Neuromodulation in multiple sclerosis.

Neuromodulation, or the utilization of advanced technology for targeted electrical or chemical neuronal stimulation or inhibition, has been expanding in several neurological subspecialties. In the past decades, immune-modulating therapy has been the main focus of multiple sclerosis (MS) research with little attention to neuromodulation. However, with the recent advances in disease-modifying therapies, it is time to shift the focus of MS research to neuromodulation and restoration of function as with other neurological subspecialties. Preliminary research supports the value of intrathecal baclofen pump and functional electrical stimulation in improving spasticity and motor function in MS patients. Deep brain stimulation can improve MS-related tremor and trigeminal neuralgia. Spinal cord stimulation has been shown to be effective against MS-related pain and bladder dysfunction. Bladder overactivity also responds to sacral neuromodulation and posterior tibial nerve stimulation. Despite limited data in MS, transcranial magnetic stimulation and brain-computer interface are promising neuromodulatory techniques for symptom mitigation and neurorehabilitation of MS patients. In this review, we provide an overview of the available neuromodulatory techniques and the evidence for their use in MS.

Human memory T cells from the bone marrow are resting and maintain long-lasting systemic memory.

In the bone marrow, a population of memory T cells has been described that promotes efficient secondary immune responses and has been considered to be preactivated, owing to its expression of CD69 and CD25. Here we show that human bone marrow professional memory T cells are not activated but are resting in terms of proliferation, transcription, and mobility. They are in the G0 phase of the cell cycle, and their transcriptome is that of resting T cells. The repertoire of CD4(+) bone marrow memory T cells compared with CD4(+) memory T cells from the blood is significantly enriched for T cells specific for cytomegalovirus-pp65 (immunodominant protein), tetanus toxoid, measles, mumps, and rubella. It is not enriched for vaccinia virus and Candida albicans-MP65 (immunodominant protein), typical pathogens of skin and/or mucosa. CD4(+) memory T cells specific for measles are maintained nearly exclusively in the bone marrow. Thus, CD4(+) memory T cells from the bone marrow provide long-term memory for systemic pathogens.

Utility of the 2023 international MOGAD panel proposed criteria in clinical practice: An institutional cohort.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a recently defined demyelinating disorder with a rapidly evolving clinical spectrum. Recently, consensus criteria have been proposed (Banwell et al., 2023) to help with disease diagnosis. However, validation of the proposed criteria in real-life MOGAD patients is lacking. In this study, we applied the proposed criteria to an institutional cohort of MOG antibody-positive patients. METHODS: A retrospective study was conducted at a tertiary neuroimmunology clinic from 2018 to 2023. Patients who had at least one core clinical feature of MOGAD and positive serum MOG antibody by cell-based assay were included. Demographics and clinical data were recorded and analyzed. Cases were divided into definite MOGAD, questionable MOGAD, and false-positive MOG antibody as determined by the treating neuroimmunology and/or neuro-ophthalmology specialists prior to applying the new MOGAD criteria by an independent investigator. We then calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the new criteria compared to the treating physicians' assessment. RESULTS: A total of 27 patients were included of which, 19 (70.4%) were female, the average age of the sample was 44 +/- 15 years. High titer MOG antibody (≥ 1:100) was found in 11 patients (40.7%); low titer (< 1: 100) in 13 (48.1%), and unreported titer in 3 patients. As determined by expert opinion; 18 (66.7%) were identified as definitive MOGAD, 6 (22.2%) as false-positive MOG antibody, and 3 (11.1%) as questionable MOGAD. All 18 patients identified by clinicians as definite MOGAD met the new 2023 criteria. Of the 9 patients with questionable MOGAD or false-positive MOG antibody, four patients met the 2023 MOGAD criteria. Those four patients had the following final diagnoses: CNS vasculitis, primary progressive MS with activity and progression, pseudotumor cerebri, and bevacizumab-induced anterior ischemic optic neuropathy in the setting of paraneoplastic retinopathy. Compared to clinician assessment, applying the 2023 MOGAD criteria to our institutional cohort yielded a sensitivity of 100%, a specificity of 55.5%, a positive predictive value of 81.5% and a negative predictive value of 100%. CONCLUSION: These findings suggest that the 2023 MOGAD criteria are highly sensitive for detection of definite MOGAD but has modest specificity. A number of MOGAD mimickers can resemble the core clinical events of MOGAD and share similar supportive clinical and MRI features. Clinicians should practice caution when evaluating patients with low titer MOG antibody even if they meet the additional supportive features proposed by the 2023 criteria. Further studies are needed to evaluate the 2023 criteria in larger cohorts and in the pediatric population.

Exacerbation of myasthenia gravis with voriconazole.

INTRODUCTION: We describe a patient with stable generalized myasthenia gravis who presented with new onset severe ophthalmoplegia and ptosis after initiation of voriconazole for aspergillosis. METHODS: Ligand-protein docking software was used to simulate the interaction of voriconazole with the acetylcholine receptor (AChR). We tested voriconazole binding to AChR in comparison to high affinity and neutral compounds. RESULTS: There was no clinical improvement after intravenous immunoglobulin infusion and plasmapheresis. However, the patient improved slowly after withdrawal of voriconazole. Based on our results, voriconazole binds favorably to AChR and may putatively block muscle nicotinic AChRs. Other theoretical explanations include blocking potassium channels and reducing their intracellular trafficking. CONCLUSIONS: The mechanisms involved in ocular exacerbation may be multi-factorial, reflecting the intricate dynamics of the neuromuscular junction. It is important to consider medications that harbor pyridine or pyrimidine moieties as potential causes of exacerbation in myasthenic patients, especially those who present with ocular symptoms.

Predictors of hypogammaglobulinemia and serious infections among patients receiving ocrelizumab or rituximab for treatment of MS and NMOSD.

BACKGROUND AND OBJECTIVES: Ocrelizumab and rituximab are monoclonal antibodies targeting the CD20 marker on B lymphocytes. The enhanced efficacy of B lymphocyte depleting therapies poses a greater risk of decreased immunoglobulin (Ig) levels. The rate and risk factors of hypogammaglobulinemia in MS and NMOSD patients treated with anti-CD20 therapies are unknown. METHODS: A retrospective study was conducted among patients who received anti-CD20 therapy for the treatment of MS, NMOSD, and other related neurological disorders. The goal was to determine the incidence and risk factors of hypogammaglobulinemia and serious infections in patients receiving ocrelizumab versus rituximab. The secondary goals were to determine the rates of lymphopenia, neutropenia, and early B cell repopulation among patients on anti-CD20 therapy. RESULTS: Overall, 184 patients (mean age 48.4 ± 13.7, 66.8% female) met inclusion criteria; 152 patients received ocrelizumab and 32 patients received rituximab. A total of 22 patients (12%) developed hypogammaglobulinemia. Patients who developed hypogammaglobulinemia were more likely to have been ≥50 years of age (p = .0275) with lower baseline IgG (p = .001) and IgA (p = .0038) levels. Serious infections were observed in 21 patients (11%) and seen more commonly in those that developed total lymphopenia (<1.0 × 109/L) and had longer duration of B-cell therapy. Multivariate analysis identified age ≥ 50 years, white race, and rituximab as independent predictors of hypogammaglobulinemia, and absolute lymphopenia as an independent risk factor for serious infections. DISCUSSION: Among patients receiving anti-CD20 therapy, 12% of patients experienced hypogammaglobulinemia which was seen more commonly in white patients, at least 50 years old, with lower baseline IgG and IgA levels and in those treated with rituximab. Serious infections were seen more commonly in patients with total lymphopenia and longer exposure to anti-CD20 therapy.

Predicting the final clinical phenotype after the first attack of optic neuritis.

BACKGROUND AND OBJECTIVES: To evaluate the factors determining the final clinical phenotype after an initial isolated attack of optic neuritis (ON). ON could be an isolated event or the initial presentation of a chronic neuroimmunological condition. METHODS: This was a retrospective analysis of patients presenting to University Hospitals Cleveland Medical Center for an initial, isolated attack of ON. Final clinical phenotypes were idiopathic ON, multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein associated disease (MOGAD), or secondary ON (e.g. neurosarcoidosis). Several potential predictors at the time of initial presentation were compared among the different phenotypes to determine early predictors. Categorical variables were compared using Pearson χ2 or Fisher's exact test, and continuous variables were compared using independent t-test. RESULTS: Sixty-four patients met criteria (average age 41.3 ± 13.3, 78.1% females). Average time to final diagnosis was 8.3 months, and average follow-up was 47 months. The final phenotypes were MS (22, 34%), idiopathic ON (14, 22%), MOGAD (11, 17%), NMOSD (10, 16%), and secondary ON (7, 11%). White race, unilateral ON, short segment hyperintensity on orbital MRI, classical demyelination on brain MRI, and not requiring PLEX were associated with MS. Older age, poor steroid responsiveness, and requiring PLEX were associated with NMOSD. African American race, bilateral ON, papillitis on fundoscopy, long segment hyperintensity on orbital MRI, and normal brain MRI were associated with MOGAD. Normal or thinned retinal nerve fiber layer on OCT, short segment hyperintensity on orbital MRI, and normal brain MRI were associated with idiopathic ON. CONCLUSION: The final clinical phenotype may be predictable at the time of initial ON presentation. This requires a careful evaluation of patient demographics, treatment response, funduscopic findings, OCT, and orbital and brain MRIs. Utilizing early predictors in clinical practice could better inform prognosis and management decisions.

Distinctive features of saccadic intrusions and microsaccades in progressive supranuclear palsy.

The eyes do not stay perfectly still during attempted fixation; fixational eye movements and saccadic intrusions (SIs) continuously change the position of gaze. The most common type of SI, square-wave jerks (SWJs), consists of saccade pairs that appear purely horizontal on clinical inspection: the first saccade moves the eye away from the fixation target, and after a short interval, the second saccade brings it back toward the target. SWJs are prevalent in certain neurological disorders, including progressive supranuclear palsy (PSP). Here, we developed an objective method to identify SWJs. We found that SWJs are more frequent, larger, and more markedly horizontal in PSP patients than in healthy human subjects. Furthermore, the loss of a vertical component in fixational saccades and SWJs was the eye movement feature that best distinguished PSP patients from controls. We moreover determined that, in PSP patients and controls, the larger the saccade the more likely it was part of a SWJ. Furthermore, saccades produced by PSP patients had equivalent properties whether they were part of a SWJ or not, suggesting that normal fixational saccades (microsaccades) are rare in PSP. We propose that fixational saccades and SIs are generated by the same neural circuit and that, both in PSP patients and in controls, SWJs result from a coupling mechanism that generates a second corrective saccade shortly after a large fixation saccade. Because of brainstem and/or cerebellum impairment, fixational saccades in PSP are abnormally large and thus more likely to trigger a corrective saccade, giving rise to SWJs.

Prevalence of iatrogenic CNS inflammation at a tertiary neuroimmunology clinic.

BACKGROUND: Various vaccines, tumor-necrosis-factor-alpha inhibitors (TNFAIs), immune-checkpoint inhibitors (ICIs), and other immunomodulators have been linked to inflammatory CNS events. The prevalence of iatrogenic events in the neuroimmunology clinic is unknown. OBJECTIVE: To evaluate the prevalence and clinical characteristics of iatrogenic CNS inflammation in a tertiary neuroimmunology clinic. METHODS: We analyzed 422 consecutive patients seen over five years at a tertiary neuroimmunology clinic who were systematically screened for exposure to vaccines, TNFAIs, ICIs, or other immunomodulators. In patients with suspected iatrogenic events, the Naranjo Adverse Drug Reaction Probability Scale was used to score the probability of iatrogenicity. RESULTS: In total, 27 potential iatrogenic events were observed, accounting for 6.4% of all new referrals. The average Naranjo score was 5.78 +/- 1.65 with 74% of the cases scored as probable and 26% scored as possible. The clinical phenotypes included MS relapses (37%); autoimmune encephalitis (30%); NMOSD attacks (15%); transverse myelitis (11%); optic neuritis (4%); and MOGAD attacks (4%). A monophasic course was observed in 44% of cases while 41% had a relapsing course. All patients stopped or interrupted treatment with the offending agent. In addition, 41% of the iatrogenic events were fully responsive to corticosteroids; 22% were partially responsive; and 15% resolved spontaneously. The most common potential triggers were vaccines (37%) followed by TNFAIs (33%) then ICIs (26%). A significantly higher number of probable iatrogenic events were observed among the ICI and vaccine groups compared to a higher number of possible events among the TNFAI group. The latter group also had a significantly longer interval since exposure. The ICI group was more likely to present with monophasic autoimmune encephalitis. CONCLUSION: Iatrogenic CNS inflammation is rare and typically involves steroid-responsive monophasic events. A subset of iatrogenic events can unmask or worsen relapsing disorders. The probability of iatrogenicity was higher in vaccine and ICI-related events compared to TNFAI-related events.

The humoral response to SARS-COV-2 vaccines in MS patients: A case series exploring the impact of DMT, lymphocyte count, immunoglobulins, and vaccine type.

BACKGROUND & OBJECTIVES: Certain disease modifying therapies may negatively impact the humoral response to SARS-CoV-2 vaccines. Many MS related clinical, demographic, and immunological characteristics can also affect vaccine response but those have not been fully explored. This study aimed to investigate potential correlations between clinical, demographic, and immunological variables in MS patients to post-vaccination spike protein antibody positivity rates and levels. METHODS: Patients with MS and related neuroimmunological disorders who requested verification of the immune response to the SARS-COV-2 vaccine were tested for the spike protein antibody from January to October 2021. We performed an exploratory analysis to compare patients with positive versus negative spike protein antibody. RESULTS: Fifty patients (mean age 53 ±12, 78% females) were included. There were 29 patients with positive post-vaccination spike protein antibody (58%) and 21 with negative antibody (42%). Patients with negative antibody were more likely to have been on B-cell therapy (86% vs 31%, P=.001) while positive patients were more likely to have been on a fumarate (31% vs 4.8%, P=.03). Thirty percent of positive patients on fumarate therapy had mild lymphopenia. No differences existed between groups in gender, age, race, disease phenotype, vaccine brand, and lymphocyte counts. Among patients on B-cell therapy, 33% had a positive spike protein antibody. There was an association between detectable CD19 cells at time of vaccination and positive humoral response to vaccination (P=0.049). There was no relationship between subgroups in terms of vaccine timing relative to B-cell therapy dose. Hypogammaglobulinemia was not associated with seroconversion rates, however it was associated with decreased quantitative spike protein antibody levels (p=0.045). DISCUSSION: B-cell therapy is associated with a negative humoral response to SARS-COV-2 vaccines. Patients on B-cell depleting therapy with detectable CD19 counts at the time of vaccination were associated with a positive humoral response. There was no relationship between hypogammaglobinemia and seroconversion rate, however it was associated with decreased spike protein antibody levels. The fumarates are associated with positive humoral response even in the presence of mild lymphopenia.

Simple Detection of Unstained Live Senescent Cells with Imaging Flow Cytometry.

Cellular senescence is a hallmark of aging and a promising target for therapeutic approaches. The identification of senescent cells requires multiple biomarkers and complex experimental procedures, resulting in increased variability and reduced sensitivity. Here, we propose a simple and broadly applicable imaging flow cytometry (IFC) method. This method is based on measuring autofluorescence and morphological parameters and on applying recent artificial intelligence (AI) and machine learning (ML) tools. We show that the results of this method are superior to those obtained measuring the classical senescence marker, senescence-associated beta-galactosidase (SA-ß-Gal). We provide evidence that this method has the potential for diagnostic or prognostic applications as it was able to detect senescence in cardiac pericytes isolated from the hearts of patients affected by end-stage heart failure. We additionally demonstrate that it can be used to quantify senescence "in vivo" and can be used to evaluate the effects of senolytic compounds. We conclude that this method can be used as a simple and fast senescence assay independently of the origin of the cells and the procedure to induce senescence.

Residual symptoms and long-term outcomes after all-cause autoimmune encephalitis in adults.

BACKGROUND AND OBJECTIVES: To evaluate residual symptoms after all-cause autoimmune encephalitis in a real-life outpatient setting and compare long-term outcome measures. A secondary objective was to identify correlates of poor outcomes. METHODS: We analyzed patients referred to the Neuroimmunology clinic for evaluation of autoimmune encephalitis for whom standardized data were collected. We compared the prevalence of symptoms at the latest follow-up to presentation and calculated symptom improvement rates. We compared the Modified Rankin Scale (mRS) to the Clinical Assessment Scale for Autoimmune Encephalitis (CASE). Non-parametric Wilcoxon rank sum tests and Fisher's exact tests were used to compare clinical attributes between patients with and without poor outcomes. RESULTS: We evaluated 54 patients from 2017 to 2021 of whom 33 met inclusion criteria (average age 47±20 years, 57% females, 55% seropositive). By latest follow-up, 94% improved compared to presentation but six patients (18%) had poor outcomes as defined by an mRS ≥3. The most common residual symptoms were cognitive and mood dysfunction. The highest improvement rates were in alertness and psychosis while the lowest were in motor function and ataxia. CASE had moderate correlation with mRS (r2 = 0.53 [95%CI:0.23,0.74, p = 0.0015) but it captured more nuances than mRS at both presentation and follow-up. Older age and higher post-treatment CASE score correlated with poor outcomes. DISCUSSION: Most autoimmune encephalitis patients experience symptom improvement post-treatment. The CASE score was more representative of the wide symptomatic spectrum of autoimmune encephalitis and correlated with poor outcomes. However, CASE did not capture patients with dysautonomia, sleep dysfunction, or death.

Small Extracellular Vesicles Secreted by Nigrostriatal Astrocytes Rescue Cell Death and Preserve Mitochondrial Function in Parkinson's Disease.

Extracellular vesicles (EVs) are emerging as powerful players in cell-to-cell communication both in healthy and diseased brain. In Parkinson's disease (PD)-characterized by selective dopaminergic neuron death in ventral midbrain (VMB) and degeneration of their terminals in striatum (STR)-astrocytes exert dual harmful/protective functions, with mechanisms not fully elucidated. Here, this study shows that astrocytes from the VMB-, STR-, and VMB/STR-depleted brains release a population of small EVs  in a region-specific manner. Interestingly, VMB-astrocytes secreted the highest rate of EVs, which is further exclusively increased in response to CCL3, a chemokine that promotes robust dopaminergic neuroprotection in different PD models. The neuroprotective potential of nigrostriatal astrocyte-EVs is investigated in differentiated versus undifferentiated SH-SY5Y cells exposed to oxidative stress and mitochondrial toxicity. EVs from both VMB- and STR-astrocytes counteract H2 O2 -induced caspase-3 activation specifically in differentiated cells, with EVs from CCL3-treated astrocytes showing a higher protective effect. High resolution respirometry further reveals that nigrostriatal astrocyte-EVs rescue neuronal mitochondrial complex I function impaired by the neurotoxin MPP+ . Notably, only EVs from VMB-astrocyte fully restore ATP production, again specifically in differentiated SH-SY5Y. These results highlight a regional diversity in the nigrostriatal system for the secretion and activities of astrocyte-EVs, with neuroprotective implications for PD.

Disorders of vergence eye movements.

PURPOSE OF REVIEW: The aim is to re-interpret disorders of vergence in the light of recent studies that view disjunctive eye movements as but one component of three-dimensional gaze control. RECENT FINDINGS: Most natural eye movements combine vergence with saccades, pursuit and vestibular eye movements. Electrophysiological studies in epileptic patients, as well as evidence from monkeys, indicate that frontal and parietal cortex govern vergence as a component of three-dimensional gaze. Clinicians apply Hering's law of equal innervation to interpret disjunctive movements as the superposition of conjugate and vergence commands. However, electrophysiological studies indicate that disjunctive saccades are achieved by programming each eye's movement independently. Patients with internuclear ophthalmoplegia (INO) may have preserved vergence, which can be recruited to compensate for loss of conjugacy. Vergence may also enable gaze shifts in saccadic palsy. Some forms of nystagmus suppress or change with convergence; co-contraction of the horizontal rectus muscles does not appear to be the explanation. Rather, effects of near viewing on central vestibular mechanisms or differential activation of specific types of extra-ocular muscle fiber may be responsible. SUMMARY: Interpretation of disorders of vergence is aided by applying a scheme in which their contributions to three-dimensional gaze control is considered.

The role of the medial longitudinal fasciculus in horizontal gaze: tests of current hypotheses for saccade-vergence interactions.

Rapid shifts of the point of visual fixation between equidistant targets require equal-sized saccades of each eye. The brainstem medial longitudinal fasciculus (MLF) plays a cardinal role in ensuring that horizontal saccades between equidistant targets are tightly yoked. Lesions of the MLF--internuclear ophthalmoparesis (INO)--cause horizontal saccades to become disjunctive: adducting saccades are slow, small, or absent. However, in INO, convergence movements may remain intact. We studied horizontal gaze shifts between equidistant targets and between far and near targets aligned on the visual axis of one eye (Müller test paradigm) in five cases of INO and five control subjects. We estimated the saccadic component of each movement by measuring peak velocity and peak acceleration. We tested whether the ratio of the saccadic component of the adducting/abducting eyes stayed constant or changed for the two types of saccades. For saccades made by control subjects between equidistant targets, the group mean ratio (±SD) of adducting/abducting peak velocity was 0.96 ± 0.07 and adducting/abducting peak acceleration was 0.94 ± 0.09. Corresponding ratios for INO cases were 0.45 ± 0.10 for peak velocity and 0.27 ± 0.11 for peak acceleration, reflecting reduced saccadic pulses for adduction. For control subjects, during the Müller paradigm, the adducting/abducting ratio was 1.25 ± 0.14 for peak velocity and 1.03 ± 0.12 for peak acceleration. Corresponding ratios for INO cases were 0.82 ± 0.18 for peak velocity and 0.48 ± 0.13 for peak acceleration. When adducting/abducting ratios during Müller versus equidistant targets paradigms were compared, INO cases showed larger relative increases for both peak velocity and peak acceleration compared with control subjects. Comparison of similar-sized movements during the two test paradigms indicated that whereas INO patients could decrease peak velocity of their abducting eye during the Müller paradigm, they were unable to modulate adducting velocity in response to viewing conditions. However, the initial component of each eye's movement was similar in both cases, possibly reflecting activation of saccadic burst neurons. These findings support the hypothesis that horizontal saccades are governed by disjunctive signals, preceded by an initial, high-acceleration conjugate transient and followed by a slower vergence component.

Current and emerging therapeutics for neuromyelitis optica spectrum disorder: Relevance to the COVID-19 pandemic.

Neuromyelitis optica spectrum disorder (NMOSD) can lead to immobility and bulbar weakness. This, in addition to the older age of onset and the higher rate of hospitalization compared to multiple sclerosis, makes this patient group a potential target for complicated COVID-19 infection. Moreover, many of the commonly used preventive therapies for NMOSD are cell-depleting immunouppsressants with increased risk of viral and bacterial infections. The emergence of several new NMOSD therapeutics, including immune-modulating agents, concurrently with the worldwide spread of the COVID-19 global pandemic call for careful therapeutic planning and add to the complexity of NMOSD management. Altering the common therapeutic approach to NMOSD during the pandemic may be necessary to balance both efficacy and safety of treatment. Selection of preventive therapy should take in consideration the viral exposure risk related to the route and frequency of administration and, most importantly, the immunological properties of each therapeutic agent and its potential impact on the risk of SARS-CoV-2 susceptibility and severity of infection. The impact of the therapeutic agent on the immune response against the future SARS-CoV-2 vaccine should also be considered in the clinical decision-making. In this review, we will discuss the immune response against SARS-CoV-2 and evaluate the potential impact of the current and emerging NMOSD therapeutics on infection risk, infection severity, and future SARS-CoV-2 vaccination. We propose a therapeutic approach to NMOSD during the COVID-19 pandemic based on analysis of the mechanism of action, route of administration, and side effect profile of each therapeutic agent.

Multiple Sclerosis Disease-Modifying Therapy and the COVID-19 Pandemic: Implications on the Risk of Infection and Future Vaccination.

The coronavirus 2019 (COVID-19) pandemic is expected to linger. Decisions regarding initiation or continuation of disease-modifying therapy for multiple sclerosis have to consider the potential relevance to the pandemic. Understanding the mechanism of action and the possible idiosyncratic effects of each therapeutic agent on the immune system is imperative during this special time. The infectious side-effect profile as well as the route and frequency of administration of each therapeutic agent should be carefully considered when selecting a new treatment or deciding on risk mitigation strategies for existing therapy. More importantly, the impact of each agent on the future severe acute respiratory syndrome coronavirus type-2 (SARS-CoV-2) vaccine should be carefully considered in treatment decisions. Moreover, some multiple sclerosis therapies may have beneficial antiviral effects against SARS-CoV-2 while others may have beneficial immune-modulating effects against the cytokine storm and hyperinflammatory phase of the disease. Conventional injectables have a favorable immune profile without an increased exposure risk and therefore may be suitable for mild multiple sclerosis during the pandemic. However, moderate and highly active multiple sclerosis will continue to require treatment with oral or intravenous high-potency agents but a number of risk mitigation strategies may have to be implemented. Immune-modulating therapies such as the fumerates, sphinogosine-1P modulators, and natalizumab may be anecdotally preferred over cell-depleting immunosuppressants during the pandemic from the immune profile standpoint. Within the cell-depleting agents, selective (ocrelizumab) or preferential (cladribine) depletion of B cells may be relatively safer than non-selective depletion of lymphocytes and innate immune cells (alemtuzumab). Patients who develop severe iatrogenic or idiosyncratic lymphopenia should be advised to maintain social distancing even in areas where lockdown has been removed or ameliorated. Patients with iatrogenic hypogammaglobulinemia may require prophylactic intravenous immunoglobulin therapy in certain situations. When the future SARS-CoV-2 vaccine becomes available, patients with multiple sclerosis should be advised that certain therapies may interfere with mounting a protective immune response to the vaccine and that serological confirmation of a response may be required after vaccination. They should also be aware that most multiple sclerosis therapies are incompatible with live vaccines if a live SARS-CoV-2 vaccine is developed. In this article, we review and compare disease-modifying therapies in terms of their effect on the immune system, published infection rates, potential impact on SARS-CoV-2 susceptibility, and vaccine-related implications. We propose risk mitigation strategies and practical approaches to disease-modifying therapy during the COVID-19 pandemic.

A model-based study of internuclear ophthalmoparesis and ocular-motor fatigue in multiple sclerosis.

Internuclear ophthalmoparesis (INO) in multiple sclerosis (MS) is due to demyelination of the medial longitudinal fasciculus (MLF). INO is typically modeled as an increased peak-velocity and peak-acceleration ratio of abducting to adducting eye (pulse-size ratio, PSR). PSR can be affected by fatigue during prolonged ocular-motor tasks (ocular-motor fatigue). We propose that an important component of horizontal disconjugacy in INO is due to a delayed delivery of the saccadic pulse to the adducting eye (pulse-time delay, PTD). We expanded a control-system model to account for both abnormal PSR and PTD reflecting faulty axonal transmission in INO and to provide a better understanding of possible changes induced by fatigue. Saccades were measured in 19 MS patients with INO and 10 controls, using a 10-min saccadic "fatigue test" consisting of repetitive back-to-back 20° saccades. In the horizontal saccades model the unitary MLF connection was partitioned into parallel sub-tracts representing progressive degrees of disease effect. INO patients showed baseline abnormal PSR and PTD with some changes during the fatigue test. Manipulations of gain and transmission delay in the model provided simulated saccades that closely resembled those of INO. Ocular-motor fatigue may be a heterogeneous phenomenon that involves inter-saccadic fluctuation of PSR and PTD and adaptation during demanding ocular-motor tasks. INO as a model of abnormal axonal conduction has a potential role in assessing efficacy of reparative therapies in MS.

Eye Movement Abnormalities in Multiple Sclerosis: Pathogenesis, Modeling, and Treatment.

Multiple sclerosis (MS) commonly causes eye movement abnormalities that may have a significant impact on patients' disability. Inflammatory demyelinating lesions, especially occurring in the posterior fossa, result in a wide range of disorders, spanning from acquired pendular nystagmus (APN) to internuclear ophthalmoplegia (INO), among the most common. As the control of eye movements is well understood in terms of anatomical substrate and underlying physiological network, studying ocular motor abnormalities in MS provides a unique opportunity to gain insights into mechanisms of disease. Quantitative measurement and modeling of eye movement disorders, such as INO, may lead to a better understanding of common symptoms encountered in MS, such as Uhthoff's phenomenon and fatigue. In turn, the pathophysiology of a range of eye movement abnormalities, such as APN, has been clarified based on correlation of experimental model with lesion localization by neuroimaging in MS. Eye movement disorders have the potential of being utilized as structural and functional biomarkers of early cognitive deficit, and possibly help in assessing disease status and progression, and to serve as platform and functional outcome to test novel therapeutic agents for MS. Knowledge of neuropharmacology applied to eye movement dysfunction has guided testing and use of a number of pharmacological agents to treat some eye movement disorders found in MS, such as APN and other forms of central nystagmus.