Childhood 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.

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.

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.

Ophthalmologic manifestations in myasthenia gravis: presentation and prognosis

We investigated the ophthalmologic manifestations and factors that influence outcomes in patients with myasthenia gravis (MG). We retrospectively analyzed the prevalence of neuro-ophthalmologic findings and clinical and outcome measures of 100 consecutive patients (53 males, 47 females), aged 55.7 ± 17.5 (range 15-85) years with an established diagnosis of MG. Forty-eight patients had purely ocular symptoms at the onset of disease (OMG) and 52 patients presented with generalized symptoms (GMG). Overall, 21 patients presented with extraocular muscle (EOM) weakness. Bilateral EOM weakness was seen in 12 patients, and unilateral EOM weakness was seen in nine patients. Diplopia responded partially to immunosuppressive treatments in 60% of patients with ophthalmoparesis. Twenty-five (52.1%) patients with ocular-onset MG converted to secondary GMG at a mean time of 14.5 months. Patients who developed secondary GMG were younger and had an earlier age of disease onset when compared with patients with pure OMG (p < 0.05). Patients with secondary GMG presented more frequently with ptosis and diplopia (72% vs. 28%) compared with patients with pure ocular MG who presented more frequently with isolated ptosis (66.7% vs. 33.3%) (p = 0.02). Remission and minimal manifestation status were achieved in 50 (79.3%) of all patients with a clinical follow-up ≥ 3 years. Poor outcome was associated with the presence of thymoma (p < 0.05). Myasthenic ophthalmoparesis is bilateral and heterogeneous and partly responds to treatment with immunotherapy. Younger patients with ptosis and diplopia at disease onset had an increased risk of secondary GMG. The presence of thymoma increases the risk for poor prognosis.

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.

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.

Strabismus in chronic progressive external ophthalmoplegia

PURPOSE

To elucidate the patterns of strabismus and ophthalmoplegia associated with chronic progressive external ophthalmoplegia (CPEO) confirmed by mitochondrial DNA (mtDNA) deletions in Asians.

METHODS

A total of 10 patients confirmed to have mtDNA deletion associated with CPEO were included. Long-range PCR encompassing the entire mtDNA was carried out. In the cases with mtDNA deletion, the exact deletion ranges of mtDNA were identified by sequencing. A full ophthalmologic examination including prism and alternate cover test in the primary position, evaluation of ductions and versions, and binocularity was performed in 10 patients with confirmed mtDNA deletions associated with CPEO.

RESULTS

All of the patients showed ophthalmoplegia as well as ptosis, even after eyelid surgeries. Ophthalmoplegia was symmetric between both eyes in nine patients (90%) while one patient (10%) showed asymmetric ophthalmoplegia with esotropia and left hypotropia. Among the nine patients with symmetric involvement, four patients (44%) showed exotropia, three (33%) had exotropia with vertical deviation, and the remaining two patients (22%) showed orthotropia. Five out of 10 patients (50%) complained of diplopia associated with strabismus, four of whom (80%) had vertical deviation. Three out of five patients (60%) without diplopia showed exotropia of 20 prism diopters (PD) to 50 PD.

CONCLUSIONS

Exotropia with/without vertical deviation is the most common form of strabismus in Asian patients with CPEO and only one of them showed a small angle of esotropia. Ophthalmoplegia could be asymmetric in 10% of CPEO patients.

Initial Treatment Response in Ocular Myasthenia Gravis: A Comparison Between Low and Moderate Doses of Prednisolone

Purpose

To evaluate the initial treatment response to low doses of prednisolone, compared with moderate doses, in ocular myasthenia gravis (OMG).

Patients and Methods

A retrospective chart review of patients with adult-onset (age ≥15 years old) OMG, who were treated with prednisolone, was conducted. Subjects were divided into two groups according to their prednisolone dosing regimen. The low-dose group was defined as those with an average 12-week cumulative dose of prednisolone <0.435 mg/kg/day and the moderate-dose group averaged 0.435–1.000 mg/kg/day. The primary outcome of interest was the comparison of clinical response to prednisolone at 12 weeks between the low-dose and moderate-dose groups. The secondary outcome was the difference in adverse events between treatment groups.

Results

Of 34 subjects, 16 subjects (47.1%) were male. The mean age at onset was 44.0±18.1 years. The most common presenting ocular feature was ptosis with ophthalmoplegia (22 subjects, 64.7%), followed by isolated ptosis (nine subjects, 26.5%) and isolated ophthalmoplegia (three subjects, 8.8%). Half of the subjects were treated with low-dose prednisolone and the other half were treated with moderate-dose prednisolone. There were no substantial differences in baseline characteristics between treatment groups. After 12 weeks of treatment, nine of 17 subjects (52.9%) and 13 of 17 subjects (76.5%) in the low- and moderate-dose groups, respectively, were regarded as responsive to the prednisolone treatment (P=0.28). Adverse events were exclusively observed in the moderate-dose group.

Conclusion

Treatment of OMG with an average 12-week cumulative dose of prednisolone <0.435 mg/kg/day (low dose) shows a comparable responsive outcome to 0.435–1.000 mg/kg/day of prednisolone (moderate dose). Treating OMG with low-dose prednisolone can minimize prednisolone-related adverse events. However, a prospective randomized controlled trial with a larger study population is warranted in order to gain more insight into the proper dosage of prednisolone for OMG.

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.

A review of the histopathological findings in myasthenia gravis: Clues to the pathogenesis of treatment-resistance in extraocular muscles

In myasthenia gravis autoantibodies target components of the neuromuscular junction causing variable degrees of weakness. In most cases, autoantibodies trigger complement-mediated endplate damage and extraocular muscles may be most susceptible. A proportion of MG cases develop treatment-resistant ophthalmoplegia. We reviewed publications spanning 65 years reporting the histopathological findings in the muscles and extraocular muscles of myasthenic patients to determine whether pathological changes in extraocular muscles differ from non-ocular muscles. As extraocular muscles represent a unique muscle allotype we also compared their histopathology in myasthenia to those in strabismus. We found that in myasthenia gravis, the non-ocular muscles frequently demonstrate neurogenic changes regardless of myasthenic serotype. Mitochondrial stress/damage was also frequent in myasthenic muscles and possibly more evident in muscle-specific kinase antibody-positive MG. Although myasthenia-associated paralysed extraocular muscles demonstrated prominent fibro-fatty replacement and mitochondrial alterations, these features appeared commonly in paralysed extraocular muscles of any cause. We postulate that extraocular muscles may be more susceptible than limb muscles to poor contractility as a consequence of myasthenia, resulting in a cascade of atrophy signaling pathways and altered mitochondrial homeostasis which contribute to the tipping point in developing treatment-resistant myasthenic ophthalmoplegia. Early strategies to improve force generation in extraocular muscles are critical.

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

BACKGROUND

Isolated ocular myasthenia gravis (MG) is sparingly common in children relative to adults, ranging from 71% to 93% of all children with MG.

PURPOSE

We aimed to characterize the ocular manifestations and outcomes in children with isolated ocular MG.

METHODS

Medical records of consecutive 62 subjects less than 15 years of age with ocular MG, were retrospectively reviewed. Demographic data, presenting ocular features, types and variabilities of duction limitation, MG confirmatory tests, types of and responses to treatment, and generalized MG conversion were reviewed.

RESULTS

Mean age at onset and follow-up time were 49 months (range, one to 173 months) and 95 months (range, six to 226 months), respectively. Female-to-male ratio was 1.5:1. Initially, ptosis was found in 60 subjects (96.8%), while duction limitation was observed in 28 subjects (45.2%). Total ophthalmoparesis was the most common type of duction limitation. Variability of duction limitation was found in 68% of subjects during the follow-up. Pyridostigmine alone was the most common medication used (48.4%); ptosis was more responsive to therapy than duction limitation. Conversion to generalized MG occurred in 19.4% of subjects, with a mean interval to conversion of nine months after symptom onset. Most conversions (91.7%) occurred in the first two years.

CONCLUSIONS

Ptosis was more responsive to treatment than duction limitation. Thus other treatment modalities, as well as strabismic amblyopia screening, should be considered in children with prolonged duction limitation that is refractory to medication. In contrast with adults, a much lower proportion of children converted to generalized MG. This may explain the higher prevalence of isolated ocular MG among the juvenile population.

Efficacy of Gaze Photographs in Diagnosing Ocular Myasthenia Gravis

Background and Purpose

The various tests that are routinely used to diagnose generalized myasthenia gravis, such as the edrophonium test, serum anti-acetylcholine-receptor antibodies (AChR-Ab), and repetitive nerve stimulation (RNS) tests, have lower diagnostic sensitivity in ocular myasthenia gravis (OMG). Diagnosing OMG becomes even more difficult when the clinical symptoms are subtle. There is no gold-standard diagnostic test available for OMG patients, and so this study compared the diagnostic sensitivity of gaze photographs with conventional tests in OMG.

Methods

Records of gaze photographs were available for 25 of 31 consecutive patients diagnosed with OMG. Each patient underwent a neuro-ophthalmologic examination, serum AChR-Ab, RNS, edrophonium test, ice tests, and the acquisition of gaze photographs. The margin reflex distance 1 (MRD1) was measured on each of the gaze photographs, with MRD1 <2 mm or an interlid MRD1 difference of ≥2 mm on any of the gaze photographs defined as a positive sign of OMG. The diagnostic sensitivities of the tests were assessed.

Results

The mean age at onset was 38.5 years (range, 2–76 years), and 13 patients (52%) were men. The diagnostic sensitivities of the RNS test, AChR-Ab test, gaze photographs, and ice test were 56%, 64%, 80%, and 73%, respectively.

Conclusions

The diagnostic sensitivity was higher for gaze photographs than for the other tests applied to OMG patients.

Low conversion rate of ocular to generalized myasthenia gravis in Singapore

INTRODUCTION

Ocular myasthenia gravis (OMG) is a common condition of the neuromuscular junction that may convert to generalized myasthenia gravis (GMG). Our aim in this study was to determine the conversion rate and predictive factors for generalization in OMG, in an Asian population.

METHODS

The investigation consisted of a retrospective study of OMG patients with a minimum 2 years of follow-up.

RESULTS

Among 191 patients with OMG, 155 had the minimum 2-year follow-up. The conversion rate at median follow-up (40.8 months) was 10.6% (95% confidence interval 7.9%-13.3%), and at the 2-year follow-up it was 7.7% (95% confidence interval 5.6%-9.8%). At baseline, the predictive factors for generalization were positive acetylcholine receptor antibodies (hazard ratio 3.71, P = 0.024), positive repetitive nerve stimulation (RNS) studies (hazard ratio 4.42, P = 0.003), and presence of radiologically presumed or pathologically confirmed thymoma (hazard ratio 3.10, P = 0.013).

DISCUSSION

The conversion rate of OMG to GMG in Asian patients is low, as predicted by presence of acetylcholine receptor antibodies, presence of thymoma, and positive RNS studies. Muscle Nerve 57: 756-760, 2018.

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.

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

Juvenile myasthenia gravis presents before 18 years of age with different characteristics according to racial background and pubertal development. The authors aimed to determine the clinical characteristics of children and adolescents of Korean ethnicity with myasthenia gravis, and evaluate the presentation and clinical outcomes according to the sex and onset age of the patients. The authors recruited 88 Korean juvenile myasthenia gravis patients between September 2005 and August 2015. Worse clinical severity from presentation, more aggressive treatment strategies, and worse final treatment outcomes were noted in girls with postpubertal onset than in the other patients. The symptoms were milder (pure ocular presentation in 96.6% [85/88]) and the disease course was more benign (94.3% [83/88]) in this study than in the literature. The homogenous racial background might have contributed to these results. These findings highlight the influence of pubertal development and the need for timely and appropriate active treatment, including thymectomy, to improve prognosis.

CHARGE syndrome with oculomotor nerve palsy

CHARGE syndrome is a congenital disorder characterized by coloboma, heart defects, atresia of the choanae, retarded growth, genital hypoplasia, ear anomalies, and/or hearing loss. We report the case of a 2-year-old boy with CHARGE syndrome who presented with left exotropia and elevation deficit since infancy. He had patent ductus arteriosus, small testicles, growth retardation, auricular deformity, left semicircular canal aplasia, and a de novo nonsense mutation (p.Ser705X) of the CHD7 gene. He had a left exotropia of 40 prism diopters, marked limitation of upgaze and mild limitation of downgaze and adduction in the left eye. On upgaze, his left eye adducted but did not elevate. The pupils of both eyes were round and isocoric. Fundus examination revealed optic disk and choroidal colobomas. CHARGE syndrome with oculomotor nerve palsy has not been reported previously.

Clinical characteristics of pediatric myasthenia: a surveillance study

OBJECTIVE

To evaluate the incidence, clinical features, diagnostic, and treatment trends of pediatric myasthenia in Canada.

METHODS

Through established Canadian Pediatric Surveillance Program methodology, physicians were anonymously surveyed for cases of pediatric myasthenia using a standardized clinical questionnaire containing deidentified data. Inclusion criteria were any child <18 years old with ≥1 of the following: (1) fluctuating ptosis or extraocular weakness, (2) skeletal muscle weakness or fatigue, and (3) any of the following supportive tests: clinical response to acetylcholinesterase inhibitor, positive antibodies, abnormal slow repetitive nerve stimulation, or single-fiber electromyography.

RESULTS

In 2 years of surveillance, 57 confirmed cases were reported. There were 34 generalized and 18 ocular reports of juvenile myasthenia gravis plus 5 congenital myasthenic syndrome cases. There were 14 incident cases in 2010 and 6 in 2011. Age of onset ranged from "birth" to 17 years for the generalized form compared with 18 months to 11 years for the ocular subtype. Positive acetylcholine receptor titers were found in 22 (67%) of 33 generalized cases and 8 (44%) of 18 ocular patients. Of patients started on pyridostigmine, improvement was noted in 33 (100%) of 33 generalized cases and 15 (88%) of 17 ocular cases.

CONCLUSIONS

This study represents the largest descriptive series of pediatric myasthenia in North America and provides valuable information about clinical characteristics. A high index of suspicion is important for this treatable disease. Children generally respond promptly to readily available therapies.

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.

Myasthenia mimicking monocular elevation deficiency

Monocular elevation deficiency is the inability to elevate the eye in abduction and adduction. Myasthenia gravis could mimic any pattern of ophthalmoplegia. However, myasthenia gravis mimicking monocular elevation deficiency appears to be very rare. A 12-month-old girl presented with the inability to elevate the left eye and blepharoptosis from 3 months of age. A neostigmine test showed a weakly positive response. Repetitive stimulation of the left orbicularis oculi produced no decremental response. Three assays for acetylcholine receptor antibodies were negative. Placing ice over the lids definitely improved left blepharoptosis. In conclusion, myasthenia gravis could mimic elevation deficiency. An ice test could be very helpful in making the diagnosis. Myasthenia gravis should be included in the differential diagnosis of monocular elevation deficiency even at a young age.

Treatment for diplopia in patients with myasthenia gravis

BACKGROUND

The purpose of this study was to describe the treatment experiences and outcomes of patients with myasthenia gravis (MG) whose initial presenting symptom was diplopia

METHODS

A retrospective review was performed on a group of patients with MG whose initial presenting symptom was diplopia.

RESULTS

The mean age of onset was 45.5 ± 16.9 years, and the mean follow-up period was 45.4 ± 39.7 months. Exotropia with vertical heterotropia was the most common type of deviation. The mean horizontal deviation was 20.1 ± 17.9 prism diopters, and the mean vertical deviation was 14.8 ± 11.1 prism diopters. Limitation of eye movement was found in 20 patients (71.4 %) during the follow-up period. After conventional treatment for MG, six patients (21.4 %) showed a good response with resolution of diplopia. Four patients (14.3 %) showed a partial response to treatment. Eighteen patients (64.3 %) showed minimal or no response; among them, ten (35.7 %) had an angle of deviation of 15 prism diopters or more. Six patients underwent strabismus surgery. Four were symptom free, and satisfactorily aligned after surgical treatment. One patient had intermittent diplopia despite the small amount of deviation, and one patient experienced recurrence of exotropia with diplopia during the 10-year follow-up. In multivariable analysis, the only factor associated with the need for strabismus surgery was the initial angle of deviation (p = 0.016).

CONCLUSIONS

Patients with MG who have a larger angle of deviation at presentation tend to require strabismus surgery after stabilization of the disease. Strabismus surgery is one treatment option for patients with MG who have a large angle of deviation and respond poorly to conventional treatment.

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.

Visual and systemic outcomes in pediatric ocular myasthenia gravis

PURPOSE

To evaluate visual and systemic outcomes in pediatric patients with purely ocular myasthenia gravis (OMG) treated at the Children's Hospital of Philadelphia.

DESIGN

Retrospective chart review.

METHODS

Pediatric patients with OMG seen at a single institution over a 16-year period with a minimum follow-up of 1 year were reviewed. Associations of demographic and clinical characteristics with disease resolution, amblyopia, and development of generalized symptoms of myasthenia gravis were analyzed.

RESULTS

Thirty-nine patients were identified, with a mean age of 5.4 ± 4.8 years and mean follow-up of 4.8 ± 4.3 years. Fifteen patients were treated with pyridostigmine only, 19 (49%) also received steroids, and 15 (38%) underwent thymectomy. Four patients (10%) received steroid-sparing immunosuppressive therapy. Resolution occurred in 10 patients, and generalized symptoms eventually occurred in 9 patients. Although 10 patients were treated for amblyopia, only 1 had amblyopia at the final visit. There was no correlation between sex or age with amblyopia or development of generalized symptoms. Thymectomy, when performed before the onset of generalized symptoms, showed a trend toward protection from the development of generalized symptoms (P = .07).

CONCLUSIONS

In our series, 24% of patients had disease resolution and 23% had generalized symptoms. Our larger cohort confirms previous findings that treated and untreated pediatric patients with OMG have a relatively low risk of developing generalized symptoms and that related amblyopia is readily reversible. Although our treatments were more aggressive than those previously reported, our rates of amblyopia and development of generalized symptoms are comparable.

Prolonged constant eye misalignment leads to failure to develop binocular vision in childhood ocular myasthenia gravis

PURPOSE

Variable eye misalignment and blepharoptosis in childhood ocular myasthenia gravis can lead to permanent binocular visual loss. However, a standard ophthalmologic intervention for this condition has yet to be fully established. This study investigated the influence of variable eye misalignment and asymmetric blepharoptosis on the development of binocular vision in childhood ocular myasthenia gravis.

METHODS

The authors retrospectively reviewed clinical records of consecutive patients with childhood ocular myasthenia gravis whose age of onset was younger than 36 months and who had follow-up periods of more than 1 year. Five patients were enrolled and were treated medically with pyridostigmine or corticosteroids. Eye alignment, eye movements, and blepharoptosis were observed during the follow-up period. Stereoacuity was recorded before and at the end of follow-up using Titmus stereoscopic and major amblyoscopic tests.

RESULTS

None of the patients had amblyopia or anisometropia, but all had blepharoptosis that improved within 2 weeks after medication was administered. There was only one case in which stereoacutiy failed to develop, and this patient had a long period of constant exotropia lasting 48 months. In the remaining four cases, there was constant exotropia lasting less than 4 months or intermittent exotropia throughout the follow-up period. All of these patients regained or maintained binocular vision.

CONCLUSION

Prolonged constant eye misalignment may be attributable to impaired binocular vision, and prompt eye alignment may be necessary in childhood ocular myasthenia gravis. Therefore, treatment based on precise assessment by a neuro-ophthalmologist or pediatric ophthalmologist that evaluates even slight eye misalignment is essential in ensuring normal development of binocular vision.

Ptosis and cranial nerve IV palsy reveal juvenile myasthenia gravis

BACKGROUND

Ptosis and strabismus are 2 common presenting complaints of preschool-age patients. In both cases, these conditions can be benign and require no further workup. However, sudden onset of these findings can indicate a more serious neurologic problem. If a patient presents with multiple neurologic signs, a sudden onset eye turn, or ptosis, the patient must undergo a workup to rule out a pathologic etiology, specifically a brain tumor. The workup should include neuroimaging. If the results of the neuroimaging are normal, and the findings are variable, myasthenia gravis should be considered, and additional testing should be ordered to assist in the diagnosis.

CASE REPORT

This case report presents a 3-year-old boy who presented with a sudden onset of ptosis and hypertropia. Diagnosis of myasthenia gravis was made based on clinical presentation and response to ice pack testing. The patient was treated with pyridostigmine (Mestinon; Valent Pharmaceuticals, Costa Mesa, California) and has shown improvement in his clinical signs.

CONCLUSIONS

Although rare, myasthenia should be considered a diagnosis in children who present with variable ptosis or strabismus. Patients can be successfully treated with medication.

Myasthenia gravis in South Africans: Racial differences in clinical manifestations

We present data on the phenotypic variation in myasthenia gravis of 205 subjects from a multi-racial South African cohort. Consecutive subjects seen more than twice from 1996 to 2006, were included. Documented observational data included a myasthenia gravis and extra-ocular eye muscle score. Results showed Black subjects were more likely than Whites to develop treatment-resistant complete ophthalmoplegia and ptosis (18% vs. 2%; p=0.041). Of the 14 patients with this phenotype, 13 had generalised disease and positive AChR antibodies. Despite similar sized cohorts, White subjects were more likely than Blacks to develop generalised myasthenia poorly responsive to therapy (p=0.005). There were no significant racial differences in the time between diagnosis to initiation of therapy, or the performance and timing of thymectomy. The racial variation in some phenotypic features of myasthenia gravis and outcome to therapy, highlights the need to study biological factors in different subgroups to develop a more rational approach to immuno-suppressive therapy.

Ocular motor dysfunction and ptosis in ocular myasthenia gravis: effects of treatment

AIM

The optimal treatment of ocular myasthenia gravis (OMG) remains unknown. The authors evaluated the efficacy of prednisone and pyridostigmine in reducing diplopia, ocular motor dysfunction, and ptosis in patients with OMG.

METHODS

Review of records from a clinical database from one neuro-ophthalmology service of patients presenting with OMG between 1990 and 2002, excluding those who developed generalised MG within the first month after diagnosis. Institutional review board approval was obtained for this study.

PARTICIPANTS/INTERVENTIONS

Non-randomised, unmasked, therapy was given. 55 patients with diplopia in primary or downward gaze and clinically demonstrable extraocular muscle dysfunction received prednisone. 34 patients who had contraindications to steroids or who refused treatment with prednisone received pyridostigmine only. Over 5 days the daily prednisone dose was increased to 50-60 mg and then gradually reduced to 10 mg, followed by further reduction as tolerated. The pyridostigmine dose was begun at 180 mg daily and increased as tolerated.

MAIN OUTCOME MEASURES

Follow up evaluations, performed at 1, 3-6, 12, and 24 months, detailed the frequency of ptosis and diplopia and the amount of ocular motor deviation in primary and downward gaze.

RESULTS

The prednisone and pyridostigmine groups were similar for age, sex, acetylcholine receptor antibody level, prism cover test results for primary and downward gaze, diplopia in primary and downward gaze, and unilateral ptosis. Bilateral ptosis was present in 32.4% of the pyridostigmine group and 10.9% of the prednisone group (p = 0.02). The prednisone group showed resolution in primary gaze diplopia, downgaze diplopia, unilateral ptosis, and bilateral ptosis in 73.5%, 75.5%, 85.7%, and 98%, respectively at 1 month. The benefit persisted at 3-6, 12, and 24 months except for the bilateral ptosis. The pyridostigmine group showed resolution in primary gaze diplopia, downgaze diplopia, unilateral ptosis, and bilateral ptosis in 6.9%, 17.2%, 50%, and 76.7% of patients after 1 month of treatment. The prism cover results improved (p = 0.003) in the prednisone group only. In the prednisone group, four patients had no response to therapy. Among the 51 prednisone responsive patients, there were 33 recurrences in 26 patients. 12 patients, all prednisone treated, had remissions. Except for three patients who developed diabetes, no patient developed a clinically significant systemic corticosteroid complication.

CONCLUSION

These results suggest that 50-60 mg daily prednisone followed by lower doses (10 mg or less) has the benefit of resolving ptosis and diplopia that lasts for at least 2 years in approximately 70% of patients.

Pediatric neuro-ophthalmology

PURPOSE OF REVIEW

This review will update the ophthalmologist on recent developments in pediatric neuro-ophthalmology.

RECENT FINDINGS

Research into the genetics of congenital strabismus syndromes has brought new insights into the development of the ocular motor system. There is also new literature on childhood ocular myasthenia gravis and childhood neurosarcoidosis. The results of three different surgical treatments for congenital nystagmus are described. Reviews on cortical visual impairment, dyslexia, Aicardi syndrome, and neuronal ceroid lipofuscinosis are presented.

SUMMARY

Pediatric neuro-ophthalmology is a diverse and challenging field. As we strive to provide excellent care to these patients, we will use the results of basic science, genetic, and neurobiological research.

Ocular myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder characterized clinically by proximal weakness and bulbar symptoms and pathologically by damage to the post-synaptic membrane at the neuromuscular junction. Ocular myasthenia gravis (ocular MG) is a form of myasthenia gravis whereby the patients' weakness is limited to the muscles of the eyes and eyelids (levator palpebrae superioris). Although not life-threatening, the limitations posed by ocular myasthenia gravis can prove disabling and distressing to patients. Acetylcholinesterase inhibitors such as pyridostigmine or neostigmine are the preferred first-line treatment for ocular myasthenia gravis, with mild cases requiring no additional intervention. However, in moderate or severe cases, treatment must be tailored to the needs and desires of the patient. Intravenous immunoglobulin, although costly, is safe and effective at treating MG. Corticosteroids are effective at reducing or eliminating symptoms and may modify the long-term course of the illness. Steroid-sparing agents such as azathioprine and mycophenolate mofetil are reasonably safe and well-tolerated alternatives to steroids. Surgical interventions such as strabismus surgery and eyelid suspension serve to correct impairments refractory to medical management. Thymectomy, although less frequently recommended, is a reasonable consideration, especially for young adults, given the potential for long-term benefit.