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Johns Hopkins Health Alert

Making the Distinction: Parkinson’s or Essential Tremor
For many older adults, the involuntary shaking of the hands, head, or any other body part conjures up fears of Parkinson’s disease — a progressive and incurable movement disorder, the most recognizable symptom of which is tremor. But the more likely explanation is a condition called essential tremor. While Parkinson’s disease and essential tremor both share the symptom of tremor, that’s just about all they have in common.
The nature of the tremors of essential tremor is quite distinct from that of the tremors of Parkinson’s disease. “Parkinson’s tremor is a resting tremor — it comes on when the hands are completely rested and goes away with directed movements,” Zoltan Mari, M.D., assistant professor of neurology at Johns Hopkins and the Director of the National Parkinson’s Foundation Center of Excellence, explains. “On the other hand, essential tremor goes away when the hands are rested and comes on when your hands are in posture or during movement, such as lifting a cup or using a fork.” Tremor with Parkinson’s disease usually begins or is more prominent on one side of the body, while essential tremor tends to affect both sides equally.
People with essential tremor also have none of the other prominent symptoms that accompany Parkinson’s disease. These include unusual slowness of movements (bradykinesia) and increasingly stiff and rigid muscles, a condition known as cogwheel rigidity.
The causes of Parkinson’s disease and essential tremor also are likely dissimilar. Parkinson’s disease stems from a deficiency of the neurotransmitter dopamine in the brain.
While the exact cause of essential tremor remains unknown, it’s thought to be the result of a distortion of neurological impulses somewhere in the brain. This, experts think, leads to oscillations that cause the tremor.
Still, for reasons that are unclear, people with essential tremor are at higher risk for developing Parkinson’s disease later in life.
Essential tremor often worsens with age, but a change in the character of the tremor can indicate the early onset of Parkinson’s disease. That is a rare occurrence, however. “Oftentimes, with advanced age an essential tremor patient’s hands or head may not shake in a rapid, fine-movement pattern as it did before, and the tremor will become slower and coarser,” Dr. Mari notes. “This can make the tremor seem more prominent, causing many people to think they are developing Parkinson’s while it’s really only a worsening of essential tremor.”

Posted in Healthy Living on February 23, 2011

Medical Disclaimer: This information is not intended to substitute for the advice of a physician