Adult-onset nemaline myopathy
A rapidly progressive type of nemaline myopathy (NM) characterized by a very late onset.
The annual incidence of NM has been estimated at 1/50,000 live births. Adult-onset NM represents <5% of total cases.
Adult onset NM is usually sporadic and no familial history of neuromuscular diseases is found.
Signs and symptoms
- Adult onset NM occurs sporadically between 20 and 50 years of age.
- It presents with a generalized weakness, myalgia and rapid progression.
- Several cases have been associated with cardiomyopathy, dropped head syndrome and respiratory involvement.
- Muscle biopsy can reveal inflammatory changes.
- Monoclonal gammopathy and paresthesiae may be a marker of poor prognosis.
For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms
- EMG: myopathic abnormalities
- Nemaline bodies
30%-79% of people have these symptoms
- Bradykinesia(Slow movements)
- Increased muscle lipid content(Fat accumulation in muscle fibers)
- Increased variability in muscle fiber diameter
- Myalgia(Muscle ache)
- Neck flexor weakness(Neck flexion weakness)
- Type 1 muscle fiber predominance
- Upper limb muscle weakness(Decreased arm strength)
5%-29% of people have these symptoms
- Bulbar signs
- Difficulty walking(Difficulty in walking)
- Dilated cardiomyopathy(Stretched and thinned heart muscle)
- Feeding difficulties(Feeding problems)
- Flexion contracture(Flexed joint that cannot be straightened)
- High palate(Elevated palate)
- Hyporeflexia(Decreased reflex response)
- Long face(Elongation of face)
- Lower limb muscle weakness(Lower extremity weakness)
- Micrognathia(Little lower jaw)
- Muscle fibrillation
- Muscle stiffness
- Narrow face(Decreased breadth of face)
- Neuromuscular dysphagia
- Reduced vital capacity
- Respiratory insufficiency due to muscle weakness(Decreased lung function due to weak breathing muscles)
1%-4% of people have these symptoms
- Mildly elevated creatine kinase
NIH genetic and rare disease info
Adult-onset nemaline myopathy is a rare disease.