Tremors -- what are they, and what causes them?
What is a tremor and what is its cause? It is an involuntary, unintentional, rhythmic muscle movement that appears as oscillations or to-and-fro movements of the involved body part, such as the hands. It is the rhythmic quality of the tremor that distinguishes the most common form of tremors from other diseases showing abnormal movements. Other parts of the body that may be affected are the arms, face, head, voice, trunk and less frequently, the legs. Tremors may be intermittent or occur all the time. Both sides of the body may or may not be involved. Women and men are equally affected.
Generally, tremors are caused by problems in the brain that control muscles either throughout the body or in specific areas. Multiple sclerosis, traumatic brain injury, stroke or other neurological diseases that damage or destroy brain cells in the brainstem or the cerebellum -- a part of the brain that routes brain signals to the appropriate places and is responsible for coordination and precision -- can cause the shakes.
There are seven different types of tremors: essential, Parkinsonian, dystonic, cerebellar, psychogenic, orthostatic and physiologic. We review four here.
- Essential tremors (ET) affect up to 10 million Americans. They are the most common form of abnormal muscle tremors. More common in the elderly and usually noticed after age 40, these tremors can start at any age. As people get older, frequency of tremors may decrease, but there may be an increase in the tremors' severity. And though many may think getting tremors is a natural part of the aging process, experts say it is not.