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Delayed Diagnosis of Congenital Myasthenic Syndromes Erroneously Interpreted as Mitochondrial Myopathies.
- Source :
-
Journal of clinical medicine [J Clin Med] 2023 May 06; Vol. 12 (9). Date of Electronic Publication: 2023 May 06. - Publication Year :
- 2023
-
Abstract
- Background: Congenital myasthenic syndromes (CMSs) and primary mitochondrial myopathies (PMMs) can present with ptosis, external ophthalmoplegia, and limb weakness.<br />Methods: Our method involved the description of three cases of CMS that were initially characterized as probable PMM.<br />Results: All patients were male and presented with ptosis and/or external ophthalmoplegia at birth, with proximal muscle weakness and fatigue on physical exertion. After normal repetitive nerve stimulation (RNS) studies performed on facial muscles, a muscle biopsy (at a median age of 9) was performed to rule out congenital myopathies. In all three cases, the biopsy findings (COX-negative fibers or respiratory chain defects) pointed to PMM. They were referred to our neuromuscular unit in adulthood to establish a genetic diagnosis. However, at this time, fatigability was evident in the physical exams and RNS in the spinal accessory nerve showed a decremental response in all cases. Targeted genetic studies revealed pathogenic variants in the MUSK , DOK7 , and RAPSN genes. The median diagnostic delay was 29 years. Treatment resulted in functional improvement in all cases.<br />Conclusions: Early identification of CMS is essential as medical treatment can provide clear benefits. Its diagnosis can be challenging due to phenotypic overlap with other debilitating disorders. Thus, a high index of suspicion is necessary to guide the diagnostic strategy.
Details
- Language :
- English
- ISSN :
- 2077-0383
- Volume :
- 12
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Journal of clinical medicine
- Publication Type :
- Academic Journal
- Accession number :
- 37176748
- Full Text :
- https://doi.org/10.3390/jcm12093308