Spinal Muscular Atrophy

What is spinal muscular atrophy?

• Progressive degeneration of anterior horn cells

• Lower motor neuron disorder

• Often autosomal recessive

• Some forms associated with chromosome 5

What characterizes Type 1 SMA?

• Acute infantile SMA

• Werdnig-Hoffmann disease

• Begins in infancy

• Rapid progression

• Severe weakness

• Historically very poor survival without respiratory support

What characterizes Type 2 SMA?

• Chronic childhood SMA

• Onset later than Type 1

• Slower progression

• Weakness remains significant

• Survival into adulthood possible

What characterizes Type 3 SMA?

• Juvenile SMA

• Kugelberg-Welander type

• Later childhood onset

• Slower progression

• Often survives into adulthood

What clinical findings are common across SMA types?

• Progressive weakness

• Muscle atrophy

• Diminished/absent DTRs

• Sensation generally intact

• Intelligence generally normal

• Respiratory compromise may develop