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PubMed This is a summary of 21 peer-reviewed journal articles Updated
Pediatrics

The Stages of DMD: What to Expect Over Time

At a Glance

Duchenne Muscular Dystrophy (DMD) typically progresses through four general stages: early ambulatory, late ambulatory, early non-ambulatory, and late non-ambulatory. Proactive treatments like daily corticosteroids and physical therapy can significantly delay these transitions and preserve mobility for years.

While every child’s experience with Duchenne Muscular Dystrophy (DMD) is unique, the condition typically follows a recognizable series of stages. Understanding these stages is not about predicting the future with certainty, but about knowing what to monitor so your care team can adjust treatments at the right time [1][2].

Modern interventions, particularly corticosteroids (like prednisone or deflazacort), have dramatically shifted these timelines, often delaying transitions by several years and keeping children in the “walking” stages much longer than in the past [3][4].

Stage 1: Early Ambulatory (Preschool to Early Childhood)

In this stage, your child is walking and active, but you may notice they are slightly slower or “clumsier” than their peers [5].

  • Physical Signs: Difficulty running or jumping, frequent falls, and the Gowers’ sign (using hands to “walk up” the legs to stand from the floor) [6].
  • Tracking Progress: Doctors often use the North Star Ambulatory Assessment (NSAA), a 17-item scale that scores activities like hopping and standing on one leg. A high score (near 34) is common in this stage [1][7].

Stage 2: Late Ambulatory (Late Childhood to Early Teens)

During this stage, walking becomes more effortful. This is often the stage where proactive equipment planning begins [8].

  • Physical Signs: Loss of the ability to jump or run. Climbing stairs becomes very difficult and eventually impossible without significant help [9].
  • Warning Signs: “Timed tests” become crucial here. If the time to stand from the floor or the 10-meter walk/run time significantly increases, it may signal a transition is approaching [10][11].
  • The Transition: Your child may begin using a manual or power wheelchair for long distances (like school trips) while still walking at home [12].

Stage 3: Early Non-Ambulatory (Teens)

This stage begins when your child can no longer walk independently and uses a power wheelchair for primary mobility [8].

  • Physical Focus: The focus of care shifts from leg strength to upper limb function (arms and hands) and protecting the heart and lungs [8][13].
  • Tracking Progress: Doctors use the Performance of the Upper Limb (PUL) scale to monitor how well your child can reach, lift objects, and use a computer or game controller [8].
  • Medical Milestone: Regular heart imaging (MRI or Echo) and lung function tests (PFTs) become even more frequent [14][15].

Stage 4: Late Non-Ambulatory (Late Teens and Beyond)

In this stage, preserving comfort, independence, and vital organ function is the priority.

  • Physical Signs: Strength in the upper arms may decline, but most individuals maintain finger and hand movement for a long time, allowing for continued use of technology [8].
  • Respiratory Support: This is typically when Non-Invasive Ventilation (NIV) (like a CPAP or BiPAP) is introduced, usually just at night, to help the breathing muscles rest [16][17].

How Treatments Shift the Timeline

It is important to remember that these stages are not fixed.

  • Steroids: Daily corticosteroids are the primary tool used to “stretch” the ambulatory phases. They can delay the loss of walking by 2–3 years or more [4][18].
  • Physical Therapy: Regular stretching and the use of nighttime leg braces (AFOs) help prevent contractures (joint tightening), which can help keep a child walking longer [19][20].
  • Avoid Fractures: A leg fracture is a major “red flag” in DMD. Because muscles weaken when not in use, a child who has to stay in bed for a fracture may never regain the strength to walk again [21]. Proactive bone health is a key part of every stage.

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Common questions in this guide

What happens in the early ambulatory stage of DMD?
In the early ambulatory stage, a child is walking and active but may be slower or clumsier than their peers. They might also show the Gowers' sign, which involves using their hands to walk up their legs to stand from the floor.
How do doctors track my child's physical progress with DMD?
Doctors use standardized assessments like the North Star Ambulatory Assessment (NSAA) and timed tests, such as the 10-meter walk, to track leg strength. Once a child stops walking, they use the Performance of the Upper Limb (PUL) scale to monitor arm and hand function.
Can treatments slow down the progression of DMD stages?
Yes, daily corticosteroids are primary tools used to prolong the ambulatory phases of DMD. They can often delay the loss of independent walking by two to three years or more.
What changes during the non-ambulatory stages of DMD?
During the non-ambulatory stages, a child transitions to using a power wheelchair for primary mobility. Medical care shifts toward preserving arm function, protecting heart health, and providing breathing support, often through nighttime ventilation.
Why is it so important to prevent leg fractures in children with DMD?
A leg fracture often requires bed rest, which causes rapid muscle weakening. Because DMD makes it difficult to rebuild muscle mass, a child who stays in bed for a fracture may permanently lose the ability to walk.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my child's current NSAA (North Star Ambulatory Assessment) score, and how has it changed since our last visit?
  2. 2.Is my child's 'time to stand' or '10-meter walk' time still in the stable range, or are we seeing a decline that suggests a stage transition?
  3. 3.Are there specific exercises or stretches we should focus on to delay the loss of stair climbing?
  4. 4.If we transition to the late ambulatory stage, how will our medication or physical therapy goals change?
  5. 5.What are the specific 'red flags' I should watch for that might signal a transition to the non-ambulatory stage?

Questions For You

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References

References (21)
  1. 1

    Categorising trajectories and individual item changes of the North Star Ambulatory Assessment in patients with Duchenne muscular dystrophy.

    Muntoni F, Domingos J, Manzur AY, et al.

    PloS one 2019; (14(9)):e0221097 doi:10.1371/journal.pone.0221097.

    PMID: 31479456
  2. 2

    Advances in Duchenne Muscular Dystrophy: Diagnostic Techniques and Dystrophin Domain Insights.

    Sarvutiene J, Ramanavicius A, Ramanavicius S, Prentice U

    International journal of molecular sciences 2025; (26(8)) doi:10.3390/ijms26083579.

    PMID: 40332074
  3. 3

    Comparing Deflazacort and Prednisone in Duchenne Muscular Dystrophy.

    Biggar WD, Skalsky A, McDonald CM

    Journal of neuromuscular diseases 2022; (9(4)):463-476 doi:10.3233/JND-210776.

    PMID: 35723111
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    Clinical Outcomes in Duchenne Muscular Dystrophy: A Study of 5345 Patients from the TREAT-NMD DMD Global Database.

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    Journal of neuromuscular diseases 2017; (4(4)):293-306 doi:10.3233/JND-170280.

    PMID: 29125504
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    Peak functional ability and age at loss of ambulation in Duchenne muscular dystrophy.

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    PMID: 35385138
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    Duchenne muscular dystrophy.

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    Revised North Star Ambulatory Assessment for Young Boys with Duchenne Muscular Dystrophy.

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    Longitudinal Analysis of PUL 2.0 Domains in Ambulant and Non-Ambulant Duchenne Muscular Dystrophy Patients: How do they Change in Relation to Functional Ability?

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    Journal of neuromuscular diseases 2023; (10(4)):567-574 doi:10.3233/JND-221556.

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    Deflazacort vs prednisone treatment for Duchenne muscular dystrophy: A meta-analysis of disease progression rates in recent multicenter clinical trials.

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    Quantitative Muscle Ultrasound: A Non-Invasive Biomarker for Monitoring Duchenne Muscular Dystrophy.

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    Multicenter prospective longitudinal study of magnetic resonance biomarkers in a large duchenne muscular dystrophy cohort.

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    Paving the way for future gene therapies: A case study of scientific spillover from delandistrogene moxeparvovec.

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    Evolution of respiratory function in Duchenne muscular dystrophy from childhood to adulthood.

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    PMID: 29437939
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    Cardiac treatment for Duchenne muscular dystrophy: consensus recommendations from the ACTION muscular dystrophy committee.

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    Respiratory Function and Sleep Disordered Breathing in Pediatric Duchenne Muscular Dystrophy.

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    Case Report: Home initiation of nocturnal non-invasive ventilation in two adolescents with Duchenne muscular dystrophy and comorbid autism spectrum disorder and ADHD.

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    Impact of Noninvasive Ventilation on Lung Volumes and Maximum Respiratory Pressures in Duchenne Muscular Dystrophy.

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This page explains the general stages of Duchenne Muscular Dystrophy for educational purposes. Your child's care team is the best source for tracking their specific progression and individual treatment needs.

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