Parkinson’s Disease vs. Parkinsonism: Understanding the difference is essential for ICD-10 code assignment

March 25th, 2019 / By Pamela Ewing, CPC

What is Parkinson’s disease? It is a neurodegenerative disorder that affects predominately dopamine-producing (“dopaminergic”) neurons in a specific area of the brain called the substantia nigra.

The substantia nigra cells produce dopamine, a chemical messenger responsible for transmitting signals within the brain that allow for coordination of movement. Loss of dopamine causes neurons to fire without normal control, leaving patients less able to direct or control their movement. Parkinson’s disease is one of several diseases categorized by clinicians as movement disorders.

Parkinson’s disease has four main symptoms:

  • Tremor (trembling) in hands, arms, legs, jaw, or head
  • Stiffness of the limbs and trunk
  • Slowness of movement
  • Impaired balance and coordination

Parkinsonism refers to symptoms of Parkinson’s disease (e.g., dementia, slow movements and tremors), regardless of the cause, and is typically caused by another condition or external agent, such as drugs. These two conditions are not classified the same.

With the Parkinson’s Disease progression listed are just a few of many symptoms. Some symptoms may include, but are not limited to:

Here is where it may seem confusing. We need a code assignment for a patient diagnosed with Parkinson disease with dementia. Let’s look at the path:

In the ICD-10-CM Alphabetic Index, go to – Disease, diseased – see also Syndrome –

Disease, Parkinson:
Disease, Parkinson
pancreas K86.9
cystic K86.2
fibrocystic E84.9
specified NEC K86.89
panvalvular I08.9
specified NEC I08.8
parametrium(noninflammatory) N83.9
parasitic B89
cerebral NEC B71.9 [G94]
intestinal NOS B82.9
mouth B37.0
skin NOS B88.9
specified type- see Infestation
tongue B37.0
parathyroid(gland) E21.5
specified NEC E21.4
Parkinson’s G20

We then look in the Alpha index for Parkinson’s and it refers us to Parkinsonism.

Parkinsonism(idiopathic) (primary) G20
with neurogenic orthostatic hypotension(symptomatic) G90.3
arteriosclerotic G21.4
dementia G31.83 [F02.80]
with behavioral disturbance G31.83 [F02.81]

You will see Parkinsonism dementia listed with the codes G31.83 and F02.80. F02.80 appears in brackets, which indicates this code would be assigned also, but as a secondary code.Codes F02.80 and F02.81 represent the manifestation of dementia in diseases classified elsewhere, with or without behavioral disturbance.

Be alert and note: Type 1 Excludes note for “Dementia with Parkinsonism (G31.83) and Refers to a (AHA) Coding Clinic about this in the 2nd Quarter 2017.

G20 would be used to indicate Parkinson’s Disease, and it would be sequenced first, followed by the manifestation(s).

F03.80 manifestation of dementia in diseases classified elsewhere.

Parkinson’s disease is a chronic, degenerative neurological disorder with a many associated signs and symptom that to date affect more than 10 million people world-wide.  For coders to capture all associated ICD-10-CM codes, we need clear documentation of the symptoms related to the stage and progression for the patient with Parkinson’s  disease.

Pamela Ewing, CPC, CLA, is a coding analyst for 3M Health Information Systems.


Resource materials

NIH National Institute on Aging
AMA Coding Clinic