Uhthoff's phenomena in MS—clinical features and pathophysiology

Multiple Sclerosis: An Emergency Medicine-Focused Narrative Review

BACKGROUND

Multiple sclerosis (MS) is a rare but serious condition associated with significant morbidity.

OBJECTIVE

This review provides a focused assessment of MS for emergency clinicians, including the presentation, evaluation, and emergency department (ED) management based on current evidence.

DISCUSSION

MS is an autoimmune disorder targeting the central nervous system (CNS), characterized by clinical relapses and radiological lesions disseminated in time and location. Patients with MS most commonly present with long tract signs (e.g., myelopathy, asymmetric spastic paraplegia, urinary dysfunction, Lhermitte's sign), optic neuritis, or brainstem syndromes (bilateral internuclear ophthalmoplegia). Cortical syndromes or multifocal presentations are less common. Radiologically isolated syndrome and clinically isolated syndrome (CIS) may or may not progress to chronic forms of MS, including relapsing remitting MS, primary progressive MS, and secondary progressive MS. The foundation of outpatient management involves disease-modifying therapy, which is typically initiated with the first signs of disease onset. Management of CIS and acute flares of MS in the ED includes corticosteroid therapy, ideally after diagnostic testing with imaging and lumbar puncture for cerebrospinal fluid analysis. Emergency clinicians should evaluate whether patients with MS are presenting with new-onset debilitating neurological symptoms to avoid unnecessary testing and admissions, but failure to appropriately diagnose CIS or MS flare is associated with increased morbidity.

CONCLUSIONS

An understanding of MS can assist emergency clinicians in better diagnosing and managing this neurologically devastating disease.

Measuring and predicting the effect of remyelinating therapy in multiple sclerosis: a randomised controlled trial protocol (RESTORE)

INTRODUCTION

Remyelination failure hampers symptomatic recovery in multiple sclerosis (MS), underlining the importance of developing remyelinating therapies. Optic neuritis is currently the most established method of measuring remyelination in MS trials. Complementary more generalisable methods of measuring remyelination are required to confirm treatment efficacy. Measuring internuclear ophthalmoplegia (INO) with infrared oculography provides such a method. Moreover, this method can be expanded with a test for selecting likely treatment responders by using fampridine. The aim of this trial is to investigate the (long-term) remyelinating effects of clemastine fumarate in patients with MS and INO and to evaluate if treatment response can be predicted using fampridine.

METHODS AND ANALYSIS

RESTORE is a single-centre double-blind randomised placebo-controlled trial of clemastine fumarate versus placebo. Prior to clemastine treatment improvement in oculographic features of INO after a single 10 mg dose of fampridine is measured in all participants and used to predict the treatment response to clemastine. Eighty individuals with MS and INO will be 1:1 randomised to 4 mg of clemastine fumarate two times a day for 6 months or equivalent placebo. Our primary outcome is improvement in the Versional Dysconjugacy Index-area under the curve, measured by infrared oculography after 6 months of treatment. Participants are assessed for persistent treatment effects 6, 18 and 30 months after end of treatment. Secondary outcome measures include other oculography parameters including double-step saccades, retinal imaging, visual acuities, physical disability, cognition and patient-reported outcomes.

ETHICS AND DISSEMINATION

Clemastine is a registered and very well-established drug with well-known safety and side effects. The protocol was approved by the medical ethical committee of the Amsterdam UMC, location VUMC and the Dutch Central Committee on Research Involving Human Subject. Written informed consent is obtained from all participants. The results will be published in peer-reviewed medical scientific journals.

TRIAL REGISTRATION NUMBER

EudraCT: 2021-003677-66, ClinicalTrials.gov: NCT05338450.

Body temperatures, thermal comfort, and neuropsychological responses to air temperatures ranging between 12°C and 39°C in people with Multiple Sclerosis

The negative effects of thermal stress on Multiple Sclerosis (MS)' symptoms have long been known. However, the underlying mechanisms of MS heat and cold intolerance remain unclear. The aim of this study was to evaluate body temperatures, thermal comfort, and neuropsychological responses to air temperatures between 12 to 39°C in people with MS compared to healthy controls (CTR). Twelve MS (5 males/7 females; age: 48.3±10.8 years; EDSS range: 1-7) and 11 CTR participants (4 males /7 females; age: 47.5±11.3 years) underwent two 50-min trials in a climatic chamber. Air temperature was ramped from 24°C to either 39°C (HEAT) or 12°C (COLD) and we continuously monitored participants' mean skin (T_sk) and rectal temperatures (T_rec), heart rate and mean arterial pressure. We recorded participants' self-reported thermal sensation and comfort, mental and physical fatigue, and we assessed their cognitive performance (information processing). Changes in mean T_sk and T_rec did not differ between MS and CTR neither during HEAT nor COLD. However, at the end of the HEAT trial, 83% of MS participants and 36% of CTR participants reported being "uncomfortable". Furthermore, self-reports of mental and physical fatigue increased significantly in MS but not CTR (p<0.05), during both HEAT and COLD. Information processing was lower in MS vs. CTR (p<0.05); yet this cognitive impairment was not exacerbated by HEAT nor COLD (p>0.05). Our findings indicate that neuropsychological factors (i.e. discomfort and fatigue) could contribute to MS heat and cold intolerance in the absence of deficits in the control of body temperature.

Multiple sclerosis-related heat sensitivity linked to absence of DMT prescription and subjective hand impairment but not autonomic or corticospinal dysfunction

OBJECTIVES

Heat sensitivity (HS) describes a temporary worsening of multiple sclerosis (MS) symptoms with increased body temperature. The pathophysiology may relate to central nervous system conduction deficits and autonomic dysfunction. We conducted deep clinical phenotyping of a cohort of persons with MS to identify predictors of HS.

METHODS

We recruited 59 MS participants with HS or No HS. Participants self-reported symptom severity (Hospital Anxiety and Depression Scale, Multiple Sclerosis Impact Scale, and fatigue visual analog scale) and underwent maximal exercise and transcranial magnetic stimulation testing to characterize autonomic and corticospinal function. We examined associations with HS using binomial logistic regression.

RESULTS

People with HS (36/59) had significantly greater disability, depression, fatigue, and physical and psychological functional effects of MS. They also had significantly lower corticospinal excitability but not conduction. After controlling for disease-modifying therapy (DMT), disability, and disease type, self-reported difficulty using hands in everyday tasks was significantly associated with a large increase in the odds of HS. Autonomic and corticospinal dysfunction were not associated with HS. Lack of DMT use alone was also associated with a large increase in the odds of HS.

DISCUSSION

Following a comprehensive assessment of plausible contributors to HS, HS was most strongly associated with lack of a DMT prescription and self-reported hand dysfunction. Surprisingly, objective measurement of autonomic and corticospinal integrity did not contribute to HS.

Somatosensory evoked potentials and magnetic resonance imaging of the central nervous system in early multiple sclerosis

BACKGROUND

Somatosensory evoked potentials (SSEP) are still broadly used, although not explicitly recommended, for the diagnostic work-up of suspected multiple sclerosis (MS).

OBJECTIVE

To relate disability, SSEP, and lesions on T2-weighted magnetic resonance imaging (MRI) in patients with early MS.

METHODS

In this monocentric retrospective study, we analyzed a cohort of patients with relapsing-remitting MS or clinically isolated syndrome, with a maximum disease duration of two years, as well as with available data on the score at the expanded disability status scale (EDSS), on SSEP, on whole spinal cord (SC) MRI, and on brain MRI.

RESULTS

Complete data of 161 patients were available. Tibial nerve SSEP (tSSEP) were less frequently abnormal than SC MRI (22% vs. 68%, p < 0.001). However, higher EDSS scores were significantly associated with abnormal tSSEP (median, 2.0 vs. 1.0; p = 0.001) but not with abnormal SC MRI (i.e., at least one lesion; median, 1.5 vs. 1.5; p = 0.7). Of the 35 patients with abnormal tSSEP, 32 had lesions on SC MRI, and 2 had corresponding lesions on brain MRI.

CONCLUSION

Compared to tSSEP, SC MRI is the more sensitive diagnostic biomarker regarding SC involvement. In early MS, lesions as detectable by T2-weighted MRI are the main driver of abnormal tSSEP. However, tSSEP were more closely associated with disability, which is compatible with a potential role of tSSEP as prognostic biomarker in complementation of MRI.

Trends in the environmental risks associated with earlier onset in multiple sclerosis

BACKGROUND

Several environmental and lifestyle factors relating to sunlight/vitamin D, body mass index (BMI), and smoking are associated with the risk of developing multiple sclerosis (MS). However, their relation to disease progression, particularly age at symptomatic onset, remains inconsistent, which may be the result of significant changes in human-environment interactions over the last century. This study investigates historical trends in the association between common MS environmental risk factors and age at disease onset.

METHODS

Using a narrative approach, we evaluated the current literature for published studies assessing the association between vitamin-D, BMI, and tobacco smoking exposures with the risk of early/pediatric-onset MS and direct correlations with age at MS onset using MEDLINE, EMBASE, and Web of Science. Measures were plotted by the average calendar year of disease onset for each cohort to examine trends over time. In total, 25, 9, and 11 articles were identified for vitamin D, BMI, and smoking-related exposures, respectively.

RESULTS

Higher sun exposure habits and residential solar radiation were associated with older age at onset. On the contrary, two studies observed a negative correlation between age at onset and serum 25-hydroxyvitamin D (25(OH)D) levels. Higher adolescent BMI was generally associated with younger age at onset, although genetic susceptibility for childhood obesity was not significantly associated. Tobacco smoking was associated with later disease onset, despite being a risk factor for MS. Association with age at onset was inflated for more recent studies relating to smoking, while often weaker for serum vitamin D and BMI.

CONCLUSION

Current findings indicate a likely association between age at onset and environmental risk factors, such as sun exposure, adolescent BMI, and tobacco smoking, in certain populations. However, findings are often inconsistent and assessment of the relationships and potential changes over time require further investigation.

Human temperature regulation under heat stress in health, disease, and injury

The human body constantly exchanges heat with the environment. Temperature regulation is a homeostatic feedback control system that ensures deep body temperature is maintained within narrow limits despite wide variations in environmental conditions and activity-related elevations in metabolic heat production. Extensive research has been performed to study the physiological regulation of deep body temperature. This review focuses on healthy and disordered human temperature regulation during heat stress. Central to this discussion is the notion that various morphological features, intrinsic factors, diseases, and injuries independently and interactively influence deep body temperature during exercise and/or exposure to hot ambient temperatures. The first sections review fundamental aspects of the human heat stress response, including the biophysical principles governing heat balance and the autonomic control of heat loss thermoeffectors. Next, we discuss the effects of different intrinsic factors (morphology, heat adaptation, biological sex, and age), diseases (neurological, cardiovascular, metabolic, and genetic), and injuries (spinal cord injury, deep burns, and heat stroke), with emphasis on the mechanisms by which these factors enhance or disturb the regulation of deep body temperature during heat stress. We conclude with key unanswered questions in this field of research.

Diagnosis and classification of optic neuritis

There is no consensus regarding the classification of optic neuritis, and precise diagnostic criteria are not available. This reality means that the diagnosis of disorders that have optic neuritis as the first manifestation can be challenging. Accurate diagnosis of optic neuritis at presentation can facilitate the timely treatment of individuals with multiple sclerosis, neuromyelitis optica spectrum disorder, or myelin oligodendrocyte glycoprotein antibody-associated disease. Epidemiological data show that, cumulatively, optic neuritis is most frequently caused by many conditions other than multiple sclerosis. Worldwide, the cause and management of optic neuritis varies with geographical location, treatment availability, and ethnic background. We have developed diagnostic criteria for optic neuritis and a classification of optic neuritis subgroups. Our diagnostic criteria are based on clinical features that permit a diagnosis of possible optic neuritis; further paraclinical tests, utilising brain, orbital, and retinal imaging, together with antibody and other protein biomarker data, can lead to a diagnosis of definite optic neuritis. Paraclinical tests can also be applied retrospectively on stored samples and historical brain or retinal scans, which will be useful for future validation studies. Our criteria have the potential to reduce the risk of misdiagnosis, provide information on optic neuritis disease course that can guide future treatment trial design, and enable physicians to judge the likelihood of a need for long-term pharmacological management, which might differ according to optic neuritis subgroups.

The pathophysiology of motor fatigue and fatigability in multiple sclerosis

Multiple Sclerosis (MS) is a heterogeneous immune mediated disease of the central nervous system (CNS). Fatigue is one of the most common and disabling symptom of MS. It interferes with daily activities on the level of cognition and motor endurance. Motor fatigue can either result from lesions in cortical networks or motor pathways (“primary fatigue”) or it may be a consequence of detraining with subsequent adaptions of muscle and autonomic function. Programmed exercise interventions are used frequently to increase physical fitness in MS-patients. Studies investigating the effects of training on aerobic capacity, objective endurance and perceived fatigability have yielded heterogenous results, most likely due to the heterogeneity of interventions and patients, but probably also due to the non-uniform pathophysiology of fatigability among MS-patients. The aim of this review is to summarize the current knowledge on the pathophysiology of motor fatigability with special reference to the basic exercise physiology that underlies our understanding of both pathogenesis and treatment interventions.

Long-term outcome after COVID-19 infection in multiple sclerosis: a nation-wide multicenter matched-control study

BACKGROUND

Long-term outcome after COVID-19 in patients with multiple sclerosis (pwMS) is scarcely studied and controlled data are lacking.

OBJECTIVE

To compare long-term outcome after COVID-19 in pwMS to a matched control group of pwMS without COVID-19.

METHODS

We included pwMS with PCR-confirmed diagnosis of COVID-19 and ≥6 months of follow-up available and, as a control group, pwMS matched 1:1 for age, sex, disability level and disease-modifying treatment type.

RESULTS

Of 211 pwMS with COVID-19 (mean age 42.6 years [SD 12.2], 69% female, median EDSS 1.5 [range: 0-7.5], 16% antiCD20), 90.5% initially had a mild COVID-19 course. At follow-up, 70% had recovered completely 3 months (M3) after COVID-19, 83% after 6 months (M6) and 94% after 12 months (M12). Mild initial COVID-19 course was the only significant predictor of complete recovery (odds ratio [OR]: 10.5; p<0.001). Most frequent residual symptoms were fatigue (M3: 18.5%, M6: 13.7%, M12: 7.3%), hyposmia (M3: 13.7%, M6: 5.2%, M12: 1.7%) and dyspnea (M3: 7.1%, M6: 6.6%, M12: 2.8%). Compared to matched controls, fatigue, hyposmia and dyspnea were significantly more frequent at M3 and still slightly at M6, while there was no difference at M12. PwMS with COVID-19 had neither a significantly increased risk for relapses (OR 1.1; p=0.70) nor disability worsening (OR 0.96; p=0.60).

DISCUSSION

Long-term outcome of COVID-19 is favourable in a large majority of pwMS with only a small proportion of patients suffering from persistent symptoms usually resolving after 3-6 months. COVID-19 is not associated with increased risk of relapse or disability.

Optic neuritis with potential for poor outcome

The Optic Neuritis Treatment Trial previously reported that corticosteroids accelerated visual recovery in optic neuritis (ON) without improving outcome. This finding related largely to multiple sclerosis (MS), and subsequently neurologists tended to await spontaneous recovery in ON. Since then, non-MS cases of ON have been identified with antibodies to aquaporin-4 (AQP4) or myelin oligodendrocyte glycoprotein (MOG). These disorders can closely mimic multiple sclerosis-associated or idiopathic demyelinating optic neuritis (MS/IDON) initially but risk a worse visual outcome. Scrutinising the clinical features and neuroimaging often enables differentiation between MS/IDON and other causes of ON. Early treatment with high-dose corticosteroids is an important determinant of visual outcome in non-MS/IDON. Prompt use of plasma exchange may also save sight. In this review, we contrast the presentations of myelin oligodendrocyte glycoprotein associated optic neuritis (MOG-ON) and aquaporin 4 associated optic neuritis (AQP4-ON) with MS/IDON and provide an approach to acute management while awaiting results of antibody testing.

Smouldering multiple sclerosis: the ‘real MS’

Using a philosophical approach or deductive reasoning, we challenge the dominant clinico-radiological worldview that defines multiple sclerosis (MS) as a focal inflammatory disease of the central nervous system (CNS). We provide a range of evidence to argue that the ‘real MS’ is in fact driven primarily by a smouldering pathological disease process. In natural history studies and clinical trials, relapses and focal activity revealed by magnetic resonance imaging (MRI) in MS patients on placebo or on disease-modifying therapies (DMTs) were found to be poor predictors of long-term disease evolution and were dissociated from disability outcomes. In addition, the progressive accumulation of disability in MS can occur independently of relapse activity from early in the disease course. This scenario is underpinned by a more diffuse smouldering pathological process that may affect the entire CNS. Many putative pathological drivers of smouldering MS can be potentially modified by specific therapeutic strategies, an approach that may have major implications for the management of MS patients. We hypothesise that therapeutically targeting a state of ‘no evident inflammatory disease activity’ (NEIDA) cannot sufficiently prevent disability accumulation in MS, meaning that treatment should also focus on other brain and spinal cord pathological processes contributing to the slow loss of neurological function. This should also be complemented with a holistic approach to the management of other systemic disease processes that have been shown to worsen MS outcomes.

Hearing abnormalities in multiple sclerosis: clinical semiology and pathophysiologic mechanisms

Auditory manifestations from multiple sclerosis (MS) are not as common as the well-recognized sentinel exacerbations of optic neuritis, partial myelitis, motor weakness, vertiginous episodes, heat intolerance, and eye movement abnormalities. This paper discusses four cases of auditory changes, secondary to MS, and describes the first case, to our knowledge, of palinacousis, the perseveration of hearing, despite cessation of the sound stimulus. For each we characterize the initial complaint, the diagnostic work up, and ultimately, underscore the individualized treatment interventions, that allowed us to achieve a remission in all four cases. Individually codifying the treatment regimens served to mitigate, if not to abolish, the clinical derangements in hearing. Special attention is focused upon examination of the clinical manifestations and the pathophysiologic mechanisms which are responsible for them. We further emphasize the differential diagnostic considerations, and physical exam findings, along with the results of laboratory testing, neuro-imaging sequences, and lesion localization. Taken together, such information is germane to organizing cogently coherent strategic treatment plan(s). We believe that this small case series represents a clinically pragmatic example of 'precision medicine'; a principal theme and goal throughout this paper, the achievement of such in MS, but also as an illustration for the assessment and management schema for neuroimmunologic disorders in general.

Thermal dysregulation in patients with multiple sclerosis during SARS-CoV-2 infection. The potential therapeutic role of exercise

Thermoregulation is a homeostatic mechanism that is disrupted in some neurological diseases. Patients with multiple sclerosis (MS) are susceptible to increases in body temperature, especially with more severe neurological signs. This condition can become intolerable when these patients suffer febrile infections such as coronavirus disease-2019 (COVID-19). We review the mechanisms of hyperthermia in patients with MS, and they may encounter when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Finally, the thermoregulatory role and relevant adaptation to regular physical exercise are summarized.

Peripheral nervous system in multiple sclerosis-understanding the involvement via autonomic nervous system

AIM

The aim of this review is to summarize the clinical and paraclinical findings that demonstrate that multiple sclerosis (MS) affects the peripheral nervous system (PNS) as well as the central nervous system (CNS). Methods: Narrative review.

RESULTS

MS is traditionally defined as a chronic demyelinating immune-mediated disease of the CNS. However, there is emerging evidence that MS is a disease that does not solely affect the CNS but can manifest with PNS involvement as well. Several pathology studies have reported on signs of demyelination in the PNS, as well as on structural and functional involvement of the PNS in persons with MS (pwMS). From the functional aspect, several studies have shown autonomic nervous system (ANS) involvement in the form of sudomotor dysfunction measured with quantitative sudomotor axon reflex test (QSART) in different stages of MS, adding to the growing body of evidence that indicate PNS involvement in MS. In this review the clinical, pathological, neurophysiological, and imaging findings that demonstrate that MS affects the PNS as well as the CNS are summarized, with the emphasis on the ANS abnormalities.

CONCLUSION

Further large-scale research is needed in order to fully understand the frequency and importance of PNS affection in MS.

Anomalously warm weather and acute care visits in patients with multiple sclerosis: A retrospective study of privately insured individuals in the US

BACKGROUND

As the global climate changes in response to anthropogenic greenhouse gas emissions, weather and temperature are expected to become increasingly variable. Although heat sensitivity is a recognized clinical feature of multiple sclerosis (MS), a chronic demyelinating disorder of the central nervous system, few studies have examined the implications of climate change for patients with this disease.

METHODS AND FINDINGS

We conducted a retrospective cohort study of individuals with MS ages 18-64 years in a nationwide United States patient-level commercial and Medicare Advantage claims database from 2003 to 2017. We defined anomalously warm weather as any month in which local average temperatures exceeded the long-term average by ≥1.5°C. We estimated the association between anomalously warm weather and MS-related inpatient, outpatient, and emergency department visits using generalized log-linear models. From 75,395,334 individuals, we identified 106,225 with MS. The majority were women (76.6%) aged 36-55 years (59.0%). Anomalously warm weather was associated with increased risk for emergency department visits (risk ratio [RR] = 1.043, 95% CI: 1.025-1.063) and inpatient visits (RR = 1.032, 95% CI: 1.010-1.054). There was limited evidence of an association between anomalously warm weather and MS-related outpatient visits (RR = 1.010, 95% CI: 1.005-1.015). Estimates were similar for men and women, strongest among older individuals, and exhibited substantial variation by season, region, and climate zone. Limitations of the present study include the absence of key individual-level measures of socioeconomic position (i.e., race/ethnicity, occupational status, and housing quality) that may determine where individuals live-and therefore the extent of their exposure to anomalously warm weather-as well as their propensity to seek treatment for neurologic symptoms.

CONCLUSIONS

Our findings suggest that as global temperatures rise, individuals with MS may represent a particularly susceptible subpopulation, a finding with implications for both healthcare providers and systems.

Individualized analysis of skin thermosensory thresholds and sensitivity in heat-sensitive people with multiple sclerosis

We investigated whether and how multiple sclerosis (MS) alters thresholds for perceiving increases and decreases in local skin temperature, as well as the sensitivity to progressively greater temperature stimuli, amongst heat-sensitive people with MS. Eleven MS patients (5 M/6 F; 51.1 ± 8.6 y, EDSS 5.7 ± 1.9) and 11 healthy controls (CTR; 7 M/4 F; 50.3 ± 9.0 y) performed warm and cold threshold tests on a hairy skin site, on both sides of the body. They also underwent a thermosensitivity test where they rated (visual analogue scale) perceived magnitude of 4 local skin stimuli (i.e. 22, 26, 34, 38°C). Individual thresholds and slopes of linear regression for thermosensitivity were z-transformed for each MS patient, and used to determine individual thermosensory abnormalities. When considering both threshold and thermosensitivity, six out of our 11 heat-sensitive patients (54.5%) exhibited skin thermosensory abnormalities. Those abnormalities varied amongst patients in terms of type (threshold vs. thermosensitivity), quality (warm vs. cold), location (left vs. right side of the body) and extent. Each of those six patients presented unique thermosensory profiles. While some patients experienced thermosensory loss in both thresholds and sensitivity and on both sides of the body, others experienced cold thermosensory loss on one side of the body only. The observed individual variability in thermosensory function among heat-sensitive MS patients highlight the need for a patient-centered approach to assessing thermosensory dysfunction and its potential implications for heat stress vulnerability in this patient group.

Neuro-ophthalmologic manifestations of multiple sclerosis other than acute optic neuritis

Acute optic neuritis is the most common neuro-opthalmologic manifestation of multiple sclerosis (MS). Treatment with high-dose intravenous corticosteroids accelerates visual recovery, although it has no long-term visual benefit. MS has several others, less common, neuro-ophthalmological manifestations, where corticotherapy may not be the best treatment option. Neuro-ophthalmologic manifestations of MS other than optic neuritis can be divided in afferent and efferent visual pathways, acute and chronic and may be associated with drugs that are employed in MS. The authors propose is to review the neuro-ophthalmologic manifestations of multiple sclerosis other than optic neuritis. Recognition of these leads to a more targeted treatment and may prevent visual deterioration.

Blunted sweating does not alter the rise in core temperature in people with multiple sclerosis exercising in the heat

The purpose of this study is to determine whether thermoregulatory capacity is altered by multiple sclerosis (MS) during exercise in the heat. Sixteen MS participants (EDSS: 2.9 ± 0.9; 47 ± 8 yr; 77.6 ± 14.0 kg) and 14 healthy control (CON) participants (43 ± 11 yr; 78.6 ± 17.0 kg) cycled at a heat production of 4 W·kg^-1 for 60 min at 30°C, 30% relative humidity (RH) (Warm). A subset of eight MS (EDSS: 2.6 ± 0.5; 44 ± 8 yr; 82.3 ± 18.2 kg) and 8 CON (44 ± 12 yr; 81.2 ± 21.1 kg) also exercised at 35°C, 30% RH (Hot). Rectal temperature (T_re), mean skin (T_sk) temperature, and local sweat rate (LSR) on the upper back (LSR_back) and forearm (LSR_arm) were measured. All CON, and only 9 of 16 and 7 of 8 MS participants completed 60 min of exercise in Warm and Hot trials, respectively. All MS participants who were unable to complete exercise stopped with a ΔT_re between 0.2 and 0.5°C. The time to reach a ΔT_re of 0.2°C was similar (MS: 28 ± 15 min, CON: 32 ± 18 min; P = 0.51). For MS participants, completing 60-min of exercise in Warm, ΔT_re (P = 0.13), ΔT_sk (P = 0.45), LSR_back (P = 0.69), and LSR_arm (P = 0.54) was similar to CON, but ΔT_b (body temperature) (MS: 0.16 ± 0.13°C, CON: 0.07 ± 0.06°C; P = 0.02) and onset time (MS: 16 ± 10 min, CON: 8 ± 5 min; P = 0.02) for sweating were greater in MS. Similarly, in Hot, ΔT_re (P = 0.52), ΔT_sk (P = 0.06), LSR_back (P = 0.59), and LSR_arm (P = 0.08) were similar, but ΔT_b (MS: 0.19 ± 0.16°C, CON: 0.06 ± 0.04°C; P = 0.04) and onset time (MS: 13 ± 7 min, CON: 6 ± 3 min; P = 0.02) for sweating were greater in MS. Even at 35°C, a delayed sweating onset did not alter heat loss to sufficiently affect exercise-induced rises in core temperature. Heat intolerance with MS does not seem attributable to thermoregulatory impairments.

Exercise-induced changes in gait kinematics in multiple sclerosis with minimal neurological disability

BACKGROUND

Exercise-induced gait deterioration is a frequently encountered symptom that limits ambulation throughout the clinical course, becoming more prominent with increasing neurological disability in people with MS (pwMS).

OBJECTIVE

We attempted to objectively document exercise-induced gait changes in pwMS with minimal neurological disability and stable disease.

METHODS

Gait kinematics and spatio-temporal parameters were recorded using 3D motion analysis before and after a 20-minute treadmill walk (Group A, n=15)/run (Group B, n=15) at a self-selected speed in pwMS and compared with healthy controls (n=15).

RESULTS

Gait analysis revealed a significant decrease in peak ankle dorsiflexion in swing of the most affected leg, post-exercise task, in both Group A (EDSS 2.5-3.5) and Group B (EDSS 1-2.5) and not in healthy controls. Fourteen out of 30 MS participants showed an exercise-induced gait deterioration, based on minimal detectable change. Pre-exercise gait parameters in Group A showed a significantly higher peak dorsiflexion in swing with shorter step length and higher cadence, whereas Group B was comparable to healthy controls.

CONCLUSION

The detection of exercise-induced gait deterioration (foot drop) in pwMS with minimal neurological disability and stable disease indicates the potential of gait kinematics, before and after an exercise task, to monitor subtle neurological deficits from an early stage of MS.

Sudomotor Dysfunction

Disorders of sudomotor function are common and diverse in their presentations. Hyperhidrosis or hypohidrosis in generalized or regional neuroanatomical patterns can provide clues to neurologic localization and inform neurologic diagnosis. Conditions that impair sudomotor function include small fiber peripheral neuropathy, sudomotor neuropathy, myelopathy, α-synucleinopathies, autoimmune autonomic ganglionopathy, antibody-mediated hyperexcitability syndromes, and a host of medications. Particularly relevant to neurologic practice is the detection of postganglionic sudomotor deficits as a diagnostic marker of small fiber neuropathies. Extensive anhidrosis is important to recognize, as it not only correlates with symptoms of heat intolerance but may also place the patient at risk for heat stroke when under conditions of heat stress. Methods for assessing sudomotor dysfunction include the thermoregulatory sweat test, the quantitative sudomotor axon reflex test, silicone impressions, and the sympathetic skin response.

A Case of Intermittent Exercise-Induced Foot Drop in a Recreational Runner

Foot drop is a reduction in ankle dorsiflexion during the swing phase of gait. We report a case of a 51-year-old recreational runner and cyclist who presented with intermittent left foot drop initially triggered by running distances in excess of 10 km. The patient was investigated with magnetic resonance imaging (MRI) of the spine and leg, nerve conduction studies, electromyography, and compartment pressure testing, which were all normal. Surgical release of fascia, which was restricting the common peroneal (fibular) nerve, failed to resolve her symptoms. Subsequent brain MRI revealed demyelination. This case describes the unusual case of a recreational runner presenting with exercise-induced foot drop secondary to multiple sclerosis (MS). Motor fatigability is a common feature of MS, and this case highlights the need to remain cognizant of central and peripheral causes of exertional lower limb pathology, particularly in the absence of pain.

Management of Multiple Sclerosis Relapses

PURPOSE OF REVIEW

This article provides an overview of the clinical and pathologic features of multiple sclerosis (MS) relapses and reviews evidence-based approaches to their treatment.

RECENT FINDINGS

Despite the increasing number and potency of MS treatments, relapses remain one of the more unpredictable and disconcerting disease aspects for many patients with MS, making their accurate recognition and treatment an essential component of good clinical care. The expanding range of relapse treatments now includes oral corticosteroids, comparable in efficacy to IV methylprednisolone at a fraction of the cost. While this development improves access to prompt treatment, it also underscores the importance of recognizing mimics of MS relapses to reduce corticosteroid overuse and its attendant risks.

SUMMARY

Like MS itself, MS relapse remains primarily a clinical diagnosis. The treatment options for MS relapse include corticosteroids, adrenocorticotropic hormone (ACTH), plasma exchange, and rehabilitation, used singly or sequentially, with the goal of limiting the duration and impact of associated disability. Even when treated promptly and effectively, clinical or subclinical sequelae of MS relapses frequently remain.

Impaired Thermoregulatory Function during Dynamic Exercise in Multiple Sclerosis

INTRODUCTION

Impairments in sudomotor function during passive whole-body heating have been reported in multiple sclerosis (MS), a demyelinating disease of the CNS that disrupts autonomic function. However, the capability of the thermoregulatory system to control body temperature during exercise has never been assessed in MS. Thus, the aim of the present study was to test the hypothesis that thermoregulatory function is impaired in MS patients compared with healthy controls (CON) exercising at similar rates of metabolic heat production.

METHODS

Sweating and skin blood flow responses were compared between 12 individuals diagnosed with relapsing-remitting MS (9 females, 3 males) and 12 sex-, age-, mass-, and BSA-matched CON during a single bout of cycling exercise (rate of metabolic heat production: ∼4.5 W·kg) for 60 min in a climate-controlled room (25°C, 30% RH).

RESULTS

Individuals with MS exhibited an attenuated increase in cumulative whole-body sweat loss after 30 min (MS, 72 ± 51 g; CON, 104 ± 37 g; P = 0.04) and 60 min (MS, 209 ± 94 g; CON, 285 ± 62 g; P = 0.02), as well as lower sweating thermosensitivity (MS, 0.49 ± 0.26 mg·cm·min·°C; CON, 0.86 ± 0.30 mg·cm·min·°C; P = 0.049). Despite evidence for thermoregulatory dysfunction, there were no differences between MS and CON in esophageal or rectal temperatures at 30- or 60-min time points (P > 0.05). Cutaneous vasculature responses were also not different in MS compared with CON (P > 0.05).

CONCLUSION

Taken together, MS blunts sweating responses during exercise while cutaneous vasculature responses are preserved. Altered mechanisms of body temperature regulation in persons with MS may lead to temporary worsening of disease symptoms and limit exercise tolerance under more thermally challenging conditions.

Wilhelm Uhthoff and Uhthoff's phenomenon

Wilhelm Uhthoff, known for his contributions to both neurology and neuro-ophthalmology, was a German ophthalmologist who specialized in neurologic disorders. The eponym "Uhthoff's phenomenon" was first used to describe the reversible, transient blurring of vision in patients with multiple sclerosis during exercise. Subsequently, it was discovered that this neurologic sign not only was triggered by physical exertion but also by other homeostatic disruptions such as hot baths, menstruation, and high external temperatures. Here, we take a look at the life and career of Wilhelm Uhthoff and discuss the basis behind this phenomenon.

Comparing Gait Trials with Greedy Template Matching

Gait assessment and quantification have received an increased interest in recent years. Embedded technologies and low-cost sensors can be used for the longitudinal follow-up of various populations (neurological diseases, elderly, etc.). However, the comparison of two gait trials remains a tricky question as standard gait features may prove to be insufficient in some cases. This article describes a new algorithm for comparing two gait trials recorded with inertial measurement units (IMUs). This algorithm uses a library of step templates extracted from one trial and attempts to detect similar steps in the second trial through a greedy template matching approach. The output of our method is a similarity index (SId) comprised between 0 and 1 that reflects the similarity between the patterns observed in both trials. Results on healthy and multiple sclerosis subjects show that this new comparison tool can be used for both inter-individual comparison and longitudinal follow-up.

New Ways of "Seeing" the Mechanistic Heterogeneity of Multiple Sclerosis Plaque Pathogenesis

BACKGROUND

Over the past few decades, we have witnessed a transformation with respect to the principles and pathobiological underpinnings of multiple sclerosis (MS). From the traditional rubric of MS as an inflammatory and demyelinating disorder restricted to central nervous system (CNS) white matter, our contemporary view has evolved to encompass a broader understanding of the variable mechanisms that contribute to tissue injury, in a disorder now recognized to affect white and grey matter compartments.

EVIDENCE ACQUISITION

A constellation of inflammation, ion channel derangements, bioenergetic supply: demand mismatches within the intra-axonal compartment, and alterations in the dynamics and oximetry of blood flow in CNS tissue compartments are observed in MS. These findings have raised questions regarding how histopathologic heterogeneity may influence the diverse clinical spectrum of MS; and, accordingly, how individual treatment needs vary from 1 patient to the next.

RESULTS

We are now on new scaffolding in MS; one that promises to translate key clinical and laboratory observations to the application of emerging patient-centered therapies.

CONCLUSIONS

This review highlights our current knowledge of the underlying disease mechanisms in MS, explores the inflammatory and neurodegenerative consequences of tissue damage, and examines physiologic factors that contribute to bioenergetic homeostasis within the CNS of affected patients.

Multiple Sclerosis: An Update for Home Healthcare Clinicians

Multiple sclerosis (MS) is a chronic neurologic disease and the most common cause of nontraumatic disability in young adults in the United States. It strikes adults in the prime of life and can gradually diminish physical and mental function, affect relationships, employment, financial capacity, and independence. Neurologic symptoms fluctuate in a pattern of remissions and exacerbations for the majority of those with MS. A multidisciplinary treatment approach is essential. There are a wide number of medications that can be used. Treating the disease at an early stage within the first 5 years of clinical symptom onset is optimal. Home healthcare clinicians can use assessment tools to evaluate disease progression, teach the patient and family how to live with the disorder, and monitor the patient for medication side effects.

Pyrexia-associated Relapse in Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy is a relapsing-remitting or chronic progressive demyelinating polyradiculoneuropathy. We report the case of a patient with chronic inflammatory demyelinating polyradiculoneuropathy who experienced relapses on four occasions after experiencing pyrexia and flu-like symptoms. Our patient showed characteristic features, such as relapse after pyrexia and flu-like symptoms, remission after pyretolysis without treatment, and the absence of remarkable improvement in a nerve conduction study in the remission phase. The serum level of tumor necrosis factor-α was elevated in the relapse phase and reduced in the remission phase; thus, the induction of cytokine release by viral infection might have caused the relapses.

Temperature sensitivity in multiple sclerosis: An overview of its impact on sensory and cognitive symptoms

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease characterized by demyelination of the central nervous system (CNS). The exact cause of MS is still unknown; yet its incidence and prevalence rates are growing worldwide, making MS a significant public health challenge. The heterogeneous distribution of demyelination within and between MS patients translates in a complex and varied array of autonomic, motor, sensory and cognitive symptoms. Yet a unique aspect of MS is the highly prevalent (60-80%) temperature sensitivity of its sufferers, where neurological symptoms are temporarily exacerbated by environmental- or exercise-induced increases (or decreases) in body temperature. MS temperature sensitivity is primarily driven by temperature-dependent slowing or blocking of neural conduction within the CNS due to changes in internal (core) temperature; yet changes in skin temperature could also contribute to symptom exacerbation (e.g. during sunlight and warm ambient exposure). The impact of temperature sensitivity, and particularly of increases in core temperature, on autonomic (e.g. thermoregulatory/cardiovascular function) and motor symptoms (e.g. fatigue) is well described. However, less attention has been given to how increases (and decreases) in core and skin temperature affect sensory and cognitive symptoms. Furthermore, it remains uncertain whether changes in skin temperature alone could also trigger worsening of symptoms. Here we review the impact of temperature sensitivity on MS sensory and cognitive function and discuss additional factors (e.g. changes in skin temperature) that potentially contribute to temperature-induced worsening of symptoms in the absence of alteration in core temperature.

Progressive multiple sclerosis patients have a higher burden of autonomic dysfunction compared to relapsing remitting phenotype

OBJECTIVE

To determine autonomic dysfunction (AD) differences in patients with relapsing remitting multiple sclerosis (pwRRMS) and progressive MS (pwPMS).

METHODS

Composite autonomic scoring scale (CASS) and heart rate variability (HRV) were performed in 40 pwRRMS and 30 pwPMS.

RESULTS

pwPMS had a significantly higher sudomotor index and total CASS score compared to pwRRMS (p < 0.001 and p < 0.001, respectively). Disease duration positively correlated with sudomotor index and total CASS (r_s = 0.409, p < 0.001 and r_s = 0.472, p < 0.001, respectively), while the Expanded Disability Status Scale (EDSS) positively correlated with sudomotor index and total CASS (r_s = 0.411, p < 0.001 and r_s = 0.402, p = 0.001, respectively) in all patients. Type of multiple sclerosis (pwRRMS or pwPMS) corrected for age, sex and disease duration, was a statistically significant predictor of CASS value (B = 1.215, p = 0.019). Compared to pwRRMS, pwPMS had a significantly lower standard deviation of NN intervals (SDNN), low frequency (LF), and high frequency (HF), during both the supine and tilt-up phases (all p-values <0.006). pwPMS had a significantly lower LF/HF (p = 0.008) during tilt-up.

CONCLUSION

There is a significant difference in autonomic function in pwRRMS and pwPMS; with pwPMS having a higher burden of AD, which is particularly evident for sweating dysfunction.

SIGNIFICANCE

Further research is needed to establish whether parasympathetic and sudomotor dysfunction may serve as markers of progressive MS.

Multiple Sclerosis and Exercise: A Literature Review

Multiple sclerosis (MS) is the most common autoimmune disabling neurological conditions of young adults and affects more than 2.3 million people worldwide. Given the high likelihood for disability and decreased neurological function, there have been concerns about the role of exercise in MS patients with a fear of increased injury. This article looks at recent articles evaluating the role of exercise in MS and can hopefully be used by patients, caregivers, and health care providers to guide decision making about the role of exercise in patients with MS.

Thermoregulatory dysfunction in multiple sclerosis

Multiple sclerosis (MS) is a progressive neurologic disorder that disrupts axonal myelin in the central nervous system. Demyelination produces alterations in saltatory conduction, slowed conduction velocity, and a predisposition to conduction block. An estimated 60-80% of MS patients experience temporary worsening of clinical signs and neurologic symptoms with heat exposure (Uhthoff's phenomenon). This heat intolerance in MS is related to the detrimental effects of increased temperature on action potential propagation in demyelinated axons, resulting in conduction slowing and/or block. Additionally, MS may produce impaired neural control of autonomic and endocrine functions. Isolating and interpreting mechanisms responsible for autonomic dysfunction due to MS can be difficult as it may involve sensory impairments, altered neural integration within the central nervous system, impaired effector responses, or combinations of all of these factors. MS lesions occur in areas of the brain responsible for the control and regulation of body temperature and thermoregulatory effector responses, resulting in impaired neural control of sudomotor pathways or neural-induced changes in eccrine sweat glands, as evidenced by observations of reduced sweating responses in MS patients. Although not comprehensive, some evidence exists concerning treatments (cooling, precooling, and pharmacologic) for the MS patient to preserve function and decrease symptom worsening during heat stress. This review focuses on four main themes influencing current understanding of thermoregulatory dysfunction in MS: (1) heat intolerance; (2) central regulation of body temperature; (3) thermoregulatory effector responses; and (4) countermeasures to improve or maintain function during thermal stress.

Recrudescence of Deficits After Stroke: Clinical and Imaging Phenotype, Triggers, and Risk Factors

Importance

Reemergence of previous stroke-related deficits (or poststroke recrudescence [PSR]) is an underrecognized and inadequately characterized phenomenon.

Objective

To investigate the clinical features, triggers, and risk factors for PSR.

Design, Setting, and Participants

This retrospective study incorporated a crossover cohort study to identify triggers and a case-control study to identify risk factors. The study used the Massachusetts General Hospital Research Patient Data Repository to identify patients for the period January 1, 2000, to November 30, 2015, who had a primary or secondary diagnosis of cerebrovascular disease, who underwent magnetic resonance imaging of the brain at least once, and whose inpatient or outpatient clinician note or discharge summary stated the term recrudescence. In all, 153 patients met the preliminary diagnostic criteria for PSR: transient worsening of residual poststroke focal neurologic deficits or transient recurrence of prior stroke-related focal deficits, admission magnetic resonance imaging showing a chronic stroke but no acute infarct or hemorrhage, no evidence of transient ischemic attack or seizure, no acute lesion on diffusion-weighted imaging, and no clinical or electroencephalographic evidence of seizure around the time of the event.

Main Outcomes and Measures

Clinical and imaging features of PSR; triggers (identified by comparing PSR admissions with adjacent admissions without PSR); and risk factors (identified by comparing PSR cases with control cases from the Massachusetts General Hospital Stroke Registry).

Results

Of the 153 patients, 145 had prior infarct, 8 had hypertensive brain hemorrhage, and 164 admissions for PSR were identified. The patients' mean (SD) age was 67 (16) years, and 92 (60%) were women. Recrudescence occurred a mean (SD) of 3.9 (0.6) years after the stroke, lasted 18.4 (20.4) hours, and was resolved on day 1 for 91 of the 131 episodes with documented resolution time (69%). Deficits were typically abrupt and mild and affected motor-sensory or language function. No patient had isolated gaze paresis, hemianopia, or neglect. During PSR, the National Institutes of Health Stroke Scale (NIHSS) score worsened by a mean (SD) 2.5 (1.9) points, and deficits were limited to a single NIHSS item in 62 episodes (38%). The underlying chronic strokes were variably sized, predominantly affected white matter tracts, and involved the middle cerebral artery territory for 112 patients (73%). Infection, hypotension, hyponatremia, insomnia or stress, and benzodiazepine use were higher during PSR admissions. Compared with the control group (patients who did not experience recrudescence), the PSR group (patients who were hospitalized for recrudescence) had more women, African American individuals, and those who self-identified as being from "other" race. The PSR group also had more diabetes, dyslipidemia, smoking, infarcts from small-vessel disease, and "other definite" causes and worse onset NIHSS scores. Six patients (4%) received intravenous tissue plasminogen activator without complications.

Conclusions and Relevance

The PSR features identified in the study should enable prompt diagnosis and distinguish recrudescence from mimics, such as transient ischemic attacks, migraine, Todd paralysis, and Uhthoff phenomenon. Prospective studies are required to validate the proposed diagnostic criteria and to decipher underlying mechanisms.

No relevant impact of ambient temperature on disability measurements in a large cohort of patients with multiple sclerosis

BACKGROUND AND PURPOSE

Many patients with multiple sclerosis (MS) report a worsening of symptoms due to high ambient temperatures, but objective data about this association are rare and contradictory. The aim of this study was to investigate the influence of ambient temperature on standard clinical tests.

METHODS

We extracted the Symbol Digit Modality Test, Nine Hole Peg Test, Timed 25 Foot Walk (T25FW), Timed Tandem Walk, Expanded Disability Status Scale (EDSS) and quality-of-life items on cognition, fatigue and depression from our clinical database and matched them to historical temperatures. We used linear mixed-effect models to investigate the association between temperature and outcomes.

RESULTS

A total of 1254 patients with MS (mean age, 42.7 years; 69.9% females; 52.1% relapsing-remitting MS, mean EDSS, 3.8) had 5751 assessments between 1996 and 2012. We observed a worsening in the T25FW with higher ambient temperatures in moderately disabled patients (EDSS ≥ 4) but not in less disabled patients. However, an increase of 10°C prolonged the T25FW by just 0.4 s. Other outcomes were not associated with ambient temperatures.

CONCLUSIONS

Higher ambient temperature might compromise walking capabilities in patients with MS with a manifest walking impairment. However, effects are small and not detectable in mildly disabled patients. Hand function, cognition, mood and fatigue do not appear to be correlated with ambient temperature.

A new role for evoked potentials in MS? Repurposing evoked potentials as biomarkers for clinical trials in MS

Evoked potentials (EP) characterize signal conduction in selected tracts of the central nervous system in a quantifiable way. Since alteration of signal conduction is the main mechanism of symptoms and signs in multiple sclerosis (MS), multimodal EP may serve as a representative measure of the functional impairment in MS. Moreover, EP have been shown to be predictive for disease course, and thus might help to select patient groups at high risk of progression for clinical trials. EP can detect deterioration, as well as improvement of impulse propagation, independently from the mechanism causing the change. Therefore, they are candidates for biomarkers with application in clinical phase-II trials. Applicability of EP in multicenter trials has been limited by different standards of registration and assessment.

Impaired sweating responses to a passive whole body heat stress in individuals with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS), disrupting autonomic function. The aim of this study was to test the hypothesis that individuals with MS have blunted control of thermoregulatory reflex increases in sweat rate (SR) and cutaneous vasodilation compared with controls during a passive whole body heat stress (WBH). Eighteen individuals with relapsing-remitting MS and 18 healthy controls (Con) participated in the study. Core temperature (T_core), skin temperature, heart rate, arterial blood pressure (10-min intervals), skin blood flow (laser-Doppler flux, LDF), and SR were continuously measured during normothermic baseline (34°C water perfusing a tube-lined suit) and WBH (increased T_core 0.8°C via 48°C water perfusing the suit). Following WBH, local heaters were warmed to 42°C, inducing peak cutaneous vasodilation at the site of LDF collection. Cutaneous vascular conductance (CVC) was calculated as the ratio of LDF to mean arterial pressure and expressed as a percentage of peak achieved during local heating. Individuals with MS had attenuated SR responses to WBH (ΔSR from baseline: Con, 0.65 ± 0.27; MS, 0.42 ± 0.17 mg·cm^-2·min^-1, P = 0.003), whereas Δ%CVC_42C from baseline was similar between groups (Con, 42 ± 16%; MS, 38 ± 12%, P = 0.39). SR responses were blunted as a function of T_core in MS (interaction: group × T_core, P = 0.03), of which differences were evident at ΔT_core 0.7°C and 0.8°C (P < 0.05). No interaction was observed in Δ%CVC_42C Taken together, the findings show MS blunts sweating responses, whereas control of the cutaneous vasculature is preserved, in response to WBH.NEW & NOTEWORTHY This study is the first to assess the reflex control of the thermoregulatory system in individuals living with multiple sclerosis (MS). The novel findings are twofold. First, attenuated increases in sweat rate in subjects with MS compared with healthy controls were observed in response to a moderate increase (0.8°C) in core temperature via passive whole body heat stress. Second, it appears the reflex control of the cutaneous vasculature is preserved in MS.

Increased postural sway in persons with multiple sclerosis during short-term exposure to warm ambient temperatures

BACKGROUND

Multiple sclerosis (MS) is a neurological disease marked by demyelination and axonal loss. Individuals with MS experience increases in clinical signs and symptoms during heat exposure.

OBJECTIVE

To test the hypothesis that moderate heat exposure adversely affects postural sway in individuals with MS.

METHODS

Ten individuals with relapsing-remitting MS (50±8y) and nine controls (47±10y) were examined under a Thermal and a Time Control trial. Following a 30min thermoneutral baseline (25°C, 30% relative humidity (RH)), stand tests randomized with eyes open and closed, were performed. For Thermal, subjects were first exposed to 60min of heating (40°C, 30%RH) followed by 60min of cooling (20°C, 30%RH). For Time Control, subjects remained in a thermoneutral environment throughout. Stand tests were repeated at consistent times in both trials.

RESULTS

No difference in skin and core temperatures between groups were observed for any trial (P>0.05). During heating, postural sway was higher in MS relative to control subjects (eyes open, P=0.03; eyes closed, P=0.011). No differences in postural sway, regardless of eye status, were observed during the Time Control trial for either group (P>0.05).

CONCLUSION

These data demonstrate that exposure to a moderate heating environment increases postural sway in patients with MS.

The topographical model of multiple sclerosis: A dynamic visualization of disease course

Relapses and progression contribute to multiple sclerosis (MS) disease course, but neither the relationship between them nor the spectrum of clinical heterogeneity has been fully characterized. A hypothesis-driven, biologically informed model could build on the clinical phenotypes to encompass the dynamic admixture of factors underlying MS disease course. In this medical hypothesis, we put forth a dynamic model of MS disease course that incorporates localization and other drivers of disability to propose a clinical manifestation framework that visualizes MS in a clinically individualized way. The topographical model encapsulates 5 factors (localization of relapses and causative lesions; relapse frequency, severity, and recovery; and progression rate), visualized utilizing dynamic 3-dimensional renderings. The central hypothesis is that, like symptom recrudescence in Uhthoff phenomenon and pseudoexacerbations, progression clinically recapitulates prior relapse symptoms and unmasks previously silent lesions, incrementally revealing underlying lesion topography. The model uses real-time simulation software to depict disease course archetypes and illuminate several well-described but poorly reconciled phenomena including the clinical/MRI paradox and prognostic significance of lesion location and burden on disease outcomes. Utilization of this model could allow for earlier and more clinically precise identification of progressive MS and predictive implications can be empirically tested.

Early indicators of relapses vs pseudorelapses in neuromyelitis optica spectrum disorder

OBJECTIVE

The purpose of this study was to review cases of neuromyelitis optica spectrum disorder (NMOSD) relapses and pseudorelapses to identify early features that differentiate between them at onset of symptoms.

METHODS

This was a retrospective analysis of 74 hospitalizations of patients with NMOSD who were admitted to the Johns Hopkins Hospital for workup and treatment of a presumed relapse. Standard workup included MRI and blood and urine testing for metabolic and infectious etiologies. The gold standard for a relapse was defined as new or worsening symptoms and a change in neurologic examination correlating with a new or enhancing MRI lesion. A pseudorelapse was a clinical exacerbation with similar symptoms and signs but the MRI was negative, and workup identified an alternative cause for the symptoms that, when treated, resulted in the improvement of neurologic symptoms. Factors considered to be early predictors of relapses vs pseudorelapses were analyzed using the Fisher test.

RESULTS

Among 74 NMOSD hospitalizations for presumed relapse, 57 were confirmed relapses while 17 had a negative MRI and an identifiable cause of pseudorelapse. The most common causes of pseudorelapse were infection, pain, and dysautonomia. The only early predictor that reliably differentiated relapse from pseudorelapse among this NMOSD patient population was vision loss (p = 0.039). Race, sex, presentations of weakness, numbness, and bowel/bladder dysfunction, white blood cell count, and urinary tract infection were not different among patients with relapses vs pseudorelapses.

CONCLUSIONS

Vision loss in NMOSD is strongly suggestive of a true relapse vs a pseudorelapse. Pseudorelapses localized to the spinal cord in patients with previous myelitis presented similarly to true relapses and could only be ruled out by a negative MRI.

Aquatic training in MS: neurotherapeutic impact upon quality of life

Three fundamental principals associated with aquatic therapy differentiate it with respect to exercise on land, and in air. These are buoyancy (reduction in weight of the body within the buoyant medium of water), viscosity (a “drag force” is generated when moving within water, when compared with the same movement in air), and the thermodynamic aspect of water exercise, during which the heat capacity of water is about 1000 times greater than that of an equivalent amount of air; equating to a heat transfer from the body into water at a rate 25 times faster than that of air. Aquatic conditioning, can improve neurologic functioning, with dividends favorably impacting activities of daily living, health maintenance, safety, and ultimately quality of life. Here, we review the application of aquatic exercise training in MS patients.

Neuroinflammation and demyelination from the point of nitrosative stress as a new target for neuroprotection

The role of nitrosative stress in the early pathogenesis of neuroinflammation and demyelination is undoubtedly wide. This review summarizes and integrates the results, found in previously performed studies, which have evaluated nitrosative stress participation in neuroinflammation. The largest number of studies indicates that the supply of nitrosative stress inhibitors has led to the opposite clinical effects in experimental studies. Some results claim that attributing the protective role to nitric oxide, outside the total changes of redox oxidative processes and without following the clinical and paraclinical correlates of neuroinflammation, is an overrated role of this mediator. The fact is that the use of nitrosative stress inhibitors would be justified in the earlier phases of neuroinflammation. The ideal choice would be a specific inducible nitric oxide synthase (iNOS) inhibitor, because its use would preserve the physiological features of nitric oxide produced by the effects of constitutive NOS. This review discusses the antinitrosative therapy as a potential mode of therapy that aims to control neuroinflammation in early phases, delaying its later phases, which are accompanied with irreversible neurological disabilities. Some parameters of nitrosative stress might serve as surrogate biomarkers for neuroinflammation intensity and its radiological and clinical correlates.

Autonomic dysfunction in multiple sclerosis: implications for exercise

Multiple sclerosis (MS), a progressive neurological disease, can result in autonomic dysfunction. Impairments in the autonomic control of cardiovascular and thermoregulatory function during exercise have been observed in MS. Attenuated elevations in blood pressure during exercise in MS patients can negatively impact blood flow to skeletal muscle. Diminished sweating during exercise may impair heat dissipation likely limiting the exercise intensity that can be performed before detrimental core temperatures are reached. Further understanding the physiologic mechanisms of autonomic dysfunction during exercise in MS may lead to the development of novel therapeutic strategies targeted at improving quality of life in individuals with this disease.