Difference Between Parkinsonism and Parkinson’s Disease (with ICD-10 Coding)

parkinsonism and Parkinson's disease with ICD-10-CM coding

Parkinsonism and Parkinson’s Disease

If a person has parkinsonism, does that mean he or she has Parkinson’s disease? Likewise, if a person has Parkinson’s disease, does that mean he or she has parkinsonism?

These are great questions! In this lesson, I’ll explain what these two terms mean, the difference between parkinsonism and Parkinson’s disease, and six of the most common types of atypical parkinsonism.

In addition, I’ll explain the ICD-10-CM coding guidelines and conventions and how to code for complications of Parkinson’s disease and parkinsonism.

My dear friend’s personal story related to Parkinson’s disease is also here to help you better understand the disease process. Bill was recently diagnosed with Parkinson’s.

Parkinsonism and Parkinson’s disease (PD) are two terms that can be confusing. According to the Parkinson’s Foundation, parkinsonism is a term used to describe a group of neurological conditions that present with motor symptoms that are also found in Parkinson’s disease. Parkinson’s disease is the most common form of parkinsonism.

Because the chief symptoms of Parkinson’s are also found in other types of parkinsonism, it can be difficult for a physician to make a definitive diagnosis in the beginning of the disease process. Parkinsonism can have several different causes that can be totally different from Parkinson’s disease.


Parkinsonism, also called atypical parkinsonism or Parkinson’s plus syndrome, is a general term used to describe the chief motor symptoms found in Parkinson’s disease. According to The Michael J. Fox Foundation, these symptoms include:

  • Tremors (involuntary shaking), mostly at rest, involving the hands, arms, legs, tongue, or jaw
  • Limb rigidity (stiffness or tightness in the arms or legs)
  • Bradykinesia (slow movement)

Approximately 10  to 15 percent of all medical cases that suggest a diagnosis of Parkinson’s disease is actually an atypical parkinsonism disorder, according to the Parkinson’s Foundation.

Atypical parkinsonism includes neurological disorders that are not only caused by cell loss in the substantia nigra, but these disorders are also caused by cell degeneration in the area of the nervous system that contains dopamine receptors. Atypical parkinsonism also includes additional signs and symptoms that are not generally present in cases of Parkinson’s; hence, the term, “Parkinson’s plus syndrome.”

Many people do not present with the cardinal symptoms necessary to make a diagnosis of a specific Parkinson’s plus syndrome. Therefore, “parkinsonism” will be the diagnosis given.

Parkinson’s plus syndromes are generally more difficult to treat than Parkinson’s disease, and their symptoms may progress more quickly than they do in Parkinson’s disease. Also, Parkinson’s plus syndromes respond minimally, if at all, to levodopa or other Parkinson’s medications.

Common Parkinson’s Plus Syndromes

There are several different Parkinson’s plus syndromes, but some have not yet been defined or named. However, the most common syndromes and their unique characteristics include:

Multiple system atrophy (MSA).  Also known as Shy-Drager syndrome (orthostatic hypotension with multisystem degeneration), MSA is a term made up of several neurodegenerative disorders which causes one or more body systems to stop working. This is the second most common form of atypical parkinsonism. 

Typical symptoms include:

  • unstable blood pressure
  • early sexual, bladder and bowel dysfunction
  • reddish-blue skin discoloration
  • sleep apnea and acting out of dreams
  • forward head tilt or body tilt while sitting
  • loss of coordination
  • quick-moving course that leads to the inability to walk within three to five years of onset

Diagnosing MSA is difficult because there is no specific test. Only the symptoms are treated, which does not include PD medications since they have little to no benefit.

Progressive supranuclear palsy (PSP). Also known as Progressive supranuclear ophthalmoplegia (Steele-Richardson-Olszewski), PSP is the most common form of atypical parkinsonism and is slightly more common than Lou Gehrig disease (ALS). 

Symptoms include:

  • balance problems with falls
  • Forgetfulness
  • vision problems (vertical gaze palsy)
  • changes in personality

Individuals with PSP often have a worried facial expression. Tremors are rare in PSP.

Diagnosis is made based on the clinical features, but there is no particular test that will definitively diagnose it. The focus of treatment is on the symptoms. Patients do not do well with PD medications, such as levodopa.

Corticobasal syndrome (CBS). Also known as corticobasal degeneration (CBD) and cortical basal ganglionic degeneration (CBGD), according to the Baylor College of Medicine. This is the rarest type of atypical parkinsonism that is characterized by cell loss and deterioration of particular areas of the brain.

Symptoms include:

  • stiffness in one side or the other
  • jerky and involuntary movements in the hand or leg
  • apraxia (inability to make purposeful movements)
  • abnormal posture and twisting

There is no specific test for CBS and no treatment available to slow the progression of CBS. Symptoms can be treated with physical, occupational, and speech therapy.

Dementia with Lewy bodies (DLB). This is the most common type of dementia in the elderly after Alzheimer’s. It causes a progression in intellectual and functional deterioration. Individuals can have early dementia prior to or at the same time as parkinsonism symptoms, as well as visual hallucinations which causes them to think they are seeing certain things.

DLB patients have the same abnormal protein in the brain that PD patients have. However, there are no specific treatments for DLB and no cure.

Drug-induced parkinsonism. This is usually a side-effect of a drug, such as antipsychotics, that affects the dopamine levels in the brain. The symptoms of tremors and postural instability are usually less severe than in Parkinson’s. Once the drug is stopped, the symptoms of parkinsonism tend to gradually disappear.

Vascular parkinsonism (VP). This is a common cause of atypical parkinsonism that is generally caused by a brain clot from multiple small strokes. The symptoms more often occur in the lower extremities and include gait and balance problems with falls.

An MRI (magnetic resonance imaging) of the brain can show evidence of vascular disease. Medications, such as levodopa, may be moderately effective depending on the location of the vascular disease in the brain.

Key Takeaway: Parkinsonism looks like Parkinson’s disease, at least in the beginning, but it is not necessarily Parkinson’s disease. The main motor symptoms of tremors, bradykinesia, and rigidity can be due to Parkinson’s disease or they may be due to another cause, such as a vascular disorder.

Parkinson’s Disease

When you think of Parkinson’s disease, actor Michael J. Fox or professional boxer Mohammed Ali may come to mind. Even actor and comedian Robin Williams, as he was in the early stages of Parkinson’s at the time of his death. Or you may know someone personally who is fighting Parkinson’s, as I do.

About a year ago, someone close to me, whom I will call Bill, started showing signs and symptoms of Parkinson’s disease and was just recently diagnosed with it. Although Bill is in the early stages of Parkinson’s, it is still heartbreaking to see him deal with the daily physical and emotional aspects of the disease.

The Parkinson’s Foundation reports that Parkinson’s disease, or idiopathic Parkinson’s, is a neurodegenerative brain disorder that mainly affects dopamine-producing neurons in the substantia nigra of the brain, which is part of the basal ganglia. Parkinson’s is the most common type of parkinsonism, and it occurs in almost 80 percent of all parkinsonism cases.

Motor Symptoms

Parkinson’s disease generally progresses slowly and is mainly characterized by its motor symptoms. The main motor symptoms include:

  • Tremors (involuntary shaking), mostly at rest, involving the hands, arms, legs, tongue, or jaw
  • Bradykinesia (slow movement)
  • Limb rigidity (stiffness or tightness in the arms or legs)

Gait and balance problems are symptoms that tend to occur later in the disease process. If they occur early, it is often a sign of atypical parkinsonism. In order to be diagnosed with Parkinson’s, a patient must have symptoms of bradykinesia and tremors or bradykinesia and limb rigidity.  

There are many other motor symptoms of PD that may occur, including temporary inability to take a step or move, soft and hoarse voice, small handwriting, and involuntary movements of the face, trunk, or limbs, among others.

Non-Motor Symptoms

Some of the many potential non-motor symptoms of Parkinson’s include:

  • Cognitive changes which may include problems with attention, planning, language, memory or dementia
  • Depression, anxiety, apathy, and irritability
  • Hallucinations and delusions
  • Sleeping problems
  • Swallowing, chewing, and speaking difficulty
  • Urinary or constipation problems

Key Takeaway: A patient with Parkinson’s disease has parkinsonism, but not all patients with parkinsonism have Parkinson’s disease. Parkinson’s disease is a form of parkinsonism. 

Bill’s Story

My dear friend Bill began having symptoms about a year ago which included occasional tremors in his right thumb and/or middle and index fingers. Then his right forearm began to shake at times. It seemed more intense, he stated, after he used it for doing such tasks as mowing the lawn or shoveling the snow. These tremors happened when he was at rest.

Other symptoms he started noticing included depression, leg stiffness in the mornings, a hoarse voice, usually in the afternoons, and smaller handwriting. 

After seeing several physicians, including movement disorder specialists, Bill was diagnosed with Parkinson’s disease. I wondered at the time if his symptoms could be caused by something other than Parkinson’s.

Bill even asked his physicians if there was a chance it could be another type of parkinsonism. His physicians told him that the only way they would know for certain was if they removed his brain to examine it. As you can guess, that pretty much took care of that.

Bill was prescribed a combination of carbidopa and levodopa. The drugs came with plenty of nasty side-effects, such as brain fog, burning in the chest and abdomen, and worse depression. The physicians had to adjust the dosage a few times before it became tolerable.

Bill still experiences depression and has less energy, but he states his mind seems pretty sharp again, and he has fewer tremors. He wakes up earlier than he did and lacks energy for about 20 minutes until it improves. At times, Bill isn’t sure if it is the medication or his body causing the symptoms. 

We know there is no cure for Parkinson’s disease, and as long as the treatment is helping, that’s all we can hope for. We are in this for the long haul.

parkinsonism and Parkinson's disease with ICD-10-CM coding

ICD-10-CM Coding

Parkinson’s Disease

The diagnosis codes for Parkinson’s disease are located in Chapter 6: Diseases of the nervous system (G00-G99) of the ICD-10-CM coding manual.  

To find the code for Parkinson’s disease in the Alphabetic Index, we can look up “disease,” which takes us to “Disease, diseased – see also Syndrome.” Looking down the list of subcategories under “Disease,” we come to “Parkinson’s, G20.”

Verified in the Tabular, G20 applies to:

  • Parkinson’s disease
  • Hemiparkinsonism
  • Idiopathic Parkinsonism or Parkinson’s disease
  • Paralysis agitans
  • Parkinsonism or Parkinson’s disease NOS
  • Primary Parkinsonism or Parkinson’s disease

Note: Don’t get confused by what you see when you look up “Parkinson’s” and see  “Parkinson’s disease, syndrome or tremor – see Parkinsonism.” It may cause you, as the coder, to think that parkinsonism is a synonym of Parkinson’s disease, and we already know that it’s not.

Before selecting G20, be sure to read all notations, inclusions, and exclusions to make sure you have the correct code.

For example, there is a Use additional note to identify:

  • dementia with behavioral disturbance (F02.81)
  • dementia without behavioral disturbance (F02.80)

There is an Excludes1 note that indicates if the patient has dementia with Parkinsonism, G20 may not be assigned. Instead, G31.83 should be reported.

There is also an Excludes2 note that indicates if the patient has Parkinson’s disease and any of the conditions listed at the Excludes2 note, both conditions should be reported. These conditions include:

  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

So, according to the ICD-10-CM Official Guidelines for Coding and Reporting, when reporting G20, you will need to also assign a code for any associated signs and symptoms that are not necessarily integral to the disease. These codes are mostly found in Chapter 18: Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99).

Associated Complications of PD

There are quite a few associated complications of Parkinson’s disease, and dementia is one of them. Therefore, if the documentation indicates the patient has dementia secondary to Parkinson’s disease, it would be reported as:

  • G20, Parkinson’s disease
  • F02.80, Dementia in other diseases classified elsewhere without behavioral disturbance

To find these codes, we can look under “dementia” and go down the list to “in (due to),” and “Parkinson’s disease G20 [F02.80].” This means the code in brackets is a secondary code and must be reported after the code for the underlying condition (G20). Parkinson’s is the underlying cause, and dementia is the manifestation of the Parkinson’s.

F02.80 applies to:

  • Dementia in other diseases classified elsewhere without behavioral disturbance
  • Dementia in other diseases classified elsewhere NOS
  • Major neurocognitive disorder in other diseases classified elsewhere
parkinsonism and Parkinson's disease with ICD-10-CM coding

Parkinsonism/Parkinson’s Plus Syndromes

To find the ICD-10-CM code for parkinsonism, we can look up “parkinsonism” in the Alphabetic Index. It takes us to Parkinsonism (idiopathic) (primary) G20. There are many subcategories listed under this category.

The diagnosis codes for the most common Parkinson’s plus syndromes are listed below with instructions on how to find them in ICD-10.

Multiple System Atrophy (MSA). In the Alphabetic Index, look up “parkinsonism” and it takes you to “Parkinsonism (idiopathic (primary) G20.” Then go down the list to “with neurogenic orthostatic hypotension (symptomatic) G90.3.”

Verified in the Tabular, G90.3 applies to:

  • Multi-system degeneration of the autonomic nervous system
  • Neurogenic orthostatic hypotension [Shy-Drager]

Progressive Supranuclear Palsy (PSP). In the Alphabetic Index, look up “palsy.” Looking down the list under “Palsy,” we see “progressive supranuclear, G23.1.”

Verified in the Tabular, G23.1 applies to:

  • Progressive supranuclear ophthalmoplegia [Steele-Richardson-Olszewski]
  • Progressive supranuclear palsy 

Corticobasal Syndrome (CBS)/Corticobasal Degeneration (CBD)/Cortical Basal ganglionic Degeneration (CBGD). Look in the Index under “degeneration” and it takes us to “Degeneration, degenerative.” Then we see “corticobasal, G31.85.”

Verified in the Tabular, G31.85 applies to Corticobasal degeneration.

The “Use additional” note at G31 indicates that for codes G31.0-G31.83, G31.85-G31.9, F02.80 (dementia without behavioral disturbance) or F02.81 (dementia with behavioral disturbance) should be assigned as a secondary code based on the documentation.

Dementia with Lewy bodies (DLB). In the Alphabetic Index, look up “dementia,” which takes us to “Dementia (degenerative (primary)) (old age) (persisting), F03.90.” There is a subcategory for “with” “Lewy bodies, G31.83 [F02.80].”

Verified in the Tabular, G31.83 applies to:

  • Dementia with Lewy bodies
  • Dementia with Parkinsonism
  • Lewy body dementia
  • Lewy body disease

There is a “Use additional” note at G31 that indicates F02.80 should be a secondary code assigned to show dementia without behavioral disturbance. There is also a note indicating if dementia with behavioral disturbance exists, F02.81 should be assigned as a secondary code.

Drug-induced Parkinsonism. In the Alphabetic Index, look up “parkinsonism,” and it takes us to Parkinsonism (idiopathic (primary) G20. Further down in the list of subcategories is “medication-induced NEC G21.19.”

Verified in the Tabular, G21.19 applies to:

  • Other drug-induced secondary parkinsonism
  • Other medication-induced parkinsonism

See the “Use additional” note that states, “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5).”

Vascular Parkinsonism (VP)In the Alphabetic Index, look up “parkinsonism,” and it takes us to Parkinsonism (idiopathic (primary) G20. Further down in the list of subcategories is “vascular, G21.4.”

Verified in the Tabular, G21.4 applies to Vascular parkinsonism.

Pay close attention to the “Use additional,” “Code First,” “Includes,” and “Excludes” notes.

Associated Complications of Parkinsonism

If the documentation indicates the patient has dementia secondary to parkinsonism, it would be reported as:

  • G31.83, Dementia with Lewy bodies
  • F02.80, Dementia in other diseases classified elsewhere without behavioral disturbance

In the Alphabetic Index under “dementia,” go down to “with” and then to “Parkinsonism.” The two codes G31.83 [F02.80] should be reported. Again, G31.83 should be sequenced first, followed by F02.80.

G31.83 applies to:

  • Dementia with Lewy bodies
  • Dementia with Parkinsonism
  • Lewy body dementia
  • Lewy body disease

Again, we need to read all the notations at G31, which indicates that F02.80 is to be added as a secondary code in this situation.

A 1-minute video on parkinsonism and Parkinson’s disease


Parkinsonism and Parkinson’s disease are not synonymous. A person can have symptoms of Parkinson’s disease without having Parkinson’s. However, if a person is diagnosed with Parkinson’s, it is safe to say he also has parkinsonism.  If a person has the symptoms of PD and also has other symptoms, chances are that he may have a Parkinson’s plus syndrome which may be due to many potential causes.

If you understand the coding guidelines and conventions and how to code for complications of Parkinson’s disease and parkinsonism, you should be able to accurately code for these diagnoses.

** This post was reviewed and updated on December 2, 2021.  **

parkinsonism and Parkinson's disease with ICD-10-CM coding

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    1. Hi Lidia. Thanks so much for commenting. I’m glad you found the post helpful and hope you checked out the other related posts I provided above.

      Keep on coding!

  1. First of all thank you mam..for giving a detailed explanation on each and every condition…it is very helpful for me…

  2. Hi, Debbie., is there an ICD 10 code for OFF PERIODS of Parkinson’s Disease. A Latorre, MD,

    1. Hi Dr. Latorre,

      Currently, there is not. However, the expansion of code G20 has been proposed, and we may see new codes related to PD and off episodes implemented in October of this year.

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