HOW IS PARKINSON'S DIEASE DIAGNOSED?

At present, the diagnosis of Parkinson's disease is made on a clinical basis. A physician, after carefully reviewing the history and conducting a physical examination, is able to come to this conclusion. There is no routine laboratory or blood test that can confirm this diagnosis. The definite diagnosis is made by examination of patient's brain after death.

Positron Emission Tomography (PET) scan can show characteristic abnormalities in patients with Parkinson's disease compared with the general population or those suffering from other neurological disorders. PET scan utilizes various radiolabeled substances and estimates the status of dopaminergic neurons in the brain. However, PET scans are mainly used as a research tool. Therefore, the diagnosis is based on finding typical clinical features of Parkinson's disease and excluding other disorders that can mimic Parkinson's disease.

An MRI (magnetic resonance imaging) scan of the brain is often performed to rule out diseases such as stroke or normal pressure hydrocephalus that can mimic this disorder. In younger patients other disorders like Wilson's disease should be excluded. Appropriate tests in this case include examining the blood for levels of copper and ceruloplasmin. It is also important to review other medications the patient is taking. A number of drugs, especially anti-psychotic medications, can cause symptoms resembling Parkinson's disease.

There are other diseases that present with symptoms similar to those of Parkinson's disease (often called as "parkinsonism"). These are Parkinson-Plus Syndromes including Progressive Supranuclear Palsy, Corticobasal Degeneration and Multiple System Atrophy. These conditions are often associated with early difficulties with balance, difficulties with memory and trouble maintaining blood pressure when upright. The physician may look for specific signs including difficulty with eye movements and extreme stiffness and inability to carry out simple tasks on one side of the body. These conditions respond poorly to medications used in Parkinson's disease and have a poorer prognosis (outcome). The diagnosis and treatment of these conditions are best handled by physicians with specific expertise in these disorders.