Upper-extremity involvement in Duchenne muscular dystrophy typically lags behind lower-extremity involvement by how many years?

• A. 1-2 years
• B. 2-3 years
• C. 3-4 years
• D. 4-5 years

Answer: (B)

In Duchenne muscular dystrophy, weakness typically begins in the proximal muscles of the lower limbs (hips and thighs) and then progresses to the shoulder girdle and upper limbs, but after a delay. The upper-extremity muscles tend to become involved a couple of years after the lower-extremity weakness starts. Clinically, this two- to three-year gap helps explain why a child may walk for several years with declining leg function before noticeable weakness appears in the arms. This pattern guides rehab planning, anticipating declines in gait first and then in activities requiring shoulder and arm strength, while recognizing that there is individual variability.