Since 2020, updates in the diagnostic criteria for various neuromuscular diseases have emerged by advancements in electrophysiological studies, biomarker research, and imaging modalities. These developments reflect an effort to improve diagnostic accuracy and allow for earlier intervention. This review summarizes the most recent revisions in the diagnostic criteria for amyotrophic lateral sclerosis, primary lateral sclerosis, Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy, and myasthenia gravis.

Respiratory muscle weakness caused by neuromuscular disease can lead to both acute and chronic respiratory failure. Respiratory failure caused by Guillain-Barré syndrome and myasthenia gravis can potentially improve with disease-specific therapy. However, respiratory failure in amyotrophic lateral sclerosis is irreversible, and it may be necessary to provide full-time ventilation support along with additional assistance. Noninvasive ventilation is recommended for managing acute or acute-on-chronic hypercapnic respiratory failure caused by neuromuscular disease. It has also been effective in weaning patients off invasive mechanical ventilation. Although noninvasive ventilation offers numerous benefits over invasive mechanical ventilation, it is crucial to consider the specific contraindications and limitations of noninvasive ventilation and ensure its appropriate usage based on the patient's condition and needs. The timely recognition of neuromuscular respiratory failure is critical, as early intervention can be life-saving. This review focused on the clinical assessment and management of acute respiratory failure in neuromuscular diseases.

Some cases of myasthenia gravis (MG) with abnormal spontaneous activity (ASA) in needle electromyography (EMG) have been reported, but the associated clinical characteristics remain to be fully elucidated. We report the case of a 36-year-old male with MG in whom ASA was observed. This study highlights that ASA may appear in needle EMG in patients with severe MG who predominantly have bulbar and/or respiratory involvement. Care is needed because this often accompanies myopathic features and can be misdiagnosed as myopathy.

Myasthenia gravis (MG) and amyotrophic lateral sclerosis (ALS) are distinct disorders. ALS affects motor neurons that control muscle movement, while MG controls communication between neurons and muscles, which occurs at neuromuscular junctions. However, on rare occasions, ALS develops after MG and vice versa. The coexistence of the two diseases represents a diagnostic challenge and requires thoughtful interpretation of clinical features. We present the case of a 53-year-old Korean male who developed ALS after MG, confirmed by clinical and electrophysiological follow-up.

Citations

• Two Cases of Sporadic Amyotrophic Lateral Sclerosis With Contrasting Clinical Phenotypes: Genetic Insights
  Andrey Frolov, Miguel A Guzman, Ghazala Hayat, John R Martin
  Cureus.2024;[Epub]     CrossRef

Muscle specific tyrosine kinase (MuSK) myasthenia gravis (MG) is a rare subtype of MG, which is immunologically distinct and differential therapeutic response. Though MG is often associated with other autoimmune disorders or malignancy, concurrence of other disease and MuSK MG has been infrequently reported. We present a patient of MuSK MG associated with multicentric Castelman disease.

Citations

• Progressive Bulbar Palsy with Facial Diplegia and Proximal Weakness Diagnosed as Juvenile-Onset Myasthenia Gravis
  Rajesh Verma, Rajarshi Chakraborty, Pooja Tripathi
  Annals of Indian Academy of Neurology.2023; 26(4): 589.     CrossRef

Both myasthenia gravis and Guillain-Barre syndrome are autoimmune disorder, but it is very rare that both of them occur together. A 53-years old woman with history of myasthenia gravis complained of weakness of extremities, worsening progressively for several days. Electrophysiologic study showed findings of motor axonal neuropathy without sensory involvement. She became improved in aspect f of clinical symptoms and electrophysiologic findings after infusion of immunoglobulin. This is a case of Guillain-Barre syndrome in a patient with myasthenia gravis.

Background
& Object : Myasthenia gravis(MG) is an autoimmune disease due to binding of antibody to acetylcholine receptors on the muscle membrane. It is well known that other autoimmune disease infrequently accompany myasthenia gravis. The aim of this study was to evaluate the clinical significance of associated autoimmune diseases(AAD) and compare prognosis between MG with AAD and MG without AAD. Method : A total of 65 MG patients(24 men and 41 women) were enrolled at this study. From the clinical records of these patients, we investigated the clinical characteristics and prognosis of MG with AAD and compared thses date with those of MG without other such disease. Results : AAD were found in 10 of 65 cases(15%). 9 cases of10 MG with AAD were generalized MG type. The most common disease was thyroid disorders. The rate of AAD was higher in thymic abnormal patients. There was no significant remission rate difference between MG with AAD and MG without AAD, but the percentage of patients experienced crisis was higher in MG with AAD. Conclusion : The occurrence of AAD may suggest a more generalized autoimmune disturbance that could be associated with a less favorable prognosis.

Electrodiagnostic studies are valuable in confirming the diagnosis of a disorder of neuromuscular transmission. They are used to distinguish presynaptic and postsynaptic abnormalities. These studies provide an objective measure of the severity of the illness and may be useful in assessing the response to therapy. This article reviews the electrodiagnostic techniques that are commonly used today and highlights their specificity, sensitivity, and pitfalls. Repetitive nerve stimulation test (RNST) and single-fiber electromyography (SFEMG) are the most available electrophysiologic test in the diagnosis of neuromuscular junction disorders. RNS showing 10% decrement in amplitude from the first to fourth or fifth intravolley waveform while stimulating at 2~5 Hz is valid for the diagnosis of MG. The degree of increment needed for the diagnosis of LEMS is at least 25% but most accurate when greater than 100%. Abnormal jitter or impulse blocking are the appropriate criteria for diagnosis of NMJ disorders when using SFEMG. SFEMG is more sensitive than RNS for the diagnosis of disorders of neuromuscular transmission, especially in MG but may be less specific or may not be available.

We report a case of 36-year-old woman with myasthenia gravis (MG) combined with mediastinal leiomyosarcoma(LMS) and Stevens-Johnson syndrome (SJS). She was admitted to ICU with the symptoms of acute onset headache,diplopia, ptosis, dysphagia, general weakness, and respiratory difficulty for several days. Physical examination revealedtachypnea, decreased breath sounds and dullness to percussion in right lower chest. Neurologic examination showedptosis, diplopia, decreased gag reflexes, and generalized proximal weakness. Laboratory studies revealed increasedserum acetylcholine receptor antibodies and positive Tensilon test. Chest CT showed a huge mass in the right middlemediastium but no evidence of thymic enlargement. Mediastinal LMS was diagnosed by ultrasound-guided needle biopsy.The myasthenic symptoms were fluctuated in spite og intravenous immunoglobulin, plasmapheresis, and corticosteroid.During therapy, SJS developed. She died 4 months after the onset of the myasthenic symptoms despite thechemotherapy for LMS.

Myasthenia gravis (MG) is occasionally associated with other autoimmune diseases. Alopecia areata has been reported to coincide with MG, particularly with thymoma. A 14-year-old woman was diagnosed as having MG. Seven months before diagnosed with MG, her hair and eyebrows had began to disappear and alopecia areata was diagnosed. We report this patient as a rare case of MG associated with alopecia areata without thymoma.

Background
Myasthenia gravis (MG) and systemic lupus erythematosus (SLE) are well recognized to coexist and have some similarities in immunologic, clinical and serologic findings. Despite several reports of the association with autoantibodies and thymectomy in these disorders, the pathomechanism of coexistence remains to be elucidated.Objective: We aimed to investigate the relationship of MG and SLE through overall features of patients with both disorders;: clinical, laboratory, and electrophysiological findings.Materials and Methods: We reviewed the medical records of 6 consecutive patients with MG and SLE (2 men, 4 women, ages 17-51, mean 30.5 years, Seoul National University Hospital, from 1998 to 2005).Results: Three patients who developed SLE first, had ocular type of MG and 2 were children showing much severe and recurrent SLE features and only 1 patient had thymic hyperplasia. The other 3 developed MG first and they were generalized type and none underwent thymectomy. In addition, the development of MG or SLE was not coincident with remission or improvement of another disorder.Conclusion: The coexistence of SLE and MG may support the hypothesis of two different antibody populations modulated by thymus in the opposite extremesThis report suggests that the systemic and extensive autoimmune response in preceding MG or SLE may effect the development of the other disorder followed, while. the coexistence of two disorders cannot be explained by the hypothesis of two different antibody populations modulated by thymus in the opposite extremes The role of thymectomy and the theorectical subsequent effect on the development of SLE have been debated with controversy. However, SLE occurred without thymectomy in MG and these disorders did not develop in the quiescent period of another disorder. Therefore, the other pathomechanism for the coexistence of MG and SLE should be elucidated.

Repetitive nerve stimulation is a simple and widely used technique to demonstrate neuromuscular transmission defect. A significant decremental response for repetitive hypoglossal nerve stimulation was obtained from the surface recordings in the tongue of a patient with dysarthria and dysphagia. Repetitive hypoglossal nerve stimulation test may be useful in diagnosis of myasthenia gravis with bulbar symptoms only. We utilized repetitive hypoglossal nerve stimulation with tongue recordings and diagnosed a case of myasthenia gravis.

Various immunotherapeutic modalities have been used based on the autoimmune pathogenic mechanisms of myasthenia gravis (MG). Cell-mediated immunity as well as auto-antibodies may play a role in the remission and relapse of MG. We recently experienced two patients with MG who showed spontaneous remission fter inadvertent severe leukopenia. These findings suggest that the cell-mediated immune process is important in the treatment of MG, and selective suppression of leukocyte may induce remission in the patients with intractable MG.

There have been several reports about coexistence of myasthenia and other autoimmune disease. Psoriasis is a papulosquamous disease defined by erythematous plaques with a silvery scale and a T-cell-mediated autoimmune disease. We report a case of a 49-year-old an with generalized myasthenia gravis (MG) superimposed by psoriasis. MG was diagnosed by clinical symptoms, increased acetylcholine receptor antibody titer and repetitive nerve stimulation test. Psoriasis was diagnosed by clinical manifestations and specific skin biopsy findings. MG and psoriasis are both autoimmune diseases. The coexistence of MG and psoriasis suggest a close connection of pathogenesis.

Autoimmune myasthenia gravis (MG) is the neuromuscular junction disorder mostly caused by antibody against the acetylcholine receptor (AChR antibody) at the muscle endplate. The goal of treatment is to induce and maintain remission, i.e., absence of symptoms, with the least cost-to-benefit ratio. Although corticosteroids are effective in inducing remission in most patients, they have numerous potentially serious adverse effects with their long-term use. In addition, some patients do not respond or are intolerant to the conventional treatment. In this article, we discuss the difficulties encountered in long-term immunosuppressive treatment of MG, and review useful tips for the use of corticosteroids. Long-term immunosuppressive agents that can be used in steroid-refractory or -dependent patients will be reviewed with their safety profiles and efficacy in MG.

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