Excerpted from Chapter One…
The following is taken from a question and answer session with neurologist Peter A. LeWitt and author Sandy Kamen Wisniewski. Dr. Peter A LeWitt was graduated from Brown University in 1972. He earned a Masters in Medical Science and M.D. from Brown in 1975. His practice, the Clinical Neuroscience Center, is located in Southfield, Mich. He is a neurologist who sub-specializes in movement disorders. Dr. LeWitt has been practicing neurology and been involved with Essential Tremor since 1980.
Q. What is Essential Tremor?
A. By definition, ET is a characteristic rhythmic shaking of muscles caused by the central nervous system. Typically this occurs during action, as, for example, a hand reaching for an object. The regular rhythmic movements of ET are separate from any other malfunctions of the brain’s motor system; hence, the term “essential” (which means tremor and nothing else). ET is initiated by signals from one or more centers in the brain, activating the involved muscle groups which are following instructions to contract in a regular manner, at rates typically between four to five times per second. This results in regular oscillations that, in the hand, are experienced as “shaking” or “jerking.” Tremor is not the same thing as in coordination, although the net result might be the same. In fact, tremor can be distinguished from a number of categories of involuntary movement. Commonly, ET can be confused with the tremor often seen in Parkinson’s disease (PD). The tremor in PD typically occurs with the limbs at rest, while in ET, the resting component is usually absent and tremor arises only during an action of that limb. Tremor brought out by handwriting is typical of ET but not so in PD.
Most commonly, ET affects one or more upper extremities. It can also affect the neck muscles (resulting in head tremor) or the muscles of the larynx involved in generating speech. Less commonly, 2 I Can’t Stop Shaking tremors in this disorder affect the legs, the chin region, or all locations simultaneously.
ET is a common and clearly recognizable clinical syndrome. It lacks any specific test to prove it (other than recordings that can record its frequency and other physical features, which might help to define the condition in contrast to other neurological disorders resembling it). Neurological testing that picture the brain, such as CAT and MRI scans, or EEG recordings, do not show abnormalities in ET. Blood test results also do not show abnormalities in this condition.