Visual and systemic outcomes in pediatric ocular myasthenia gravis

[Pediatric myasthenia with ocular involvement]

PURPOSE

Myasthenia is a rare disease in children, with an estimated incidence of 1 to 5 per million children. However, the potential severity of its consequences and the existence of specific treatments require prompt diagnosis by pediatric ophthalmologists.

METHODS

Retrospective review of patient records. Patients were identified from a rare disease database. Patients under the age of 18 years with confirmed diagnosis of myasthenia and ocular symptoms seen in a specialized clinic between 2005 and 2021 were included.

RESULTS

Twenty-six (16 girls) with confirmed myasthenia and ocular symptoms were included. Ten patients had definite autoimmune myasthenia gravis (AIMG); 6 had suspected AIMG with negative antibody testing. Six patients had definite congenital myasthenic syndrome (CMS); 4 had suspected CMS with no evidence of mutation. Mean age at diagnosis of myasthenia was 5 years-3 years and 5 months for CMS and 6 years and 3 months for AIMG. Male to female (M:F) ratio was 6/10 for autoimmune myasthenia gravis and 4/6 for CMS. Ptosis was present in all cases; strabismus in 21 patients (68%). The clinical forms of myasthenia were ocular myasthenia in 12 patients (10 AIMG and 2 CMS), generalized in 12 patients (7 CMS and 5 AIMG) and secondary generalization of ocular myasthenia in 2 patients (2 AIMG).

DISCUSSION

These results are based on only 26 cases, which can be explained by the rarity of this diagnosis in children. As in adults, the first signs are often ophthalmologic - ptosis alone or associated with strabismus. Diagnosis is difficult because of the absence of clinical signs, laboratory tests or electrophysiological signs with high sensitivity. Thus, the work-up may remain completely negative in secondarily proven forms. In addition, electroneuromyograms and oculomotor recordings in small children are more difficult to perform than in adults. For these reasons, the clinical examination is essential. In the case of strong suspicion, all additional medical examinations are carried out in a day unit, in order to reach a positive diagnosis of myasthenia. The so-called "congenital" forms, which are genetic, are proportionately higher than in adults, and diagnosis and treatment are often more difficult than in the classic autoimmune forms.

CONCLUSION

Myasthenia can affect children from a very young age and can present as ptosis, initially isolated or associated with strabismus. Diagnosis and treatment may be difficult and should be organized in specialized centers.

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.

Immunotherapy for ocular myasthenia gravis: an observational study in Japan

Background

Treatment for ocular myasthenia gravis (OMG) has not yet been well established. Few reports have been published on the clinical practice and outcomes of OMG.

Objectives

We investigated treatment of OMG and its outcomes in Japan.We investigated treatment of OMG and its outcomes in Japan.

Design

We performed a retrospective cross-sectional survey of OMG patients from eight hospitals in Japan.

Methods

Clinical information, including sex, age at onset, initial symptoms, autoantibodies, clinical course, treatment history, complications, and outcomes, was obtained. In addition, we recorded the total number of patients with MG and OMG separately.

Results

In total, 135 patients with OMG (67 men, 68 women) were included. Treatment of OMG was not simple and involved various immunotherapeutic strategies. Eight patients went into remission spontaneously without immunotherapy. A total of 117 patients showed improvements after treatment, whereas 10 patients showed refractory responses to treatment. Overall outcomes were good; however, symptoms persisted in 60.7% of patients even after treatment. Among 90 patients who received immunotherapy, only two showed a refractory response. Meanwhile, for 45 patients who did not receive immunotherapy, 8 were refractory. Thus, the rate of refractory disease in the group with immunotherapy was significantly lower (p = 0.001, u-test) than in the group without immunotherapy. The proportion of generalized MG patients among all MG cases was low in medical centers where immunotherapy for OMG was frequently performed.

Conclusion

Although the overall prognosis for patients with OMG was good, symptoms remained in more than half of the patients. Immunotherapy, including corticosteroids, may be beneficial for patients with OMG.

Plain language summary

Is immunosuppressive therapy beneficial for myasthenia gravis patients with ocular symptoms only? Patients with ocular myasthenia gravis (OMG) have only eye symptoms for more than 2 years. Whether this condition is an initial stage of the disease before eventually progressing to generalized myasthenia gravis (gMG) is still uncertain. Different from gMG, OMG is not life-threatening. But eye symptoms often cause troublesome problems in life. Doctors have treated OMG patients similarly to patients with gMG. There is no standard clinical practice for OMG. In this study, we examined how patients with OMG were treated at eight different specialist centers in Japan. In 135 patients with OMG, 8 patients became symptom free without treatment, 117 patients showed improvements after treatment, whereas 10 patients did not get well. Overall outcomes were good, but symptoms remained in 60.7% of patients even after treatment. Among 90 patients who received one or more immunotherapies, only 2 did not get well. Meanwhile, for 45 patients who did not receive immunotherapy, 8 remained ill. We found that treatment of OMG was not simple and often needed multiple immunotherapies. Administering immunotherapy, including corticosteroids, may be beneficial for patients with OMG.

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.

Outcomes of Juvenile Myasthenia Gravis: A Comparison of Robotic Thymectomy With Medication Treatment

BACKGROUND

The study aimed to compare the clinical outcomes of patients with juvenile myasthenia gravis (MG) who underwent robotic thymectomy with that of those who only received medication therapy.

METHODS

We retrospectively reviewed patients who visited our institution for the diagnosis or treatment of MG with an age at onset younger than 18 years. Patients who underwent thymectomy comprised the surgical group and those who received only medication therapy comprised the nonsurgical group. The clinical outcomes were assessed according to the Myasthenia Gravis Foundation of America Post-Intervention Status.

RESULTS

Forty-seven patients (35 female, 12 male) were included as the surgical group and 20 patients (15 female, 5 male) comprised the nonsurgical group. Significant differences were observed between the surgical and nonsurgical groups in antibody against acetylcholinesterase receptor (91.5% vs 65%; P = .012), disease duration (median 16 [interquartile range, 7-25] months vs 96 [interquartile range, 42-480] months; P < .001), and corticosteroids requirement (53.2% vs 15%; P = .004) at baseline. Kaplan-Meier analysis showed a higher cumulative probability of complete stable remission in the surgical group (P = .002) compared with the nonsurgical group. Moreover, thymectomy (hazard ratio, 3.842; 95% confidence interval, 1.116-13.230; P = .033) and age at onset (hazard ratio, 0.89; 95% confidence interval, 0.80-0.99; P = .037) were still associated with the achievement of complete stable remission in the multivariable analysis. Furthermore, a significant steroid-sparing effect was observed in the surgical group but not in the nonsurgical group.

CONCLUSIONS

Robotic thymectomy seems to be more effective than medication therapy on juvenile MG in terms of inducing remission and reducing the use of corticosteroids.

Controversies in Ocular Myasthenia Gravis

Myasthenia gravis (MG) with symptoms limited to eye muscles [ocular MG (OMG)] is a rare disease. OMG incidence varies according to ethnicity and age of onset. In recent years, both an increase in incidence rate, particularly in the elderly, and a lower risk for secondary generalization may have contributed to the growing disease prevalence in Western countries. OMG should be considered in patients with painless ptosis and extrinsic ophthalmoparesis. Though asymmetric muscle involvement and symptom fluctuations are typical, in some cases, OMG can mimic isolated cranial nerve paresis, internuclear ophthalmoplegia, and conjugate gaze palsy. Diagnostic confirmation can be challenging in patients negative for anti-acetylcholine receptor and anti-muscle-specific tyrosine kinase antibodies on standard radioimmunoassay. Early treatment is aimed at relieving symptoms and at preventing disease progression to generalized MG. Despite the absence of high-level evidence, there is general agreement on the efficacy of steroids at low to moderate dosage; immunosuppressants are considered when steroid high maintenance doses are required. The role of thymectomy in non-thymoma patients is controversial. Prolonged exposure to immunosuppressive therapy has a negative impact on the health-related quality of life in a proportion of these patients. OMG is currently excluded from most of the treatments recently developed in generalized MG.

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.

Prediction of generalization of ocular myasthenia gravis under immunosuppressive therapy in Northwest China

BACKGROUND

It is well demonstrated that immunosuppressants can reduce, but not eliminate the risk of generalized development in ocular myasthenia gravis (OMG). In this study, we aimed to explore the predictive factors of generalized conversion of OMG patients who received immunosuppressive treatments.

METHODS

OMG patients under immunosuppressive treatments in Tangdu Hospital from June 2008 to June 2012 were retrospectively reviewed. Baseline clinical characteristics were documented. Patients were followed up regularly by face-to-face interview and the main outcome measure was generalized conversion. The logistic regression analysis was performed to determine the predictive factors of generalization of OMG.

RESULTS

Two hundred twenty-three eligible OMG patients completed the final follow-up visit and 38 (17.0%) progressed to generalized MG (GMG) at a median time to generalization of 0.9 year. Patients with adult onset and positive repetitive nerve stimulation (RNS) of facial or axillary nerve had higher conversion rate than those with juvenile onset and negative RNS (p = 0.001; p = 0.019; p = 0.015, respectively). Adult-onset patients converted earlier than juvenile-onset OMG patients (p = 0.014). Upon multivariate logistic regression analysis, age of onset (Odds ratio [OR] 1.023, 95% confidence interval [CI] 1.006-1.041, p = 0.007) and positive facial nerve RNS (OR 2.826, 95%CI 1.045-5.460, p = 0.038) were found to be positively associated with generalized development. Moreover, an obviously negative association was found for disease duration (OR 0.603, 95%CI 0.365-0.850, p = 0.019).

CONCLUSIONS

Age of onset, disease duration and facial nerve RNS test can predict generalized conversion of OMG under immunosuppressive therapy. Adult-onset, shorter disease duration and facial nerve RNS-positive OMG patients have a higher risk of generalized development.

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.

Response to treatment in pediatric ocular myasthenia gravis

INTRODUCTION

Juvenile myasthenia gravis (JMG), a pediatric autoimmune neuromuscular junction disorder, includes generalized (GMG), and ocular (OMG) variants. We sought to determine whether differences existed between OMG and GMG children regarding demographics or treatment response.

METHODS

We performed retrospective analysis of 60 children with JMG seen between 1990 and 2018. Osserman scores were used to define OMG and GMG. The myasthenia scale of Millichap and Dodge was used to assess treatment responses.

RESULTS

There were no differences between GMG and OMG regarding time interval from disease onset to prednisone initiation (P = .42), or treatment response according to Millichap and Dodge (P = .12). Compared with GMG, OMG children showed younger age of disease onset and better outcomes after treatment. No OMG patients progressed to generalized disease during the follow-up period.

DISCUSSION

Compared with GMG, OMG patients had earlier disease onset and improved outcomes after treatment.

Generalized Myasthenia Gravis: Classification, Clinical Presentation, Natural History, and Epidemiology

Myasthenia gravis (MG) is a rare disease, but the most common disorder of the neuromuscular junction. It is the prototypic autoimmune disease most commonly caused by antibodies to the acetylcholine receptor (AChR) leading to characteristic fatigable weakness of the ocular, bulbar, respiratory, axial, and limb muscles. The majority of patients with MG first present with ocular symptoms. Most patients with MG will experience at least 1 exacerbation of symptoms throughout the course of their illness. This article will cover the epidemiology, clinical presentation, classification, and natural history of MG.

"Mummy, my eyelids are heavy": A case series of juvenile myasthenia gravis

PURPOSE

To report three cases of juvenile myasthenia gravis aged between 18 and 24 months with ocular symptoms as their first presentation.

METHOD

A case series.

RESULTS

We present a case series of juvenile myasthenia gravis in a tertiary centre in Malaysia. Two of the three cases consist of a pair of twins who presented with ptosis of bilateral eyes; the first twin presented 4 months later than the second twin. These two cases were positive for anti-acetylcholine receptor antibodies and had generalized myasthenia gravis, whereas the other case was negative for receptor antibodies and was purely ocular myasthenia gravis.

CONCLUSION

Juvenile myasthenia gravis is relatively rare in toddlers. Early diagnosis and commencement of treatment is important to slow the progression of the disease and avoiding life-threatening events.

Don't Miss This! Red Flags in the Pediatric Eye Examination: Ophthalmoplegia in Childhood

Paralytic strabismus in children is rare, occurring in about 0.1% of children. This rate is far less common than the 3% rate usually noted for comitant strabismus. The relative rates of ocular motor pareses were fourth nerve palsies in 36%, sixth in 33%, third in 22%, with multiple ocular motor nerve palsies in 9%. In a single population series from Minnesota, few cases were associated with neoplasm. However, institutional case series reports a high rate of neoplasm for acquired third nerve and sixth nerve palsies after excluding trauma and congenital causes. Tumor is rare in children with fourth cranial nerve palsies, usually associated with other neurologic disease. Rare causes of external ophthalmoplegia, to be considered when the motility pattern is variable or not fitting an ocular motor nerve pattern, include myasthenia gravis and congenital fibrosis of the extraocular muscles. Myasthenia most often presents as ptosis with exotropia. Rarer still is involvement of the extraocular muscles in childhood thyroid disease.

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.

Tacrolimus Improves Symptoms of Children With Myasthenia Gravis Refractory to Prednisone

BACKGROUND

Myasthenia gravis tends to affect children in China. Oral pyridostigmine and prednisone could effectively improve the symptoms, but multiple side effects become a major concern after long-term oral prednisone. To avoid the long-term complications of prednisone therapy and to obtain more satisfactory improvement, we tested the efficacy and safety of tacrolimus in children with myasthenia gravis.

METHODS

Children with myasthenia gravis who had not achieved satisfactory improvement or who experienced severe side effects after prednisone therapy were recruited between January 2015 and December 2016 at Tongji Hospital. All the children were treated with tacrolimus 1 mg to 2 mg daily and the dose was adjusted on the basis of the clinical response and the serum concentration. The dosage of prednisone, the severity of symptoms, blood samples, the serum concentration of tacrolimus, and titers of antiacetylcholine receptor antibodies were evaluated every four weeks.

RESULTS

Fourteen children were enrolled. One child withdrew two weeks after the enrollment. Thirteen children have completed the therapy for one year. At the end point, the dosage of prednisone was significantly decreased (P < 0.05), the symptoms were evaluated by the quantitative myasthenia gravis score, and myasthenia gravis-specific manual muscle testing and myasthenia gravis-activities of daily living scores were significantly improved (P < 0.05, P < 0.05, and P < 0.01, respectively). More importantly, ten (76.9%) patients had completely discontinued prednisone, and the major side effects were nearly reversed. The mean titer of antiacetylcholine receptor antibodies significantly dropped from 1.96±2.62 nmol/L to 0.70±1.04 nmol/L (P < 0.05). No severe adverse events were reported.

CONCLUSIONS

Our results suggest that tacrolimus is a promising agent for children with refractory myasthenia gravis. Randomized clinical trials are needed to confirm the observation.

Clinical features and evolution of juvenile myasthenia gravis in a French cohort

INTRODUCTION

In this study we determined the clinical, paraclinical, and treatment-related features of juvenile myasthenia gravis (JMG) as well as the clinical course in a cohort of French children.

METHODS

We conducted a retrospective study of 40 patients with JMG at 2 French pediatric neurology departments from April 2004 to April 2014.

RESULTS

Among the patients, 70% had generalized JMG, 52% had positive acetylcholine receptor antibodies, 8% had muscle-specific kinase antibodies, and 40% were seronegative. Treatment with acetylcholinesterase inhibitors was effective and sufficient in 47% of patients. The 6 patients with generalized JMG treated with rituximab and/or immunoadsorption showed improvement. Thirty percent of the patients required hospitalization in an intensive care unit during follow-up (mean 4.7 years). Remission without treatment occurred in 18% of patients.

DISCUSSION

As with adults, JMG has high morbidity, particularly among children with generalized symptoms, and rituximab should be considered early in the course of the disease as a second-line treatment. Muscle Nerve 57: 603-609, 2018.

The role of thymectomy in the treatment of juvenile myasthenia gravis: a systematic review

BACKGROUND

The role of thymectomy in the treatment of juvenile myasthenia gravis (JMG) is poorly defined. The objective of this systematic review was to evaluate the effect of thymectomy on survival, disease severity, and peri-operative complications for patients with JMG.

METHODS

A search of MEDLINE, EMBASE, and the Cochrane Library (1/1/2000-3/1/2016) identified all English language, human studies of thymectomy for JMG. The population was patients with JMG age ≤18 years who underwent thymectomy (comparator group was unexposed to thymectomy). Outcomes included survival, disease severity, and post-operative complications. Data extraction was performed by independent reviewers.

RESULTS

Sixteen retrospective studies included 1131 participants with JMG and 488 (43%) underwent thymectomy. Post-operative improvement in JMG severity occurred for 77% (n = 376/488). Comparisons of thymectomy to non-operative management were mixed. Post-operative complications were poorly recorded. Power to compare surgical approaches was limited. Outcomes specific to antibodies, surgical pathology findings, severity of JMG, and timing of thymectomy were sparse.

CONCLUSIONS

Existing data regarding thymectomy for JMG are limited and entirely retrospective. The majority of patients who underwent thymectomy had improvement in disease severity and post-operative complications were rare. Prospective, multicenter study of thymectomy for JMG is warranted.

Pediatric Myasthenia Gravis

Myasthenia gravis is a disorder of neuromuscular transmission that leads to fatigue of skeletal muscles and fluctuating weakness. Myasthenia that affects children can be classified into the following 3 forms: transient neonatal myasthenia, congenital myasthenic syndromes, and juvenile myasthenia gravis (JMG). JMG is an autoimmune disorder that has a tendency to affect the extraocular muscles, but can also affect all skeletal muscles leading to generalized weakness and fatigability. Respiratory muscles may be involved leading to respiratory failure requiring ventilator support. Diagnosis should be suspected clinically, and confirmatory diagnostic testing be performed, including serum acetylcholine receptor antibodies, repetitive nerve stimulation, and electromyography. Treatment for JMG includes acetylcholinesterase inhibitors, immunosuppressive medications, plasma exchange, intravenous immunoglobulins, and thymectomy. Children with myasthenia gravis require monitoring by a pediatric ophthalmologist for the development of amblyopia from ptosis or strabismus.

Ocular myasthenia gravis: a review

Myasthenia gravis (MG) is a disease that affects the neuro-muscular junction resulting in classical symptoms of variable muscle weakness and fatigability. It is called the great masquerader owing to its varied clinical presentations. Very often, a patient of MG may present to the ophthalmologist given that a large proportion of patients with systemic myasthenia have ocular involvement either at presentation or during the later course of the disease. The treatment of ocular MG involves both the neurologist and ophthalmologist. Thus, the aim of this review was to highlight the current diagnosis, investigations, and treatment of ocular MG.

Clinical Features and Diagnostic Usefulness of Antibodies to Clustered Acetylcholine Receptors in the Diagnosis of Seronegative Myasthenia Gravis

IMPORTANCE

Cell-based assays (CBAs) were shown to improve detection of acetylcholine receptor (AChR) antibodies in patients with myasthenia gravis (MG). Herein, we asked whether these assays were able to help determine the diagnosis in patients studied in routine clinical practice.

OBJECTIVES

To determine the diagnostic usefulness of CBAs in the diagnosis of MG and to compare the clinical features of patients with antibodies only to clustered AChRs with those of patients with seronegative MG (SNMG).

DESIGN, SETTING, AND PARTICIPANTS

All patients with clinical suspicion of MG who were seen within the Division of Clinical Neurology at the John Radcliffe Hospital in Oxford, England, between November 1, 2009, and November 30, 2013. Their serum antibodies and clinical features were studied.

EXPOSURES

Radioimmunoprecipitation assay (RIPA) and CBA were used to test for standard AChR antibodies and antibodies to clustered AChRs in 138 patients. All available samples from patients with SNMG were retrospectively tested for lipoprotein receptor-related protein 4 (LRP4) antibodies.

MAIN OUTCOMES AND MEASURES

Demographic, clinical, neurophysiological, and laboratory data.

RESULTS

In total, 138 patients were tested for antibodies to clustered AChRs, and 42 had a final diagnosis of MG. The clustered AChR CBA detected antibodies in 38.1% (16 of 42) of RIPA-negative patients with MG with 100% specificity. All patients with SNMG who were tested for LRP4 antibodies (21 of 26) were negative by CBA. Compared with patients with SNMG, patients with antibodies only to clustered AChRs had frequent prepubertal onset (62.5% [median age, 6 years; age range, 1-52 years] vs 11.5% [median age, 38 years; age range, 2-72 years], P ≤ .05), high prevalence of ocular MG (62.5% vs 42.3%), milder disease severity with less bulbar involvement (25.0% vs 46.2%), and absence of respiratory symptoms (0% vs 23.1%). Response to treatment and prognosis was good, with a reduced need for thymectomy (6.3% vs 19.2%) and a high proportion of patients going into remission (50.0% vs 8.3%, P ≤ .05). These observations also apply to the classic AChR MG phenotype seen in large series.

CONCLUSIONS AND RELEVANCE

Cell-based assay is a useful procedure in the routine diagnosis of RIPA-negative MG, particularly in children. Patients with antibodies only to clustered AChRs appear to be younger and have milder disease than other patients with MG. These observations will have implications in planning treatment.

An increase in circulating B cell-activating factor in childhood-onset ocular myasthenia gravis

BACKGROUND

Myasthenia gravis is a B cell-mediated autoimmune disorder. The pathophysiology of childhood-onset ocular myasthenia gravis remains unclear. We investigated serum B cell-activating factor levels and other immunological parameters in child patients with ocular myasthenia gravis.

METHODS

Blood samples were obtained from 9 children with ocular myasthenia gravis and 20 age-matched controls. We assayed serum concentrations of B cell-activating factor, anti-acetylcholine receptor antibody titers, 7 types of cytokines (interleukins-2, -4, -6, -10, and -17A; interferon-γ; tumor necrosis factor-α) as well as the percentages of peripheral blood CD4+, CD8+, and CD19+ cells.

RESULTS

Serum B cell-activating factor levels were significantly higher before immunosuppressive therapy in patients with childhood-onset ocular myasthenia gravis than in controls and decreased after immunosuppressive therapy. A significant positive correlation was observed between serum B cell-activating factor levels and anti-acetylcholine receptor antibody titers in patients with myasthenia gravis. Serum B cell-activating factor concentrations did not correlate with the percentages of CD4+, CD8+, and CD19+ cells or the CD4+/CD8+ ratio. No significant differences were observed in the levels of the 7 different types of cytokines examined, including interleukin-17A, between preimmunosuppressive therapy myasthenia gravis patients and controls.

CONCLUSIONS

Circulating B cell-activating factor may play a key role in the pathophysiology of childhood-onset ocular myasthenia gravis.

Management of juvenile myasthenia gravis

Juvenile myasthenia gravis is an uncommon autoimmune disorder. Its management is not standardized. Juvenile myasthenia gravis is pathophysiologically similar to myasthenia gravis in adults. However, a number of significant particularities related to race, age at onset, severity, and antibody status complicate the management. We summarize the unique clinical features of juvenile myasthenia gravis and review the therapeutic options.

Treatment of ocular myasthenia gravis

OPINION STATEMENT

Myasthenia gravis (MG) is an autoimmune disorder that is characterized by variable weakness and fatigability. Often, MG presents with only ocular symptoms such as ptosis and diplopia. Treatment of ocular MG is aimed at relieving the symptoms of ptosis and diplopia, as well as preventing the development of generalized MG symptoms. Immune suppression with steroids is often the main therapy. Steroid doses must be increased slowly because of a risk of precipitating myasthenic crisis. After achieving the highest target dose, steroids are then slowly tapered down to the lowest effective dose. Often, acetylcholinesterase inhibitors such as pyridostigmine and neostigmine are also employed to help control symptoms. When steroids are contraindicated, acetylcholinesterase inhibitors can be tried as the primary therapy. Steroid-sparing agents such as azathioprine and mycophenolate may also have a role in treating ocular MG. Other treatments for MG include plasmapheresis, intravenous immunoglobulin, and other immunosuppressive agents, but these are rarely required for ocular MG. Patients should also be evaluated for thymoma. Thymoma should be resected surgically. Ocular MG without thymoma is not usually treated with thymectomy. Topical agents may be useful as additional therapy for mild or moderate ptosis. Nonpharmacologic treatments include occlusive devices, prisms, eyelid supports, contact lenses, and (in long-standing, stable cases) strabismus surgery or eyelid elevation surgery.

Juvenile myasthenia gravis: a paediatric perspective

Myasthenia gravis (MG) is an autoimmune disease in which antibodies are directed against the postsynaptic membrane of the neuromuscular junction, resulting in muscle weakness and fatigability. Juvenile myasthenia gravis (JMG) is a rare condition of childhood and has many clinical features that are distinct from adult MG. Prepubertal children in particular have a higher prevalence of isolated ocular symptoms, lower frequency of acetylcholine receptor antibodies, and a higher probability of achieving remission. Diagnosis in young children can be complicated by the need to differentiate from congenital myasthenic syndromes, which do not have an autoimmune basis. Treatment commonly includes anticholinesterases, corticosteroids with or without steroid-sparing agents, and newer immune modulating agents. Plasma exchange and intravenous immunoglobulin (IVIG) are effective in preparation for surgery and in treatment of myasthenic crisis. Thymectomy increases remission rates. Diagnosis and management of children with JMG should take account of their developmental needs, natural history of the condition, and side-effect profiles of treatment options.