Diagnosis of Parkinson's Disease
Parkinson's disease diagnosis is based on signs and symptoms and ruling out other disorders that produce similar symptoms. A patient must have two or more of the primary symptoms of Parkinson's, one of which is a resting tremor or bradykinesia. In many cases, a diagnosis of Parkinson's is made after observing that symptoms have developed and become established over a period of time.
After performing a thorough neurological exam and medical history, the neurologist may order a CT scan or MRI scan to meet the other criterion for a diagnosis of Parkinson's disease: ruling out other disorders (e.g., brain tumor, stroke, focal lesions) that produce parkinsonian symptoms. Laboratory analysis (e.g., blood tests) may also be performed to detect particular blood abnormalities that may be associated with other disorders.
Even experienced neurologists often find it difficult to diagnose the early stages of Parkinson's disease accurately. No blood or laboratory tests are available to aid in diagnosis, and the physician must rely on his or her observation of the patient. In many cases, this must be done over a period of time, as tremor or other classic symptoms become consistently present. Accurate diagnosis is crucial, because other forms of parkinsonism often have similar features, but require different treatments.
Parkinson's Disease & Other Disorders with Similar Symptoms
The term "parkinsonism" is used to describe the clinical features that are seen in true Parkinson's disease, but occur because of some other disease cause (etiology).
These other causes of rigidity, bradykinesia, and in some cases of tremor, include the following:
- Side effects of medications (e.g., antipsychotic medications, anti-nausea medications)
- Multiple strokes located in the basal ganglia and appropriate brain regions
- Progressive supranuclear palsy (disorder with Parkinsonian features, plus dementia and abnormal movements of the eyes)
- Shy-Drager Syndrome (disorder with Parkinsonian features plus severe orthostatic hypotension [low blood pressure when standing upright])
- Wilson's Disease (genetic disorder with some Parkinsonian features, liver dysfunction, and tremors)