MRI evidence of extraocular muscle atrophy and fatty replacement in myasthenia gravis

A controlled clinical study on efficacy and safety of periocular triamcinolone acetonide injection for treating ocular myasthenia gravis

OBJECTIVE

To evaluate the efficacy and safety of peribulbar triamcinolone acetonide injection for treating ocular myasthenia gravis (OMG), with a comparison of traditional oral drug therapy.

METHODS

A total of 22 patients with OMG who received periocular triamcinolone acetonide injection (initially 20 mg weekly, then once per month later if symptoms were improved) from July 2019 to July 2022 were evaluated by a comparison of symptom degree before and after treatment. Adverse reactions were also monitored during the period of treatment. The period of follow-up was more than 6 months. Additionally, a comparison of the treatment efficacy between this periocular injection and traditional oral administration was performed in OMG patients.

RESULTS

After 4 weeks of treatment, the degree of ptosis in OMG patients decreased to -3.00 ± 0.69, compared to the value (-0.86 ± 1.32) before treatment. The degree of ophthalmoplegia also decreased from 3.12 ± 0.72 to 0.86 ± 0.88 (P < 0.001) after treatment. The achievement rates of minimal manifestations status (MMS)for ptosis and ophthalmoplegia after 4 week-treatment were 86.3% and 75%, respectively, while they were 50% and 30% in patients with traditional oral administration. There was statistically significant difference only in MMS (rather than symptom relief rate and generalization conversion rate) between two groups. No serious complications (except for intraorbital hematoma) were found in OMG patients during the treatment period.

CONCLUSION

Repeated peribulbar injection of triamcinolone acetonide can effectively alleviate the initial symptoms of OMG patients. However, the evaluation of its long-term efficacy is still needed.

CLINICAL TRIAL REGISTRY

This study has been clinically registered by Chinese Clinical Trial Registry (ChiCTR), first trial registration date:05/07/2019, registration number: ChiCTR1900024285.

Remodeling of the neuromuscular junction in myasthenia gravis increases serum neurofilament heavy chain levels

INTRODUCTION/AIMS

In myasthenia gravis, prolonged muscle denervation causes muscle atrophy. We re-visited this observation using a biomarker hypothesis. We tested if serum neurofilament heavy chain levels, a biomarker for axonal degeneration, were elevated in myasthenia gravis.

METHODS

We enrolled 70 patients with isolated ocular myasthenia gravis and 74 controls recruited from patients in the emergency department. Demographic data were collected alongside serum samples. Serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) for the neurofilament heavy chain (NfH-SMI35). The statistical analyses included group comparisons, receiver operator characteristic (ROC) curves, area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values.

RESULTS

Serum neurofilament heavy chain levels were significantly (p < 0.0001) higher in individuals with myasthenia gravis (0.19 ng/mL) than in healthy control subjects (0.07 ng/mL). A ROC AUC optimized cutoff level of 0.06 ng/mL gave a diagnostic sensitivity of 82%, specificity of 76%, positive predictive value of 0.77 and a negative predictive value of 0.81.

DISCUSSION

The increase of serum neurofilament heavy chain levels in myasthenia gravis is consistent with observations of muscle denervation. We suggest that there is ongoing remodeling of the neuromuscular junction in myasthenia gravis. Longitudinal quantification of neurofilament isoform levels will be needed to investigate the prognostic value and potentially guide treatment decisions.

Clinical and imaging clues to the diagnosis and follow-up of ptosis and ophthalmoparesis

Ophthalmoparesis and ptosis can be caused by a wide range of rare or more prevalent diseases, several of which can be successfully treated. In this review, we provide clues to aid in the diagnosis of these diseases, based on the clinical symptoms, the involvement pattern and imaging features of extra-ocular muscles (EOM). Dysfunction of EOM including the levator palpebrae can be due to muscle weakness, anatomical restrictions or pathology affecting the innervation. A comprehensive literature review was performed to find clinical and imaging clues for the diagnosis and follow-up of ptosis and ophthalmoparesis. We used five patterns as a framework for differential diagnostic reasoning and for pattern recognition in symptomatology, EOM involvement and imaging results of individual patients. The five patterns were characterized by the presence of combination of ptosis, ophthalmoparesis, diplopia, pain, proptosis, nystagmus, extra-orbital symptoms, symmetry or fluctuations in symptoms. Each pattern was linked to anatomical locations and either hereditary or acquired diseases. Hereditary muscle diseases often lead to ophthalmoparesis without diplopia as a predominant feature, while in acquired eye muscle diseases ophthalmoparesis is often asymmetrical and can be accompanied by proptosis and pain. Fluctuation is a hallmark of an acquired synaptic disease like myasthenia gravis. Nystagmus is indicative of a central nervous system lesion. Second, specific EOM involvement patterns can also provide valuable diagnostic clues. In hereditary muscle diseases like chronic progressive external ophthalmoplegia (CPEO) and oculo-pharyngeal muscular dystrophy (OPMD) the superior rectus is often involved. In neuropathic disease, the pattern of involvement of the EOM can be linked to specific cranial nerves. In myasthenia gravis this pattern is variable within patients over time. Lastly, orbital imaging can aid in the diagnosis. Fat replacement of the EOM is commonly observed in hereditary myopathic diseases, such as CPEO. In contrast, inflammation and volume increases are often observed in acquired muscle diseases such as Graves' orbitopathy. In diseases with ophthalmoparesis and ptosis specific patterns of clinical symptoms, the EOM involvement pattern and orbital imaging provide valuable information for diagnosis and could prove valuable in the follow-up of disease progression and the understanding of disease pathophysiology.

Sarcopenia and nervous system disorders

Sarcopenia has an insidious start that can induce physical malfunction, raise the risk of falls, disability, and mortality in the old, severely impair the aged persons' quality of life and health. More and more studies have demonstrated that sarcopenia is linked to neurological diseases in recent years. This review examines the advancement of sarcopenia and neurological illnesses research.

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.