SMA and muscular dystrophy Flashcards
how is SMA inherited?
autosomal recessive
what part of the body is affected by SMA?
Spinal muscular atrophy affects the lower motor neurones in the spinal cord.
This means there will be lower motor neurone signs, such as fasciculations, reduced muscle bulk, reduced tone, reduced power and reduced or absent reflexes.
how many types of SMA are there?
4
what happens in type 1 sma?
SMA type 1 has an onset in the first few months of life, usually progressing to death within 2 years.
what happens in type 2 SMA?
as an onset within the first 18 months. Most never walk, but survive into adulthood.
what happens in type 3 SMA?
has an onset after the first year of life. Most walk without support, but subsequently loose that ability. Respiratory muscles are less affected and life expectancy is close to normal.
what happens in SMA type 4?
has an onset in the 20s. Most will retain the ability to walk short distances but require a wheelchair for mobility. Everyday tasks can lead to significant fatigue. Respiratory muscles and life expectancy are not affected.
how is SMA managed?
- no cure
- physiotherapy to support muscle strength
- NIV- for resp support
- type 1 may require trachyostomy
- PEG may be required for reduced swallow
what is muscular dystrophy?
an umbrella term for genetic conditions that cause gradual weakening and wasting of muscles.
what is the technique children with muscular dystrophy use to stand?
gowers sign
- like the downward dog yoga pose
which gene is responsible for duchene muscular dystrophy?
- dystrophin gene on the X chromosome
what is the inheritence pattern for duchene muscular dystrophy?
x linked recessive
how does duchene muscular dystrophy present and progress?
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.
how is duchene muscular dystrophy managed?
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
what are features of myotonic dystrophy?
Progressive muscle weakness
Prolonged muscle contractions
Cataracts
Cardiac arrhythmias
- may be unable to let go when shaking hands
