From the Guidelines
Duchenne Muscular Dystrophy (DMD) does not typically present with hypotonia, but rather with progressive muscle weakness and stiffness due to the absence of dystrophin protein. The disease is characterized by delayed motor milestones, difficulty rising from the floor (Gowers' sign), enlarged calf muscles (pseudohypertrophy), and a waddling gait 1. As the disease progresses, muscles become weaker but remain stiff rather than floppy, distinguishing DMD from conditions that cause true hypotonia.
Key Characteristics of DMD
- Progressive muscle weakness and muscle wasting
- Delayed motor milestones
- Difficulty rising from the floor (Gowers' sign)
- Enlarged calf muscles (pseudohypertrophy)
- Waddling gait
- Muscle stiffness rather than hypotonia
The underlying pathophysiology involves the absence of dystrophin causing muscle fiber damage during contraction, leading to inflammation, fibrosis, and eventual replacement of muscle with fat and connective tissue, resulting in the characteristic muscle stiffness rather than hypotonia 1.
Clinical Implications
- Respiratory complications are a major cause of morbidity and mortality in DMD
- Cardiac involvement can impact respiratory function and vice versa
- Early introduction of cardiac medication and corticosteroids can delay the onset and/or slow progression of cardiomyopathy and respiratory decline in DMD 1
- Maintaining respiratory health is vital to prolonging survival and quality of life in DMD
In summary, DMD is characterized by progressive muscle weakness and stiffness, rather than hypotonia, and requires early intervention and management to delay disease progression and improve quality of life.
From the Research
Presentation of Duchenne Muscular Dystrophy (DMD)
- DMD is a progressive neuromuscular disorder characterized by muscle weakness and degeneration 2, 3.
- The primary manifestations of DMD include progressive muscle weakness, which can lead to various secondary complications such as respiratory, cardiac, and orthopedic issues 2, 4.
- However, the provided studies do not specifically mention hypotonia as a presenting feature of DMD.
Clinical Management of DMD
- The management of DMD requires a multidisciplinary approach, including respiratory, cardiology, orthopedic, and nutritional care 2, 4.
- Corticosteroid therapy is a common treatment option for DMD, and several other therapeutic options have been recently approved for use 5.
- Despite the availability of various treatment options, there is no mention of hypotonia as a characteristic of DMD in the provided studies.
Diagnosis and Treatment of DMD
- DMD is characterized by a progressive muscular weakness manifesting in early childhood, with subsequent appearance of musculoskeletal, respiratory, and cardiac complications 4.
- The diagnosis and treatment of DMD involve a multidisciplinary approach, with a focus on symptomatic treatment and support 4, 6.
- However, the studies do not provide evidence to suggest that hypotonia is a typical presentation of DMD.