In the kNOW is covering an ICD-10-CM Index update related to Parkinson’s disease and Parkinsonism highlighted in the April 2026 coding updates. While these terms are often used interchangeably in everyday conversation, they represent different clinical concepts that coding professionals must understand in order to assign the correct diagnosis code.
Parkinsonism is an umbrella term used to describe a group of neurological conditions that produce symptoms affecting movement, such as tremors, rigidity, and slowed movement. Conditions that fall under Parkinsonism include drug-induced Parkinsonism, progressive supranuclear palsy, multiple system atrophy, dementia with Lewy bodies, vascular Parkinsonism, and corticobasal degeneration.
Parkinson’s disease, on the other hand, is a specific neurodegenerative disorder that progresses slowly over time. In addition to movement-related symptoms, individuals with Parkinson’s disease may also experience cognitive changes, depression, and other non-motor symptoms as the condition advances.
The April 2026 update revised the ICD-10-CM Index to help clarify this distinction. The index entry for Parkinson’s disease, syndrome, or tremor was deleted and replaced with guidance directing users to Parkinsonism or to Disease, Parkinson’s as appropriate.
Alphabetic Index Entry
Parkinsonism (idiopathic) (primary) G20.C
- due to
- - drugs NEC G21.19
- - - neuroleptic G21.11
- - Parkinson's disease -see Disease, Parkinson's
Parkinson's disease -see Disease, Parkinson's
Parkinson's syndrome or tremor -see Parkinsonism
This change reinforces the importance of carefully reviewing provider documentation to determine whether the diagnosis reflects Parkinson’s disease itself or another condition categorized under Parkinsonism.
Understanding these distinctions ensures accurate code assignment and supports more precise clinical data reporting.
Parkinsonism is an umbrella term used to describe a group of neurological conditions that produce symptoms affecting movement, such as tremors, rigidity, and slowed movement. Conditions that fall under Parkinsonism include drug-induced Parkinsonism, progressive supranuclear palsy, multiple system atrophy, dementia with Lewy bodies, vascular Parkinsonism, and corticobasal degeneration.
Parkinson’s disease, on the other hand, is a specific neurodegenerative disorder that progresses slowly over time. In addition to movement-related symptoms, individuals with Parkinson’s disease may also experience cognitive changes, depression, and other non-motor symptoms as the condition advances.
The April 2026 update revised the ICD-10-CM Index to help clarify this distinction. The index entry for Parkinson’s disease, syndrome, or tremor was deleted and replaced with guidance directing users to Parkinsonism or to Disease, Parkinson’s as appropriate.
Alphabetic Index Entry
Parkinsonism (idiopathic) (primary) G20.C
- due to
- - drugs NEC G21.19
- - - neuroleptic G21.11
- - Parkinson's disease -see Disease, Parkinson's
Parkinson's disease -see Disease, Parkinson's
Parkinson's syndrome or tremor -see Parkinsonism
This change reinforces the importance of carefully reviewing provider documentation to determine whether the diagnosis reflects Parkinson’s disease itself or another condition categorized under Parkinsonism.
Understanding these distinctions ensures accurate code assignment and supports more precise clinical data reporting.
Now you are In the kNOW!!
About the Author
Dianna Foley, RHIA, CCS, CDIP, CHPS, has 25 years of HIM experience. She earned her bachelor’s degree from the University of Cincinnati and holds RHIA, CHPS, CDIP, and CCS certifications from AHIMA. Dianna’s an AHIMA-approved ICD-10-CM/PCS trainer, an AHIMA-published author, a participant in AHIMA credential item writing and exam development, and served on the AHIMA Nominating Committee. Dianna has held various HIM positions and is now an independent coding consultant. She previously served as a program director for Medical Coding and HIT. She presents on coding topics at the national, state, and regional levels and serves as OHIMA’s Education Coordinator.
