Juvenile Ocular Myasthenia Gravis: Presentation and Outcome of a Large Cohort

Targeted Treatments for Myasthenia Gravis in Children and Adolescents

Myasthenia gravis (MG) is an antibody-mediated disorder of the neuromuscular junction affecting children and adults. MG is a treatable condition with most patients requiring immunosuppression for disease control and/or remission. Juvenile myasthenia gravis (JMG) is rare in comparison with adult-onset MG but given the same underlying pathophysiology, treatment strategies are similar to those in adults. Until recently, there were only a few randomised controlled trials (RCTs) for MG treatments in adults and none in children, and management strategies were primarily based on expert consensus. In addition, treatment options for refractory MG cases have been severely limited, resulting in poor long-term quality of life in such patients due to the significant disease burden. Recently, there have been several RCTs focussing on novel therapeutic strategies with potentially promising outcomes, suggesting a change in MG management over the coming years and access to more effective and faster-acting drugs for MG patients. This paper will review current and new MG treatments including efgartigimod, eculizumab, rozanolixizumab, ravulizumab, and zilucoplan, with a focus on juvenile myasthenia gravis.

Clinical Characteristics and Treatment of Juvenile Myasthenia Gravis-A Single-Center Experience

Juvenile myasthenia gravis (MG) is a rare autoimmune neuromuscular disease, often treated with anticholinesterases, corticosteroids, and immunosuppressants. However, optimal treatment durations remain unclear. This study investigated the clinical characteristics and treatment of juvenile MG, including medication duration. The administration period for all drugs, immunosuppressants, and prednisolone at doses greater than 0.35 mg/kg daily was extracted retrospectively from medical records. Nineteen participants (8 boys, 11 girls) aged 8 months to 14 years (median, 2.5 years) at onset were identified. Fourteen patients (73.7%) had ocular MG and five (26.3%) had generalized MG. Drug treatment was conducted in 18 cases; however, 7 patients did not complete the treatment. Among the patients who completed drug treatment, the duration of treatment ranged from 11 to 100 months (median, 47 months). In the six patients treated with continuous administration of prednisolone or immunosuppressants, the treatment duration ranged from 33 to 99 months (median, 56 months). No severe adverse effects requiring hospitalization were reported. The patients treated with prednisolone or immunosuppressants required at least 33 months of treatment. These results will help develop protocols for juvenile MG treatment.

Pediatric Ocular Myasthenia Gravis: Single-Center Experience

BACKGROUND

Currently, there is no universally accepted standard treatment for ocular myasthenia gravis (OMG) in children. We aimed to investigate the possible proper regimens and timing of treatment for pediatric OMG cases based on the clinical manifestations: OMG with ptosis only and OMG with other features.

METHODS

One hundred and forty two OMG cases attended at the Department of Pediatrics, Xiangya Hospital, Central South University, from 2010 to 2019 were included, and information from medical records was reviewed and recorded. Comparisons of clinical characteristics between patients with OMG with ptosis only and patients with OMG with other features as well as between patients treated with glucocorticoid (GC) within or after six months from disease onset were performed.

RESULTS

OMG with other features constituted about 54.9% of the cases, and 66.2% of the patients achieved optimal outcome. Patients with OMG with ptosis only responded to pyridostigmine alone more than patients with OMG with other features who required several therapies (P < 0.001). Patients with OMG with ptosis only had a larger proportion of optimal outcome than the patients with OMG with other features (P = 0.002), and the difference remained significant even when the individual outcome groups were compared (P < 0.001). Patients who received GC within six months had a greater proportion of optimal outcome than those who received it after six months (P < 0.001).

CONCLUSIONS

Although OMG with other features is a more common subtype of OMG, it is also more severe than OMG with ptosis only. An earlier addition of GC leads to optimal outcome.

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.

Demographics and ocular findings in children with myasthenia

PURPOSE

To report the demographics and ocular features of myasthenia gravis in the paediatric population.

METHODS

Retrospective revision of the medical records of all patients younger than 18 years of age with myasthenia who were examined at Great Ormond Street Hospital between the 1st of January 2016 and 1st of January 2020.

RESULTS

A total of 49 children were assessed during the 4-year period. There was a female predominance, with only 12 males (24.5%). 26 children (53.1%) had juvenile myasthenia gravis (JMG) while 18 (36.7%) had congenital myasthenic syndrome (CMS). 4 patients (8.2%) were diagnosed with probable CMS while 1 (2.0%) was classified as probable JMG. The mean age at diagnosis was 5.3 years old (SD 3.9) whereas the mean age at onset was 3.7 years old (SD 3.9). Almost half of the children (49%) had ocular involvement, present in 19 patients in the JMG group (70.4%) and in 5 children (22.7%) in the CMS cohort. Ptosis was the most common sign at presentation, seen in 32 patients (65.3%). Nine patients (18.4%) presented with a squint and another 7 (14.3%) developed it later on. Anti-acetylcholine receptor antibodies were positive in 18 of the 26 JMG patients (69.2%) whereas identifiable mutations were found in the 18 CMS patients (100%). Pyridostigmine was the drug of choice in our series, used by thirty-three patients (67.3%). The majority of the patients (73.5%) improved after treatment.

CONCLUSIONS

JMG was the most common type of paediatric MG, specifically the ocular form. Ptosis was the most common sign at presentation. The majority of the patients improved after medical treatment.

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.

Pediatric Ocular Myasthenia Gravis: A Review

Pediatric ocular myasthenia gravis (OMG) is difficult to diagnose and manage, owing to its rarity and low index of suspicion in the early stage of the disease. Also, many other conditions having similar presentation cause a further delay in diagnosis. In this review, we highlighted various pointers in history and described bedside clinical tests that can aid in its timely diagnosis. The antibody spectrum in myasthenia is ever increasing and includes anti-muscle specific kinase and low-density lipoprotein-receptor related protein 4 antibodies in addition to acetylcholine receptor antibodies besides many others. However, pediatric OMG patients often test negative for all three antibodies, making the diagnosis even more difficult in triple seronegative patients. Edrophonium and electrophysiological tests, which help in confirming myasthenia in adults, have a limited utility in diagnosing pediatric ocular myasthenia cases. Various practical difficulties are encountered like nonavailability of edrophonium, risk of bradycardia associated with neostigmine use and its lower sensitivity, noncooperative children, and limited technical expertise in performing electrophysiological tests in children. In this article, we described a pragmatic approach to diagnose pediatric OMG along with the important aspects of its management.

Myasthenia Gravis: Epidemiology, Pathophysiology and Clinical Manifestations

Myasthenia gravis (MG) is an autoimmune neurological disorder characterized by defective transmission at the neuromuscular junction. The incidence of the disease is 4.1 to 30 cases per million person-years, and the prevalence rate ranges from 150 to 200 cases per million. MG is considered a classic example of antibody-mediated autoimmune disease. Most patients with MG have autoantibodies against the acetylcholine receptors (AChRs). Less commonly identified autoantibodies include those targeted to muscle-specific kinase (MuSK), low-density lipoprotein receptor-related protein 4 (Lrp4), and agrin. These autoantibodies disrupt cholinergic transmission between nerve terminals and muscle fibers by causing downregulation, destruction, functional blocking of AChRs, or disrupting the clustering of AChRs in the postsynaptic membrane. The core clinical manifestation of MG is fatigable muscle weakness, which may affect ocular, bulbar, respiratory and limb muscles. Clinical manifestations vary according to the type of autoantibody, and whether a thymoma is present.

Pediatric Autoimmune Ocular Myasthenia Gravis: Evaluation of Presentation and Treatment Outcomes in a Large Cohort

BACKGROUND

In autoimmune myasthenia gravis (MG), autoantibodies target the neuromuscular junction. Ocular myasthenia gravis (OMG) is localized, affecting only extraocular and/or levator palpebrae muscles. OMG presents across all ages, varying in presentation, treatment modalities, and outcomes. Recently, there have been advances in MG/OMG treatment; their utilization and effectiveness are an important part of optimal disease management.

METHODS

We completed a retrospective chart review of children aged 18 years or younger with a confirmed diagnosis of OMG presenting from 2002 to 2019.

RESULTS

Forty-two patients were included with mean age at presentation of 8.5 years (2 to 18 years). Twenty-one patients (50%) had positive antibodies; 90% had acetylcholine receptor antibodies. Ten patients developed generalized symptoms with mean time to generalization of 13.6 months. Multiple logistic regression showed that older age of onset was a trend predictive factor (P = 0.054; odds ratio 1.17) for generalized disease. All patients were treated with pyridostigmine. Immunomodulating agents included steroids (15), mycophenolate mofetil (four), and intravenous immunoglobulin (one). Three patients underwent thymectomy. Twenty patients reached minimal manifestation status, and 12 achieved remission. Gender, race, and positive antibody status were not statistically significant predictors for advanced immunosuppressive therapy.

CONCLUSIONS

We summarize one of the largest cohorts of pediatric patients with OMG who have undergone up-to-date diagnostic and therapeutic regimens. The predictors of outcome and treatment pathway for OMG patients suggested by this report may be further elucidated by future prospective studies.

Local use of dexamethasone in the treatment of ocular myasthenia gravis

Background

At present, patients with ocular myasthenia gravis (OMG) are typically treated with systemic drugs. We investigated the use of dexamethasone injected in the peribulbar region or extraocular muscle to treat patients with OMG.

Methods

Patients with OMG were given dexamethasone via peribulbar injection or direct injection into the main paralyzed extraocular muscles, once a week, for 4–6 weeks. The severity of diplopia, blepharoptosis, eye position, and eye movement were evaluated before and after treatment. The duration of follow-up time was ≥6 months.

Results

Among the 14 patients with OMG who received this treatment, mean age was 38.7 ± 29.7 years. After treatment, symptoms were relieved in 12 patients (85.7%), 1 patient (7.1%) had partial response to treatment, and 1 patient (7.1%) had no response. Two patients (14.2%) experienced symptom recurrence during the follow-up period.

Conclusions

Dexamethasone peribulbar or extraocular muscle injection is effective in the treatment of patients with OMG and may replace systemic drug therapy.

Trial registration

Chinese Clinical Trial Registry, ChiCTR2000038863, October 7, 2020.Retrospectively registered.

Supplementary information

The online version contains supplementary material available at 10.1186/s12886-020-01697-2.

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.

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.