Types
Duchene
Becker
Myotonic
Spinal Muscular Atrophy
Juvenile Dermatomyositis
Guillian Barre
Becker Muscular Dystrophy
Similar to Duchene but milder
- mild proximal muscle weakness
- calf hypertrophy
Myotonic Dystrophy
Most common form of adult muscular dystrophy
Inheritance
AD
- chronic
- slowly progressive
- highly variable
- often associated with intellectual impairment
Clinical Features
Gradual onset of muscle weakness
- myotonia - difficulty grasp release
- expressionless face - typical
Check mother's grip
- difficulty with grasp release
Variable expression
- muscle weakness
- talipes, pes cavus and scoliosis
- dysphagia and constipation
- drop foot, high stepping gait
High anaesthetic risk
Investigation
CK Normal
EMG - pathognomonic pattern
DNA analysis
Spinal Muscular Atrophy
Anterior horn cell degeneration
Types
Type 1
- die soon after birth from resp failure
Type 2
- normal until 6 months
- never learn to walk independently
Type 3
- milder
- normal milestones for first year
- present similar to Duchene
- flat footed (compared with Duchenne which tip toe walk)
- reflexes are depressed
Signs
Proximal > distal weakness
- suppressed reflexes
- extremely floppy
Develop
- respiratory compromise
- scoliosis
- flexion contractures
Investigations
CK Normal
DNA testing
Juvenile Dermatomyositis
Onset insidious age 2 onward
- miserable weak child
- butterfly facial rash
- toe walk
- violaceous rash
Management
Steroids and immunosuppressives
Guillain Barre
Demyelinating polyneuropathy
- common in childhood
- may be life-threatening
20% present with waddling gait like Duchene
- most present with distal > proximal weakness
- minimal sensory findings
Management
Immunoglobulin