A tremor is an unintentional and uncontrollable rhythmic movement of one part of your body. A tremor can occur in any part of the body at any time. It is usually the result of a problem in the part of the brain that controls your muscles. Although tremors are not always serious, in some cases they may indicate a serious disorder. Most tremors cannot be treated, but will often go away on their own.
It’s important to note that muscle spasms, muscle twitches, and tremors are not the same thing. A muscle spasm is the involuntary contraction of a muscle. A muscle twitch is an uncontrolled fine movement of a small part of a larger muscle. This twitch may be visible under the skin.
Tremors are divided into two types: resting or action.
Resting tremors occur when you are sitting or lying still. Once you begin to move around, you will notice that the tremor goes away. Resting tremors often affect only the hands or fingers.
Action tremors occur during movement of the affected body part. Action tremors are further divided into several subcategories:
- An intention tremor occurs during targeted movement, such as touching your finger to your nose.
- A postural tremor occurs when holding a position against gravity, such as holding your arm or leg outstretched.
- Task-specific tremors occur during a specific activity, such as writing.
- Kinetic tremors occur during movement of a body part, such as moving your wrist up and down.
- Isometric tremors occur during the voluntary contraction of a muscle without other movement of the muscle.
In addition to type, tremors are also classified by their appearance and cause.
Essential tremors are the most common type of movement disorder. Essential tremors are usually postural- or intention-type tremors. Essential tremors may be mild and nonprogressive or may slowly progress, starting on one side, and then affecting both sides within a few years.
Essential tremors were thought not to be associated with any disease processes; however, recent studies have connected them to mild degeneration in the cerebellum (the part of the brain that controls motor movement). Essential tremors are often associated with mild walking difficulty and hearing disability, and tend to run in families.
A Parkinsonian tremor is usually a resting tremor and is often the first sign of Parkinson’s disease. It is caused by damage to parts of the brain that control movement. The onset is usually after age 60. It begins in one limb or on one side of the body, and then progresses to the other side.
Dystonic tremors occur irregularly and can be relieved by complete rest. They occur in people affected by dystonia—a movement disorder characterized by involuntary muscle contractions that cause twisting and repetitive motions or abnormal postures, such as twisting of the neck. These can occur at any age.
A cerebellar tremor is a type of intention tremor caused by lesions or damage to the cerebellum from a stroke, tumor, or disease, such as multiple sclerosis. It may also be the result of chronic alcoholism or overuse of certain medications.
A psychogenic tremor may present as any of the tremor types. It is characterized by sudden onset and remission, changes in the direction of the tremor and the body part affected, and greatly decreased activity when the individual is distracted. Patients with psychogenic tremors often have conversion disorder (a psychological condition that produces physical symptoms) or another psychiatric disease.
Orthostatic tremors are rapid, rhythmic muscle contractions that occur immediately after standing. They are often perceived as unsteadiness. There are no other clinical signs or symptoms, and the unsteadiness stops when the person sits, is lifted, or starts walking.
Physiologic tremors are generally caused by a reaction to certain drugs, alcohol withdrawal, or medical conditions, such as hypoglycemia (low blood sugar) or an overactive thyroid gland. They usually go away when the cause is eliminated.
Prescription medications, diseases, injuries, stress, and caffeine can all cause tremors.
The most common causes of tremors are:
- muscle fatigue
- ingesting too much caffeine
- low blood sugar levels
Medical conditions that cause tremors include:
- traumatic brain injury
- Parkinson’s disease (a degenerative disease caused by loss of dopamine-producing brain cells)
- multiple sclerosis (a condition in which your immune system attacks your brain and spinal cord)
- hyperthyroidism (when the body produces too much thyroid hormone)
Are All Tremors Dangerous?
Sometimes, tremors are perfectly normal. When you’re under a lot of stress or experiencing anxiety or fear, tremors may occur. Once the feeling subsides, the tremor usually stops. Tremors are often part of medical disorders that affect the brain, nervous system, or muscles.
If you develop unexplained tremors that occur frequently, you should see your doctor for diagnosis.
During a physical examination, the doctor will observe the affected area. Tremors are apparent upon visual inspection; however, the cause of the tremor cannot be diagnosed until further tests are performed. Your doctor may request that you write or hold an object to evaluate the severity of your tremor. Blood and urine samples are often collected to check for signs of thyroid disease or other disorders.
The doctor may also order a neurological exam. This exam will check the functioning of your nervous system. It will measure your tendon reflexes, coordination, posture, muscle strength, muscle tone, and ability to feel touch. During the exam, you may be asked to touch a finger to your nose, draw a spiral, or perform other tasks or exercises.
In addition, your doctor may order an electromyogram. This test measures involuntary muscle activity and muscle response to nerve stimulation.
Treating the underlying condition causing the tremor may be enough to cure it. However, medications may also be prescribed to treat the tremor itself.
Common medications prescribed to treat tremors are:
- beta-blockers: Beta-blockers are normally used to treat people with high blood pressure. However, they have been shown to reduce tremors in some people.
- tranquilizers: Tranquilizers, such as Xanax, may be prescribed to relieve tremors that are triggered by anxiety.
- anti-seizure medication: Anti-seizure medications are often given to people who cannot take beta-blockers or who are not helped by beta-blockers.
Botox injections may also relieve tremors. These chemical injections are often given to people who have tremors that affect the face and head.
Physical therapy may be offered to help strengthen your muscles and improve your coordination. In addition, tremors may be helped by the use of wrist weights and adaptive devices, such as heavier utensils.
Brain stimulation surgery may be the only option for those with debilitating tremors. During this operation, the surgeon inserts an electrical probe into the portion of your brain responsible for the tremors. Once the probe is in place, a wire is fed from the probe into your chest, under your skin. The surgeon places a small device in your chest and attaches the wire to it. This device sends pulses to the probe, which stops the brain from producing tremors.
Written by: April Kahn
Published on Jul 07, 2012
Medically reviewed by George Krucik, MD