Muscular Dystrophy Flashcards
What is muscular dystrophy?
Muscular dystrophy is an umbrella term for genetic conditions that cause gradual weakening and wasting of muscles.
The main muscular dystrophy to know about for the purpose of exams is Duchennes muscular dystrophy. It is worth being aware of the others.
Types of muscular dystrophy?
Duchennes muscular dystrophy Beckers muscular dystrophy Myotonic dystrophy Facioscapulohumeral muscular dystrophy Oculopharyngeal muscular dystrophy Limb-girdle muscular dystrophy Emery-Dreifuss muscular dystrophy
Gower’s sign?
Children with proximal muscle weakness use a specific technique to stand up from a lying position. This is called Gower’s sign.
To stand up, they get onto their hands and knees, then push their hips up and backwards like the “downward dog” yoga pose. They then shift their weight backwards and transfer their hands to their knees. Whilst keeping their legs mostly straight they walk their hands up their legs to get their upper body erect. This is because the muscles around the pelvis are not strong enough to get their upper body erect without the help of their arms.
TOM TIP: Gower’s sign is a favourite in exams. If there is a 5 year old boy presenting with vague symptoms of muscle weakness and the description is that you notice them using their hands on their legs to help them stand up, the answer is probably Duchennes muscular dystrophy. They may ask “what is the underlying genetic inheritance of the most likely cause?” The answer is X-linked recessive.
Management of muscular dystrophy?
There is no curative treatment for muscular dystrophy. Management is aimed at allowing the person to have the highest quality of life for the longest time possible. This usually involves input from occupational therapy, physiotherapy and medical appliances (such as wheelchairs and braces) as well as surgical and medical management of complications such as spinal scoliosis and heart failure.
Duchennes muscular dystrophy pathophys? Genetics? Presentation? Prognosis? Treatment?
Duchennes muscular dystrophy is the most likely muscular dystrophy to turn up in your exams. It is caused by a defective gene for dystrophin on the X-chromosome. Dystrophin is a protein that helps hold muscles together at the cellular level. Given that boys have a single X-chromosome and girls have two, girls have a spare copy of the dystrophin gene. Female carriers of the condition do not usually notice any symptoms. This makes Duchennes muscular dystrophy an X-linked recessive condition. If a mother is a carrier (meaning she has one faulty gene) and she has a child, that child will have a 50% change of being a carrier if they female and 50% change of having the condition if they are male.
Boys with Duchennes present around 3 – 5 years with weakness in the muscles around their pelvis. The weakness tends to be progressive and eventually all muscles will be affected. They are usually wheelchair bound by the time they become a teenager. They have a life expectance of around 25 – 35 years with good management of the cardiac and respiratory complications.
Oral steroids have been shown to slow the progression of muscle weakness by as much as two years. Creatine supplementation can give a slight improvement in muscle strength. Genetic trials are ongoing.
