Juvenile Myasthenia Gravis in Korea: Subgroup Analysis According to Sex and Onset Age

Serum globulin in children with myasthenia gravis: predicting relapse and prognosis

OBJECTIVE

Serum globulin is associated with inflammatory or immune disorders. However, it has not been established whether it is associated with myasthenia gravis (MG). We investigated the association between globulin with relapse and prognosis in children with MG.

METHODS

A cohort of 148 MG cases and 150 healthy children were retrospectively enrolled from January 2015 to December 2021. Multivariate logistic and Cox regression models were used to analyze the treatment outcomes and recurrence of case group, exploring the influence of globulin.

RESULTS

Compared with the control group, globulin levels in the MG group were slightly increased (t = 7.244, p < 0.001). After a mean follow-up of 2.25 ± 1.05 years, 35 cases relapsed, with a relapse rate of 23.65%. Logistic regression analysis showed that globulin levels at admission [adjusted odds ratio (OR) = 1.233, 95% confidence interval (CI) 1.028-1.472, p = 0.018] were independent risk factors for relapse. Cox regression analysis confirmed that globulin levels at admission affects relapse-free time [adjusted hazard ratio (HR) = 0.552, 95% CI 0.357-0.852, p = 0.007]. Receiver operating characteristic curve determined 25.10 as the optimal cutoff value for globulin. Cox regression showed that high globulin levels (>25.10) at admission (adjusted HR = 0.607, 95% CI 0.383-0.961, p = 0.033) were independent risk factors for poor therapeutic outcomes at follow-up. Ordinal logistic regression showed that globulin affects the treatment plan (OR = 1.445, 95% CI 1.223-1.847, p = 0.014).

CONCLUSIONS

Elevated globulin levels in children with MG on admission predicts a high relapse rate and poor long-term therapeutic efficacies.

Refocusing generalized myasthenia gravis: Patient burden, disease profiles, and the role of evolving therapy

BACKGROUND AND PURPOSE

Generalized myasthenia gravis (gMG) continues to present significant challenges for clinical management due to an unpredictable disease course, frequent disease fluctuations, and varying response to therapy. The recent availability of new pharmacologic therapies presents a valuable opportunity to reevaluate how this disease is classified, assessed, and managed and identify new ways to improve the clinical care of patients with gMG.

METHODS

Narrative review was made of publications identified via searches of PubMed and selected congresses (January 2000-September 2022).

RESULTS

New consensus definitions are required to ensure consistency, to better characterize patients, and to identify patients who will benefit from specific drugs and earlier use of these agents. There is a need for more frequent, standardized patient assessment to identify the cause of motor function deficits, provide a clearer picture of the disease burden and its impact on daily living and quality of life (QoL), and better support treatment decision-making. Novel approaches that target different components of the immune system will play a role in more precise treatment of patients with gMG, alongside the development of new algorithms to guide individualized patient management.

CONCLUSIONS

gMG has a physical, mental, and social impact, resulting in a considerable burden of disease and substantially decreased QoL, despite standard treatments. The availability of novel, targeted treatments that influence key pathological mediators of gMG, together with new biomarkers, offers the potential to optimize patient management and ultimately enables a greater number of patients to achieve minimal manifestation status and a reduced burden of disease.

Pathophysiology of Childhood-Onset Myasthenia: Abnormalities of Neuromuscular Junction and Autoimmunity and Its Background

The pathophysiology of myasthenia gravis (MG) has been largely elucidated over the past half century, and treatment methods have advanced. However, the number of cases of childhood-onset MG is smaller than that of adult MG, and the treatment of childhood-onset MG has continued to be based on research in the adult field. Research on pathophysiology and treatment methods that account for the unique growth and development of children is now desired. According to an epidemiological survey conducted by the Ministry of Health, Labour and Welfare of Japan, the number of patients with MG by age of onset in Japan is high in early childhood. In recent years, MG has been reported from many countries around the world, but the pattern of the number of patients by age of onset differs between East Asia and Western Europe, confirming that the Japanese pattern is common in East Asia. Furthermore, there are racial differences in autoimmune MG and congenital myasthenic syndromes according to immunogenetic background, and their pathophysiology and relationships are gradually becoming clear. In addition, treatment options are also recognized in different regions of the world. In this review article, I will present recent findings focusing on the differences in pathophysiology.

Genetic, serological and clinical evaluation of childhood myasthenia syndromes- single center subgroup analysis experience in Turkey

BACKGROUND

Congenital myasthenic syndrome is a disease that occurs due to several types such as mutations in different pre-synaptic, synaptic, post-synaptic proteins and, glycosylation defects associated with congenital myopathy. Juvenile myasthenia gravis is an autoimmune condition usually caused by antibodies targeting the acetylcholine receptor.

AIMS

Our objective is to conduct an analysis on the subgroup traits exhibited by patients who have been diagnosed with congenital myasthenic syndrome and juvenile myasthenia gravis, with a focus on their long-term monitoring and management.

METHODS

This study was conducted on children diagnosed with myasthenia gravis, who were under the care of Dokuz Eylul University's Department of Pediatric Neurology for a period of ten years.

RESULTS

A total of 22 (12 congenital myasthenic syndrome, 10 juvenile myasthenia gravis) patients were identified. Defects in the acetylcholine receptor (6/12) were the most common type in the congenital myasthenic syndrome group. Basal-lamina-related defects (5/12) were the second most prevalent. One patient had a GFPT1 gene mutation (1/12). Patients with ocular myasthenia gravis (n = 6) exhibited milder symptoms. In the generalized myasthenia gravis group (n = 4), specifically in postpubertal girls, a more severe clinical progression was observed, leading to the implementation of more aggressive treatment strategies.

CONCLUSION

This study highlights that clinical recognition of congenital myasthenic syndrome and knowledge of related genes will aid the rapid diagnosis and treatment of these rare neuromuscular disorders. Findings in the juvenile myasthenia gravis group demonstrate the impact of pubertal development and the need for timely and appropriate active therapy, including thymectomy, to improve prognosis.

Prevalence of Neuromuscular Diseases in Young South Korean Males; A Korean Military Manpower Administration and Medical Command Data-Based Study

BACKGROUND AND PURPOSE

All young males in South Korea must undergo a physical examination for their participation in military service. We aimed to determine the prevalence rate (PR) of various neuromuscular diseases in young South Korean males using the data of exempted patients and soldiers.

METHODS

The number of males exempted based on specific items of physical examination corresponding to neuromuscular disease during 2011-2020 were obtained from the records of the Military Manpower Administration. The list of enlisted soldier patients who were discharged from military service due to neuromuscular diseases during 2011-2020 was obtained from the Armed Forces Medical Command, and their medical records were reviewed.

RESULTS

The PR of neuromuscular diseases was calculated among 948 identified males: 713 exempted males and 235 soldiers. The PRs of overall hereditary neuropathies, Hirayama disease (HD), myasthenia gravis (MG), and inherited muscle diseases in South Korean males in their early 20s were 8.34 (95% confidence interval [CI], 7.39-9.30), 5.54 (95% CI, 4.76-6.32), 2.97 (95% CI, 2.40-3.55), and 10.38 (95% CI, 9.31-11.46) per 100,000 persons, respectively. Among the enlisted soldiers, hereditary neuropathy with liability to pressure palsy was the most common neuromuscular disease, with a prevalence among the enlisted soldiers of 3.11 (95% CI, 2.42-3.80) per 100,000 persons. Myotonic dystrophy was the most prevalent myopathy, followed by facioscapulohumeral muscular dystrophy.

CONCLUSIONS

The 10-year PRs of hereditary polyneuropathies, HD, MG, and inherited muscle diseases in young South Korean males have been reported. These data could be valuable to understanding each neuromuscular disease in the young male population of South Korea.

Clinical Features, Treatment, and Prognostic Factors of Childhood-Onset Myasthenia Gravis in a Large Chinese Cohort

BACKGROUND

To describe the clinical features of patients with childhood-onset myasthenia gravis (MG) (CMG) and explore predictors affecting the treatment outcomes.

METHODS

A retrospective observational cohort analysis of 859 patients with CMG with disease onset before age 14 years was performed at Tongji Hospital.

RESULTS

Patients in the pubertal-onset group (n = 148) had a worse disease course than those in the prepubertal group (n = 711), including a higher incidence of generalized MG (GMG) at presentation, generalization of ocular MG (OMG), and more severe Myasthenia Gravis Foundation of America (MGFA) classification. All patients were initially treated with pyridostigmine, 657 with prednisone, and 196 with immunosuppressants (ISs). However, 226 patients were resistant to prednisone treatment. Multivariate analysis revealed that thymic hyperplasia, higher MGFA class, disease duration before prednisone administration, and thymectomy before prednisone administration were independent predictors of prednisone resistance. At the last visit, 121 of the 840 patients with OMG had developed GMG after a median of 10.0 years from symptom onset and 186 patients (21.7%) achieved complete stable remission (CSR). In multivariable analysis, age at onset, thymic hyperplasia, prednisone, and IS treatment were associated with generalization, whereas age at onset, disease duration, anti-acetylcholine receptor antibodies (AChR-ab), MGFA class II, short-term prednisone treatment, and IS treatment were associated with CSR.

CONCLUSIONS

The majority of patients with CMG have mild clinical symptoms and favorable outcomes, especially those with earlier onset age, shorter disease duration, and negative AChR-ab. In addition, early prednisone and ISs are shown to be effective and safe for most patients with CMG.

Outcome and clinical features in juvenile myasthenia gravis: A systematic review and meta-analysis

Background

Juvenile myasthenia gravis (JMG) is a rare autoimmune disease that has so far only been described in small cohort studies. We defined the clinical characteristics, management, and outcomes of JMG patients over the past 22 years.

Methods

A search of PubMed, EMBASE, and web of science (1/2000–2/2022) identified all English language and human studies of JMG. The population was patients diagnosed with JMG. Outcomes included the history of myasthenic crisis, autoimmune comorbidity, mortality, and treatment outcome. Data extraction was performed by independent reviewers. And we performed a pooled reanalysis of all published data in the included studies and compared with other studies of adult cohorts.

Results

We identified 11 articles describing 1,109 patients diagnosed between 2006 and 2021. JMG occurred in 60.4% of female patients. The mean age at presentation was 7.38 years old, and 60.6% of the patients had ocular symptoms as the first clinical manifestation. The most common initial presentation was ptosis, which occurred in 77.7% patients. AchR-Ab positive accounted for 78.7%. 641 patients received thymus examination, found to have thymic hyperplasia in 64.9% and thymoma in 2.2%. Autoimmune comorbidity was found in 13.6% and the most common one is thyroid disease (61.5%). First-line therapy, including pyridostigmine and steroids, was initiated in 97.8 and 68.6%, respectively. Six patients resolved spontaneously without treatment. Thymectomy was performed in 45.6%. 10.6% of patients had a history of myasthenic crisis. Completely stable remission was achieved in 23.7% and mortality was reported in 2 studies, which reported 8 deaths.

Conclusion

JMG is a rare disease with a relatively benign course, and differs from adult MG in some clinical features. The treatment regimen guideline for children is still not well-established. There is a need for prospective studies to properly evaluate treatment regimes.

The Epidemiology and Phenotypes of Ocular Manifestations in Childhood and Juvenile Myasthenia Gravis: A Review

Myasthenia gravis (MG) appears to have a similar incidence among adult populations worldwide. However, epidemiological and phenotypic differences have been noted among children and juveniles with MG. We reviewed the literature on childhood- and juvenile-onset MG among different populations, with the focus on ocular involvement, antibody profiles, the genetic susceptibility to juvenile MG phenotypes, the use of immune treatments, and the reported responses of extraocular muscles to therapies. Although epidemiological studies used different methodologies, reports from Asia, compared to Europe, showed more than two-fold higher proportions of prepubertal onset (before 12 years) vs. postpubertal-onset juveniles with MG. Compared to European children, ocular MG was 4-fold more frequent among Asian children, and 2–3-fold more frequent among children with African ancestry both in prepubertal and postpubertal ages at onset. These results suggest genetic influences. In Asia, HLA-B^*46 and DRB1^*09 appeared overrepresented in children with ocular MG. In Europe, children with MG had a significantly higher rate of transforming from ocular to generalized disease and with an overrepresentation of HLADRB1^*04. Although treatment regimens vary widely and the responses to immune therapies of the ocular muscles involved in MG were generally poorly described, there were indications that earlier use of steroid therapy may have better outcomes. Reports of treatment-resistant ophthalmoplegia may be more frequent in African and Asian juvenile MG cohorts compared to Europeans. Genetic and muscle gene expression studies point to dysregulated muscle atrophy signaling and mitochondrial metabolism pathways as pathogenetic mechanisms underpinning treatment-resistant ophthalmoplegia in susceptible individuals. In conclusion, phenotypic differences in juveniles with ocular manifestations of MG were evident in different populations suggesting pathogenetic influences. Treatment responses in MG-associated ocular disease should attract more careful descriptive reports. In MG, extraocular muscles may be vulnerable to critical periods of poor force generation and certain individuals may be particularly susceptible to developing treatment-resistant ophthalmoplegia. The development of prognostic biomarkers to identify these susceptible individuals is an unmet need.

Clinical characteristics and outcome predictors of a Chinese childhood-onset myasthenia gravis cohort

Myasthenia gravis is an organ-specific autoimmune disease. Currently there is no universal guidelines for childhood-onset myasthenia gravis, therefore, treatment strategies are usually based on the guidelines from adult myasthenia gravis patients. In order to contribute in the process of the development of the universal childhood-onset myasthenia gravis guideline, we have summarized the clinical characteristics, treatment strategies, outcome and the related predictors of childhood-onset myasthenia gravis. We recruited 343 childhood-onset myasthenia gravis cases who were followed up at the Department of Pediatrics, Xiangya Hospital from June, 2010 to December, 2019. The data about clinical characteristics, treatments and outcome were collected and analyzed. Among of the 343 cases, 164 cases were followed up for longer than 2 years, of whom 142 still remained with ocular myasthenia gravis at the endpoint. About the treatments, 27 cases (27/164) accepted pyridostigmine only while the rest accepted glucocorticoid and/or other immunosuppressants. At the endpoint, the proportion of optimal outcome was 66.2% in the group remaining with ocular myasthenia gravis and 31.8% in the generalized myasthenia gravis group. Multivariate logistic regression analysis revealed that generalized myasthenia gravis type and positive status of antibodies against acetylcholine receptors were the independent risk factors for poor outcome. In conclusion, our childhood-onset myasthenia gravis patients present mainly as ocular myasthenia gravis, adequate immunotherapy improve the long-term outcome, and generalized myasthenia gravis phenotype as well as positive status of antibodies against acetylcholine receptors relate to poor outcome.

Management of Juvenile Myasthenia Gravis

Juvenile Myasthenia Gravis (JMG) is a rare disorder, defined as myasthenia gravis in children younger than 18 years of age. While clinical phenotypes are similar to adults, there are a number of caveats that influence management: broader differential diagnoses; higher rates of spontaneous remission; and the need to initiate appropriate treatment early, to avoid the long-term physical and psychosocial morbidity. Current practice is taken from treatment guidelines for adult MG or individual experience, with considerable variability seen across centers. We discuss our approach to treating JMG, in a large specialist JMG service, and review currently available evidence and highlight potential areas for future research. First-line treatment of generalized JMG is symptomatic management with pyridostigmine, but early use of immunosuppression, where good control is not achieved is important. Oral prednisolone is used as first-line immunosuppression with appropriate prevention and monitoring of side effects. Second-line therapies including azathioprine and mycophenolate may be considered where there is: no response to steroids, inability to wean to a reasonable minimum effective dose or if side-effects are intolerable. Management of ocular JMG is similar, but requires close involvement of ophthalmology in young children to prevent amblyopia. Muscle-specific tyrosine kinase (MuSK)-JMG show a poorer response to pyridostigmine and anecdotal evidence suggests that rituximab should be considered as second-line immunosuppression. Thymectomy is indicated in any patient with a thymoma, and consideration should be given in acetylcholine receptor (AChR) positive JMG allowing time for spontaneous remission. The benefit is less clear in ocular JMG and is not advised in MuSK-JMG. Children experiencing a myasthenic crisis require urgent hospital admission with access to the intensive care unit. PLEX is preferred over IVIG due to rapid onset of action, but this needs to be balanced with feasibility in very young children. Key questions remain in the management of JMG: when to initiate both first- and second-line treatments, choosing between steroid-sparing agents, and determining the optimal dose and treatment duration. We feel that given the rarity of this disease, the establishment of national registries and collaboration across groups will be needed to address these issues and facilitate future drug trials in JMG.

Adult Ocular Myasthenia Gravis Conversion: A Single-Center Retrospective Analysis in China

INTRODUCTION

The conversion rate from ocular myasthenia gravis (OMG) to generalized myasthenia gravis (GMG) was reported to be much lower in Asian population since most OMG patients are juvenile onset. However, the exact conversion rate for adult-onset OMG to GMG is still unknown.

OBJECTIVE

We aimed to delineate the conversion rate and risk factors for adult patients with ocular onset to GMG.

METHODS

Adult myasthenia gravis (MG) patients with ocular onset (age > 18 years) were retrospectively reviewed. Patients with confined ocular involvement lasting more than 2 years (pure OMG group) and those who converted into GMG (converted OMG group) were enrolled for subsequent analysis. We then analyzed 5 clinical variables, including onset age, sex, onset symptoms, anti-acetylcholine receptor antibody (AChR Ab), and thymus CT. Survival analysis was applied to all enrolled patients to explore risk factors associated with conversion.

RESULTS

In a total number of 249 ocular-onset MG patients initially enrolled, we excluded 122 patients with OMG lasting less than 2 years. The remaining 127 patients were enrolled, including 106 converted OMG and 21 pure OMG patients. Converted OMG patients had an older onset age (threshold: 43 years) and higher anti-AChR Ab titer (threshold: 6.13 nmol/L). The estimated conversion rate was 70.64%. Moreover, 67% of conversion occurred within 2 years after onset. Cox regression of survival analysis revealed that higher anti-AChR Ab titer and bilateral ptosis were associated with a higher conversion rate.

CONCLUSIONS

The conversion of adult OMG was associated with anti-AChR Ab titer, onset age, and bilateral ptosis. The estimated conversion rate of Chinese adult OMG patients was 70%.

Paediatric myasthenia gravis: Prognostic factors for drug free remission

Our aim was to identify clinical outcomes, serological features and possible prognostic indicators of paediatric myasthenia gravis (MG). We collected 74 MG patients with disease onset before the age of 16 years (73% pre-pubertal onset defined as ≤10 years), seen regularly at two UK specialist centres, over a period of 11 years. The cohort was multi-ethnic, with a high number of non-Caucasians (52%). Ocular presentation was seen in 38 (51%) and only 8 (21%) of these generalised. Fifty-two (70%) patients had antibodies to the acetylcholine receptor (AChR) measured by radioimmunoprecipitation, 10 (14%) had antibodies only to clustered AChRs detected by a cell based assay, 3 (4%) had muscle-specific kinase and one (1%) low-density lipoprotein receptor-related protein 4 antibody. Only 8 (11%) had no detectable antibodies. Seventeen patients attained drug free remission (Kaplan Meyer survival curve estimates 25% by 7 years). Several factors were associated with a higher likelihood of free remission: onset age ≤10 years, Asian and Caucasian races, lack of AChR antibodies on RIA, and normal repetitive nerve stimulation at diagnosis. However, in a multifactorial regression analysis, the antibody status was the only significant predictor for drug free remission, with 60% of patients with antibodies only to clustered AChR achieving this outcome. Complete drug free remission is not uncommon in paediatric MG and several factors appear to influence this outcome with antibody status being the most important. These factors can be easily evaluated at diagnosis, and may help to determine whose patients are likely to require more intensive treatments.

Cell-Based Versus Enzyme-Linked Immunosorbent Assay for the Detection of Acetylcholine Receptor Antibodies in Chinese Juvenile Myasthenia Gravis

BACKGROUND

Patients in China with juvenile-onset myasthenia gravis present early, with a high prevalence of purely ocular symptoms, spontaneous remission rates, and low antibody seropositivity. Antibody detection using a cell-based assay has been reported to increase the diagnostic sensitivity in adult-onset myasthenia gravis. However, this method in patients with juvenile-onset myasthenia gravis has not been investigated.

METHODS

Patients with juvenile-onset myasthenia gravis who had not received prednisone or immunosuppressive therapy were recruited between June 2015 and April 2018 at the Huashan Hospital. Clinical information was collected. Serum anti-acetylcholine receptor antibodies were detected via cell-based assay with HEK293T cells expressing acetylcholine receptor subunits and rapsyn. Additionally, the IgG antibody subclass was identified.

RESULTS

Eighty-two patients with juvenile-onset myasthenia gravis were enrolled in the current study. Among them, 48 patients were anti-acetylcholine receptor positive (58.5%) and 34 were seronegative (41.5%), as assessed via enzyme-linked immunosorbent assay. Cell-based assay yielded 63 positive subjects (76.8%) and 19 seronegative subjects (23.2%). All the enzyme-linked immunosorbent assay-positive samples showed robust immunofluorescence in the cell-based assay, whereas 15 of 34 enzyme-linked immunosorbent assay-negative patients (44.1%) were found to have low-affinity acetylcholine receptor antibodies. Among all the cell-based assay-positive patients, 41 were positive for both adult and fetal acetylcholine receptor antibodies (50.0%), 18 were found positive for only adult acetylcholine receptor antibodies (21.9%), and four were found to possess only fetal acetylcholine receptor antibodies (4.9%). Fifteen antibody-positive samples underwent subclassification and were confirmed to be IgG1 subclass predominant (n = 15, including eight adult and fetal acetylcholine receptor antibody positive, five only adult acetylcholine receptor antibody positive, and two only fetal acetylcholine receptor antibody positive). There were no significant differences in clinical features among patients with different antibody profiles.

CONCLUSIONS

The cell-based assay showed increased sensitivity in acetylcholine receptor antibody detection in Chinese patients with juvenile-onset myasthenia gravis, and most cases of Chinese juvenile-onset myasthenia gravis are still acetylcholine receptor autoantibody mediated. Furthermore, the antibodies detected are predominately of the IgG1 subclass.

Incidence and Ocular Features of Pediatric Myasthenias

PURPOSE

To report the incidence, demographics, and ocular findings of children with myasthenia.

DESIGN

Retrospective cohort study.

METHODS

The medical records of all children (<19 years) examined at Mayo Clinic with any form of myasthenia from January 1 1966, through December 31, 2015, were retrospectively reviewed.

RESULTS

A total of 364 children were evaluated during the study period, of which 6 children were residents of the Olmsted County at the time of their diagnosis, yielding an annual age- and sex-adjusted incidence of 0.35 per 100 000 <19 years, or 1 in 285 714 <19 years. The incidence of juvenile myasthenia gravis (JMG) and congenital myasthenic syndrome (CMS) was 0.12 and 0.23 per 100 000, respectively. Of the 364 study children, 217 (59.6%) had JMG, 141 (38.7%) had CMS, and 6 (1.7%) had Lambert-Eaton syndrome, diagnosed at a median age of 13.5, 5.1, and 12.6 years, respectively. A majority of the JMG and CMS patients had ocular involvement (90.3% and 85.1%, respectively), including ptosis and ocular movement deficits. Among children with at least 1 year of follow-up (JMG; median, 7.1 years, CMS; median, 7.0 years), improvement was seen in 88.8% of JMG patients (complete remission in 31.3%) and in 58.3% of CMS patients.

CONCLUSION

Although relatively rare, myasthenia gravis in children has 2 predominant forms, CMS and JMG, both of which commonly have ocular involvement. Improvement is more likely in children with the juvenile form.

Clinical Characteristics of Juvenile Myasthenia Gravis in Southern China

Objectives

To describe the clinical profile, clinical outcomes and factors that may affect the outcome of juvenile myasthenia gravis (JMG) patients in southern China.

Methods

We reviewed information relating to JMG patients treated and evaluated at the First Affiliated Hospital, Sun Yat-sen University, between 1998 and 2015. The study involved 327 JMG patients who had been followed up for ≥1 year.

Results

Overall, 77.4% patients showed initial symptoms in the prepubertal period (<12 years). 306 patients showed only ocular symptoms at onset. By the final follow-up, 61 ocular myasthenia gravis (OMG) patients (61/306, 19.9%) had developed generalized myasthenia gravis (GMG). Anti-acetylcholine receptor antibodies (AChR-Ab) titer was an independent risk factor for generalization. Eleven patients (3.4%) experienced spontaneous remission, but four relapsed. Low-dose oral prednisone (0.25 mg/kg) was administered when symptoms did not significantly improve after pyridostigmine treatment. Immunosuppressants were administered when prednisone was unsatisfactory. Optimal outcome was achieved in 59.6% of patients. Specifically, 60 patients (18.3%) attained complete stable remission (CSR), 12 (3.7%) attained pharmaceutical remission (PR), and 123 (37.6%) attained minimal manifestation (MM). In total, 53 OMG patients (21.5%) attained CSR, a significantly higher proportion than among the GMG patients (8.6%, P = 0.009). Moreover, 67.2% of patients with duration <2 years showed significant clinical improvement compared with 46.3% of those with duration >2 years (P < 0.001). Thymectomy did not exhibit definite efficacy for JMG patients.

Conclusion

There was a low frequency of cases positive for AChR-Ab in the Chinese population. AChR-Ab titer was revealed as an independent risk factor for generalization. Low doses of prednisone could treat JMG effectively with few side effects.

Juvenile myasthenia gravis in Norway: Clinical characteristics, treatment, and long-term outcome in a nationwide population-based cohort

BACKGROUND

This study aimed to characterize juvenile myasthenia gravis in a national population-based cohort in Norway, and to evaluate long-term outcome and potential differences correlated with prepubertal versus postpubertal disease onset.

PATIENTS AND METHODS

Patients with onset of myasthenia gravis aged ≤18 years were identified through multiple strategies. Retrospective clinical data were collected by means of medical charts. All patients had an updated clinical examination. Cases were divided into prepubertal and postpubertal onset using age 12 years as the cut off.

RESULTS

In total, 75 patients were identified of whom 63 were included in the study: 21 in the prepubertal and 42 in the postpubertal onset group. There was a female preponderance in both groups. In total, 59% presented with ocular symptoms, but the great majority of patients in both groups generalized during the two first years of the disease. Myasthenic crisis was more frequent in the prepubertal onset group. All patients were initially treated with pyridostigmine, 26 with steroids, and 17 with other immunosuppressive treatment. The postpubertal cases were more often treated with immunosuppressive therapy. Fifty patients (79%) underwent thymectomy. The general outcome was favourable: 57% became asymptomatic and only four subjects failed to attain clinical improvement. One-third had at least one additional autoimmune disease.

CONCLUSION

Despite frequent symptom generalization and a subgroup of prepubertal onset with severe disease, the long-term outcome was good, especially in the thymectomized prepubertal onset group. Polyautoimmunity occurred in both groups in one-third.