Neurology | Tremor Causes & Symptoms

Tremor is an unintentional and uncontrolled rhythmic muscle movement of one or more parts of the body. It most often affects the hands, but can also affect the arms, head, face, voice, trunk and legs. In some people tremor is due to a neurological disorder; it may also be due to a side effect of certain drugs. Tremor is not the same as muscle spasms or twitches.

Tremor is typically caused by problems in the part of the brain that control muscles throughout the body or the part of the brain that controls muscles in particular areas such as the hands. Some neurological disorders can produce tremor, such as: multiple sclerosis, stroke, traumatic brain injury and neurodegenerative diseases that damage or destroy parts of the brainstem or the cerebellum. Other causes of tremor include the use of certain drugs, alcohol abuse or withdrawal, overactive thyroid or liver failure. Some forms of tremor are genetic, while others have no known cause.

When describing tremors, it is useful to define them according to type. The types of tremor are resting tremors and action tremors. Resting tremors occur when the muscle is relaxed. Action tremors occur during movement of the affected body part.

Actions tremor are divided into subtypes:

postural tremor, which occurs when the person maintains a position against gravity such as holding the arms outstretched
kinetic tremor, which occurs during movement of a body part

intention tremor, which occurs during a purposeful movement toward a target, such as touching a finger to one’s nose or attempting to eat or drink
task-specific tremor, which occurs when performing highly skilled, goal-oriented tasks such as handwriting

TREMOR CATEGORIES BY SYMPTOMS AND CAUSE

In addition to types, tremors are also categorized by their symptoms and cause:

Essential tremors

Essential tremors are the most common type of abnormal tremor. Essential tremors may be mild and non-progressive in some patients and in others may slowly progress, starting on one side of the body and progressing to the other within a few years. Essential tremors are an action type tremor.

Parkinsonian tremor

Parkinsonian tremor is usually a resting tremor and is often an early symptom of Parkinson’s disease. It typically begins in one limb or on one side of the body and can progress to the other side.

Orthostatic tremors

Orthostatic tremors are characterized by rhythmic muscle contractions that occur in the legs and trunk immediately after standing and are typically perceived as unsteadiness rather than an actual tremor. There are no other clinical signs or symptoms and the tremor stops when the person sits, is lifted or starts walking.

Dystonic tremor

Dystonic tremor occurs in people of all ages affected by dystonia, which is a movement disorder in which sustained involuntary muscle contractions cause twisting and repetitive motions and abnormal positions, such as writer’s cramp or cervical dystonia, also known as torticollis.

Cerebellar tremor

Cerebellar tremor is a slow tremor of the extremities that occurs at the end of a purposeful movement, such as trying to press a button. Cerebellar tremor is caused by damage to the cerebellum resulting from stroke, tumor, a disease such as multiple sclerosis or some inherited degenerative disorder. It may also be the result of chronic alcoholism or a side effect of certain medications.

Physiologic tremors

Physiologic tremors are generally caused by a reaction to certain drugs, excess caffeine, alcohol withdrawal or medical conditions such as hypoglycemia (low blood sugar) or an overactive thyroid gland. This type of tremor will usually go away when the cause is eliminated.

Diagnosing Tremor

Tremor is diagnosed during a thorough neurological and physical exam. However, the cause of the tremor may not be diagnosed until further tests are performed. These may include:

family history
blood and urine tests to check for signs of thyroid disease or other disorders
electromyogram to measure involuntary muscle activity and muscle response to nerve stimulation

Treating Tremor

Beta blockers – normally prescribed to treat high blood pressure, but have been shown to reduce tremors in some people.
Anti-seizure medications – frequently used, especially in people who cannot take beta - blockers or who are not helped by beta-blockers.
Botulinum toxin (Botox) injections – useful in tremors that affect the face, head or voice.
Physical therapy may help strengthen muscles and improve coordination.
Brain stimulation surgery.