Skip to Main Content

Condition/Disorder Synonyms

  • Motor neuron disease

ICD-9-CM Code

  • 335.24 Primary lateral sclerosis

ICD-10-CM Code

  • G12.2 Motor neuron disease

Preferred Practice Pattern

Key Features


  • 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)

Clinical Findings

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)

Means of Confirmation or Diagnosis

Laboratory Tests

  • Blood tests to help rule out other diagnoses


  • MRI

Diagnostic Procedures

  • Electromyography (EMG)

Findings and Interpretation

  • 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 ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.