Muscle Diseases in Children: Weakness, Dystrophy

Muscle diseases (myopathies) cause weakness that comes from the muscle tissue itself: the nerves and brain are healthy, but the muscle fibers do not work properly or gradually break down. The most common group in children is the inherited muscular dystrophies; there are also congenital myopathies, metabolic myopathies and inflammatory muscle diseases (myositis). What they all share is muscle weakness, but in a child it often looks like "laziness," "clumsiness" or "walking late," so the diagnosis is delayed. In Duchenne muscular dystrophy, an average of 1.5–2.5 years has been reported between the parents' first concern and the diagnosis. Yet an early diagnosis gives the family time and gives the child access to treatment.

Early signs

Gowers' sign: when getting up from the floor, the child first pushes up on the knees and then on the thighs, "climbing up their own body"
Holding on to the rail and climbing stairs one step at a time; falling behind peers when running; frequent falls
Waddling gait (swaying from side to side), walking on tiptoes, an increased curve in the lower back
Unusually enlarged calf muscles (pseudohypertrophy), a typical sign of Duchenne dystrophy
In a baby, excessive floppiness ("floppy baby"), weak sucking, late head control
Fatigue, muscle pain after exercise, sometimes brown urine (in metabolic myopathies)
Drooping eyelids, weak facial muscles (in some congenital myopathies)
Weakness together with a skin rash: purplish discoloration on the eyelids, a rash over the knuckles (juvenile dermatomyositis)

Main conditions

Duchenne and Becker muscular dystrophy

Passed on through the X chromosome, so it occurs almost only in boys. Duchenne dystrophy is the most common childhood dystrophy: according to a meta-analysis, about 20 of every 100,000 male births (1 in 5,000). Signs usually begin at ages 2–5: late walking, Gowers' sign, a waddling gait, enlarged calves. Becker dystrophy is a milder variant involving the same gene and begins later. The diagnosis is made by a sharply elevated creatine kinase (CK) level in the blood and by genetic testing; a muscle biopsy is rarely needed today.

Congenital myopathies and dystrophies

Floppiness visible from birth or the first months, weak sucking, breathing difficulty, delayed motor milestones. Many are identified genetically; the course depends on the type, and in many the weakness stays stable for years.

Metabolic myopathies

A disorder of the muscle's energy metabolism: pain, stiffness and weakness after physical exertion, and sometimes muscle protein in the urine. Because the symptoms come in episodes, they are often missed.

Inflammatory muscle diseases

Juvenile dermatomyositis is the most common inflammatory myopathy of childhood: gradually increasing symmetric weakness (trouble with stairs, combing hair), fatigue and a characteristic skin rash. According to international consensus recommendations, early recognition and immune treatment significantly improve the outcome; treatment is carried out together with a pediatric rheumatologist.

Evaluation plan

History and exam: the distribution of weakness (hips and shoulders, or hands and feet), its course, similar cases in the family, gait, getting up from the floor, calves, skin, joints.
Creatine kinase (CK): the first and most important test. In Duchenne dystrophy the level is many times above normal; checking CK in a boy who walks late or seems "clumsy" can bring the diagnosis forward by years.
Genetic testing: confirms the diagnosis in many dystrophies and myopathies and can replace a biopsy.
EMG/nerve conduction studies: distinguishes weakness that comes from muscle from weakness that comes from nerve.
Muscle MRI, biopsy: in selected cases.
Heart and breathing: ECG, echocardiography and lung function tests are part of the planned follow-up in dystrophies.

Treatment and follow-up

In Duchenne dystrophy, international recommendations call for corticosteroid treatment, which preserves muscle strength and the ability to walk for longer. Alongside this, physical therapy, stretching exercises and night splints, heart treatment, breathing support, bone health and nutrition are managed by a multidisciplinary team. For certain genetic variants, new molecular treatments are available, and eligibility is determined by the genetic result. In juvenile dermatomyositis, steroids and immune treatment are central, and in metabolic myopathies, nutrition and an activity plan. The neurologist makes the diagnosis, coordinates the team and regularly assesses your child's function using standard scales.

Frequently asked questions

My child is 18 months old and not walking yet. Could it be a muscle disease?

Late walking has many causes, but in boys a CK test is a simple and inexpensive check; if it is high, genetic testing follows. Developmental delay

Is walking on tiptoes always a sign of disease?

No. In a population study of 5-year-olds, toe walking was recorded in about 5% of children, and in more than half it went away on its own. But if toe walking comes with weakness, enlarged calves, frequent falls or increased muscle tone, muscle and nerve diseases should be ruled out.

Can muscle diseases be treated?

In many forms there is treatment that slows the course of the disease and preserves function, and for some genetic forms there are targeted drugs. The outcome depends on early diagnosis and consistent follow-up.

Can girls have Duchenne dystrophy?

Very rarely. But girls and women who are carriers may have mild muscle weakness and heart problems, so genetic counseling is important when there is Duchenne in the family.

The information on this page is for education only and does not replace an examination by a doctor. If you are worried about your child, book an appointment. In an emergency, call 103.

Muscle diseases in children