Delivering the diagnosis of multiple system atrophy: a multicenter survey on Japanese neurologists' perspectives.

BACKGROUND: Multiple system atrophy (MSA) is a progressive, incurable, life-threatening neurodegenerative disease uniquely characterized by the risk of sudden death, which makes diagnosis delivery challenging for neurologists. Empirical studies on breaking a diagnosis of MSA are scarce, with no guidelines currently established. This study aimed to investigate neurologists' current practices and experiences in delivering the diagnosis of MSA. METHODS: We conducted a multicenter online survey and employed a mixed-methods (quantitative and qualitative) study design in which responses to open-ended questions were analyzed qualitatively using critical incident technique. RESULTS: Among the 194 neurologists surveyed, 166 opened the survey (response rate = 85.6%), of whom 144 respondents across various Japanese regions completed the survey. Accordingly, 92.3% and 82.8% of the participating neurologists perceived delivering the diagnosis of MSA and explaining the risk of sudden death as difficult, respectively. Factors independently associated with difficulties in diagnosis delivery included explaining the importance of the family decision making process in life-prolonging treatment, perceived difficulties in delivering information regarding the risk of sudden death, and perceived difficulties in differential diagnosis of MSA. CONCLUSIONS: Our findings showed that the majority of neurologists perceived delivering the diagnosis of MSA and explaining the risk of sudden death as difficult, which could have been associated with the difficulty of breaking the diagnosis of MSA. Difficulty in conveying bad news in MSA are caused by various factors, such as empathic burden on neurologists caused by the progressive and incurable nature of MSA, the need to explain complex and important details, including the importance of the family decision-making process in life-prolonging treatment, difficulty of MSA diagnosis, and communication barriers posed by mental status and cognitive impairment in patients or their family members. Neurologists consider various factors in explaining the risk of sudden death (e.g., patient's personality, mental state, and degree of acceptance and understanding) and adjust their manner of communication, such as limiting their communication on such matters or avoiding the use of the term "sudden death" in the early stages of the disease. Although neurologists endeavor to meet the basic standards of good practice, there is room for the multiple aspects for improvement.

Novel approaches to assessing upper motor neuron dysfunction in motor neuron disease/amyotrophic lateral sclerosis: IFCN handbook chapter.

Identifying upper motor neuron (UMN) dysfunction is fundamental to the diagnosis and understanding of disease pathogenesis in motor neuron disease (MND). The clinical assessment of UMN dysfunction may be difficult, particularly in the setting of severe muscle weakness. From a physiological perspective, transcranial magnetic stimulation (TMS) techniques provide objective biomarkers of UMN dysfunction in MND and may also be useful to interrogate cortical and network function. Single, paired- and triple pulse TMS techniques have yielded novel diagnostic and prognostic biomarkers in MND, and have provided important pathogenic insights, particularly pertaining to site of disease onset. Cortical hyperexcitability, as heralded by reduced short interval intracortical inhibition (SICI) and increased short interval intracortical facilitation, has been associated with the onset of lower motor neuron degeneration, along with patterns of disease spread, development of specific clinical features such as the split hand phenomenon, and may provide an indication about the rate of disease progression. Additionally, reduction of SICI has emerged as a potential diagnostic aid in MND. The triple stimulation technique (TST) was shown to enhance the diagnostic utility of conventional TMS measures in detecting UMN dysfunction in MND. Separately, sophisticated brain imaging techniques have uncovered novel biomarkers of neurodegeneration that have bene associated with progression. The present review will discuss the utility of TMS and brain neuroimaging derived biomarkers of UMN dysfunction in MND, focusing on recently developed TMS techniques and advanced neuroimaging modalities that interrogate structural and functional integrity of the corticomotoneuronal system, with an emphasis on pathogenic, diagnostic, and prognostic utility.

Reduction in short interval intracortical inhibition from the early stage reflects the pathophysiology in amyotrophic lateral sclerosis: A meta-analysis study.

BACKGROUND AND PURPOSE: Cortical hyperexcitability has been identified as a diagnostic and pathogenic biomarker of amyotrophic lateral sclerosis (ALS). Cortical excitability is assessed by transcranial magnetic stimulation (TMS), a non-invasive neurophysiological technique. The TMS biomarkers exhibiting highest sensitivity for cortical hyperexcitability in ALS remain to be elucidated. A meta-analysis was performed to determine the TMS biomarkers exhibiting the highest sensitivity for cortical hyperexcitability in ALS. METHODS: A systematic literature review was conducted of all relevant studies published in the English language by searching PubMed, MEDLINE, Embase and Scopus electronic databases from 1 January 2006 to 28 February 2023. Inclusion criteria included studies reporting the utility of threshold tracking TMS (serial ascending method) in ALS and controls. RESULTS: In total, more than 2500 participants, incorporating 1530 ALS patients and 1102 controls (healthy, 907; neuromuscular, 195) were assessed with threshold tracking TMS across 25 studies. Significant reduction of mean short interval intracortical inhibition (interstimulus interval 1-7 ms) exhibited the highest standardized mean difference with moderate heterogeneity (-0.994, 95% confidence interval -1.12 to -0.873, p < 0.001; Q = 38.61, p < 0.05; I2 = 40%). The reduction of cortical silent period duration along with an increase in motor evoked potential amplitude and intracortical facilitation also exhibited significant, albeit smaller, standardized mean differences. CONCLUSION: This large meta-analysis study disclosed that mean short interval intracortical inhibition reduction exhibited the highest sensitivity for cortical hyperexcitability in ALS. Combined findings from this meta-analysis suggest that research strategies aimed at understanding the cause of inhibitory interneuronal circuit dysfunction could enhance understanding of ALS pathogenesis.

Prevalence and clinical profiles of anti-myelin-associated glycoprotein neuropathy in Japan: A nationwide survey study of 133 patients.

BACKGROUND AND PURPOSE: The aim of this study was to determine the prevalence of anti-myelin-associated glycoprotein (MAG) neuropathy and the current status of such patients in Japan. METHODS: We conducted a nationwide survey in 2021 using established epidemiological methods. Questionnaires were sent to all neurology and pediatric neurology departments throughout Japan to identify patients with anti-MAG neuropathy. An initial questionnaire was used to determine the number of patients, with a second one used to collect detailed clinical information. RESULTS: The estimated number of patients with anti-MAG neuropathy was 353, with a prevalence of 0.28 per 100,000 and an incidence of 0.05 per 100,000. The detailed clinical profiles of 133 patients were available. The median (range) age of onset was 67 (30-87) years, with a prominent peak in the age range 66-70 years, and the male-to-female ratio was 3.6. Most patients had distal sensory-predominant polyneuropathy, and neuropathic pain (50%), or sensory ataxia (42%), while 18% had Waldenström's macroglobulinemia or multiple myeloma. Intravenous immunoglobulin was the most frequently used treatment (65%), but the response rate was <50%, whereas rituximab was given in 32% of patients, and 64% of these showed improvement. At the last visit, 27% of patients could not walk independently. CONCLUSIONS: This study on anti-MAG neuropathy provides updated insights into the epidemiology of this disease, clinical profiles, and treatment approaches in Japan. Rituximab therapy, used for only one-third of the patients, demonstrated efficacy. During the final visit, a quarter of the patients were unable to walk independently. Further studies are warranted to determine the optimal management of this rare and intractable disorder.

Prevalence, Clinical Profiles, and Prognosis of CIDP in Japanese Nationwide Survey: Analyses of 1,257 Diagnosis-Confirmed Patients.

BACKGROUND AND OBJECTIVES: To investigate the current epidemiology, clinical profile, and treatment of chronic inflammatory demyelinating polyneuropathy (CIDP) using a nationwide survey in Japan. METHODS: We conducted a nationwide survey using an epidemiologic method established in 2021. Questionnaire sheets were sent to the hospital departments of neurology and pediatric neurology throughout Japan. A primary questionnaire was used to determine the number of patients and their prevalence, and a second questionnaire was used to collect detailed clinical information. RESULTS: The primary survey showed that the estimated number of patients with CIDP was 4,180, with a prevalence of 3.3 per 100,000 persons. In the secondary survey, detailed clinical data were available for 1,257 patients. The male-to-female ratio was 1.5:1, and the median age at onset was 52 years. Typical CIDP was the most frequent subtype (52%), followed by distal (17%) and multifocal/focal CIDP (17%). Initial treatments included immunoglobulin therapy (72%), corticosteroids (15%), and others (13%). Among patients with CIDP, 78% had a progressive/relapsing course, 14% did not respond to first-line treatments, and 18% could not walk independently at the last visit. Among the subtypes, typical CIDP had the most severe disability before treatment (44% of patients could not walk independently). However, they showed a more favorable response to treatment than those with distal or multifocal CIDP. In the subgroup analyses, logistic regression analyses showed that younger age at onset, no muscle atrophy, and abnormal median-normal sural sensory nerve responses were associated with a higher probability of independent walking. DISCUSSION: Our study represents the largest cohort study on CIDP to demonstrate the current epidemiologic and clinical status of CIDP in Japan. Clinical subtypes seem to be associated with different treatment responses and outcomes; therefore, an appropriate treatment strategy according to the pathophysiology of each subtype is required to improve the prognosis of CIDP.

Effects of motor cortical and peripheral axonal hyperexcitability on survival in amyotrophic lateral sclerosis.

BACKGROUND: Increased 'cortical' and 'peripheral' excitability are reportedly associated with shorter survival in amyotrophic lateral sclerosis (ALS) patients, suggesting that hyperexcitability contributes to motor neuron death. However, whether upper or lower motor function has a greater impact on survival is unclear. We aimed to investigate the component that strongly impacts the prognosis of ALS. METHODS: A total of 103 consecutive patients with ALS who underwent cortical (threshold tracking transcranial magnetic stimulation (TMS)) and motor nerve excitability tests were included. Motor cortical excitability was evaluated using short-interval intracortical inhibition (SICI) during TMS. Motor axonal excitability was assessed using the strength-duration time constant (SDTC). Survival time was defined as the time from examination to death or tracheostomy. RESULTS: Compared with healthy subjects, patients with ALS had lower SICI and longer SDTC (p<0.05), indicating increased excitability of cortical motor neurons and motor axons. According to the SICI and SDTC findings, patients were divided into the following four groups: 'cortical high and peripheral high (high-high)', 'high-low', 'low-high' and 'low-low' groups. In Kaplan-Meier curves, the 'high-high' and 'low-high' groups showed significantly shorter survival than the other groups. Multivariate analysis revealed that increased cortical (HR=5.3, p<0.05) and peripheral (HR=20.0, p<0.001) excitability were significantly associated with shorter survival. CONCLUSIONS: In patients with ALS, both motor cortical and peripheral hyperexcitability independently affected survival time, with peripheral hyperexcitability having a greater impact on shorter survival. The modulation of neuronal/axonal excitability is a potential therapeutic target for ALS.

Diagnostic utility of Gold Coast criteria for amyotrophic lateral sclerosis in Asia.

Objective: This study aimed to reveal the diagnostic utility of Gold Coast (GC) criteria in Japanese patients with amyotrophic lateral sclerosis (ALS) by comparing the sensitivity/specificity with revised El Escorial (R-EE) and Awaji criteria, because its utility has not been studied in Asian ALS. Methods: Consecutive 639 patients (529 with ALS and 110 with ALS mimics), who were suspected of ALS and referred to three Japanese ALS centers, were enrolled. Diagnostic accuracy and characteristics of false positive and negative in GC criteria were compared with those of the Awaji and R-EE criteria. Patients were categorized as definite, probable or possible ALS according to each criterion. Results: The sensitivity of GC criteria (96.8%, 95% confidence interval [CI]: 95.3-98.3%) was higher than that of Awaji (89.6%, 95% CI: 87.0-92.2%) and R-EEC (89.2, 95% CI: 86.6-91.8%) criteria (both, p < 0.001). The specificity was also higher with GC criteria (77.3%, 95% CI: 69.5-85.1%) than Awaji (65.5%, 95% CI: 56.6-74.4%) and R-EEC (66.4, 95% CI: 57.6-75.2%) criteria (both, p < 0.01). Using GC criteria, patients with cervical spondylosis and Parkinson's syndrome tended to be diagnosed with ALS (i.e. "false positive"). Additionally, ALS patients diagnosed only by GC criteria less frequently had upper motor neuron (UMN) signs, compared with the other two criteria. Conclusion: Gold Coast criteria improve diagnostic accuracy for ALS in an Asian population, especially in patients with subtle UMN signs.

Neuropathological features of levodopa-responsive parkinsonism in multiple system atrophy: an autopsy case report and comparative neuropathological study.

Background: In typical patients with multiple system atrophy with predominant parkinsonism (MSA-P) levodopa is ineffective. However, there are some of these patients who respond well to levodopa treatment. Levodopa efficacy in MSA-P patients is thought to be related to the degree of putaminal damage, but the pathological causation between the putaminal involvement and levodopa efficacy has not been established in detail. Objective: This study aimed to evaluate the neuropathological features of the nigrostriatal dopaminergic system in a "levodopa-responsive" MSA-P patient in comparison with "levodopa-unresponsive" conventional MSA-P patients. Materials and methods: Clinicopathological findings were assessed in a 53-year-old Japanese man with MSA who presented with asymmetric parkinsonism, levodopa response, and later wearing-off phenomenon. During autopsy, the nigrostriatal pathology of presynaptic and postsynaptic dopaminergic receptor density and α-synuclein status were investigated. The other two patients with MSA-P were examined using the same pathological protocol. Results: Four years after the onset, the patient died of sudden cardiopulmonary arrest. On autopsy, numerous α-synuclein-positive glial cytoplasmic inclusions in the basal ganglia, pons, and cerebellum were identified. The number of neurons in the putamen and immunoreactivity for dopamine receptors were well-preserved. In contrast, significant neuronal loss and decreased dopamine receptor immunoreactivity in the putamen were observed in the "levodopa-unresponsive" MSA-P control patients. These putaminal pathology results were consistent with the findings of premortem magnetic resonance imaging (MRI). All three patients similarly exhibited severe neuronal loss in the substantia nigra and decreased immunoreactivity for dopamine transporter. Conclusion: Levodopa responsiveness in patients with MSA-P may be corroborated by the normal putamen on MRI and the preserved postsynaptic nigrostriatal dopaminergic system on pathological examination. The results presented in this study may provide a rationale for continuation of levodopa treatment in patients diagnosed with MSA-P.

Pulmonary lesions with asteroid bodies in a pig experimentally infected with Actinobacillus pleuropneumoniae serovar 15.

Five pigs experimentally infected with Actinobacillus pleuropneumoniae serovar 15 isolated in our previous study were pathologically examined. One pig died at 2 days post inoculation (dpi) and four pigs were euthanized at 7 dpi. Autopsy revealed fibrinohemorrhagic pleuropneumonia in all pigs. Histopathologically, the lesions were characterized by extensive hemorrhage and necrosis, fibrin deposition, and multifocal abscesses composed of numerous neutrophils including oat cells and numerous Gram-negative bacilli. In one survived pig, asteroid body formation was confirmed in the lung. The bacteria within the abscesses and asteroid bodies were immunohistochemically positive for antiserum raised against A. pleuropneumoniae serovar 15. This is the first report describing porcine pleuropneumonia with asteroid bodies in a pig experimentally infected with A. pleuropneumoniae serovar 15.

Genetic factors affecting survival in Japanese patients with sporadic amyotrophic lateral sclerosis: a genome-wide association study and verification in iPSC-derived motor neurons from patients.

BACKGROUND: Several genetic factors are associated with the pathogenesis of sporadic amyotrophic lateral sclerosis (ALS) and its phenotypes, such as disease progression. Here, in this study, we aimed to identify the genes that affect the survival of patients with sporadic ALS. METHODS: We enrolled 1076 Japanese patients with sporadic ALS with imputed genotype data of 7 908 526 variants. We used Cox proportional hazards regression analysis with an additive model adjusted for sex, age at onset and the first two principal components calculated from genotyped data to conduct a genome-wide association study. We further analysed messenger RNA (mRNA) and phenotype expression in motor neurons derived from induced pluripotent stem cells (iPSC-MNs) of patients with ALS. RESULTS: Three novel loci were significantly associated with the survival of patients with sporadic ALS-FGF1 at 5q31.3 (rs11738209, HR=2.36 (95% CI, 1.77 to 3.15), p=4.85×10-9), THSD7A at 7p21.3 (rs2354952, 1.38 (95% CI, 1.24 to 1.55), p=1.61×10-8) and LRP1 at 12q13.3 (rs60565245, 2.18 (95% CI, 1.66 to 2.86), p=2.35×10-8). FGF1 and THSD7A variants were associated with decreased mRNA expression of each gene in iPSC-MNs and reduced in vitro survival of iPSC-MNs obtained from patients with ALS. The iPSC-MN in vitro survival was reduced when the expression of FGF1 and THSD7A was partially disrupted. The rs60565245 was not associated with LRP1 mRNA expression. CONCLUSIONS: We identified three loci associated with the survival of patients with sporadic ALS, decreased mRNA expression of FGF1 and THSD7A and the viability of iPSC-MNs from patients. The iPSC-MN model reflects the association between patient prognosis and genotype and can contribute to target screening and validation for therapeutic intervention.

Cardiovascular autonomic dysfunction induced by mechanical insufflation-exsufflation in Guillain-Barré syndrome.

Mechanical insufflation-exsufflation (MI-E) is an effective airway clearance device for impaired cough associated with respiratory muscle weakness caused by neuromuscular disease. Its complications on the respiratory system, such as pneumothorax, are well-recognized, but the association of the autonomic nervous system dysfunction with MI-E has never been reported. We herein describe two cases of Guillain-Barré syndrome with cardiovascular autonomic dysfunction during MI-E: a 22-year-old man who developed transient asystole and an 83-year-old man who presented with prominent fluctuation of blood pressure. These episodes occurred during the use of MI-E with abnormal cardiac autonomic testing, such as heart rate variability in both patients. While Guillain-Barré syndrome itself may cause cardiac autonomic dysfunction, MI-E possibly caused or enhanced the autonomic dysfunction by an alternation of thoracic cavity pressure. The possibility of MI-E-related cardiovascular complications should be recognized, and its appropriate monitoring and management are necessary, particularly when used for Guillain-Barré syndrome patients.

Experimental inoculation of a tissue homogenate containing porcine circovirus type 3 obtained after two in vivo passages in NIBS miniature pigs.

Porcine circovirus type 3 (PCV3) is a novel porcine circovirus that has been detected in pigs showing various clinical and pathological conditions, as well as in many asymptomatic pigs. The pathogenesis of PCV3 infection in pigs remains unclear. To evaluate the in vivo growth and pathogenicity of PCV3, we performed two experiments on PCV3 infection in laboratory-grade miniature pigs with strictly controlled genetic backgrounds and microbiological status. A PCV3 passage experiment confirmed PCV3 genome detection in the sera and multiple organs via in vivo serial passage generations. PCV3 was successively passaged in miniature pigs by inoculating tissue homogenates from infected pigs supporting Koch's principles. In the PCV3 infection experiment, viremia was observed in all the inoculated pigs, and transient neurological signs were observed in one of the three pigs. Histopathologically, all three pigs in the PCV3 inoculation group exhibited lung disorders such as interstitial pneumonia and lymphoplasmacytic perivasculitis. In addition, one pig with neurological signs in the PCV3 inoculation group showed focal thrombosis in the meninges of the cerebellum. Vascular lesions in both the lungs and brain suggest that PCV3 may cause injury to vascular tissues. In situ hybridization (ISH)-RNA analysis demonstrated that the PCV3 genome was localized in the lymph nodes of pigs inoculated with PCV3. The PCV3 in vivo passage system in NIBS miniature pigs will help investigate the pathogenicity of PCV3.

Loss of hypothalamic MCH decreases food intake in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is associated with impaired energy metabolism, including weight loss and decreased appetite which are negatively correlated with survival. Neural mechanisms underlying metabolic impairment in ALS remain unknown. ALS patients and presymptomatic gene carriers have early hypothalamic atrophy. The lateral hypothalamic area (LHA) controls metabolic homeostasis through the secretion of neuropeptides such as orexin/hypocretin and melanin-concentrating hormone (MCH). Here, we show loss of MCH-positive neurons in three mouse models of ALS based on SOD1 or FUS mutations. Supplementation with MCH (1.2 µg/d) through continuous intracerebroventricular delivery led to weight gain in male mutant Sod1G86R mice. MCH supplementation increased food intake, rescued expression of the key appetite-related neuropeptide AgRP (agouti-related protein) and modified respiratory exchange ratio, suggesting increased carbohydrate usage during the inactive phase. Importantly, we document pTDP-43 pathology and neurodegeneration in the LHA of sporadic ALS patients. Neuronal cell loss was associated with pTDP-43-positive inclusions and signs of neurodegeneration in MCH-positive neurons. These results suggest that hypothalamic MCH is lost in ALS and contributes to the metabolic changes, including weight loss and decreased appetite.

Characterization of an atypical Actinobacillus pleuropneumoniae serovar 2 isolate with a rough-type lipopolysaccharide.

We describe phenotypic and genetic characterization of an atypical Japanese Actinobacillus pleuropneumoniae isolate OT761. Nucleotide sequence analysis revealed that gene clusters involved in capsular polysaccharide and O-polysaccharide (O-PS) biosynthesis of the isolate were nearly identical to those of serovar 2 reference strain. The main difference found between the O-PS loci is the shortening of 31 amino acids from the C terminus of WcaJ in the atypical isolate due to a 93 bp deletion at the 3' end of wcaJ gene. Immunoblot analysis revealed that this isolate could not produce O-PS. Taken together, our results showed that the C-terminal domain of the A. pleuropneumoniae WcaJ plays a critical role in enzyme function of WcaJ involved in the biosynthesis of O-PS.

Combined Therapy with Ixazomib, Lenalidomide, and Dexamethasone for Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal Gammopathy, and Skin Changes Syndrome.

Objective Immunomodulatory drugs and proteasome inhibitors are therapeutic options for polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome. This study aimed to evaluate the efficacy and safety of the combination of ixazomib, lenalidomide, and dexamethasone (IRd) for POEMS syndrome. Methods Six consecutive patients with POEMS syndrome who were treated with the IRd regimen at Chiba University Hospital between April 2018 and August 2021 were included. Serum M-protein and serum vascular endothelial growth factor (sVEGF) levels, overall neuropathy limitation scales (ONLS), clinical symptoms, and adverse events were assessed. Results Of the six patients, five had received prior treatments. Patients received a median of 5 cycles (range, 3-28 cycles) of IRd. Following treatment, serum M-protein disappeared in two patients, sVEGF levels returned to normal in two patients, two patients showed a reduction in the ONLS of 1, and clinical symptoms improved in four patients. The median level of sVEGF decreased from 2,395 pg/mL (range, 802-6,120 pg/mL) to 1,428 pg/mL (range, 183-3,680 pg/mL) in three months. Adverse events, including rash, neutropenia, sensory peripheral neuropathy, and nausea, were observed in three patients, which necessitated dose reduction or discontinuation of treatment. Conclusion IRd can be a therapeutic option for POEMS syndrome, albeit with careful monitoring of adverse events.

Relationship between motor cortical and peripheral axonal hyperexcitability in amyotrophic lateral sclerosis.

BACKGROUND: Previous studies have shown that patients with amyotrophic lateral sclerosis (ALS) have hyperexcitability in both the motor cortex and peripheral motor axons, but the relationship between central and peripheral excitability has not been fully disclosed. METHODS: Threshold tracking transcranial magnetic stimulation (TMS) and motor nerve excitability testing were prospectively performed in 53 patients with ALS and 50 healthy subjects, and their relations to compound muscle action potential (CMAP) amplitude and revised ALS Functional Rating Scale were cross-sectionally analysed. RESULTS: Compared with controls, patients with ALS showed both cortical and peripheral hyperexcitability; TMS showed reduced short-interval intracortical inhibition (interstimulus interval 1-7 ms) (p<0.001) and shortened silent period (p<0.05), and median nerve excitability testing revealed greater changes in depolarising threshold electrotonus (TEd) and greater superexcitability (p<0.0001, both), suggesting reduced axonal potassium currents. Significant correlations between cortical and peripheral excitability indices were not found. Greater changes in TEd (90-100 ms) (R=-0.33, p=0.03) and superexcitability (R=0.36, p=0.01) were associated with smaller amplitude of CMAP, whereas cortical excitability indices had no correlation with CMAP amplitude. More rapid motor functional decline was associated with only greater TEd (90-100 ms) (ß=0.46, p=0.001). CONCLUSIONS: Our results suggest that in ALS, cortical excitability is continuously high regardless of the extent of the peripheral burden, but peripheral hyperexcitability is associated with the extent of the peripheral burden and disease evolution speed. Alterations of ion channel function may play an important role in ALS pathophysiology.

Efficacy and Safety of Ultrahigh-Dose Methylcobalamin in Early-Stage Amyotrophic Lateral Sclerosis: A Randomized Clinical Trial.

Importance: The effectiveness of currently approved drugs for amyotrophic lateral sclerosis (ALS) is restricted; there is a need to develop further treatments. Initial studies have shown ultrahigh-dose methylcobalamin to be a promising agent. Objective: To validate the efficacy and safety of ultrahigh-dose methylcobalamin for patients with ALS enrolled within 1 year of onset. Design, Setting, and Participants: This was a multicenter, placebo-controlled, double-blind, randomized phase 3 clinical trial with a 12-week observation and 16-week randomized period, conducted from October 17, 2017, to September 30, 2019. Patients were recruited from 25 neurology centers in Japan; those with ALS diagnosed within 1 year of onset by the updated Awaji criteria were initially enrolled. Of those, patients fulfilling the following criteria after 12-week observation were eligible for randomization: 1- or 2-point decrease in the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) total score, a percent forced vital capacity greater than 60%, no history of noninvasive respiratory support and tracheostomy, and being ambulatory. The target participant number was 64 in both the methylcobalamin and placebo groups. Patients were randomly assigned through an electronic web-response system to methylcobalamin or placebo. Interventions: Intramuscular injection of methylcobalamin (50-mg dose) or placebo twice weekly for 16 weeks. Main Outcomes and Measures: The primary end point was change in ALSFRS-R total score from baseline to week 16 in the full analysis set. Results: A total of 130 patients (mean [SD] age, 61.0 [11.7] years; 74 men [56.9%]) were randomly assigned to methylcobalamin or placebo (65 each). A total of 129 patients were eligible for the full analysis set, and 126 completed the double-blind stage. Of these, 124 patients proceeded to the open-label extended period. The least square means difference in ALSFRS-R total score at week 16 of the randomized period was 1.97 points greater with methylcobalamin than placebo (-2.66 vs -4.63; 95% CI, 0.44-3.50; P = .01). The incidence of adverse events was similar between the 2 groups. Conclusions and Relevance: Results of this randomized clinical trial showed that ultrahigh-dose methylcobalamin was efficacious in slowing functional decline in patients with early-stage ALS and with moderate progression rate and was safe to use during the 16-week treatment period. Trial Registration: ClinicalTrials.gov Identifier: NCT03548311.

Neuronal Hyperexcitability and Free Radical Toxicity in Amyotrophic Lateral Sclerosis: Established and Future Targets.

Amyotrophic lateral sclerosis (ALS) is a devastating disease with evidence of degeneration involving upper and lower motor neuron compartments of the nervous system. Presently, two drugs, riluzole and edaravone, have been established as being useful in slowing disease progression in ALS. Riluzole possesses anti-glutamatergic properties, while edaravone eliminates free radicals (FRs). Glutamate is the excitatory neurotransmitter in the brain and spinal cord and binds to several inotropic receptors. Excessive activation of these receptors generates FRs, inducing neurodegeneration via damage to intracellular organelles and upregulation of proinflammatory mediators. FRs bind to intracellular structures, leading to cellular impairment that contributes to neurodegeneration. As such, excitotoxicity and FR toxicities have been considered as key pathophysiological mechanisms that contribute to the cascade of degeneration that envelopes neurons in ALS. Recent advanced technologies, including neurophysiological, imaging, pathological and biochemical techniques, have concurrently identified evidence of increased excitability in ALS. This review focuses on the relationship between FRs and excitotoxicity in motor neuronal degeneration in ALS and introduces concepts linked to increased excitability across both compartments of the human nervous system. Within this cellular framework, future strategies to promote therapeutic development in ALS, from the perspective of neuronal excitability and function, will be critically appraised.

Different patterns of sensory nerve involvement in chronic inflammatory demyelinating polyneuropathy subtypes.

INTRODUCTION/AIMS: Among subtypes of chronic inflammatory demyelinating polyneuropathy (CIDP), different immune pathophysiologies have been proposed. In this study, sensory nerve conduction studies were compared among clinical subtypes to attempt to better understand the underlying pathophysiology. METHODS: A total of 138 patients with CIDP was classified into clinical subtypes: typical CIDP (N = 68), multifocal CIDP (N = 27), or other (N = 2). Patients with immunoglobulin M (IgM) neuropathy anti-myelin-associated glycoprotein neuropathy (MAG; N = 19) were also included as disease controls. Sensory nerve action potentials (SNAPs) were recorded in the median, ulnar, and superficial radial and sural nerves. RESULTS: SNAP amplitudes (P < .05) and conduction velocities (P < .01) in the median nerve and conduction velocities (P < .05) in the ulnar nerve were lower in typical CIDP than in multifocal CIDP, whereas those in the radial and sural nerves were comparable in each group. Low median and normal sural SNAP amplitudes were more common in typical CIDP (P < .005) than in multifocal CIDP, suggesting predominant involvement at terminal portions of the nerves. DISCUSSION: Terminal portions of sensory nerves are preferentially affected in typical CIDP compared with multifocal CIDP. These findings might be partially explained by the hypothesis of antibody-mediated demyelination in typical CIDP at the regions where the blood-nerve barrier is anatomically deficient, whereas multifocal CIDP predominantly affects the nerve trunks, largely due to cell-mediated demyelination, with disruption of the blood-nerve barrier.

Fatigue and activity-dependent conduction block in neuromuscular disorders.

Objective: Fatigue is a major disabling problem in patients with neuromuscular disorders. Both nerve demyelination and increased axonal branching associated with collateral sprouting reduce the safety factor for impulse transmission and could cause activity-dependent hyperpolarization and conduction block during voluntary contraction, and thus fatigue. This study aimed to investigate whether activity-dependent conduction block is associated with fatigue in demyelinating neuropathies and lower motor neuron disorders. Methods: This study included 31 patients (17 with chronic inflammatory demyelinating polyneuropathy [CIDP] and 14 with spinal and bulbar muscular atrophy [SBMA]). Sixteen healthy subjects served as normal controls. Fatigue was assessed using the Fatigue Scale for Motor and Cognitive Functions (FSMC). Compound muscle action potential (CMAP) recording and nerve excitability testing after median nerve stimulation in the wrist were performed before and after maximal voluntary contraction of the abductor pollicis brevis for 1 min. Results: Patients with CIDP/SBMA had prominent fatigue with higher FSMC motor scores (P < 0.0001) than normal controls. After voluntary contractions, CMAP amplitudes decreased significantly in four of the 17 patients with CIDP and one of the 14 patients with SBMA. The reduction in CMAP amplitude was associated with the fatigue score in the motor but not in the cognitive domain. After voluntary contraction, excitability testing showed axonal hyperpolarization in the normal and CIDP/SBMA groups. Conclusions: In CIDP or SBMA, fatigue is caused by voluntary contraction-induced membrane hyperpolarization and conduction block, presumably due to the critically lowered safety factor due to demyelination or increased axonal branching. Significance: Peripheral fatigue can be objectively assessed using CMAP amplitudes and nerve excitability testing.