Myasthenia gravis presenting with unusual neurogenic muscle atrophy

Samuraki, Miharu; Furui, Eisuke; Komai, Koichiro; Takamori, Masaharu; Yamada, Masahito

doi:10.1002/mus.20757

Cited by 13 publications

(9 citation statements)

References 20 publications

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“…Abnormal spontaneous activity may be seen in acute to chronic cases, and it can resolve after treatment. The presence of muscle atrophy has been described previously in MuSK and AChR antibody‐positive MG . Lymphorrhages have been demonstrated in skeletal muscle end plates in patients with MG .…”

Section: Clinical Features and Diagnostic Studiessupporting

confidence: 52%

Abnormal spontaneous activity on needle electromyography in myasthenia gravis

et al. 2017

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Section: Clinical Features and Diagnostic Studiessupporting

confidence: 52%

Abnormal spontaneous activity on needle electromyography in myasthenia gravis

et al. 2017

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“…Our steroid-naïve patient adds to the individual case reports of AChR-antibody-positive MG presenting with prominent atrophy during the early course of the disease. 2,3 Unlike the other two cases reported in the literature, our patient had no evidence of ocular involvement or fluctuating fatigable muscle weakness. 2,3 Muscular atrophy may occur in MG patients with longstanding disease, in those who have been taking corticosteroids for long periods of time, or in patients with seropositivity for the MuSK antibody.…”

Section: Jcncontrasting

confidence: 53%

“…2,3 Unlike the other two cases reported in the literature, our patient had no evidence of ocular involvement or fluctuating fatigable muscle weakness. 2,3 Muscular atrophy may occur in MG patients with longstanding disease, in those who have been taking corticosteroids for long periods of time, or in patients with seropositivity for the MuSK antibody. 4,5 In MuSK-antibody-positive MG, atrophy may be an early and typical feature affecting the facial and bulbar muscles.…”

Section: Jcncontrasting

confidence: 53%

Acetylcholine Receptor-Antibody-Positive Myasthenia Gravis Presenting with Early Atrophy and Nonfluctuating Weakness of Proximal Limb Muscles

et al. 2020

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Dear Editor, Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission caused by antibodies targeting postsynaptic muscle end plates at the neuromuscular junction. 1 The cardinal symptom of MG is fluctuating weakness of voluntary muscles. 1 An 82-year-old male presented with an 8-month history of slowly progressive dysphagia and weakness predominantly involving the proximal muscles of the upper limbs. No fatigability, myalgia, cramps, fasciculation, dysarthria, shortness of breath, or sensory symptoms were present. His past and family histories were unremarkable. A neurological examination revealed that the patient could lift his arms only up to 90° (Fig. 1A). There was mild symmetric muscle weakness of the shoulder abductors, elbow extensors and flexors, hip flexors, and knee flexors, which did not worsen with repeated or sustained exertion. The neck extensors and orbicularis oculi muscles also exhibited mild weakness. Eyelid ptosis or weakness of extraocular muscles was not noticed even after provocative tests, and there was no evidence of tongue atrophy. The patient had mild-to-moderate wasting of the periscapular muscles, especially the deltoid, with scapular winging, of the pectoralis major, biceps brachii, and quadriceps muscles (Fig. 1A, B, and C, Supplementary Fig. 1 in the online-only Data Supplement). Deep tendon reflexes, sensation, and the findings of a cerebellar examination were normal. Laboratory investigations including serum creatine kinase (CK) and tumor markers produced findings that were all within the normal ranges. A workup for dysphagia that included a videofluoroscopic swallowing study and esophagogastroduodenoscopy did not reveal any structural abnormalities. The findings of nerve conduction studies were normal, and needle electromyography (EMG) recorded normal motor-unit potentials with a full interference pattern and no spontaneous activity in the deltoid, vastus lateralis, and gastrocnemius muscles. Repetitive nerve stimulation of the deltoid muscle at 2-5 Hz induced a 30% decrease in the amplitude of compound muscle action potentials, and increased jitter in the single-fiber EMG of the extensor digitorum communis muscle with a mean consecutive difference of 75.9 μsec (range 45.7-133 μsec; normal value <55 μsec). MG was suspected based on the neurophysiological findings. Serum testing for acetylcholine receptor (AChR)-binding antibody was positive, with a titer of 95 pmol/mL (normal <0.25 pmol/mL) confirming the diagnosis, while a radioimmunoprecipitation assay showed negativity for anti-musclespecific tyrosine kinase (MuSK) antibodies. A whole-body computed tomography scan showed no evidence of thymoma or other tumors, and cervical spine imaging was unremarkable. The patient was started on pyridostigmine at 90 mg per day, which was gradually increased to 300 mg per day to produce a partial response that was not sustained. However, adding prednisone at up to 12.5 mg per day led to long-lasting clinical improvement. At 4

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“…In that situation, the main problem lies in not mistakenly attribute worsening of the patient's condition to MG. Marked muscle atrophy may occasionally be present in MG[6,7] and fasciculation can be seen as a side effect of cholinesterase inhibitor therapy. Conversely, the presence of pyramidal signs should attract attention and the diagnosis of concomitant ALS should be considered if EMG evaluation shows acute and chronic denervation outside of motor deficit territories.…”

mentioning

confidence: 99%

Unusual association of amyotrophic lateral sclerosis and myasthenia gravis: A dysregulation of the adaptive immune system?

Amador

Vandenberghe

Berhoune

et al. 2016

Neuromuscular Disorders

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Myasthenia gravis is an autoimmune disorder affecting neuromuscular junctions that has been associated with a small increased risk of amyotrophic lateral sclerosis (ALS). Here, we describe a retrospective series of seven cases with a concomitant diagnosis of ALS and myasthenia gravis, collected among the 18 French reference centers for ALS in a twelve year period. After careful review, only six patients strictly met the diagnostic criteria for both ALS and myasthenia gravis. In these patients, limb onset of ALS was reported in five (83%) cases. Localization of myasthenia gravis initial symptoms was ocular in three (50%) cases, generalized in two (33%) and bulbar in one (17%). Median delay between onset of the two conditions was 19 months (6-319 months). Anti-acetylcholine receptor antibodies testing was positive in all cases. All patients were treated with riluzole and one had an associated immune-mediated disease. In the one last ALS case, the final diagnosis was false-positivity for anti-acetylcholine receptor antibodies. The co-occurrence of ALS and myasthenia gravis is rare and requires strict diagnostic criteria. Its demonstration needs thoughtful interpretation of electrophysiological results and exclusion of false positivity for myasthenia gravis antibody testing in some ALS cases. This association may be triggered by a dysfunction of adaptive immunity.

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Myasthenia gravis presenting with unusual neurogenic muscle atrophy

Cited by 13 publications

References 20 publications

Abnormal spontaneous activity on needle electromyography in myasthenia gravis

Abnormal spontaneous activity on needle electromyography in myasthenia gravis

Acetylcholine Receptor-Antibody-Positive Myasthenia Gravis Presenting with Early Atrophy and Nonfluctuating Weakness of Proximal Limb Muscles

Unusual association of amyotrophic lateral sclerosis and myasthenia gravis: A dysregulation of the adaptive immune system?

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