Parkinson's Disease - Diagnosis

Research is ongoing to determine how well imaging tests can detect early and late stages of Parkinson's and allow physicians to gauge disease progression and effectiveness of treatment. Single photon emission computed tomography (SPECT) and PET, the best neuroimaging techniques available today, are playing a vital role in Parkinson's research as well. By enabling the detection of small changes in brain function early on, they are paving the way for studies of neuroprotective agents. Before these imaging methods were available, there was no adequate way to determine if neuroprotective drugs could slow the progression of early disease.

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Ruling out Causes of Parkinsonism and Diseases that Mimic Parkinson's Disease

When symptoms resemble Parkinson's disease but have an identifiable cause, the syndrome is known as parkinsonism. People who have parkinsonism, but not Parkinson's disease, often have additional neurologic symptoms. A number of conditions can also have similar or some of these symptoms.

Other Neurologic Conditions. Many medical conditions may cause symptoms of Parkinson's disease:

Hardening of the arteries (arteriosclerosis) in the brain can cause multiple small strokes, which can produce loss of motor control.

Developmental process of atherosclerosis

Click the icon to see an image of plaque in an artery..

Alzheimer's disease can be very similar. In one study 23% of people with Alzheimer's also met the criteria for Parkinson's disease. The two diseases also often coexist, and research suggests that Alzheimer's and Parkinson's disease may sometimes share a common biologic origin, the accumulation of the protein alpha synuclein and Lewy bodies in the brain.
Lewy bodies variant (LBV), also called dementia with Lewy bodies, is a separate disease from both Alzheimer's and Parkinson's disease. It has similar symptoms to both but is marked by early dementia.
Encephalitis caused by influenza has been known to cause parkinsonism.
Primary progressive freezing gait is a progression condition, in which freezing gait occurs at the onset. Other Parkinson-like features, such as slow movement, often develop. Although very similar to PD, this condition does not respond to L-dopa or other PD medications.
Essential tremor, unlike the tremor of Parkinson's disease, often occurs in the head and voice and is usually worse during motion, as opposed to rest.
Progressive supranuclear palsy has similar symptoms, but involves less tremor and earlier rigidity, and it tends to affect both sides of the body symmetrically. Magnetic resonance imaging scans that measure parts of the midbrain may be a reliable method for distinguishing between PD and progressive supranuclear palsy.
Multiple system atrophy (previously called Shy-Drager syndrome) is a degenerative nerve disease that also affects movement and blood pressure and has many of the symptoms of Parkinson's disease. Some research suggests that a trial using the drug apomorphine may help differential between the two.
Other problems that may mimic Parkinson's disease include Wilson's disease, thyroid abnormalities, hydrocephalus, tumors, having the fragile X trait (but not the full disorder), and a number of degenerative neurologic diseases.