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.

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.

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.

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.

Subclinical articulatory changes of vowel parameters in Korean amyotrophic lateral sclerosis patients with perceptually normal voices.

The available quantitative methods for evaluating bulbar dysfunction in patients with amyotrophic lateral sclerosis (ALS) are limited. We aimed to characterize vowel properties in Korean ALS patients, investigate associations between vowel parameters and clinical features of ALS, and analyze subclinical articulatory changes of vowel parameters in those with perceptually normal voices. Forty-three patients with ALS (27 with dysarthria and 16 without dysarthria) and 20 healthy controls were prospectively collected in the study. Dysarthria was assessed using the ALS Functional Rating Scale-Revised (ALSFRS-R) speech subscores, with any loss of 4 points indicating the presence of dysarthria. The structured speech samples were recorded and analyzed using Praat software. For three corner vowels (/a/, /i/, and /u/), data on the vowel duration, fundamental frequency, frequencies of the first two formants (F1 and F2), harmonics-to-noise ratio, vowel space area (VSA), and vowel articulation index (VAI) were extracted from the speech samples. Corner vowel durations were significantly longer in ALS patients with dysarthria than in healthy controls. The F1 frequency of /a/, F2 frequencies of /i/ and /u/, the VSA, and the VAI showed significant differences between ALS patients with dysarthria and healthy controls. The area under the curve (AUC) was 0.912. The F1 frequency of /a/ and the VSA were the major determinants for differentiating ALS patients who had not yet developed apparent dysarthria from healthy controls (AUC 0.887). In linear regression analyses, as the ALSFRS-R speech subscore decreased, both the VSA and VAI were reduced. In contrast, vowel durations were found to be rather prolonged. The analyses of vowel parameters provided a useful metric correlated with disease severity for detecting subclinical bulbar dysfunction in ALS patients.

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.

Serum C3 complement levels predict prognosis and monitor disease activity in Guillain-Barré syndrome.

OBJECTIVE: Biomarkers are needed to predict prognosis and disease activity in patients with Guillain-Barré syndrome (GBS). The complement system is a key player in the pathogenesis of GBS. This study aimed to assess the potential utility of serum complement proteins as novel biomarkers in GBS. METHODS: We reviewed the medical records of 76 GBS patients with C3 and C4 measurements during hospitalization between 2010 and 2021. Clinical outcomes were correlated with baseline serum C3, C4, and seven additional predictors: four existing biomarkers (GM1, albumin, immunoglobulin G, neutrophil-lymphocyte ratio) and three clinical factors from the modified Erasmus GBS outcome score model. Five complement activation products (C3a, C4a, C5a, soluble C5b-9, factor Bb) were measured in 35 patients and were compared with C3 and C4 levels. Longitudinal changes in C3 and C4 levels were compared with the disease course in 12 patients. RESULTS: Higher C3, but not C4, was associated with poorer outcomes: lower Medical Research Council sum scores (MRCSS), higher GBS disability score (GBSDS), longer hospitalization, and more frequent treatment-related fluctuations. Age, MRCSS at admission, and baseline serum C3 were significant independent indicators of 1- and 3-month GBSDS. We found that C3 was positively correlated with C3a (r = 0.32) and C5a (r = 0.37), which indicates an activated complement cascade with high C3. Longitudinal change of C3 coincided with clinical severity of the disease course. INTERPRETATION: This study highlights the use of serum C3 as a novel mechanistic biomarker in GBS. Larger prospective studies are needed to validate our findings.

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.

Skin Biopsy as a Novel Diagnostic Aid in Immune-Mediated Neuropathies.

Immune-mediated neuropathies are a heterogenous group of inflammatory peripheral nerve disorders. They can be classified according to the domain where the autoimmune process begins: the internode, paranode, or node. However, conventional diagnostic tools, electrodiagnosis (EDX), and autoantibody testing do not fully address this issue. In this institutional cohort study, we investigated the value of dermal myelinated fiber analysis for target domain-based classification. Twenty-seven consecutive patients with immune-mediated neuropathies underwent skin biopsies. The sections were stained with antibodies representative of myelinated fiber domains and were scanned using a confocal microscope. Clinical and pathological features of each patient were reviewed comprehensively. Quantitative morphometric parameters were subjected to clustering analysis, which stratified patients into 3 groups. Cluster 1 ("internodopathy") was characterized by prominent internodal disruption, intact nodes and paranodes, demyelinating EDX pattern, and absence of nodal-paranodal antibodies. Cluster 2 ("paranodopathy") was characterized by paranodal disruption and corresponding antibodies. Morphological changes were restricted to the nodes in cluster 3; we designated this cluster as "nodopathy." This report highlights the utility of skin biopsy as a diagnostic aid to gain pathogenic insight and classify patients with immune-mediated neuropathies.

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.

Sensory Guillain-Barre syndrome following the ChAdOx1 nCov-19 vaccine: Report of two cases and review of literature.

Massive vaccination against COVID-19 has become a global priority. Simultaneously, concerns regarding the safety of vaccines are growing. We describe two patients who developed sensory Guillain-Barre syndrome (GBS) shortly after the first dose of the ChAdOx1 vaccine. We also summarize 12 published cases of GBS after ChAdOx1 vaccination, highlighting their unique clinical and paraclinical features. We propose a possible association between the risk of GBS and the ChAdOx1 vaccine and recommend surveillance for GBS following vaccination. Population-based studies are needed to determine causality and whether specific subpopulations are susceptible.

Incidence patterns of nervous system diseases after carbon monoxide poisoning: a retrospective longitudinal study in South Korea from 2012 to 2018.

OBJECTIVE: To analyze the incidence patterns of nervous system diseases in survivors of carbon monoxide (CO) poisoning using nationwide claims data from South Korea. METHODS: A national cohort was abstracted from a database that includes patients diagnosed with CO poisoning between January 2012 and December 2018. For all nervous system diseases, we investigated the frequency, pattern of incidence, effect of intensive care unit admission, and the standardized incidence ratios (SIRs) to estimate the risk of nervous system disease after CO poisoning. RESULTS: Of 26,778 patients, 18,720 (69.9%) were diagnosed with nervous system diseases after CO poisoning. The most common disease was disorders of sleep initiation and maintenance (n=701, 3.74%), followed by tension-type headache (n=477, 2.55%) and anoxic brain injury (n=406, 2.17%). Over half of the nervous system diseases occurred within the first year after CO poisoning. The cumulative hazard ratio for nervous system diseases in patients admitted to the intensive care unit was 2.25 (95% confidence interval [CI], 2.07-2.44). Among the frequent nervous system diseases after CO poisoning, patients had a higher risk of disorders of initiating and maintaining sleep (SIR, 1.61; 95% CI, 1.52-1.71), tension-type headache (SIR, 2.41; 95% CI, 2.23-2.61), anoxic brain injury (SIR, 58.76; 95% CI, 53.95-63.88), and post-zoster neuralgia (SIR, 1.94; 95% CI, 1.70-2.20). CONCLUSION: Patients who experience CO poisoning are at higher risk for several nervous system diseases. Therefore, monitoring for specific nervous system diseases is important after CO poisoning within the first year.

Differential response to scrambler therapy by neuropathic pain phenotypes.

Scrambler therapy is a noninvasive electroanalgesia technique designed to remodulate the pain system. Despite growing evidence of its efficacy in patients with neuropathic pain, little is known about the clinical factors associated with treatment outcome. We conducted a prospective, open-label, single-arm trial to assess the efficacy and safety of scrambler therapy in patients with chronic neuropathic pain of various etiologies. A post-hoc analysis was performed to investigate whether cluster analysis of the Neuropathic Pain Symptom Inventory (NPSI) profiles could identify a subgroup of patients regarding neuropathic pain phenotype and treatment outcome. Scrambler therapy resulted in a significant decrease in the pain numerical rating scale (NRS) score over 2 weeks of treatment (least squares mean of percentage change from baseline, - 15%; 95% CI - 28% to - 2.4%; p < 0.001). The mean score of Brief Pain Inventory (BPI) interference subdimension was also significantly improved (p = 0.022), while the BPI pain composite score was not. Hierarchical clustering based on the NPSI profiles partitioned the patients into 3 clusters with distinct neuropathic pain phenotypes. Linear mixed-effects model analyses revealed differential response to scrambler therapy across clusters (p = 0.003, pain NRS; p = 0.072, BPI interference subdimension). Treatment response to scrambler therapy appears different depending on the neuropathic pain phenotypes, with more favorable outcomes in patients with preferentially paroxysmal pain rather than persistent pain. Further studies are warranted to confirm that capturing neuropathic pain phenotypes can optimize the use of scrambler therapy.

Association between the body mass index and outcomes of patients resuscitated from out-of-hospital cardiac arrest: a prospective multicentre registry study.

BACKGROUND: The effects of the body mass index (BMI) on outcomes of patients resuscitated from cardiac arrest are controversial. Therefore, the current study investigated the association between the BMI and the favourable neurologic outcomes and survival to discharge of patients resuscitated from out-of-hospital cardiac arrest (OHCA). METHODS: This multicentre, prospective, nationwide OHCA registry-based study was conducted using data from the Korean Cardiac Arrest Resuscitation Consortium (KoCARC). We enrolled hospitals willing to collect patient height and weight and included patients who survived to the hospital between October 2015 and June 2018. The included patients were categorised into the underweight (< 18.5 kg/m2), normal weight (≥18.5 to < 25 kg/m2), overweight (≥25 to < 30 kg/m2), and obese groups (≥30 kg/m2) according to the BMI per the World Health Organization (WHO) criteria. The primary outcome was a favourable neurologic outcome; the secondary outcome was survival to discharge. Univariate and multivariate analyses were performed to investigate the association between BMI and outcomes. RESULTS: Nine hospitals were enrolled; finally, 605 patients were included in our analysis and categorised per the WHO BMI classification. Favourable neurologic outcomes were less frequent in the underweight BMI group than in the other groups (p = 0.002); survival to discharge was not significantly different among the BMI groups (p = 0.110). However, the BMI classification was not associated with favourable neurologic outcomes or survival to discharge after adjustment in the multivariate model. CONCLUSION: The BMI was not independently associated with favourable neurologic and survival outcomes of patients surviving from OHCA.

Guillain-Barré Syndrome and Variants Following COVID-19 Vaccination: Report of 13 Cases.

BACKGROUND: Amidst growing concern about an increased risk of Guillain-Barré syndrome (GBS) following COVID-19 vaccination, clinical and electrodiagnostic features have not been fully characterized. METHODS: We retrospectively reviewed medical records of the patients diagnosed with GBS and its variants following COVID-19 vaccination at four referral hospitals during the period of the mass vaccination program in South Korea (February to October 2021). RESULTS: We identified 13 patients with GBS and variants post COVID-19 vaccination: AstraZeneca vaccine (Vaxzevria) in 8, and Pfizer-BioNTech vaccine (Comirnaty) in 5. The mean time interval from vaccination to symptom onset was 15.6 days (range 4-30 days). Electrodiagnostic classification was demyelinating in 7, axonal in 4 and normal in 2 cases. Clinical manifestations were diverse with varying severity: classical GBS in 8 cases, paraparetic variant in 3, Miller-Fisher syndrome in 1 and acute cervicobrachial weakness in 1. Four patients developed respiratory failure, and 2 of them showed treatment-related fluctuations. CONCLUSION: Our observations suggest that COVID-19 vaccines may be associated with GBS of distinctive clinical features characterized by severe quadriplegia, disproportionately frequent bilateral facial palsy or atypical incomplete variants. Continuous surveillance and further studies using robust study designs are warranted to fully assess the significance of the association.