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  • Motor neuron disease

  • 335.24 Primary lateral sclerosis

  • G12.2 Motor neuron disease


  • Motor neuron disease
  • Degenerative neurologic disorder of the upper motor neurons in the brain and spinal cord
  • First described by Dr. Jean-Martin Charcot
  • Progressive weakness in the voluntary muscles
  • Nerve cells degenerate causing weakness

Essentials of Diagnosis1

  • Progression of symptoms over 3 years without evidence of lower motor neuron dysfunction
  • Disease is progressive, but may persist for decades
  • Evidence of loss of function in the lower extremities (LEs) first, then progressing to the muscles of speech and swallowing, and then loss in the upper extremities (UEs)

General Considerations

  • Spontaneous onset for adults
  • Breathing may be affected in the later stages of the disease
  • Juvenile primary lateral sclerosis (JPLS) is linked to a mutation in the ALS2 gene


  • Onset 40 to 60 years-old; mean of 50 years-old
  • Juvenile primary lateral sclerosis (JPLS)

Signs and Symptoms

  • Antalgic gait
  • Dysarthria
  • Drooling, weakness of bulbar muscles
  • LE onset with spastic paraparesis
  • Later develop symptoms in the UEs and oropharyngeal muscles
  • Entirely upper motor neuron signs and symptoms
  • Sensation is spared
  • Hyperactive reflexes
  • Babinski sign
  • Painful muscle spasms

Functional Implications

  • Declining independence with bed mobility, transfers, ambulation
  • Declining balance in sitting and standing
  • Declining respiratory support for all daily and recreational activities
  • Increasing need for advanced adaptive equipment

Possible Contributing Causes

  • Sporadic, no know familial link for adults
  • Juvenile form linked to gene mutation: ALS2

Differential Diagnoses

  • Amyotrophic lateral sclerosis (ALS)
  • Henoch-Schönlein purpura (HSP)
  • Multiple sclerosis (MS)
  • Spondylosis
  • Meningioma
  • Familial spastic paraplegia
  • Tropical spastic paraparesis (TSP)
  • Cerebral palsy (CP)

Laboratory Tests

  • Blood tests to help rule out other diagnoses


Diagnostic Procedures

  • Electromyography (EMG) will show neuropathic changes
  • MRI may show slight atrophy of the motor cortices and Wallerian degeneration of the motor tracts


  • Benzodiazepines or dantrolene sodium for spasticity

Medical Procedures

  • To neurologist for confirmation of diagnosis and disease management
  • To respiratory therapist for breathing support and devices
  • To occupational therapist for ADL, UE splinting, and adaptive equipment
  • To ALS Association for support and services

  • Gait
  • Wheelchair (w/c) mobility
  • Depression
  • Balance
    • Static sit
    • Dynamic sit
    • Static stand
    • Dynamic stand
    • Moving base of support (BOS)
  • Muscle strength
  • Muscle recruitment
  • ...

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