Muscular atrophy, spinal

• Bulbospinal muscular atrophy
• Hereditary neuronopathy
• Progressive muscular atrophy1
• Werdnig-Hoffman disease

• 335.0 Werdnig-Hoffman disease
• 335.1 Spinal muscular atrophy
• 335.10 Spinal muscular atrophy unspecified
• 335.19 Other spinal muscular atrophy

• G12.0 Infantile spinal muscular atrophy, type I [Werdnig-Hoffman]
• G12.8 Other spinal muscular atrophy and related syndromes
• G12.9 Spinal muscular atrophy, unspecified

• Pattern 5E: Impaired Motor Function and Sensory Integrity Associated With Progressive Disorders of the Central Nervous System

Description

• Group of 4 subtypes of degeneration of anterior horn cells that results in progressive muscle atrophy
  • Spinal muscular atrophy (SMA I), Werdnig-Hoffman (acute)
  • Spinal muscular atrophy (SMA II), Werdnig-Hoffman (chronic)
  • Spinal muscular atrophy (SMA III), Kugelberg-Welander
  • Spinal muscular atrophy (SMA IV)

Essentials of Diagnosis

• Autosomal recessive genetic disorder that results in a lack of survival motor neuron gene1 on chromosome 5q11.2-133

General Considerations

• SMA type I: weakness between birth and 3 months of age
• SMA type II: signs and symptoms by 3 years of age
• SMA type III: signs and symptoms between 2 to 9 years of age
• SMA type IV: adult onset

Demographics3

• Type I: 27% of all SMA cases
• Types II and III: 46% of all SMA cases
• Type IV: 8% of all SMA cases
• Werdnig-Hoffman 1:10,000 births
• Kugelberg-Welander 6:100,000 births

Signs and Symptoms

• Fasciculations (especially of tongue)
• Muscle weakness
• Hypotonia
• Muscle atrophy
• Decreased or absent deep tendon reflexes
• Difficulty feeding (infant)
• Lack of extension during Landau reflex
• Contractures (type 1)
• Scoliosis
• Trendelenburg sign during gait

Functional Implications

• Inability to sit independently
• Inability to ambulate
• Require assistance with all activities of daily living

Possible Contributing Causes

• Autosomal recessive genetic disorder on chromosome 5q11.2-133

Differential Diagnosis

• Muscular dystrophy
• Guillain-Barré
• Brachial plexus birth injury
• Other genetic syndromes

Laboratory Tests

• Genetic testing

Imaging

• Plain radiograph for scoliosis

Diagnostic Procedures

• Electromyography (EMG)
• Muscle biopsy

Medication

• Hydroxyurea
• Valproic acid

• Geneticist
• Occupational therapist

• Head lag when infant pulled into a sitting position from supine
• Poor head control
• Inability to sit
• Inability to pull to stand
• Inability to walk
• Contractures of biceps and wrist flexors

• Hammersmith functional motor scale for children3
• Dynamometer
• 2-minute walk test
• Manual muscle test
• Forced vital capacity

• It is important to avoid fatigue during intervention with patients who have SMA.
• Strengthening
• Stretching to prevent contractures especially of wrist flexors
• Developmental activities
  • Prone on elbows with assistance
  • Supported sitting
  • Supported ...