Delay in age of walking can herald muscular dystrophy in boys with cognitive delays

PUBLIC RELEASE DATE:

15-Sep-2014

Contact: Ekaterina Pesheva epeshev1@jhmi.edu 410-502-9433 Johns Hopkins Medicine @HopkinsMedNews

The timing of a toddler's first steps is an important developmental milestone, but a slight delay in walking is typically not a cause of concern by itself.

Now a duo of Johns Hopkins researchers has found that when walking and cognitive delays occur in concert, the combination could comprise the earliest of signals heralding a rare but devastating disorder known as Duchenne muscular dystrophy (DMD).

The study, published ahead of print in The Journal of Pediatrics and conducted by a medical student and a pediatric neurologist, reveals that delays in the onset of walking which should occur between 9 and 16 months of age are common among boys with DMD and often happen alongside cognitive delays. That combination, the investigators say, can give pediatricians a critical early diagnostic clue and tip them off to the presence of DMD.

"Our review of patient records shows that delayed walking along with cognitive delays represents an ominous combination that should prompt pediatricians to conduct further testing and could speed up diagnosis and treatment," says Kara Mirski, a fourth-year medical student at the Johns Hopkins University School of Medicine. "Earlier diagnosis means that we can start treating these kids sooner and greatly improve their long-term outcomes."

DMD is caused by a defective muscle protein. It is marked by progressive loss of muscle strength and function and, eventually, inability to walk at all. In its advanced forms, the condition can also compromise the function of the heart and breathing muscles. DMD, which almost exclusively affects males, is estimated to occur in one out of 3,500 boys.

Current guidelines from the American Academy of Neurology and the Child Neurology Society do not include DMD on the suspected diagnoses list for boys with developmental delays. While neither cognitive delays nor delayed walking by themselves are necessarily caused by DMD, when the two occur in tandem they should raise the index of suspicion and seriously narrow the range of diagnostic possibilities, the team says.

"The bottom line is that any delay in walking should lead to further probing, or at least vigilant monitoring, and when late walking occurs in the context of other developmental delays, it should put DMD on every pediatrician's radar as a possible cause," says study author Tom Crawford, M.D., a pediatric neurologist and muscular dystrophy expert at the Johns Hopkins Children's Center.

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Delay in age of walking can herald muscular dystrophy in boys with cognitive delays