As we age, neurological complications become more common. In many people, the development of neurological complications can lead to loss of mobility and, to some extent, loss of independence.
One symptom most common in neurological disorders is tremor. Tremor is the involuntary, somewhat rhythmic to-and-fro movement of one or more parts of the body. Most tremors occur in the hands, but they also occur in the arms, head, face, vocal cords, trunk and legs. Characteristics can include a shaky voice, difficulty writing or drawing, or problems holding and controlling utensils, such as a fork.
In some people, tremor is a symptom of another neurological disorder, such as Parkinson’s disease or multiple sclerosis. The most common form of tremor, however, occurs in otherwise healthy people. While tremor can occur at any age, it is most common in middle-aged and older adults, affecting both men and women equally. The frequency of tremor can be occasional, temporary or intermittent. The severity of tremor can range from hardly noticeable to mild to disabling.
Although tremor is not life-threatening, the condition can be emotionally troubling and embarrassing to some sufferers, and it can hamper the ability to perform daily tasks.
Causes of Tremor
Tremor is generally caused by problems in parts of the brain that control muscles throughout the body or in particular areas of the body, such as the hands. Neurological disorders or conditions that can produce tremor include neurodegenerative diseases, such as Parkinson’s, which damage or destroy parts of the brainstem or the cerebellum. Other causes include cellebellar lesions; the use of some medications (e.g., amphetamines, corticosteroids and drugs used for certain psychiatric disorders); alcohol abuse or withdrawal; mercury poisoning; overactive thyroid; and liver failure. Some forms of tremor are inherited and run in families. Others have no known cause.
Classifications and Types of Tremor
When seeking medical treatment for a neurological disorder that has resulted in the development of a tremor, it is important that a neurologist first classify the tremor. Tremor is primarily classified on the basis of when it occurs, either with a certain posture, while at rest or during action. For example, “resting tremor” occurs when a person’s limb is fully supported against gravity and the muscles are not voluntarily activated, such as when the hands are resting in the lap. “Postural tremor” occurs when a person tries to maintain a position against gravity, such as holding the arms out in front of the body. “Action tremor” occurs during any type of movement of an affected body part.
Of the more than 20 types of tremor, here are some of the most common:
- Essential tremor is the most common type of tremor, affecting approximately 1.5 million Americans. Although this postural tremor can be mild and non-progressive in some people, in others, the tremor is slowly progressive, starting on one side of the body but affecting both sides within a few years.
- Parkinsonian tremor is the second most common type of tremor, affecting approximately 1 million Americans. It is caused by damage to structures within the brain that control movement. This resting tremor, which can occur as an isolated symptom or be seen in other disorders, is often a precursor to Parkinson’s disease.
- Dystonic tremor is the third most common type of tremor, affecting approximately 250,000 Americans. It occurs in people of all ages who are affected by dystonia, a movement disorder in which sustained, involuntary muscle contractions cause twisting and repetitive motions and/or painful and abnormal postures or positions.
- Cerebellar tremor is a slow, broad tremor of the extremities that occurs at the end of a purposeful movement, such as pressing an elevator button. It is caused by lesions in or damage to the brain (cerebellum), resulting from stroke, tumor or disease. It also can result from chronic alcoholism or overuse of some medications. In classic cerebellar tremor, a lesion on one side of the brain produces a tremor in that same side of the body, which worsens with directed movement. Cerebellar tremor can be accompanied by speech problems; rapid, involuntary rolling of the eyes; gait problems; and postural tremor of the trunk and neck.
Treatment of Tremor
While there is no “cure” for tremor, appropriate treatment depends on accurate diagnosis of the cause. Identification of the type of tremor depends on keen, medical observation. The location of the tremor or the patient’s position when the tremor occurs should be identified first, and special attention must be paid to other signs of illness. A neurological exam can determine whether the tremor occurs primarily during action or inaction, and provide information on sensory loss, muscle weakness or atrophy, or decreased reflexes. A detailed family history taken during a neurological exam can indicate if the tremor is inherited. Blood or urine tests can detect metabolic or chemical causes of tremor. Diagnostic imaging can help determine if the tremor is the result of a structural defect or degeneration of the brain. Effective treatment of tremor requires distinguishing this type of movement disorder from other movement disorders. With proper diagnosis, treatments for tremor range from medication therapy to surgery, including deep brain stimulation and non-invasive radiosurgery procedures.