Impact of COVID-19 Infection and Its Association With Previous Vaccination in Patients With Myasthenia Gravis in Korea: A Multicenter Retrospective Study.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, patients with myasthenia gravis (MG) were more susceptible to poor outcomes owing to respiratory muscle weakness and immunotherapy. Several studies conducted in the early stages of the COVID-19 pandemic reported higher mortality in patients with MG compared to the general population. This study aimed to investigate the clinical course and prognosis of COVID-19 in patients with MG and to compare these parameters between vaccinated and unvaccinated patients in South Korea. METHODS: This multicenter, retrospective study, which was conducted at 14 tertiary hospitals in South Korea, reviewed the medical records and identified MG patients who contracted COVID-19 between February 2022 and April 2022. The demographic and clinical characteristics associated with MG and vaccination status were collected. The clinical outcomes of COVID-19 infection and MG were investigated and compared between the vaccinated and unvaccinated patients. RESULTS: Ninety-two patients with MG contracted COVID-19 during the study. Nine (9.8%) patients required hospitalization, 4 (4.3%) of whom were admitted to the intensive care unit. Seventy-five of 92 patients were vaccinated before contracting COVID-19 infection, and 17 were not. During the COVID-19 infection, 6 of 17 (35.3%) unvaccinated patients were hospitalized, whereas 3 of 75 (4.0%) vaccinated patients were hospitalized (P < 0.001). The frequencies of ICU admission and mechanical ventilation were significantly lower in the vaccinated patients than in the unvaccinated patients (P = 0.019 and P = 0.032, respectively). The rate of MG deterioration was significantly lower in the vaccinated patients than in the unvaccinated patients (P = 0.041). Logistic regression after weighting revealed that the risk of hospitalization and MG deterioration after COVID-19 infection was significantly lower in the vaccinated patients than in the unvaccinated patients. CONCLUSION: This study suggests that the clinical course and prognosis of patients with MG who contracted COVID-19 during the dominance of the omicron variant of COVID-19 may be milder than those at the early phase of the COVID-19 pandemic when vaccination was unavailable. Vaccination may reduce the morbidity of COVID-19 in patients with MG and effectively prevent MG deterioration induced by COVID-19 infection.

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.

Validation of the Individualized Neuromuscular Quality of Life Questionnaire in Korean Patients With Genetic Neuromuscular Diseases.

BACKGROUND AND PURPOSE: The Individualized Neuromuscular Quality of Life questionnaire (INQoL) is a widely used measure of the quality of life in patients with neuromuscular diseases. The purpose of this study was to translate and validate the Korean version of INQoL in Korean patients with neuromuscular diseases. METHODS: We translated the original INQoL version into Korean while applying appropriate language adaptations. The internal consistency, known-group validity, and test-retest reliability were also assessed. Construct validity was measured using the modified Rankin Scale (mRS) score and the manual muscle testing (MMT)-sum score based on the Medical Research Council scale, and concurrent validity was measured using the 36-item Short Form Survey (SF-36) questionnaire. RESULTS: This study enrolled 193 patients. The coefficients for internal consistency (Cronbach's α=0.805 to 0.987) and test-retest reliability (Spearman's ρ=0.453 to 0.886) were adequately high for all subscales except in the 'treatment effects' dimension. INQoL subscales other than those for locking, droopy eyelids, double vision, and swallowing difficulties were significantly associated with their relevant SF-36 domains (Spearman's ρ=-0.274 to -0.833). Functional status and muscle strength were most strongly associated with independence (Spearman's ρ=0.753 and p<0.001 for mRS score, Spearman's ρ=-0.741 and p<0.001 for MMT-sum score). CONCLUSIONS: The Korean INQoL is a reliable and validated measurement tool for Korean patients with neuromuscular diseases.

Old age and multiple comorbidity are associated with delayed diagnosis of Guillain-Barre syndrome.

To assess whether older age and presence of comorbidities were associated with a delayed diagnosis of Guillain-Barré syndrome (GBS). The medical records of 140 patients diagnosed with GBS at Severance Hospital from March 2011 to December 2020 were retrospectively reviewed. Comorbidity profiles were assessed using the Charlson comorbidity index (CCI). The age-adjusted CCI (ACCI) score was calculated, which further incorporated the effect of age. Patients were classified into the early diagnosis group (diagnosis duration ≤ 14 days) and late diagnosis group (diagnosis duration > 14 days). Clinical features and comorbidity profiles were compared between the two groups. The cumulative incidence of diagnosis was compared between the low and high ACCI groups. Age was significantly higher in the late diagnosis group (61.8 ± 15.0 years) than in the early diagnosis group (49.1 ± 18.4, p = 0.001). The CCI score was higher in the late diagnosis group (≥ 3 in 26.1%) than in the early diagnosis group (≥ 3 in 5.1%, p = 0.01). The ACCI score demonstrated a positive correlation with the diagnosis duration (ß = 1.636, p < 0.001), indicating that the diagnosis was delayed in patients with a higher ACCI score. The duration from onset to diagnosis was longer in the high ACCI group than in the low ACCI group (log-rank test, p < 0.001). The diagnosis duration was significantly longer, especially in patients with malignancy and cardiovascular diseases. Delayed diagnosis of GBS is associated with older age and multiple comorbidities. Diagnostic delay was significant in patients with malignancies and cardiovascular diseases. Early suspicion of GBS is required in these patients.

Serum uric acid level predicts the progression of amyotrophic lateral sclerosis following treatment with edaravone.

INTRODUCTION: Uric acid and edaravone might exert a neuroprotective effect in amyotrophic lateral sclerosis (ALS) by reducing oxidative stress. We analyzed whether the treatment effect of edaravone is pronounced in patients whose uric acid level increased after the treatment with edaravone. MATERIALS AND METHODS: Forty patients with ALS who underwent treatment with edaravone were included. Baseline uric acid level and the rate of decline in uric acid after edaravone treatment were recorded. The rate of change of ALS functional rating scale-revised (ΔALSFRS-R/month) was calculated based on baseline ALSFRS-R score and ALSFRS-R score 6-24 weeks after the treatment. RESULTS: The serum uric acid levels decreased after treatment in 26 (65%) patients and increased in 12 (30%) patients. The ΔALSFRS-R/month was significantly faster in patients whose uric acid decreased (median 1.5 [Q1-Q3, 0.7-3.1]) than in patients whose uric acid increased (0.2 [0-1.0], p = 0.021). A high baseline uric acid level and low rate of decline in uric acid was associated with slower disease progression after adjusting for age, initial symptoms, and riluzole administration (p = 0.030 and p = 0.041, respectively). DISCUSSION: High baseline values and low rate of decline in uric acid may predict slow disease progression in ALS patients treated with edaravone.

Hybrid Signal-Processing Method Based on Neural Network for Prediction of NO3, K, Ca, and Mg Ions in Hydroponic Solutions Using an Array of Ion-Selective Electrodes.

In closed hydroponics, fast and continuous measurement of individual nutrient concentrations is necessary to improve water- and nutrient-use efficiencies and crop production. Ion-selective electrodes (ISEs) could be one of the most attractive tools for hydroponic applications. However, signal drifts over time and interferences from other ions present in hydroponic solutions make it difficult to use the ISEs in hydroponic solutions. In this study, hybrid signal processing combining a two-point normalization (TPN) method for the effective compensation of the drifts and a back propagation artificial neural network (ANN) algorithm for the interpretation of the interferences was developed. In addition, the ANN-based approach for the prediction of Mg concentration which had no feasible ISE was conducted by interpreting the signals from a sensor array consisting of electrical conductivity (EC) and ion-selective electrodes (NO3, K, and Ca). From the application test using 8 samples from real greenhouses, the hybrid method based on a combination of the TPN and ANN methods showed relatively low root mean square errors of 47.2, 13.2, and 18.9 mg∙L-1 with coefficients of variation (CVs) below 10% for NO3, K, and Ca, respectively, compared to those obtained by separate use of the two methods. Furthermore, the Mg prediction results with a root mean square error (RMSE) of 14.6 mg∙L-1 over the range of 10-60 mg∙L-1 showed potential as an approximate diagnostic tool to measure Mg in hydroponic solutions. These results demonstrate that the hybrid method can improve the accuracy and feasibility of ISEs in hydroponic applications.