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.
Types
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
Technique des by children with proximal muscle weakness to stand up from a lying position
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
Management
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)
Surgical and medical management of complications such as spinal scoliosis and heart failure.
Duchennes Muscular Dystrophy
Pathology
Inheritance
Presentation
PATHOLOGY
Caused by a defective gene for dystrophin on the X-chromosome
INHERITANCE
X-linked recessive
PRESENTATION
- Boys 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
- 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
- Gower’s Sign
MANAGEMENT
- 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.
Beckers Muscular Dystrophy
Similar to Duchenne’s except dystrophin gene less severely affected
Less predictable clinical course
Present around 8-12 years old
May be able to walk in adulthood with assistance
Myotonic Dystrophy
Clinical Features
Genetic Inheritance
CLINICAL FEATURES
Presents in adulthood
Progressive muscles weakness
Prolonged muscle contractions: difficulty letting go of handshake
Frontal balding
Bilateral Ptosis
Cataracts
Cardiomyopathy / arrhythmia
Metabolic Syndrome / Insulin resistance
INHERITANCE
Autosomal dominant inheritance of trinucleotide repeat disorder
Facioscapulohumeral Muscular Dystrophy
Presentation
presents in childhood with weakness around the face, progressing to the shoulders and arms
A classic initial symptom is sleeping with their eyes slightly open and weakness in pursing their lips
They are unable to blow their cheeks out without air leaking from their mouth.
Oculopharyngeal Muscular Dystrophy
Presentation
presents in late adulthood with weakness of the ocular muscles and pharynx
It typically presents with bilateral ptosis, restricted eye movement and swallowing problems.
Muscles around the limb girdles are also affected to varying degrees.
Limb-girdle Muscular Dystrophy
Presentation
presents in teenage years with progressive weakness around the limb girdles (hips and shoulders)
Emery-Dreifuss Muscular Dystrophy
Presentation
presents in childhood with contractures, most commonly in the elbows and ankles.
Contractures are shortening of muscles and tendons that restrict the range of movement in limbs.
Patients also suffer with progressive weakness and wasting of muscles, starting with the upper arms and lower legs.
