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Learn to Code: Parkinson’s Disease

AHA Central Office

ICD-10-CM; Parkinson's; Parkinson's Disease; Parkinsonism; awareness; medical coding

Senior woman sitting on couch with care worker and both are smiling

2 min read

Did you know? April is Parkinson’s Awareness Month! Read more to learn about Parkinson’s Disease, its symptoms, and how it is classified in ICD-10-CM.

Parkinson’s Disease is named after James Parkinson, who first identified symptoms of the disease more than 200 years ago. (James Parkinson was born in April, which is why this month was selected.) Parkinson’s Disease is a progressive disorder of the nervous system, and it affects movement. Tremors are a well-known sign of the disease, but there may also be involuntary, seemingly purposeful, jerky movements of parts of the body, such as in the face, arms, legs, and trunk. Another symptom is dyskinesia, which is fidgeting or writhing of the entire body.  

There are also nonmotor symptoms of Parkinson’s disease. These include depression, anxiety, hallucination, sleep disruptions, apathy, and cognitive changes.  

It is important to note that while there are treatments available today that can lessen some symptoms of Parkinson’s disease, the effectiveness of treatments decreases as the disease progresses. The dopamine replacement agent levodopa is commonly used by clinicians to treat both motor and nonmotor symptoms of the condition. When medications are effective, patients experience periods of improvement in both motor and nonmotor symptoms. These periods are called “on.” “Off” periods are when symptoms reappear or worsen as the response to medication wanes. Parkinsonism refers to symptoms that are characteristic of Parkinson’s disease, such as slow movements and tremors, regardless of the cause. Parkinsonism is typically caused by another condition or external agent, such as drugs.

When coding Parkinson’s disease, it is assigned to category G20. Codes are provided for whether the condition includes dyskinesia or is without dyskinesia. The fifth character describes whether the condition involves “off” episodes or is without fluctuations, or off, episodes. Code G20.C is for unspecified parkinsonism and includes primary parkinsonism.

If you would like to learn more about Parkinson’s disease, please visit the Parkinson’s Foundation[]. To learn more about coding this condition, please consult Chapter 17 of the ICD-10-CM and ICD-10-PCS Coding Handbook [/handbook].  


  1. National Institute of Neurological Disorders and Stroke. (2023, April). Parkinson’s Disease Awareness Month: NINDS Contributions to Research and Potential Treatments. U.S. Department of Health and Human Services, National Institute of Health.'s%20Disease%20Awareness,more%20than%20200%20years%20ago.  
  2. National Library of Medicine. (2023, April). Levodopa (L-Dopa). U.S. Department of Health and Human Services, National Institute of Health.,symptoms%20apparent%20in%20Parkinson%20disease.
  3. Leon-Chisen, N., Harper, D. M., Rapier, A., & Young-Charles, G. (2023). ICD-10-CM and ICD-10-PCS Coding Handbook With Answers (2024 rev. Ed.). Chapter 17, Parkinson’s Disease (pp. 213–214). American Hospital Association.