increased in CSM.

Changes in oxygen saturation and the retinal nerve fibre layer in patients with optic neuritis - a pilot study

PURPOSE

Assessment of retinal oxygen saturation, thickness of a retinal nerve fibre layer (RNFL) and functional changes in the optic nerve during optic neuritis (ON) in patients with multiple sclerosis (MS).

METHODS

Thirty-two patients with ON due to MS within 3 months of onset of symptoms were enrolled [22 females, 10 males, age 34 ± 9 years, median 32.5 years, 22 patients with the clinically isolated syndrome (CIS), 10 patients with relapsing-remitting from of MS (RRMS)]. All patients were examined using optical coherence tomography (OCT model 4000, Carl Zeiss Meditec, Dublin, CA, USA), automatic optical oximetry (Oxymap ehf, Reykjavik, Iceland) and using visual evoked potentials (VEP) (Metronic Keypoint^® , Minneapolis, MN, USA).

RESULTS

Arterio-venous difference (AVD) was increased in patients ON affected eye compared to patients' unaffected eye (PUE) [34.2 ± 4.7 versus 31.3 ± 4.6, p = 0.044 (mean ± standard deviation)]. No statistically significant difference was found in vessel oxygen saturation as well as in RNFL thickness in ON affected eyes when compared to unaffected MS eyes and healthy individuals. Significantly lower optic nerve conduction velocity was found in the affected eye when compared to unaffected MS eye and healthy (p < 0.0001 for both comparisons). No correlation between oxygen saturation values and VEP was observed in patients with MS.

CONCLUSION

The AVD in oxygen saturation is altered in patients with acute ON. In the early stage of ON, AVD could reflect inflammatory and metabolic changes in the affected eye. Therefore, oximetry could be used as another diagnostic method in MS patients in suspicion of ON. This result would be promising for future investigation in this field.

Magnetic resonance imaging findings at the first episode of acute optic neuritis

BACKGROUND

Optic neuritis (ON) is a focal demyelinating event, which may evolve into multiple sclerosis (MS).

OBJECTIVE

To study MRI characteristics in the acute phase of the first ON episode.

METHODS

A prospective population-based study was performed on 31 patients with a first episode of acute ON with a one year follow-up. MRI, clinical evaluation, and detection of aquaporin-4 (AQP4)-IgG and myelin oligodendrocyte glycoprotein (MOG)-IgG was undertaken. For lesion characterization on MRI the optic nerves were divided into three segments: intra-orbital (IO), canalicular (CAN) and chiasmal (CHI).

RESULTS

Lesions of the optic nerve were observed in 80.6%(25/31), with IO location in 48%(12/25), CAN in 8% (2/25) and both IO and CAN in 44%(11/25). Patients who converted to MS had lesions located at IO in 77%(10/13), whereas the group with isolated ON had IO and CAN in 73% (8/11), p = 0.003. Brain lesions were observed in 84% (21/25) at onset of ON; 62%(13/25) progressed to MS with more frequent location in brainstem (p = 0.030) and lesions in periventricular areas (p = 0.015). Spinal cord lesions were detected only in patients who progressed to MS (p = 0.002). MOG-IgG was detected in one patient with an optic nerve lesion located at IO and CAN. Serum AQP4-IgG was detected in none. Follow-up MRI showed progression in optic nerve lesions in 55% (11/20) patients.

CONCLUSIONS

Specific location of optic nerve and brain lesions and the presence of spinal cord lesions in the acute phase of the first ON episode facilitated an MS diagnosis. The extension of optic nerve lesions following ON suggests a long-term progressive degeneration as an important element of ON pathology.

Calibrated imaging reveals altered grey matter metabolism related to white matter microstructure and symptom severity in multiple sclerosis

Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to examine the extent to which specific, evoked grey matter physiological processes were associated with white matter diffusion in MS. Evoked changes in BOLD, cerebral blood flow (CBF), and oxygen metabolism (CMRO₂ ) were measured in visual cortex. Individual differences in the diffusion tensor measure, radial diffusivity, within occipital tracts were strongly associated with MS patients' BOLD and CMRO₂ . However, these relationships were in opposite directions, complicating the interpretation of the relationship between BOLD and white matter microstructural damage in MS. CMRO₂ was strongly associated with individual differences in patients' fatigue and neurological disability, suggesting that alterations to evoked oxygen metabolic processes may be taken as a marker for primary symptoms of MS. This work demonstrates the first application of calibrated and diffusion imaging together and details the first application of calibrated functional MRI in a neurological population. Results lend support for neuroenergetic hypotheses of MS pathophysiology and provide an initial demonstration of the utility of evoked oxygen metabolism signals for neurology research. Hum Brain Mapp 38:5375-5390, 2017. © 2017 Wiley Periodicals, Inc.

Visual system pathology in humans and animal models of blast injury

Injury from blast exposure is becoming a more prevalent cause of death and disability worldwide. The devastating neurological impairments that result from blasts are significant and lifelong. Progress in the development of effective therapies to treat injury has been slowed by its heterogeneous pathology and the dearth of information regarding the cellular mechanisms involved. Within the last decade, a number of studies have documented visual dysfunction following injury. This brief review examines damage to the visual system in both humans and animal models of blast injury. The in vivo use of the retina as a surrogate to evaluate brain injury following exposure to blast is also highlighted.

Evaluation of Visual-Evoked Cerebral Metabolic Rate of Oxygen as a Diagnostic Marker in Multiple Sclerosis

A multiple sclerosis (MS) diagnosis often relies upon clinical presentation and qualitative analysis of standard, magnetic resonance brain images. However, the accuracy of MS diagnoses can be improved by utilizing advanced brain imaging methods. We assessed the accuracy of a new neuroimaging marker, visual-evoked cerebral metabolic rate of oxygen (veCMRO₂), in classifying MS patients and closely age- and sex-matched healthy control (HC) participants. MS patients and HCs underwent calibrated functional magnetic resonance imaging (cfMRI) during a visual stimulation task, diffusion tensor imaging, T₁- and T₂-weighted imaging, neuropsychological testing, and completed self-report questionnaires. Using resampling techniques to avoid bias and increase the generalizability of the results, we assessed the accuracy of veCMRO₂ in classifying MS patients and HCs. veCMRO₂ classification accuracy was also examined in the context of other evoked visuofunctional measures, white matter microstructural integrity, lesion-based measures from T₂-weighted imaging, atrophy measures from T₁-weighted imaging, neuropsychological tests, and self-report assays of clinical symptomology. veCMRO₂ was significant and within the top 16% of measures (43 total) in classifying MS status using both within-sample (82% accuracy) and out-of-sample (77% accuracy) observations. High accuracy of veCMRO₂ in classifying MS demonstrated an encouraging first step toward establishing veCMRO₂ as a neurodiagnostic marker of MS.

Validity of low-contrast letter acuity as a visual performance outcome measure for multiple sclerosis

Low-contrast letter acuity (LCLA) has emerged as the leading outcome measure to assess visual disability in multiple sclerosis (MS) research. As visual dysfunction is one of the most common manifestations of MS, sensitive visual outcome measures are important in examining the effect of treatment. Low-contrast acuity captures visual loss not seen in high-contrast visual acuity (HCVA) measurements. These issues are addressed by the MS Outcome Assessments Consortium (MSOAC), including representatives from advocacy organizations, Food and Drug Administration (FDA), European Medicines Agency (EMA), National Institute of Neurological Disorders and Stroke (NINDS), academic institutions, and industry partners along with persons living with MS. MSOAC goals are acceptance and qualification by regulators of performance outcomes that are highly reliable and valid, practical, cost-effective, and meaningful to persons with MS. A critical step is elucidation of clinically relevant benchmarks, well-defined degrees of disability, and gradients of change that are clinically meaningful. This review shows that MS and disease-free controls have similar median HCVA, while MS patients have significantly lower LCLA. Deficits in LCLA and vision-specific quality of life are found many years after an episode of acute optic neuritis, even when HCVA has recovered. Studies reveal correlations between LCLA and the Expanded Disability Status Score (EDSS), Multiple Sclerosis Functional Composite (MSFC), retinal nerve fiber layer (RNFL) and ganglion cell layer plus inner plexiform layer (GCL + IPL) thickness on optical coherence tomography (OCT), brain magnetic resonance imaging (MRI), visual evoked potential (VEP), electroretinogram (ERG), pupillary function, and King-Devick testing. This review also concludes that a 7-point change in LCLA is clinically meaningful. The overall goal of this review is to describe and characterize the LCLA metric for research and clinical use among persons with MS.

Retinal biomarkers provide "insight" into cortical pharmacology and disease

The retina is an easily accessible out-pouching of the central nervous system (CNS) and thus lends itself to being a biomarker of the brain. More specifically, the presence of neuronal, vascular and blood-neural barrier parallels in the eye and brain coupled with fast and inexpensive methods to quantify retinal changes make ocular biomarkers an attractive option. This includes its utility as a biomarker for a number of cerebrovascular diseases as well as a drug pharmacology and safety biomarker for the CNS. It is a rapidly emerging field, with some areas well established, such as stroke risk and multiple sclerosis, whereas others are still in development (Alzheimer's, Parkinson's, psychological disease and cortical diabetic dysfunction). The current applications and future potential of retinal biomarkers, including potential ways to improve their sensitivity and specificity are discussed. This review summarises the existing literature and provides a perspective on the strength of current retinal biomarkers and their future potential.

Discrepancy between structural and functional visual recovery in patients after trans-sphenoidal pituitary adenoma resection

OBJECTIVE

The relationship between functional and structural measurements is of fundamental importance in monitoring treatment and progression in patients with pituitary adenoma. In the present study, we examined the association between longitudinal changes in standard automated perimetry (SAP), retinal nerve fiber layer (RNFL) thickness and multifocal visual evoked potential (mfVEP) amplitude after transsphenoidal surgery.

METHODS

Thirty patients with pituitary adenoma were recruited from Huashan Hospital between September 2010 and January 2014. The examination included pupil examination, anterior and posterior segment examination, SAP, RNFL and mfVEP. At three months and nine months after transsphenoid surgery, follow-up measurements were conducted in twenty-three patients, and at 18 months after surgery, the same examinations were performed in seven patients.

RESULTS

The average age of patients was 42.6±12.1years, with 23 males and 7 females. The mean score of SAP improved significantly: 1.75 before surgery; 0.62 at three months after surgery (p=0.00) and 0.50 at nine months after surgery (p=0.00). No significant improvement in RNFL thickness was observed at three months or nine months after surgery. The mean score of mfVEP also improved significantly: 0.85 before surgery; 0.53 at three months (p=0.00) and 0.38 at nine months after surgery (P=0.00). No statistical difference was observed in the outcome of patients at nine months of follow-up and 18 months of follow-up.

CONCLUSION

Visual field and mfVEP recovery with unchanged RNFL thickness was observed in patients after transsphenoid pituitary adenoma resection.

Influence of clinical history on MRI interpretation of optic neuropathy

Background and purpose

Clinical history is known to influence interpretation of a wide range of radiologic examinations. We sought to evaluate the influence of the clinical history on MRI interpretation of optic neuropathy.

Materials and methods

107 consecutive orbital MRI scans were retrospectively reviewed by three neuroradiologists. The readers independently evaluated the coronal STIR sequence for optic nerve hyperintensity and/or atrophy (yes/no) and the coronal post-contrast T1WI for optic nerve enhancement (yes/no). Readers initially evaluated the cases blinded to the clinical history. Following a two week washout period, readers again evaluated the cases with the clinical history provided. Inter-reader and reader-clinical radiologist agreement was assessed using Cohen's simple kappa coefficient.

Results

Intra-reader agreement, without and with provision of clinical history, was 0.564–0.716 on STIR and 0.270–0.495 on post-contrast T1WI. Inter-reader agreement was overall fair-moderate. On post-contrast T1WI, inter-reader agreement was significantly higher when the clinical history was provided (p = 0.001). Reader-clinical radiologist agreement improved with provision of the clinical history to the readers on both the STIR and post-contrast T1WI sequences.

Conclusions

In the MRI assessment of optic neuropathy, only modest levels of inter-reader agreement were achieved, even after provision of clinical history. Provision of clinical history improved inter-reader agreement, especially when assessing for optic nerve enhancement. These findings confirm the subjective nature of orbital MRI interpretation in cases of optic neuropathy, and point to the importance of an accurate clinical history. Of note, the accuracy of orbital MRI in the context of optic neuropathy was not assessed, and would require further investigation.

Impact of region-of-interest method on quantitative analysis of DTI data in the optic tracts

Background

To extract DTI parameters from a specific structure, a region of interest (ROI) must be defined. ROI selection in small structures is challenging; the final measurement results could be affected due to the significant impact of small geometrical errors. In this study the optic tracts were analyzed with the aim to assess differences in DTI parameters due to ROI method and to identify the most reliable method.

Methods

Images of 20 healthy subjects were acquired. Fractional anisotropy (FA) was extracted from the optic tracts by four different ROI methods. Manual tracing was performed in 1) the b0 image and 2) a T1-weighted image registered to the FA image. Semi-automatic segmentation was performed based on 3) tractography and 4) the FA-skeleton algorithm in the tract-based spatial statistics (TBSS) framework. Results were analyzed with regard to ROI method as well as to inter-scan, intra-rater and inter-rater reliability.

Results

The resulting FA values divided the ROI methods into two groups that differed significantly: 1) the FA-skeleton and the b0 methods showed higher FA values compared to 2) the tractography and the T1-weighted methods. The intra- and inter-rater variabilities were similar for all methods, except for the tractography method where the inter-rater variability was higher. The FA-skeleton method had a better reproducibility than the other methods.

Conclusion

Choice of ROI method was found to be highly influential on FA values when the optic tracts were analyzed. The FA-skeleton method performed the best, yielding low variability and high repeatability.

Retinal nerve fiber layer changes after transsphenoidal and transcranial pituitary adenoma resection

PURPOSE

Retinal nerve fiber layer (RNFL) will show retrograde degeneration following damage to the optic nerve or the optic tract in patients with pituitary adenoma. RNFL changes after surgery have not been studied thoroughly in patients with the transsphenoidal surgery and patients with the transcranial surgery.

METHODS

Thirty-seven patients with pituitary adenoma were recruited from Huashan hospital between September 2010 and July 2014. Patients were divided into two groups: the transsphenoidal group and the transcranial group. Before surgery, 3 and 9 months after surgery, follow-up optic coherence tomography were conducted.

RESULTS

Twenty-one patients underwent transsphenoidal surgery and 16 patients underwent transcranial surgery. No obvious difference were observed between these two groups before surgery. The mean RNFL thickness did not change significantly in patients who underwent transsphenoidal surgery: 91.1 before surgery, 92.7 at 3 months after surgery (p = 0.392) and 92.8 at 9 months after surgery( p = 0.395). The mean RNFL thickness decreased inpatients who underwent transcranial surgery: 93.6 before surgery, 86.1 at 3 months after surgery (p = 0.000) and 88.1 at 9 months after surgery (p = 0.005).

CONCLUSIONS

In the short time follow-up, there was no change of RNFL thickness in pituitary adenoma patients underwent transsphenoidal surgery, but a decrease inpatients underwent transcranial surgery.

Delayed P100-Like Latencies in Multiple Sclerosis: A Preliminary Investigation Using Visual Evoked Spread Spectrum Analysis

Conduction along the optic nerve is often slowed in multiple sclerosis (MS). This is typically assessed by measuring the latency of the P100 component of the Visual Evoked Potential (VEP) using electroencephalography. The Visual Evoked Spread Spectrum Analysis (VESPA) method, which involves modulating the contrast of a continuous visual stimulus over time, can produce a visually evoked response analogous to the P100 but with a higher signal-to-noise ratio and potentially higher sensitivity to individual differences in comparison to the VEP. The main objective of the study was to conduct a preliminary investigation into the utility of the VESPA method for probing and monitoring visual dysfunction in multiple sclerosis. The latencies and amplitudes of the P100-like VESPA component were compared between healthy controls and multiple sclerosis patients, and multiple sclerosis subgroups. The P100-like VESPA component activations were examined at baseline and over a 3-year period. The study included 43 multiple sclerosis patients (23 relapsing-remitting MS, 20 secondary-progressive MS) and 42 healthy controls who completed the VESPA at baseline. The follow-up sessions were conducted 12 months after baseline with 24 MS patients (15 relapsing-remitting MS, 9 secondary-progressive MS) and 23 controls, and again at 24 months post-baseline with 19 MS patients (13 relapsing-remitting MS, 6 secondary-progressive MS) and 14 controls. The results showed P100-like VESPA latencies to be delayed in multiple sclerosis compared to healthy controls over the 24-month period. Secondary-progressive MS patients had most pronounced delay in P100-like VESPA latency relative to relapsing-remitting MS and controls. There were no longitudinal P100-like VESPA response differences. These findings suggest that the VESPA method is a reproducible electrophysiological method that may have potential utility in the assessment of visual dysfunction in multiple sclerosis.

Therapeutic Advances and Future Prospects in Progressive Forms of Multiple Sclerosis

Identifying effective therapies for the treatment of progressive forms of multiple sclerosis (MS) is a highly relevant priority and one of the greatest challenges for the global MS community. Better understanding of the mechanisms involved in progression of the disease, novel trial designs, drug repurposing strategies, and new models of collaboration may assist in identifying effective therapies. In this review, we discuss various therapies under study in phase II or III trials, including antioxidants (idebenone); tyrosine kinase inhibitors (masitinib); sphingosine receptor modulators (siponimod); monoclonal antibodies (anti-leucine-rich repeat and immunoglobulin-like domain containing neurite outgrowth inhibitor receptor-interacting protein-1, natalizumab, ocrelizumab, intrathecal rituximab); hematopoetic stem cell therapy; statins and other possible neuroprotective agents (amiloride, riluzole, fluoxetine, oxcarbazepine); lithium; phosphodiesterase inhibitors (ibudilast); hormone-based therapies (adrenocorticotrophic hormone and erythropoietin); T-cell receptor peptide vaccine (NeuroVax); autologous T-cell immunotherapy (Tcelna); MIS416 (a microparticulate immune response modifier); dopamine antagonists (domperidone); and nutritional supplements, including lipoic acid, biotin, and sunphenon epigallocatechin-3-gallate (green tea extract). Given ongoing and planned clinical trial initiatives, and the largest ever focus of the global research community on progressive MS, future prospects for developing targeted therapeutics aimed at reducing disability in progressive forms of MS appear promising.

Deficits in tongue motor control are linked to microstructural brain damage in multiple sclerosis: a pilot study

Background

Deterioration of fine motor control of the tongue is common in Multiple Sclerosis (MS) and has a major impact on quality of life. However, the underlying neuronal substrate is largely unknown. Here, we aimed to explore the association of tongue motor dysfunction in MS patients with overall clinical disability and structural brain damage.

Methods

We employed a force transducer based quantitative-motor system (Q-Motor) to objectively assess tongue function in 33 patients with MS. The variability of tongue force output (TFV) and the mean applied tongue force (TF) were measured during an isometric tongue protrusion task. Twenty-three age and gender matched healthy volunteers served as controls. Correlation analyses of motor performance in MS patients with individual disease burden as expressed by the Expanded Disability Status Scale (EDSS) and with microstructural brain damage as measured by the fractional anisotropy (FA) on Diffusion Tensor Imaging were performed.

Results

MS patients showed significantly increased TFV and decreased TF compared to controls (p < 0.02). TFV but not TF was correlated with the EDSS (p < 0.04). TFV was inversely correlated with FA in the bilateral posterior limb of the internal capsule expanding to the brain stem (p < 0.001), a region critical to tongue function. TF showed a weaker, positive and unilateral correlation with FA in the same region (p < 0.001).

Conclusions

Changes in TFV were more robust and correlated better with disease phenotype and FA changes than TF. TFV might serve as an objective and non-invasive outcome measure to augment the quantitative assessment of motor dysfunction in MS.

Optic Neuritis and the Visual Pathway: Evaluation of Neuromyelitis Optica Spectrum by Resting-State fMRI and Diffusion Tensor MRI

BACKGROUND AND PURPOSE

Optic neuritis (ON) is an acute episode of inflammation in the visual pathway (VP). It may occur as part of a demyelinating disease, which can affect white matter (WM) throughout the VP. Compensatory cortical adaptations may occur following WM damage to maintain visual integrity. Our aim was to investigate whether resting-state functional MRI (rsfMRI) can detect cortical adaptations following ON attacks and to correlate rsfMRI with diffusion tensor imaging (DTI) of WM within the VP.

MATERIALS AND METHODS

Neuromyelitis optica spectrum patients were compared to healthy controls at least 6 months after ON onset. DTI and rsfMRI were performed and post-processed using FSL tools (TBSS for DTI and MELODIC for fMRI).

RESULTS

Ptients had higher synchronization values than controls in the visual network (3.48 vs. 2.12, P < .05). A weak trend of correlation was revealed between fMRI and structural analysis by DTI using fractional anisotropy (right side: R = -.36, P < .08; left side: R = .075, P < .73).

CONCLUSIONS

The rsfMRI detected cortical reorganization following ON attack, but WM was considerably preserved in the posterior VP.

Transorbital sonography in acute optic neuritis: a case-control study

BACKGROUND AND PURPOSE

Acute unilateral optic neuritis is associated with a thickening of the retrobulbar portion of the optic nerve as revealed by transorbital sonography, but no comparison has been made between nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis versus healthy controls. We evaluated optic nerve sheath diameter and optic nerve diameter in patients with acute optic neuritis and healthy controls and compared optic nerve sheath diameter and optic nerve diameter with visual-evoked potentials in patients.

MATERIALS AND METHODS

A case-control study was performed in 2 centers. Twenty-one consecutive patients with onset of visual loss during the prior 10 days and established acute noncompressive unilateral optic neuritis were compared with 21 healthy controls, matched for sex and age (±5 years). Two experienced vascular sonographers performed the study by using B-mode transorbital sonography. Visual-evoked potentials were performed on the same day as the transorbital sonography and were evaluated by an expert neurophysiologist. Sonographers and the neurophysiologist were blinded to the status of the patient or control and to clinical information, including the side of the affected eye.

RESULTS

The median optic nerve sheath diameter was thicker on the affected side (6.3 mm; interquartile range, 5.9-7.2 mm) compared with the nonaffected side (5.5 mm; interquartile range, 5.1-6.2 mm; P < .0001) and controls (5.2 mm; interquartile range, 4.8-5.5 mm; P < .0001). The median optic nerve diameter was 3.0 mm (range, 2.8-3.1 mm) on the affected side and 2.9 mm (range, 2.8-3.1 mm) on the nonaffected side (P = not significant.). Both sides were thicker than those in controls (2.7 mm; interquartile range, 2.5-2.8 mm; P = .001 and .009). No correlation was found between optic nerve sheath diameter and optic nerve diameter and amplitude and latency of visual-evoked potentials in patients with optic neuritis.

CONCLUSIONS

Transorbital sonography is a promising tool to support the clinical diagnosis of acute optic neuritis. Further studies are needed to define its specific role in the diagnosis and follow-up of optic neuritis.

Neuroplasticity and functional recovery in multiple sclerosis

The development of therapeutic strategies that promote functional recovery is a major goal of multiple sclerosis (MS) research. Neuroscientific and methodological advances have improved our understanding of the brain's recovery from damage, generating novel hypotheses about potential targets and modes of intervention, and laying the foundation for development of scientifically informed recovery-promoting strategies in interventional studies. This Review aims to encourage the transition from characterization of recovery mechanisms to development of strategies that promote recovery in MS. We discuss current evidence for functional reorganization that underlies recovery and its implications for development of new recovery-oriented strategies in MS. Promotion of functional recovery requires an improved understanding of recovery mechanisms that can be modulated by interventions and the development of robust measurements of therapeutic effects. As imaging methods can be used to measure functional and structural alterations associated with recovery, this Review discusses their use to obtain reliable markers of the effects of interventions.

Distinguishing and quantification of the human visual pathways using high-spatial-resolution diffusion tensor tractography

Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high-spatial-resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways. Five healthy males, age range 24-37years, were studied after approval of the institutional review board (IRB) at The University of Texas Health Science Center at Houston. We acquired diffusion tensor imaging (DTI) data with 1-mm slice thickness on a 3.0-Tesla clinical MRI scanner and analyzed the data using DTT with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high-spatial-resolution DTI protocol with FACT algorithm, we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm, optic tract, optic radiations free of contamination from neighboring white matter tracts.

Development of a high-resolution fat and CSF-suppressed optic nerve DTI protocol at 3T: application in multiple sclerosis

Clinical trials of neuroprotective interventions in multiple sclerosis require outcome measures that reflect the disease pathology. Measures of neuroaxonal integrity in the anterior visual pathways are of particular interest in this context, however imaging of the optic nerve is technically challenging. We therefore developed a 3T optic nerve diffusion tensor imaging protocol incorporating fat and cerebrospinal fluid suppression and without parallel imaging. The sequence used a scheme with six diffusion-weighted directions, b = 600 smm(-2) plus one b ≈ 0 (b(0)) and 40 repetitions, averaged offline, giving an overall scan time of 30 minutes. A coronal oblique orientation was used with voxel size 1.17 mm x 1.17 mm x 4 mm, We validated the sequence in 10 MS patients with a history of optic neuritis and 11 healthy controls: mean fractional anisotropy was reduced in the patients: 0.346(±0.159) versus 0.528(±0.123), p<0.001; radial diffusivity was increased: 0.940(±0.370)x10(-6) mm(2) s(-1) compared to 0.670(± 0.221)x10(-6) mm(2) s(-1) (p<0.01). No significant differences were seen for mean diffusivity or mean axial diffusivity.

Optic neuritis

Acute optic neuritis is the most common optic neuropathy affecting young adults. Exciting developments have occurred over the past decade in understanding of optic neuritis pathophysiology, and these developments have been translated into treatment trials. In its typical form, optic neuritis presents as an inflammatory demyelinating disorder of the optic nerve, which can be associated with multiple sclerosis. Atypical forms of optic neuritis can occur, either in association with other inflammatory disorders or in isolation. Differential diagnosis includes various optic nerve and retinal disorders. Diagnostic investigations include MRI, visual evoked potentials, and CSF examination. Optical coherence tomography can show retinal axonal loss, which correlates with measures of persistent visual dysfunction. Treatment of typical forms with high-dose corticosteroids shortens the period of acute visual dysfunction but does not affect the final visual outcome. Atypical forms can necessitate prolonged immunosuppressive regimens. Optical coherence tomography and visual evoked potential measures are suitable for detection of neuroaxonal loss and myelin repair after optic neuritis. Clinical trials are underway to identify potential neuroprotective or remyelinating treatments for acutely symptomatic inflammatory demyelinating CNS lesions.

The Contribution of Resting State Networks to the Study of Cortical Reorganization in MS

Resting State fMRI (RS-fMRI) represents an emerging and powerful tool to explore brain functional connectivity (FC) changes associated with neurologic disorders. Compared to activation/task-related fMRI, RS-fMRI has the advantages that (i) BOLD fMRI signals are self-generated and independent of subject's performance during the task and (ii) a single dataset is sufficient to extract a set of RS networks (RSNs) that allows to explore whole brain FC. According to these features RS-fMRI appears particularly suitable for the study of FC changes related to multiple sclerosis (MS). In the present review we will first give a brief description of RS-fMRI methodology and then an overview of most relevant studies conducted so far in MS by using this approach. The most interesting results, in particular, regard the default-mode network (DMN), whose FC changes have been correlated with cognitive status of MS patients, and the visual RSN (V-RSN) whose FC changes have been correlated with visual recovery after optic neuritis. The executive control network (ECN), the lateralized frontoparietal network (FPN), and the sensory motor network (SMN) have also been investigated in MS, showing significant FC rearrangements. All together, RS-fMRI studies conducted so far in MS suggest that prominent RS-FC changes can be detected in many RSNs and correlate with clinical and/or structural MRI measures. Future RS-fMRI studies will further clarify the dynamics and clinical impact of RSNs changes in MS.

Assessment of structural and functıonal vısual outcomes ın relapsıng remıttıng multıple sclerosıs wıth vısual evoked potentıals and optıcal coherence tomography

The purpose of this study is to consider the clinical utility of optical coherence tomography (OCT) and find a correlation with VEP. Effects of different disease modifying treatments (DMT) were further evaluated by measuring OCT parameters and whether a correlation exists between the RNFL thickness, disease duration and expanded disability status scale (EDSS) were also assessed. 13 patients were on interferon beta-1a (IFN), 14 patients were receiving glatiramer acetate (GA), 19 patients were not being treated with any DMT and 21 healthy controls were included the study. During OCT examination, retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness was found to be lower in all MS groups but macular volume (MV) was lower only in GA group than controls. Although, P100 latencies were longer than controls in all MS groups, there was no statistically significant difference between IFN and w/o DMT groups. Patients with ON history, P100 latencies were found significantly longer than those without ON. VEP amplitudes were found lower with ON history patients than those without ON, however this was not statistically significant. EDSS strongly correlated with P100 latency, RNLF, GCC but no correlation was observed with VEP amplitude and MV. Our results show that RNFL, GCC and MV were all decreased in MS patients with or without DMT comparing to controls and it is more prominent in eyes with ON. Further follow-up studies are warranted to understand the pathophysiology of CNS axonal degeneration and involvement of optic nerves.

Visual pathway abnormalities were found in most multiple sclerosis patients despite history of previous optic neuritis

OBJECTIVE

It was to investigate visual field (VF) abnormalities in a group of multiple sclerosis (MS) patients in the remission phase and the presence of magnetic resonance imaging (MRI) lesions in the optic radiations.

METHODS

VF was assessed in 60 participants (age range 20-51 years): 35 relapsing-remitting MS patients [20 optic neuritis (+), 15 optic neuritis (-)] and 25 controls. MRI (3-Tesla) was obtained in all patients.

RESULTS

Visual parameters were abnormal in MS patients as compared to controls. The majority of VF defects were diffuse. All patients except one had posterior visual pathways lesions. No significant difference in lesion number, length and distribution was noted between patients with and without history of optic neuritis. One patient presented homonymous hemianopsia.

CONCLUSION

Posterior visual pathway abnormalities were found in most MS patients despite history of previous optic neuritis.

Functional assessment of the visual pathway with multifocal visual evoked potentials, and their relationship with disability in patients with multiple sclerosis

Objective:

To objectively evaluate the visual function, and the relationship between disability and optic nerve dysfunction, in patients with multiple sclerosis (MS) and optic neuritis (ON), using multifocal visual evoked potentials (mfVEP).

Methods:

This observational, cross-sectional study assessed 28 consecutive patients with clinically definite MS, according to the McDonald criteria, and 19 age-matched healthy subjects. Disability was recorded using the Expanded Disability Status Scale (EDSS) score. The patients’ mfVEP were compared to their clinical, psychophysical (Humphrey perimetry) and structural (optic coherence tomography (OCT)) diagnostic test data.

Results:

We observed a significant agreement between mfVEP amplitude and Humphrey perimetry/OCT in MS-ON eyes, and between mfVEP amplitude and OCT in MS but non-ON eyes. We found significant differences in EDSS score between patients with abnormal and normal mfVEP amplitudes. Abnormal mfVEP amplitude defects (from interocular and monocular probability analysis) were found in 67.9% and 73.7% of the MS-ON and MS-non-ON group eyes, respectively. Delayed mfVEP latencies (interocular and monocular probability analysis) were seen in 70.3% and 73.7% of the MS-ON and MS-non-ON groups, respectively.

Conclusions:

We found a significant relationship between mfVEP amplitude and disease severity, as measured by EDSS score, that suggested there is a role for mfVEP amplitude as a functional biomarker of axonal loss in MS.

Wallerian and trans-synaptic degeneration contribute to optic radiation damage in multiple sclerosis: a diffusion tensor MRI study

Background:

Optic radiation (OR) damage occurs in multiple sclerosis (MS).

Objectives:

The purpose of this study was to explore the contribution of local and distant mechanisms associated with OR damage in MS.

Methods:

Diffusion tensor (DT) magnetic resonance imaging (MRI) tractography probability maps of the ORs were derived from 102 MS patients and 11 controls. Between-group differences of OR normal-appearing white matter (NAWM) damage and topographical distribution of OR damage were assessed using quantitative and voxel-wise analyses, considering the influence of previous optic neuritis (ON+) and T2 OR lesions (T2 OR+).

Results:

OR NAWM diffusivity abnormalities were more severe in ON+ patients vs patients without previous optic neuritis (ON–) and T2 OR+ vs T2 OR– patients. Damage to the anterior portions of the ORs was more severe in ON+ vs ON– patients. Compared to controls and T2 OR– patients, T2 OR+ patients experienced a more distributed pattern of DT MRI abnormalities along the ORs, with an increased axial diffusivity limited to the anterior portions of the ORs. In T2 OR+ group, ON+ vs ON– patients showed DT MRI abnormalities in the middle portion of the ORs, in correspondence with focal lesions. OR damage correlated with OR T2 lesion volume, visual dysfunction and optic nerve atrophy.

Conclusions:

Both trans-synaptic degeneration secondary to optic nerve damage and Wallerian degeneration due to local T2 lesions contribute to OR damage in MS.

Neuroprotection for acute optic neuritis-Can it work?

Optic neuritis is a common manifestation of MS and the acute inflammatory lesion in the optic nerve resembles demyelinating plaques elsewhere in the CNS. As with other MS relapses, treatment with corticosteroids has little or no impact on the extent to which vision eventually recovers after an attack of optic neuritis. Neuroaxonal loss is now recognised as a major cause of permanent disability. Imaging of the retinal nerve fibre layer with optical coherence tomography (OCT) and of the optic nerve with MRI both demonstrate significant volume loss which correlates with impaired visual function. The extent of axonal loss correlates with the magnitude of inflammation and there is robust evidence that excessive accumulation of sodium ions within axons in an inflammatory environment leads to axonal degeneration. Partial blockade of sodium channels protects against axonal loss and improves clinical outcome in experimental models of MS. The recent randomised placebo-controlled trial of lamotrigine in secondary progressive MS did not demonstrate a protective effect on brain atrophy, and indeed the opposite effect was observed during the first year of treatment. Despite this, there were some positive treatment signals. Specifically the rate of decline of walking speed was halved in the active group compared to placebo and the treatment compliant group had a significantly lower serum concentration of neurofilament. The limitiations in the design of the lamotrigine trial have been addressed in the ongoing trial of neuroprotection with phenytoin in acute optic neuritis. Specifically, treatment will be tested in an early inflammatory lesion and the readout will be timed beyond the lag in development of atrophy in the optic nerve and retina and after any treatment related volume changes have subsided. If the treatment is successful, this form of neuroprotection should improve the recovery from relapses in general, since the pathophysiology of optic neuritis resembles that of other MS relapses.

Deimination restores inner retinal visual function in murine demyelinating disease

Progressive loss of visual function frequently accompanies demyelinating diseases such as multiple sclerosis (MS) and is hypothesized to be the result of damage to the axons and soma of neurons. Here, we show that dendritic impairment is also involved in these diseases. Deimination, a posttranslational modification, was reduced in the retinal ganglion cell layer of MS patients and in a transgenic mouse model of MS (ND4 mice). Reduced deimination accompanied a decrease in inner retinal function in ND4 mice, indicating loss of vision. Local restoration of deimination dramatically improved retinal function and elongation of neurites in isolated neurons. Further, neurite length was decreased by downregulation of deimination or siRNA knockdown of the export-binding protein REF, a primary target for deimination in these cells. REF localized to dendrites and bound selective mRNAs and translation machinery to promote protein synthesis. Thus, protein deimination and dendritic outgrowth play key roles in visual function and may be a general feature of demyelinating diseases.