How Parkinson’s Disease is Diagnosed
Parkinson’s disease is usually diagnosed clinically, meaning that a physician looks for the presence or absence of the possible symptoms of Parkinson’s disease by interviewing the patient and performing a detailed neurologic examination.
While there is presently no definitive test for Parkinson’s, it can often be identified by a general neurologist, who is trained to diagnose and treat neurologic disorders. To avoid misdiagnosis, consultation with a movement disorder specialist (MDS) is recommended. A movement disorder specialist is a physician who has undergone additional, subspecialty training in the diagnosis and treatment of movement disorders, such as Parkinson’s, after training in general neurology.
Typically, a trained physician will only consider the diagnosis of Parkinson’s disease if the person being examined has at least two of the core motor symptoms of Parkinson’s, including tremor, the characteristic bradykinesia (slowness of movement), or rigidity. At the end of your visit, the physician should discuss with you why you may or may not have Parkinson’s disease and the level of certainty about the diagnosis. This determination is based on your medical history and examination at this visit.
In addition to taking a history and performing a detailed neurologic examination, physicians sometimes use brain imaging to help support a particular diagnosis. However, these studies have their limitations in the diagnosis of Parkinson’s disease and are typically used only in select patients. Brain imaging is not routinely performed by neurologists or movement disorder specialists when they are considering a diagnosis, especially if the person’s symptoms strongly suggest to the physician that idiopathic Parkinson’s disease is the correct diagnosis.
When you or someone you know first visits a physician for the evaluation of potential early Parkinson’s disease symptoms, it is helpful to know what to expect. During the first visit, the physician should do the following:
- Take a complete and careful medical history
- Take your blood pressure while you sit and stand
- Assess your thinking (or cognitive) skills
- Examine your facial expression
- Look for tremor in your face, hands, arms, or legs
- Examine whether there is stiffness in your arms, legs, torso, or shoulders
- Determine whether you can get up easily from a chair, especially without using your arms
- Examine your walking pattern
- Assess your balance as you stand
Helping diagnose Parkinson’s with DaTscan and other tests
Rather, use of imaging is most helpful when the diagnosis is uncertain, or when physicians are looking for changes in the brain that are more typical of one of several Parkinsonian syndromes (and not idiopathic Parkinson’s) and other conditions that can mimic Parkinson’s. Imaging studies to evaluate Parkinson’s disease and Parkinsonian syndromes include magnetic resonance imaging (MRI), which examines the structure of the brain, and DaTscan, an imaging test approved by the Food and Drug Administration (FDA) to detect the dopamine function in the brain. A DaTscan may help differentiate idiopathic Parkinson’s disease from certain other neurologic disorders. Most physicians’ offices will have access to MRI; however, DaTscan imaging may only be available at larger hospitals or medical centers.
Other imaging studies that can be done, but that are not used routinely in the clinic, include functional MRI (fMRI), a specialized form of brain imaging that examines brain function, and positron emission tomography (PET), which can measure certain brain functions.
Determining diagnosis through response to Parkinson’s medication
If a person’s symptoms and neurologic examination are only suggestive of Parkinson’s disease or if the diagnosis is otherwise in doubt, the physician may, nevertheless, prescribe a medication intended for Parkinson’s disease to provide additional information. In the case of idiopathic Parkinson’s, there is typically a positive, predictable response to Parkinson’s disease medication; in the case of some related Parkinsonian syndromes, the response to medication may not be particularly robust, or it may be absent entirely.
Unfortunately, there are no standard biological tests for the disease, such as a blood test. However, researchers are actively trying to find biomarkers in blood and other bodily fluids that could help confirm the diagnosis.
If it’s not Parkinson’s disease, what else could it be?
There are several other conditions that might produce symptoms that can be mistaken for Parkinson’s disease. Here are some possibilities:
- Medication side effects: Certain drugs can produce or exacerbate symptoms.
- Essential, or familial, tremor: This is a relatively common and benign cause of recurrent tremor and is often confused with the tremor of idiopathic Parkinson’s. A general neurologist or movement disorder specialist is the best physician to help differentiate between these two conditions.
- A Parkinsonian syndrome: The symptoms of several neurologic conditions are similar to those of idiopathic Parkinson’s, but they are often managed differently and often do not respond to the typical medications.
Remember: Only a general neurologist or movement disorder specialist can tell you with reasonable certainty if you have idiopathic Parkinson’s. If for some reason you are not comfortable with the results of your first physician visit, getting a second opinion from another general neurologist or movement disorder specialist is always an option. It is important that you feel comfortable with your physician to ensure the best possible outcome for you.
Once you or your loved one has a diagnosis of Parkinson’s disease, it is time to discuss treatment options with your physician.
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