A tremor is a shaking of a body part that is usually uncontrollable. It can happen in the hand or arm, the head, the leg, or even in the voice. Tremors of the hands are the most common.
Tremors can occur in individuals of any age, but they are more common in middle-aged and older adults. The severity of the shaking can range from barely noticeable to so severe as to interfere with normal activities such as writing and eating.
Muscles that allow us to move are prompted to do so by motor nerves that travel from the brain and central nervous system. Every muscle is therefore innervated by a nerve. So, when you want to move your arm, your brain sends a signal through the motor nerves to the arm muscles to cause this movement. However, these nerves can also send abnormal signals to the muscle causing it to contract involuntarily.
There are different types of tremors. Those that occur when an individual’s body is at rest are called resting tremors. Tremors that occur when the body part is moving, such as when writing or pouring a drink, are call intention tremors or kinetic tremors. Finally, a tremor that occurs when an arm or leg is held out against gravity is called a postural tremor.
At any time, anyone can have a “normal” tremor. For example, if you are trying to hold something very still, like threading a needle, you may notice a slight shaking.
Additionally, we can also develop a tremor when we get nervous, very tired, have drank too much caffeine, or have taken a medication that affects the nervous system.
Tremors caused by medications are quite common and the culprits include decongestants, stimulants, steroids, certain antidepressants, and heart medications. On the flip side, withdrawal from drugs and alcohol can elicit tremors as well.
Up to six percent of individuals will inherit a tremor. This type of “benign essential tremor” may begin in early adulthood and can progress as the person gets older. Other causes of tremors include metabolic diseases such as an overactive thyroid gland; alterations in blood sugar levels; and the accumulation of minerals in the body, such as in rare metabolic diseases including Wilson disease, caused by a copper buildup.
Individuals who have had a stroke or a head injury can develop a tremor. These types of tremors are due to damage to the nerves involved with movement. Some of these tremors can improve with time since the brain can, in some circumstances, remodel its circuitry. However, because brain cells cannot regenerate, in many instances the tremors are permanent.
Other causes of tremor include neurological disorders such as Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease) and brain tumors. Although these diseases are less common causes of tremor, occurring in less than 1 percent of Americans, their severity often leads sufferers to think of them first.
As you can see, there are so many possible causes of tremors that the task of pinpointing the diagnosis becomes difficult. The best approach is to start with a thorough medical history and physical examination by your physician.
The content in this column is for informational purposes only. Consult your physician for appropriate individual treatment. Dr. Reynolds practices Family Medicine in Chesterfield.