What are the signs and symptoms of congenital muscular dystrophy (CMD)?

Updated: Jul 03, 2019
  • Author: Emad R Noor, MBChB; Chief Editor: Amy Kao, MD  more...
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Answer

Congenital muscular dystrophy manifests at birth or within the first 2 years of life. The typical presentation is congenital hypotonia, delayed motor skills, and slowly progressive muscle weakness. Phenotypic expression varies greatly among patients, such as with the distribution of hypotonia and weakness. Some patients have predominant axial hypotonia with head lag and later spine rigidity, as in selenoprotein 1; SEPN1-related and lamin A/C (LMNA)-related congenital muscular dystrophies, while patients with generalized hypotonia/weakness and contractures, with or without joint laxity, are likely to have collagen-related congenital muscular dystrophies.

CNS involvement and MRI findings are key in the differential diagnosis of congenital muscular dystrophy. Patients can present with mild to severe cognitive impairment and learning disabilities. Seizures occur in patients with MDC1A at a frequency of 8% to 20%. [53]  Brain MRI findings include white matter changes (T2 hyperintensity) and cortical dysplasia in α-dystroglycanopathy congenital muscular dystrophy. Ophthalmic abnormalities, including visual impairment and retinal abnormalities, are often present in α-dystroglycanopathy congenital muscular dystrophy. Cardiomyopathy can be seen in late stages but is usually limited to a few types of congenital muscular dystrophy including fukutin, fukutin-related protein (FKRP), protein-O-mannosyltransferase 1 (POMT1)-related congenital muscular dystrophies or limb-girdle muscular dystrophy, and LMNA-related congenital muscular dystrophy. In a study of 115 patients with α-dystroglycanopathy congenital muscular dystrophy in Italy, only seven were found to have abnormal cardiac function: [54] five with dilated cardiomyopathy, one with a cardiac conduction defect, and one with mitral regurgitation. Sudden cardiac death was reported almost exclusively in LMNA-related congenital muscular dystrophy.    

Respiratory failure can be an early symptom after birth, requiring ventilation. Otherwise, restrictive lung disease, nocturnal hypoventilation, and respiratory failure may not be evident until more advanced stages of disease. In the same Italian study, 14 patients out of 115 with α-dystroglycanopathy congenital muscular dystrophy had abnormal respiratory function. Ten of the 14 required nocturnal noninvasive ventilatory support (NIV), while the others required invasive ventilation. In a case series of patients with SEPN1-related congenital muscular dystrophy, respiratory function data were collected from 41 patients between 1 and 60 years old. The need for nocturnal NIV increased with age. At the age of 15 years, 50% of the patients required a ventilator, with an increase to 75% at the age of 20 years. Sleep studies were found to be abnormal at a mean age of 13.2 years, anticipating the need for nocturnal NIV, which became necessary in 66% of patients during the second decade of life. [55]


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