In late stages of the disease, respiratory impairment and swallowing impairment can occur, which can result in pneumonia. A classic sign of DMD is trouble getting up from lying or sitting position, as manifested by a positive Gowerss sign. When a child tries to arise from lying on his stomach, he compensates for pelvic muscle weakness through use of the upper extremities: first by rising to stand on his arms and knees, and then "walking" his hands up his legs to stand upright. Another characteristic sign of DMD is pseudohypertrophy (enlarging) of the muscles of the tongue, calves, buttocks, and shoulders (around age 4 or 5). The muscle tissue is eventually replaced by fat and connective tissue, hence the term pseudohypertrophy. Muscle fiber deformities and muscle contractures of Achilles tendon and hamstrings can occur, which impair functionality because the muscle fibers shorten and fibrose in connective tissue. Skeletal deformities can occur, such as lumbar hyperlordosis, scoliosis, anterior pelvic tilt, and chest deformities. Lumbar hyperlordosis is thought to be compensatory mechanism in response to gluteal and quadriceps muscle weakness, all of which cause altered posture and gait (e.g. : restricted hip extension).Non musculoskeletal manifestations of DMD occur. There is a higher risk of neurobehavioral disorders (e.g., ADHD), learning disorders (dyslexia), and non-progressive weaknesses in specific cognitive skills (in particular short-term verbal memory), which are believed to be the result of absent or dysfunctional dystrophin in the brain.
Inactivity (such as bed rest) can worsen the muscle disease. Physical therapy is helpful to maintain muscle strength, flexibility, and function. Orthopedic appliances (such as braces and wheelchairs) may improve mobility and the ability for self-care. Form-fitting removable leg braces that hold the ankle in place during sleep can defer the onset of contractures. Appropriate respiratory support as the disease progresses is important. Cardiac problems may require a pacemaker.The medication eteplirsen, a Morpholino antisense oligo, has been approved in the United States for the treatment of mutations amenable to dystrophin exon 51 skipping. The US approval has been controversial as eteplirsen failed to establish a clinical benefit; it has been refused approval by the European Medicines Agency.The medication ataluren (Translarna) is approved use in the European Union.The antisense oligonucleotide golodirsen (Vyondys 53) was approved for medical use in the United States in 2019, for the treatment of cases that can benefit from skipping exon 53 of the dystrophin transcript.The Morpholino antisense oligonucleotide viltolarsen (Viltepso) was approved for medical use in the United States in August 2020, for the treatment of Duchenne muscular dystrophy (DMD) in people who have a confirmed mutation of the DMD gene that is amenable to exon 53 skipping. It is the second approved targeted treatment for people with this type of mutation in the United States.