Ann Clin Neurophysiol.  2021 Apr;23(1):53-55. 10.14253/acn.2021.23.1.53.

Familial congenital myopathy with prominent decremental responses in repetitive nerve stimulation testing

• Kim D
• Sunwoo IN
• Oh J

• KMID: 2515608
• DOI: http://doi.org/10.14253/acn.2021.23.1.53

Abstract

Congenital myasthenic syndromes (CMSs) are rare genetic disorders characterized by weakness and fatigue resulting from impaired neuromuscular transmission. Genetic testing can confirm the diagnosis for some types of CMS; however, variations in genotype, clinical phenotypes, age at disease onset, and responses to treatment make diagnosis very difficult. Here we present two adult patients who had significant decremental responses in repetitive nerve stimulation testing and multi-minicore pathology, and who responded to treatment with a cholinesterase inhibitor.

Keyword

Multi-minicore disease; Myasthenic syndrome, Myopathy; Nerve conduction

Figure

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  Fig. 1. Significant decremental response in the right trapezius muscle upon 3-Hz repetitive nerve stimulation testing (A). Hematoxylin-eosin staining of a biopsy specimen of the patient’s biceps muscle demonstrated fiber size variation, central nuclei, and increased connective tissues (B, ×100). Nicotinamide adenine dinucleotide staining revealed multiple focal areas lacking oxidative activity (arrows) (C, ×100), and electron microscopy revealed severe focal disorganization of the myofibrillar structures and streaming of the Z-band (D, ×10,000).

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