What is (are) Tremor ?
Tremor is an unintentional, rhythmic, muscle movement involving to-and-fro movements of one or more parts of the body. Most tremors occur in the hands, although they can also affect the arms, head, face, voice, trunk, and legs. Sometimes tremor is a symptom of another neurological disorder or a side effect of certain drugs, but the most common form occurs in otherwise healthy people. Some forms of tremor are inherited and run in families, while others have no known cause. Excessive alcohol consumption or alcohol withdrawal can kill certain nerve cells, resulting in tremor, especially in the hand. Other causes include an overactive thyroid and the use of certain drugs. Tremor may occur at any age but is most common in middle-aged and older persons.
                
There are several forms of tremor, including:
                
Essential tremor (sometimes called benign essential tremor) is the most common form of abnormal tremor.The hands are most often affected but the head, voice, tongue, legs, and trunk may also be involved. Head tremor may be seen as a "yes-yes" or "no-no" motion. Onset is most common after age 40, although symptoms can appear at any age. Parkinsonian tremor is caused by damage to structures within the brain that control movement. The tremor is classically seen as a "pill-rolling" action of the hands but may also affect the chin, lips, legs, and trunk. Dystonic tremor occurs in individuals of all ages who are affected by dystonia, a movement disorder in which sustained involuntary muscle contractions cause twisting motions or painful postures or positions.