Making the Diagnosis
Currently, the diagnosis of Parkinson’s disease is purely a clinical one. This means it is based on:
- Medical Examination
- Medical history or description of your problem
This surprises many people, given the medical tests, laboratory work, and imaging studies that are used to diagnose other conditions. In 2011, the FDA approved an imaging technique called the DaTscan.
The diagnosis of Parkinson’s is usually done by a neurologist or a movement disorder specialist. The following criteria are used in determining if a person has Parkinson’s disease:
Medical History and Examination
Two of the three movement problems must be present:
- Tremors*
- (can typically be found in the arm, leg or chin. It is present when the arm is in a resting position and improves with movement unlike familial tremor in which the tremor is worse with movement and not noted at rest. Not everyone has tremor, but they are found in 70-80% of people with Parkinson’s.)
- Bradykinesia or slowness of movements
- Rigidity or stiffness in the arms and legs
Other features that are helpful in diagnosis:
- Symptoms start on one side of the body
- Micrographia or small hand writing
- Decreased arm swing when walk
- Masked like or loss of spontaneous facial expression
Non-movement symptoms that can precede movement symptoms can be a clue to early diagnosis.
Medical Testing
Laboratory Testing
Blood and urine copper studies can be helpful in younger people to test for Wilson’s disease (a genetic condition associated with abnormal body tissue copper levels.)
Vitamin B12, vitamin D, thyroid levels, blood count and metabolic panel are labs that can help identify additional cause (unrelated to Parkinson’s) for symptoms of fatigue, depression, and cognitive change.
Brain Imaging
MRI
This scans does not typically reveal problems in Parkinson’s and is therefore not routinely done. However, other conditions such as stroke or normal pressure hydrocephalus can be identified. These conditions are described in the related article atypical Parkinsonism.
DaTscan
A DaTscan is a scan of the Dopamine System in your brain. This involved injecting a small amount of a radioactive drug. The drug binds with dopamine transmitters in the brain, lighting up the neurons that are still currently transmitting dopamine. The center image below shows the amount of dopaminergic nerve cells in the basal ganglia. However, at this point the scan is not able to diagnose Parkinson’s disease from atypical Parkinson’s so it is only part of the puzzle. It will, however, help differentiate Essential or familial tremor from tremor caused by Parkinson’s disease.
