Muscular Dystrophies

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