Duchenne Muscular Dystrophy Treatment: Signs of Slower Progression

For Duchenne muscular dystrophy (DMD), treatment may be helping even when strength and movement continue to decline. Current therapies can slow the condition’s progression, but they don’t stop or reverse it. That makes the most meaningful signs of benefit changes measured over months or years, rather than a clear improvement from one visit to the next.

DMD is a genetic condition that almost always affects males. A change in the gene for dystrophin prevents the body from making this protein, which helps keep muscle cells sturdy. Over time, muscle tissue breaks down and is replaced by scar tissue and fat. Jessie Nance, MD, a pediatric neurologist at Johns Hopkins Medicine, says care discussions need to consider both whether a treatment is helping and whether its side effects are manageable.

Walking can last longer, even as the condition progresses

Corticosteroids, often called steroids, are a standard treatment for DMD. They’re thought to reduce inflammation linked to damage in fragile muscle cells. Options include prednisone, deflazacort and vamorolone.

Starting daily steroids in early childhood, typically between ages 4 and 6, gives children an average of one or two additional years of walking ability, Nance says. Most people with DMD stop walking by about age 12, though the timing varies. The aim is to preserve walking longer than it might otherwise have lasted; treatment doesn’t prevent mobility challenges indefinitely.

That benefit can be hard to see in an individual child. There’s no way to know exactly how that child would have progressed without treatment, so a family may see continued decline without being able to observe the slower decline the medication may be providing.

Steroids can cause weight gain, behavioral changes, thinning bones, delayed puberty and shorter height. If side effects are difficult to manage, a clinician may consider changes to the dose, schedule or steroid type. Any change should be discussed with the treating clinician before it happens.

Repeated tests help reveal changes in function

Clinicians can compare movement and strength assessments over time. Two commonly used measures are the six-minute walk test, which records how far a person walks in six minutes, and the North Star ambulatory assessment, which scores performance on 17 movements.

A neuromuscular specialist may assess strength, function and flexibility about every six months. Using the same measures at each visit makes results easier to compare and can help the care team decide whether the treatment plan needs to change.

Newer treatments make the picture more complicated. Exon-skipping medicines—casimersen (Amondys 45), eteplirsen (Exondys 51), golodirsen (Vyondys 53) and viltolarsen (Viltepso)—are designed for people with particular genetic changes. The gene therapy delandistrogene moxeparvovec (Elevidys) and givinostat (Duvyzat), which reduces inflammation and muscle scarring, are other treatment options.

Exon-skipping medicines and gene therapy aim to help the body produce some dystrophin, though not a typical version of the protein. For some of these treatments, evidence of increased dystrophin in muscle samples helped support their use, even when studies hadn’t shown large differences in what participants could physically do. Nance describes a trend toward motor improvement but says it can be difficult to measure how much difference treatment makes in everyday life.

The studies that supported these newer treatments focused on walking and included participants who could still walk. More research is needed to understand whether they protect heart and breathing muscles, and whether they help people at later stages of DMD. A change in a muscle sample doesn’t by itself answer those questions.

Arm function remains important after walking stops

Losing the ability to walk doesn’t mean that other measures of treatment benefit no longer matter. Continuing steroids after walking stops may help preserve arm strength and function, slow scoliosis, and support heart and lung function, Nance says.

Arm function can shape daily independence, including the ability to write, eat with less help, use a computer, and brush hair and teeth. Clinicians can follow these abilities with the Performance of the Upper Limb assessment. For families and care teams, preserving upper-body function is a separate, meaningful part of tracking how someone is doing.

Breathing and heart health need regular checks

DMD also weakens the muscles used for breathing and the heart muscle. Heart muscle damage can lead to cardiomyopathy. These complications are among the condition’s most serious, and they may not be obvious from day-to-day activity alone.

Pulmonary function tests measure breathing capacity and should be done at least once a year, according to Nance. Between appointments, daytime tiredness, headaches on waking or frequent nighttime waking can sometimes signal breathing problems during sleep. These symptoms can have other explanations too, so they’re useful to raise with a clinician rather than interpret on their own. Steroids may slow weakening of the breathing muscles.

Heart assessments are also important because changes can begin before symptoms appear. Nance says a full evaluation with a heart specialist should start in early childhood, take place at least every other year until age 10, and usually happen every year thereafter. Medicines such as ACE inhibitors and beta blockers can slow heart muscle damage when started early.

There isn’t one visible sign that proves a DMD treatment is working. The clearest picture comes from comparing repeated assessments and keeping up with heart and breathing checks, while weighing benefits against side effects. Families can discuss those trends with the care team, including what each measure can—and can’t—show about the treatment’s effect.