Duchenne Muscular Dystrophy Management
On this page
Direct answer
Corticosteroids are the standard of care in Duchenne muscular dystrophy: prednisolone 0.75 mg/kg per day or deflazacort 0.9 mg/kg per day, started once function plateaus — usually around four to six years — prolong independent ambulation by two to three years, delay scoliosis and preserve respiratory function. Management is surveillance on a fixed calendar: echo and ECG for cardiomyopathy from diagnosis, spirometry once ambulation is lost, bone health for steroid osteoporosis, and genetic confirmation naming the mutation — because mutation-specific therapy, exon-skipping agents for amenable deletions and ataluren for nonsense mutations, is part of the landscape even where Indian access is cost-constrained.
What you must remember
- Clinical anchors: X-linked recessive, onset of gait abnormality at two to five years, Gowers sign, calf pseudohypertrophy, waddling gait and a positive toe-walking habit; creatine kinase typically 10,000 to over 50,000 U/L.
- Genetics: frameshift deletions, duplications or point mutations of the DMD gene abolish dystrophin; multiplex PCR and MLPA detect deletions in about two thirds of cases, with sequencing resolving most of the rest — and the reading-frame rule separating Duchenne from the milder Becker phenotype.
- Steroid benefit beyond walking: preserved respiratory function, delayed scoliosis, reduced cardiac dysfunction — daily dosing in Indian practice usually means prednisolone, with deflazacort where its profile suits.
- Steroid adverse effects: weight gain, growth attenuation, behavioural change, cataract with deflazacort, glucose intolerance and osteoporosis — monitor weight, height, blood pressure, vision and bone health.
- Cardiac: cardiomyopathy is near-universal over time; ACE inhibitors or ARNI start early on echo evidence, with surveillance at least every one to two years — female carriers need it too.
- Respiratory: forced vital capacity declines after loss of ambulation; cough assist, non-invasive ventilation for nocturnal hypoventilation and vigilant infection management determine survival into the third decade and beyond.
- Newer therapy map: exon 51 skipping with eteplirsen and golodirsen or viltolarsen for exon 53, casimersen for exon 45; ataluren for nonsense mutations in Europe; gene-transfer trials ongoing — all mutation-stratified, hence the importance of complete gene analysis.
- Standards of care demand multidisciplinary review — neurology, cardiology, respiratory, orthopaedics, endocrine, genetics, rehabilitation — around a functional assessment such as North Star.
The surveillance calendar
Build the follow-up as a calendar, because that is how the exam and the clinic both run it. At diagnosis, around four to five years: confirm the mutation in writing with exon boundaries, since it gates every future therapy; baseline echo, ECG and a functional measure such as time to stand from the floor; teach the family the natural history so the coming years are a plan, not a series of shocks. Age four to six, as function plateaus: start the steroid with the dietitian and physiotherapist engaged from day one — weight control preserves the therapeutic window; begin calcium and vitamin D. Every visit: growth, blood pressure, weight trajectory, functional timing, and a Gowers video so progression is documented objectively. Every one to two years: echo and ECG, with low threshold for ACE inhibition when dysfunction appears — evidence supports early treatment before symptoms. Around loss of ambulation, typically the early teens: switch to respiratory surveillance — six-monthly spirometry, cough assessment, sleep studies for morning headaches, non-invasive ventilation for nocturnal hypoventilation — with scoliosis screening while surgery is still possible. Bone: vitamin D, bisphosphonates for vertebral fractures after steroid exposure. Late adolescence: transition to adult services, with carrier testing for sisters and genetic counselling — a recurring NEET-SS theme.
How the exam frames it
Three stem formats dominate. First, the steroid question: a boy of five with plateauing function — "best next step" is corticosteroid initiation, not physiotherapy alone or waiting for loss of ambulation. Second, the CK-versus-biopsy sequencing: the boy with a classic phenotype and massive CK gets MLPA-based deletion testing on blood, with biopsy only if negative — ordering a biopsy first is the planted error. Third, the system-complication item: the teenager with palpitations or breathlessness who needs the cardiac answer — early ACE inhibitor with echo follow-up; or the morning headache with low vital capacity — nocturnal hypoventilation needing non-invasive ventilation. The sister question — why test the mother and sisters — closes the loop on carrier risk and genetic counselling.
Frequently asked questions
What dose of prednisolone is standard in Duchenne?
0.75 mg/kg per day, or deflazacort 0.9 mg/kg per day, started when motor function plateaus, usually at four to six years.
Why is the exact DMD mutation required?
Because exon-skipping and nonsense-suppression therapies are mutation-specific, applicable only to deletions amenable to particular exons or to stop-codon disease.
Which cardiac intervention is started early?
An ACE inhibitor or ARNI once echo shows dysfunction, with echo and ECG surveillance from diagnosis — lifelong, and for carriers too.
What respiratory support is instituted after loss of ambulation?
Regular spirometry with cough assistance, and non-invasive ventilation for nocturnal hypoventilation detected on sleep studies.
What are the main steroid adverse effects to monitor?
Weight gain, growth attenuation, behavioural change, cataract with deflazacort, glucose intolerance and osteoporosis, with fracture-prevention vitamin D and calcium.