Muscular Dystrophies PDF

Muscular Dystrophies Dr : Ola alnadhari Case senario  Parents worry about their 4-year-old son’s ability to walk. He began walking at 16 months, but he was clumsy and fell frequently; they were reassured by another pediatrician that he would “outgrow it.” He remains clumsier than h...

Muscular Dystrophies Dr : Ola alnadhari Case senario  Parents worry about their 4-year-old son’s ability to walk. He began walking at 16 months, but he was clumsy and fell frequently; they were reassured by another pediatrician that he would “outgrow it.” He remains clumsier than his peers, falls during simple tasks, and has developed a “waddling” gait. Within the last month he has experienced increasing difficulty arising from a sitting position on the floor.  What is the most likely diagnosis?  What is the diagnostic test of choice?  What is the mechanism of disease? Def.  The term dystrophy means abnormal growth, derived from the Greek trophe,meaning nourishment  A muscular dystrophy is distinguished from all other neuromuscular diseases by four obligatory criteria:  It is a primary myopathy  It has a genetic basis  The course is progressive  Degeneration and death of muscle fibers occur at some stage in the disease. Duchenne and Becker Muscular Dystrophies Duchenne muscular dystrophy  (DMD) is the most common hereditary neuromuscular disease affecting all races and ethnic groups  The incidence is 1 in 3,600 liveborn infant boys.  This disease is inherited as an X-linked recessive trait. The abnormal gene is at the Xp21 locus and is one of the largest genes  There is reduced muscle content of the structural protein dystrophin. In DMD, the dystrophin content is 0% to 5% of normal Clinical picture  Infant boys with DMD are rarely symptomatic at birth or in early infancy,although some are mildly hypotonic.  Early gross motor skills, such as rolling over, sitting, and standing, are usually achieved at the appropriate ages or may be mildly delayed.  Walking is often accomplished at the normal age of approximately 12 mo, but hip girdle weakness may be seen in a subtle form as early as the 2ndyr. follow  First sign may be poor head control in infancy.  By year 2, may have subtle findings of hip-girdle weakness  Gower sign as early as age 3 years but fully developed by age 5–6 years; with hipwaddle gait and lordotic posturing  Calf pseudohypertrophy (fat and collagen) and wasting of thigh muscles  Most walk without orthotic devices until age 7–10 years, then with devices until 12; once wheelchair- bound, significant acceleration of scoliosis  Rare presentation is by malignant hyperthermia after anesthesia. following into second decade:  Respiratory insufficiency  Repeated pulmonary infections  Pharyngeal weakness (aspiration)  Contractures  Scoliosis (further pulmonary compromise)  Cardiomyopathy is a constant feature.  Intellectual impairment in all; IQ