What Are the Stages of Muscular Dystrophy?

Symptoms of DMD usually appear between 2-5 years of age. The child lags in achieving their developmental milestones, which include walking, crawling, and talking, although they eventually catch up. In some cases, there may be a delay in reaching other developmental milestones such as speaking.

A child with DMD will have large calves and difficulty getting up from a sitting position, taking more time than other children of the same age. Climbing stairs also becomes a huge task for them. Between 6-9 years of age, the child may walk on their toes or have a wobbly, abnormal gait. They may seem awkward and clumsy and also get tired easily compared to their peers.

Signs of the late ambulatory stage appear during the late childhood or adolescence. As the disease progresses, muscle weakness and wasting (atrophy) start to affect the lower legs, forearms, neck, and trunk. Difficulty walking becomes more pronounced at this stage and is often accompanied by fatigue when walking long distances. 

The affected child or adolescent will not be able to maintain the same pace when walking as their healthy peers. They will need physical therapy treatment to help them with walking and other routine physical activities.

Leg braces may be needed by the time the affected child turns 8-9 years old to assist them in walking. By about the age of 10-12 years, most affected children require a wheelchair. Curvature of the spine may increase (scoliosis) because of the weakening of muscles in the trunk. Children with DMD have weak bones and may develop fractures of the hip and spine easily after falls. 

Most children with DMD manage to write or use a computer. However, many may display intellectual impairment and learning disabilities.

The nonambulatory stage is often seen during the teenage years, which worsens as the teen transitions to adulthood. In this stage, most affected teens experience difficulty using their hands and legs. They become dependent on power wheelchairs at all times.

Affected teenagers in their late teen years are also at high risk of developing complications, including weakness and deterioration of the heart muscle (cardiomyopathy). Cardiomyopathy decreases the ability of the heart to pump blood effectively to other organs of the body. It also causes a condition called arrhythmia, or irregular heartbeats. Muscle atrophy of the ribcage can lead to infections, such as pneumonia, as well as a life-threatening complication called respiratory failure.