Prognostic factors of first-onset optic neuritis based on diagnostic criteria and antibody status: a multicentre analysis of 427 eyes.

BACKGROUND: Optic neuritis (ON) prognosis is influenced by various factors including attack severity, underlying aetiologies, treatments and consequences of previous episodes. This study, conducted on a large cohort of first ON episodes, aimed to identify unique prognostic factors for each ON subtype, while excluding any potential influence from pre-existing sequelae. METHODS: Patients experiencing their first ON episodes, with complete aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibody testing, and clinical data for applying multiple sclerosis (MS) diagnostic criteria, were enrolled. 427 eyes from 355 patients from 10 hospitals were categorised into four subgroups: neuromyelitis optica with AQP4 IgG (NMOSD-ON), MOG antibody-associated disease (MOGAD-ON), ON in MS (MS-ON) or idiopathic ON (ION). Prognostic factors linked to complete recovery (regaining 20/20 visual acuity (VA)) or moderate recovery (regaining 20/40 VA) were assessed through multivariable Cox regression analysis. RESULTS: VA at nadir emerged as a robust prognostic factor for both complete and moderate recovery, spanning all ON subtypes. Early intravenous methylprednisolone (IVMP) was associated with enhanced complete recovery in NMOSD-ON and MOGAD-ON, but not in MS-ON or ION. Interestingly, in NMOSD-ON, even a slight IVMP delay in IVMP by >3 days had a significant negative impact, whereas a moderate delay up to 7-9 days was permissible in MOGAD-ON. Female sex predicted poor recovery in MOGAD-ON, while older age hindered moderate recovery in NMOSD-ON and ION. CONCLUSION: This comprehensive multicentre analysis on first-onset ON unveils subtype-specific prognostic factors. These insights will assist tailored treatment strategies and patient counselling for ON.

Early rituximab treatment reduces long-term disability in aquaporin-4 antibody-positive neuromyelitis optica spectrum.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) causes relapsing inflammatory attacks in the central nervous system, leading to disability. As rituximab, a B-lymphocyte-depleting monoclonal antibody, is an effective in preventing NMOSD relapses, we hypothesised that earlier initiation of rituximab can also reduce long-term disability of patients with NMOSD. METHODS: This multicentre retrospective study involving 19 South Korean referral centres included patients with NMOSD with aquaporin-4 antibodies receiving rituximab treatment. Factors associated with the long-term Expanded Disability Status Scale (EDSS) were assessed using multivariable regression analysis. RESULTS: In total, 145 patients with rituximab treatment (mean age of onset, 39.5 years; 88.3% female; 98.6% on immunosuppressants/oral steroids before rituximab treatment; mean disease duration of 121 months) were included. Multivariable analysis revealed that the EDSS at the last follow-up was associated with time to rituximab initiation (interval from first symptom onset to initiation of rituximab treatment). EDSS at the last follow-up was also associated with maximum EDSS before rituximab treatment. In subgroup analysis, the time to initiation of rituximab was associated with EDSS at last follow-up in patients aged less than 50 years, female and those with a maximum EDSS score ≥6 before rituximab treatment. CONCLUSIONS: Earlier initiation of rituximab treatment may prevent long-term disability worsening in patients with NMOSD, especially among those with early to middle-age onset, female sex and severe attacks.

The Profile of Early Sedation Depth and Clinical Outcomes of Mechanically Ventilated Patients in Korea.

BACKGROUND: Current international guidelines recommend against deep sedation as it is associated with worse outcomes in the intensive care unit (ICU). However, in Korea the prevalence of deep sedation and its impact on patients in the ICU are not well known. METHODS: From April 2020 to July 2021, a multicenter, prospective, longitudinal, noninterventional cohort study was performed in 20 Korean ICUs. Sedation depth extent was divided into light and deep using a mean Richmond Agitation-Sedation Scale value within the first 48 hours. Propensity score matching was used to balance covariables; the outcomes were compared between the two groups. RESULTS: Overall, 631 patients (418 [66.2%] and 213 [33.8%] in the deep and light sedation groups, respectively) were included. Mortality rates were 14.1% and 8.4% in the deep and light sedation groups (P = 0.039), respectively. Kaplan-Meier estimates showed that time to extubation (P < 0.001), ICU length of stay (P = 0.005), and death (P = 0.041) differed between the groups. After adjusting for confounders, early deep sedation was only associated with delayed time to extubation (hazard ratio [HR], 0.66; 95% confidence interval [CI], 0.55-0.80; P < 0.001). In the matched cohort, deep sedation remained significantly associated with delayed time to extubation (HR, 0.68; 95% CI, 0.56-0.83; P < 0.001) but was not associated with ICU length of stay (HR, 0.94; 95% CI, 0.79-1.13; P = 0.500) and in-hospital mortality (HR, 1.19; 95% CI, 0.65-2.17; P = 0.582). CONCLUSION: In many Korean ICUs, early deep sedation was highly prevalent in mechanically ventilated patients and was associated with delayed extubation, but not prolonged ICU stay or in-hospital death.

Associations of neuralgic amyotrophy with COVID-19 vaccination: Disproportionality analysis using the World Health Organization pharmacovigilance database.

INTRODUCTION/AIMS: There are limited studies on the association of COVID-19 vaccination with neuralgic amyotrophy (NA). Therefore, we evaluated the association between COVID-19 vaccination and the occurrence of NA. METHODS: We explored unexpected safety signals for NA related to COVID-19 vaccination through disproportionality analysis using VigiBase, the World Health Organization's pharmacovigilance database. RESULTS: On October 15, 2021, 335 cases of NA were identified in the database. The median time to onset of NA after vaccination was around 2 weeks. A significant signal of disproportionality of NA was observed for the ChAdOx1 nCoV-19 vaccine (AstraZeneca) (information component [IC]025  = 0.33, reporting odds ratio [ROR]025  = 1.30) and two mRNA-based COVID-19 vaccines (BNT162b2 [Pfizer and BioNTech] and mRNA-1273 [Moderna]) (IC025  = 1.74, ROR025  = 3.82) compared with the entire database. However, when compared with influenza vaccines, we did not detect any signal of disproportionality of NA for both the ChAdOx1 nCoV-19 vaccine (IC025  = -2.71, ROR025  = 0.05) and mRNA-based COVID-19 vaccines (IC025  = -1.38, ROR025  = 0.13). DISCUSSION: A weak association was observed between NA and COVID-19 vaccines. However, the risk did not surpass that of influenza vaccines.

Associations of Guillain-Barré syndrome with coronavirus disease 2019 vaccination: Disproportionality analysis using the World Health Organization pharmacovigilance database.

Vaccinations against the severe acute respiratory syndrome coronavirus 2 which causes COVID-19 have been administered worldwide. We aimed to investigate associations of COVID-19 vaccination with the occurrence of Guillain-Barré syndrome (GBS). We explored potential safety signals regarding the development of GBS using disproportionality analyses to compare COVID-19 vaccination with all adverse drug reaction (ADR) reports and influenza vaccines reported to VigiBase. As of October 15, 2021, a total of 2163 cases (0.13%) of GBS and its variants (including 46 cases of Miller-Fisher syndrome and 13 cases of Bickerstaff's encephalitis) were identified in entire ADR database after vaccination with the ChAdOx1 nCoV-19 (AstraZeneca, Cambridge, UK) or the two messenger RNA-based COVID-19 (BNT162b2; Pfizer and BioNTech) or mRNA-1273; Moderna) vaccines. The median time to onset of GBS after vaccination was around 2 weeks. The ChAdOx1 nCoV-19 and two messenger RNA-based COVID-19 vaccines demonstrated a higher risk for GBS against entire database (information component [IC]025  = 1.73 reporting odds ratio [ROR]025  = 3.51; IC025  = 1.07, ROR025  = 2.22, respectively). When compared with influenza vaccines, neither the ChAdOx1 nCoV-19 nor mRNA-based vaccines were found to be associated with greater risks of GBS (IC025  = -1.84, ROR025  = 0.11; IC025  = -1.86, ROR025  = 0.06, respectively). Although potential safety signals associated with GBS COVID-19 vaccines have been identified, the risk of GBS from COVID-19 vaccines were low and did not surpass those of influenza vaccines; however, because of the heterogeneity of the sources of information in the WHO pharmacovigilance database, further epidemiological studies are warranted to confirm these observations.

Stroke Incidence in Survivors of Carbon Monoxide Poisoning in South Korea: A Population-Based Longitudinal Study.

BACKGROUND Carbon monoxide (CO) poisoning is a suspected risk factor for stroke. However, the association between stroke occurrence and carbon monoxide poisoning remains unclear. This nationwide study in Korea analyzed the incidence of stroke in survivors of CO poisoning. MATERIAL AND METHODS In this nationwide, population-based longitudinal study, the database of the Health Insurance Review and Assessment Service was searched to identify patients diagnosed with CO poisoning from 2012 to 2018. Their incidence of ischemic and hemorrhagic strokes, the patterns of stroke incidences, the annual incidence rates in sequential time, the standardized incidence ratio (SIR), and the effects of hyperbaric oxygen therapy (HBOT) were analyzed. RESULTS Of the 29 301 patients diagnosed with CO poisoning during the study period, 984 (3.36%) were diagnosed with stroke after CO poisoning, with approximately 50% occurring within 1 year after CO poisoning. The overall SIR for stroke was 19.49 (95% confidence interval [CI], 17.92-21.12) during the first year, decreasing to 5.64 (95% CI, 4.75-6.66) during the second year. Overall stroke hazard ratio (HR) in the patients admitted to the ICU for CO poisoning was 2.28 (95% CI, 1.19-2.27), compared with 2.35 (95% CI, 1.94-2.84) for ischemic stroke and 1.76 (95% CI, 1.11-2.78) for hemorrhagic stroke. Cumulative HRs did not differ between patients who were and were not treated with HBOT for stroke. CONCLUSIONS CO poisoning is a high-risk factor for the development of stroke, evidenced by high incidences of stroke after CO poisoning. Practical strategies for preventing stroke after CO poisoning are needed, because stroke after CO poisoning affects adults of almost all ages, significantly increasing their socioeconomic burden.

Does Exposure to Computed Tomography Contrast Media Increase Risk of End-Stage Renal Disease?

BACKGROUND There are many studies on acute kidney injury (AKI) after exposure to contrast media in patients with chronic kidney disease (CKD). However, whether the risk of end-stage renal disease (ESRD) increases after exposure to contrast media in the long term, regardless of development of AKI after such exposure, has not been studied. MATERIAL AND METHODS The electronic health records of patients diagnosed with CKD and followed up from 2014 to 2018 at a tertiary university hospital were retrospectively collected. Patients were divided into patients who progressed to ESRD (ESRD group) and those who did not (non-ESRD group). Patients in the non-ESRD group were matched 1: 1 to those in the ESRD group by using disease risk score generation and matching. Multivariate logistic regression analysis was performed to assess the effect of contrast media exposure on progression to ESRD. RESULTS In total, 179 patients were enrolled per group; 178 (99.4%) were in CKD stage 3 or above in both groups. Average serum creatinine was 4.31±3.02 mg/dl and 3.64±2.55 mg/dl in the ESRD and non-ESRD groups, respectively (p=0.242). Other baseline characteristics were not statistically significant, except for the number of times contrast-enhanced computed tomography (CECT) was performed (0.00 [Interquartile range (IQR) 0.00-2.00] in the ESRD group and 0.00 [IQR 0.00-1.00] in the non-ESRD group [p=0.006]); in multivariate logistic regression, this number (OR=1.24, 95% CI=1.08-1.47, p=0.006) was significantly related to progression to ESRD. CONCLUSIONS The use of CECT increased the risk of ESRD 1.2-fold in advanced and stable CKD outpatients after 5-year follow-up.

Patterns of pontine strokes mimicking Bell's palsy.

BACKGROUND: Peripheral-type facial palsy very rarely arises from pontine stroke. We attempted to identify unique clinico-radiologic patterns associated with this condition. CASE PRESENTATION: Patients with pontine tegmentum stroke and acute onset of peripheral-type facial weakness were reviewed from the acute stroke registry of a tertiary hospital. The clinico-radiologic patterns of 10 patients were classified into one of three types based on the respective stroke mechanism. Type A (n = 5) was characterized by relatively diverse clinical presentations and larger, multiple infarctions resulting from large-artery atherosclerosis. Three cases with small lacunar infarcts were classified to type B (small vessel occlusion), and they showed only limited symptoms including horizontal gaze disturbance and facial paralysis. The two hemorrhagic cases (type C) presented with a focal pontine hemorrhage, likely due to a cavernous hemangioma. CONCLUSIONS: Peripheral-type facial palsy often occurs in pontine stroke with specific patterns. Type recognition helps to determine the underlying mechanism and the appropriate clinical approach. In particular, focal pontine tegmental infarctions showing stereotypic combinations of ophthalmoplegia and peripheral-type facial weakness (type B) might be recognized as a new type of lacunar syndrome.

The Emerging Method of Suicide by Electronic Cigarette Liquid: a Case Report.

Electronic cigarettes (ECs) are a device that aerosolize liquid nicotine by heating a solution of nicotine, glycerol and flavoring agents. The awareness and the usage of ECs has increased in many countries. Due to the online sales and the absence of EC regulations, the prevalence of EC usage is especially high in adolescents and young adults. Due to the large amount and the high nicotine concentration of EC liquid, the ingestion for suicide can lead to cardiac death. We had two patients, a 27-year-old male who ingested about 23 mg/kg of nicotine and a 17-year-old female who ingested about 30 mg/kg of nicotine. Both patients presented seizure-like movement and cardiac arrest. They had metabolic acidosis and transient cardiomyopathy. They were ultimately discharged with a cerebral performance category of 2 and 4, respectively. Increasing EC use may produce more cases of medical problems or suicide by nicotine intoxication.

Usefulness of Ultralow-Dose (Submillisievert) Chest CT Using Iterative Reconstruction for Initial Evaluation of Sharp Fish Bone Esophageal Foreign Body.

OBJECTIVE: The purpose of this article was to evaluate the usefulness of ultralow-dose chest CT as an initial imaging study for evaluation of sharp fish bone esophageal foreign body (FB). MATERIALS AND METHODS: A total of 57 subjects who underwent ultralow-dose chest CT were included in this retrospective study. All subjects had a history of ingestion and symptoms of esophageal FB. All ultralow-dose chest CT data were reconstructed twice, once with filtered back projection (FBP) and once with iterative reconstruction, and three observers reviewed the images independently. ROC analysis was used to evaluate diagnostic performance of ultralow-dose chest CT. Intraclass correlation coefficient (ICC) was calculated for analysis of interobserver agreement. RESULTS: Among 57 patients, 42 were confirmed as having esophageal FB. Significant objective noise reduction of mediastinum was achieved using an iterative reconstruction technique. Subjective image noise of iterative reconstruction was significantly better than that of FBP. Overall diagnostic performance of ultralow-dose chest CT for esophageal FB of iterative reconstruction (AUC = 0.999) was significantly better than that of FBP (AUC = 0.95) (p = 0.02). Interobserver agreement was greater for iterative reconstruction (ICC = 0.944) than for FBP (ICC = 0.778). CONCLUSION: Ultralow-dose chest CT using iterative reconstruction provided satisfactory diagnostic image quality for identifying fish bone esophageal FB with reduced radiation dose and high observer accuracy. Therefore, ultralow-dose chest CT would be adequate as a first-line imaging modality for fish bone esophageal FB.

Carbon monoxide-induced cardiomyopathy.

BACKGROUND: Previous reports demonstrated mechanisms of cardiac toxicity in acute carbon monoxide (CO) poisoning. Still, none established CO-induced cardiomyopathy (CMP) as a clinical entity. The aim of this study is to investigate CO-induced CMP in patients with acute CO poisoning in terms of its epidemiology, clinical characteristics, and prognosis. METHODS AND RESULTS: A retrospective study was conducted on consecutive patients who were diagnosed with acute CO poisoning at the emergency department of Ajou University Hospital during the period of 62 month. Six hundred and twenty-six patients were diagnosed with acute CO poisoning. During the initial echocardiography, 19 patients were abnormal: (1) global hypokinesia/akinesia (n=7), (2) regional wall hypokinesia/akinesia [n=12; takotsubo type (n=6), reverse takotsubo type (n=2), non-specific type (n=4)]. The ejection fraction (EF) was 36.3±13.5% (from 15% to 55%) and less than 45% for 14 patients. In the follow-up echocardiography performed within 12 days after the initial performance, most patients were found to have cardiac wall motion abnormalities, and their EF had returned to normal (ie, EF ≥50%). CONCLUSIONS: CO-induced CMP was identified in 3.04% (n=19) of all patients (n=626). It might not be too critical in acute clinical courses of acute CO poisoning because the prognosis seems favorable. Considering the common factors between CO-induced CMP and takotsubo CMP, myocardial stunning subject to a catecholamine surge most likely plays a central role in the development of CO-induced CMP.

Evaluation of exhaled nitric oxide in acute paraquat poisoning: a pilot study.

BACKGROUND: Fractional exhaled nitric oxide (FENO) is nitric oxide (NO) in the lower airway measured by oral exhalation. FENO can be a useful non-invasive marker for asthma. Paraquat-mediated lung injury can be reflective of an ROS-induced lung injury. We aimed to verify if FENO is a clinical parameter of ROS formation and responsiveness to medical therapies in acute paraquat intoxication. MATERIAL AND METHODS: We recruited 12 patients admitted with acute paraquat poisoning. A portable and noninvasive device called NIOX MINO™ (Aerocrine AB, Solna, Sweden) was used to measure FENO. Measurements were made at the time of hospital admission and at 24, 48, 72, 96, and 120 h after paraquat ingestion. RESULTS: Six out of the total 12 recruited patients had general conditions (e.g. oral pain) that made it difficult for them to exhale with adequate force. Mean plasma paraquat level was 1.4 ± 2.5 g/mL. We found no direct correlation between the paraquat levels (both ingestion amount and plasma concentration) and FENO (initial, maximal, and minimal values). All the measured FENO values were no greater than 20 ppb for the 2 patients who died. FENO did not vary more than 20% from the baseline. Compared to the above findings, FENO measurements were found to be greater than 20 ppb for the patients who survived. FENO tends to reach its peak value at between 50 h and 80 h. CONCLUSIONS: FENO did not predict mortality, and there was no increase of FENO in patients with severe paraquat intoxication.

Does ondansetron have an effect on intramuscular ketamine-associated vomiting in children? A prospective, randomised, open, controlled study.

AIM: Ketamine is one of the most commonly used sedatives for facilitating painful procedures for paediatric patients in the emergency department (ED). However, the use of ketamine is associated with a common, though not serious, adverse event usually called ketamine-associated vomiting (KAV). The purpose of this study is to evaluate the anti-emetic effect of adjunctive ondansetron in paediatric patients receiving ketamine sedation in the ED. METHODS: We conducted a prospective, randomised, open, controlled study in children from 1 to 18 years of age who had undergone intramuscular ketamine sedation in the ED. The patients were randomised into two groups: a ketamine-only group and a ketamine/ondansetron group. The patients in the first group received ketamine alone, while those in the second group received ketamine with oral ondansetron. The incidence of KAV was estimated in the ED and after discharge, and the time to resumption of a normal diet was measured after sedation. RESULTS: A total of 237 patients were analysed. The incidence of KAV was 29.7% in the ketamine-only group and 25.2% in the ketamine/ondansetron group (P = 0.47). After administration of ketamine, the mean time to resumption of a normal diet was 8 h 54 min in the ketamine-only group and 8 h 39 min in the ketamine/ondansetron group (P = 0.67). CONCLUSIONS: A relatively high rate of KAV (29.7%) was observed, and the time to resumption of a normal diet after ketamine sedation was rather long. It turned out that, however, the adjunctive administration of ondansetron did not effectively reduce the incidence of KAV.

Superior oblique palsy as the initial manifestation of anti-contactin-1 IgG4 autoimmune nodopathy: A case report.

Autoimmune nodopathy (AN) is a group of peripheral neuropathies caused by antibodies targeting the nodes of Ranvier or paranodes. It typically presents with sensory ataxia, distal limb weakness, and tremor, and often has a subacute onset, with limited response to immunoglobulin or corticosteroids. We report a case of anti-contactin-1 neuropathy initially manifesting as isolated superior oblique palsy, aiming to broaden the clinical spectrum of the disease. A 68-year-old male with well-controlled diabetes, hypertension, and hyperlipidemia developed acute binocular vertical diplopia, progressing over two months to include distal paresthesia, sensory ataxia, ageusia, and dysarthria. Concurrent nephrotic syndrome was identified. Nerve conduction studies supported demyelination. Despite treatment with intravenous methylprednisolone followed by long-term immunosuppression, some disability persisted. Serum archived during his admission tested positive for anti-contactin-1 IgG, with IgG4 as the predominant subclass, in the flow cytometry assay for AN. This case extends the clinical spectrum of AN. Some cases of isolated cranial nerve palsies, especially in the relevant context like nephrotic syndrome, may be attributed to AN. Prompt initiation of more effective therapies, such as rituximab, could significantly improve outcomes.

Association of serum Spp1 levels with disease progression in ALS and SBMA.

OBJECTIVE: In comparison with amyotrophic lateral sclerosis (ALS), the contribution of neuroinflammation in spinobulbar muscular atrophy (SBMA) has been less explored. We investigated the role of neuroinflammation in the pathogenesis of ALS and SBMA by analyzing systemic inflammatory markers and osteopontin (Spp1). METHODS: This study involved 105 ALS, 77 SBMA, and 55 healthy controls. We measured their systemic inflammatory markers, serum Spp1, and cytokine levels (interferon-γ, interleukin [IL]-1ß, IL-6, IL-8, IL-10, tumor necrosis factor-α, and IL-17A), investigated correlations between Spp1 levels and clinical features, and evaluated ALS survival rates according to Spp1 levels. RESULTS: In the ALS group, systemic inflammatory markers were significantly higher than in the control and SBMA groups. Spp1 levels were observed to be higher in ALS patients, but the difference was not statistically significant among the study groups. Cytokine profiles were comparable. In ALS, higher Spp1 levels were correlated with lower ALS Functional Rating Scale-Revised (ALSFRS-R) scores (r = -0.25, p = 0.02) and faster disease progression rate (r = 0.37, p < 0.001). After adjusting for other prognostic indicators, high Spp1 levels were independently associated with shorter survival in ALS patients (hazard ratio 13.65, 95% confidence interval 2.57-72.53, p < 0.01). INTERPRETATION: Neuroinflammation does not appear to be a primary contributor to the pathogenesis of SBMA. Serum Spp1 levels may serve as a reliable biomarker for disease progression and prognosis in ALS. These findings expand our understanding of these two distinct motor neuron disorders and offer a potential biomarker for future studies.

Genetic Risk Factors for Bortezomib-induced Neuropathic Pain in an Asian Population: A Genome-wide Association Study in South Korea.

Bortezomib-induced neuropathic pain (BINP) poses a challenge in multiple myeloma (MM) treatment. Genetic factors play a key role in BINP susceptibility, but research has predominantly focused on Caucasian populations. This research explored novel genetic risk loci and pathways associated with BINP development in Korean MM patients while evaluating the reproducibility of variants from Caucasians. Clinical data and buffy coat samples from 185 MM patients on bortezomib were collected. The cohort was split into discovery and validation cohorts through random stratification of clinical risk factors for BINP. Genome-wide association study was performed on the discovery cohort (n = 74) with Infinium Global Screening Array-24 v3.0 BeadChip (654,027 single nucleotide polymorphism [SNPs]). Relevant biological pathways were identified using the pathway scoring algorithm. The top 20 SNPs were validated in the validation cohort (n = 111). Previously reported SNPs were validated in the entire cohort (n = 185). Pathway analysis of the genome-wide association study results identified 31 relevant pathways, including immune systems and endosomal vacuolar pathways. Among the top 20 SNPs from the discovery cohort, 16 were replicated, which included intronic variants in ASIC2 and SMOC2, recently implicated in nociception, as well as intergenic variants or long noncoding RNAs. None of the 17 previously reported SNPs remained significant in our cohort (rs2274578, P = .085). This study represents the first investigation of novel genetic loci and biological pathways associated with BINP occurrence. Our findings, in conjunction with existing Caucasian studies, expand the understanding of personalized risk prediction and disease mechanisms. PERSPECTIVE: This article is the first to explore novel genetic loci and pathways linked to BINP in Korean MM patients, offering novel insights beyond the existing research focused on Caucasian populations into personalized risk assessment and therapeutic strategies of BINP.

Therapeutic Outcomes and Electrophysiological Biomarkers in Anti-Myelin-Associated Glycoprotein Neuropathy: A Multicenter Cohort Study in South Korea.

BACKGROUND AND PURPOSE: Unlike other immune-mediated neuropathies, anti-myelin-associated glycoprotein (MAG) neuropathy is often refractory to immunotherapy. It is necessary to compare the relative efficacies of various immunotherapies and develop objective biomarkers in order to optimize its clinical management. METHODS: This study recruited 91 patients with high anti-MAG antibody titers from 7 tertiary hospitals in South Korea. We analyzed the baseline characteristics, therapeutic outcomes, and nerve conduction study (NCS) findings of 68 patients and excluded 23 false positive cases. RESULTS: The rate of positive responses to treatment was highest using zanubrutinib (50%) and rituximab (36.4%), followed by corticosteroids (16.7%), immunosuppressants (9.5%), intravenous immunoglobulin (5%), and plasma exchange (0%). Disability and weakness were significantly associated with multiple NCS parameters at the time of diagnosis, especially distal compound muscle action potential (CMAP) amplitudes. Moreover, the longitudinal trajectory of the average CMAP amplitudes paralleled the clinical courses, with a 16.2 percentile decrease as an optimal cutoff for predicting a clinical exacerbation (area under the receiver operating characteristic curve=0.792). CONCLUSIONS: Our study supports the use of NCS as an objective marker for estimating disease burden and tracking clinical changes in patients with anti-MAG neuropathy. We have described the beneficial effects of rituximab and a new drug, zanubrutinib, compared with conventional immunotherapies.