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Condition/Disorder Synonym

  • Paralysis agitans

ICD-9-CM Code

  • 332.0 Paralysis agitans

ICD-10-CM Code

  • G20 Parkinsonism (idiopathic) (primary)

Preferred Practice Pattern1

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

Key Features


  • Progressive degenerative disorder of the central nervous system

  • Death of dopamine-producing cells in the substantia nigra

  • Named after English MD, James Parkinson

  • Parkinsonian syndromes (4 types)

    • Primary or idiopathic, no known cause

    • Secondary or acquired

    • Hereditary parkinsonism

    • Parkinson plus syndrome or multiple system degeneration

Essentials of Diagnosis

  • Core features include a tetrad of hypo- or bradykinesia, resting tremor, postural instability, and rigidity

  • Some people have a rigidity-dominant presentation; others have a dyskinesia-dominant presentation (predominantly those with onset at a young age)

  • Pathophysiology

General Considerations

  • Positive diagnosis of PD is made with a successful levodopa (l-dopa) trial


  • Onset generally between 45 to 70 years of age

  • More common in men

  • Impacts all ethnic groups and socioeconomic classes

  • Most cases are idiopathic; genetic variants exist, but are rare

Clinical Findings

Signs and Symptoms

  • Tremor: usually asymmetrical

  • Gait disturbance, usually described as “festinating”

  • Postural instability

  • Stooped posture

  • Stiffness/rigidity: begins on one side

  • Slowness of movement

  • Dizziness

  • Freezing of movement

  • Bradykinesia or hypokinesia

  • Muscle ache

  • Loss of dexterity

  • Mask-like facial expression

  • Micrographia (small, cramped handwriting)

  • Depression

  • Neuropsychiatric problems

  • Speech disturbance: decreased volume and pitch, as well as motoric loss

  • Dementia in the later stages of the disease

  • Loss of smell

  • Constipation

Functional Implications

  • Progressive loss of

    • Balance reactions

    • Ambulation ability and safety

    • Respiratory capacity to support activity

    • Interaction with home and community environments

Possible Contributing Causes

  • Unknown

  • Drug-induced parkinsonism (DIP)

Differential Diagnoses

  • Hemiparkinson-hemiatrophy syndrome

  • Progressive supranuclear palsy (PSP)

  • Basal ganglia tumors

  • Vascular pathology

  • Multiple system atrophy (MSA)

  • Lewy body disease

  • Corticobasal ganglionic degeneration (CBGD)

  • Encephalitis

  • Pseudobulbar palsy

  • Binswanger's disease

  • Normal-pressure hydrocephalus (NPH)

  • Multiple sclerosis (MS)

Means of Confirmation or Diagnosis

Laboratory Tests

  • Blood test to help rule out other disorders


  • Positron emission tomography (PET) scan

  • Magnetic resonance imaging (MRI) and Computed tomography (CT) usually normal

Diagnostic Procedures

  • Confirmation is made by a positive response to l-dopa trial in a patient with the tetrad of symptoms brady- or hypokinesia, resting tremor, postural changes and instability, cogwheel rigidity

Findings and Interpretation

  • PET scan would demonstrate decreased activity in the basal ganglia


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