Multifocal motor neuropathy in Japan: A nationwide survey on prevalence, clinical profiles, and treatment.

INTRODUCTION/AIMS: Multifocal motor neuropathy (MMN) is a rare disease for which epidemiological and clinical data are limited. We conducted a nationwide survey to determine disease prevalence, incidence, clinical profile, and current treatment status in Japan. METHODS: A nationwide survey was conducted in 2021 using an established epidemiological method. Questionnaires were sent to all neurology and pediatric neurology departments in Japan. An initial questionnaire was administered to determine the number of patients with and incidence of MMN. A second questionnaire was administered to collect detailed clinical information. The European Federation of Neurological Societies/Peripheral Nerve Society 2010 guidelines were used as diagnostic criteria. RESULTS: The estimated number of patients with MMN was 507. The estimated prevalence was 0.40 per 100,000 individuals. Detailed clinical profiles were available for 120 patients. The male-to-female ratio was 2.3:1 and the median onset age was 42 years. The median disease duration at diagnosis was 25 months. Most patients presented with upper limb-dominant muscle weakness. Motor nerve conduction blocks were found in 62% of patients and positive anti-GM1 IgM antibody results in 54%. A total of 117 (98%) patients received immunoglobulin therapy, and 91% of them showed improvement. At the time of the last visit (median, 82 months from treatment initiation), 89 (74%) patients were receiving maintenance immunoglobulin therapy. A slight progression of neurological deficits was observed during follow-up. DISCUSSION: Most patients with MMN in Japan received induction and maintenance immunoglobulin therapies, which appear to suppress long-term disease progression.

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.

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.

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.

Two Cases of Encephalitis without Anti-N-methyl-D-aspartate Receptor Antibody Successfully Treated with Ovarian Teratoma Resection and Immunotherapy.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder sometimes accompanied by ovarian teratoma. However, the concept of encephalitis without anti-NMDAR antibodies successfully treated with ovarian teratoma resection and immunotherapy has not been established. We herein report two such cases. Case 1 exhibited delayed magnetic resonance imaging abnormalities in the thalamus and basal ganglia, despite clinical improvement. Case 2 presented with brainstem encephalitis similar to Bickerstaff's encephalitis. Although both patients tested negative for anti-NMDAR antibodies, the recovery of the neurological function and good prognosis following tumor resection with immunotherapy indicated a close association between these diseases and ovarian teratoma.

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.

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.