Diagnosing Parkinson's disease can be difficult, especially in its early stages. It has been estimated that nearly 40% of people with the disease may not be diagnosed, and as many as 25% are misdiagnosed. Even as the disease progresses, symptoms may be difficult to assess and may mirror other disorders. For example, tremor may not be apparent while a person is sitting or posture changes may be written off as osteoporosis or simply a sign of aging. Some doctors, who think that tremor is a requirement for diagnosis, may not realize that as many as a third of people with Parkinson's disease may not have tremor.
Furthermore, making the diagnosis is even more difficult since there are currently no blood or lab tests available to diagnose the disease. Some tests, such as a CT Scan (computed tomography) or MRI (magnetic resonance imaging), may be used to rule out other disorders that cause similar symptoms. Given these circumstances, a doctor may need to observe the patient over time to recognize signs of tremor and rigidity, and pair them with other characteristic symptoms. The doctor will also compile a comprehensive history of the patient's symptoms, activity, medications, other medical problems, and exposures to toxic chemicals. This will likely be followed up with a rigorous physical exam with concentration on the functions of the brain and nervous system. Tests are conducted on the patient's reflexes, coordination, muscle strength, and mental function. Making a precise diagnosis is essential for prescribing the correct treatment regimen. The treatment decisions made early in the illness can have profound implications on the long-term success of treatment.
Usually, the outward symptoms of Parkinson's are distinctive enough for a doctor to make a diagnosis in the office. There is no blood test or brain scan that confirms the diagnosis. But if you don't respond to the drugs used to treat Parkinson's disease, it’s possible you may have another type of movement disorder that causes the same type of symptoms. Doing additional tests can help your doctor determine if some other problem is causing your parkinsonian symptoms.
Because the diagnosis is based on the doctor's exam of the patient, it is very important that the doctor be experienced in evaluating and diagnosing patients with Parkinson's disease. If Parkinson's disease is suspected, you should see a specialist, preferably a movement disorders trained neurologist.