Tremors are unintentional trembling or shaking movements. Most tremors occur in the hands, but you can also have arm, head, face, vocal cord, trunk and leg tremors. Although most common in middle-aged and older people, anyone can have tremors.
Tremors may not be a sign of other neurological problems, as they commonly occur in otherwise healthy people. Sometimes, however, diseases such as Parkinson's disease, multiple sclerosis, stroke or certain medicines can cause them. Some forms of tremors are genetic, while others have no known cause.
Tremors are not life threatening. Some people find them embarrassing, however, and they can make it hard to perform daily tasks.
There are a number of different categories of tremor, including:
- Essential tremor, the most common abnormal tremor, is most common after age 40, though symptoms can appear at any age. The hands are most often affected but the head, voice, tongue, legs and trunk may also be involved. Heightened emotion, stress, fever, physical exhaustion or low blood sugar may trigger tremors and/or increase their severity. Recent studies suggest that there is a mild degeneration of certain parts of the cerebellum that may cause essential tremor.
- Parkinsonian tremor is caused by damage to structures within the brain that control movement and is often the first symptom of Parkinson’s disease. This tremor appears characteristically as a resting tremor and can be markedly increased by stress or emotions. Onset of Parkinsonian tremor is generally after age 60. Movement starts in one limb or on one side of the body and usually progresses to include the other side.
- 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 or touching a finger to the tip of one’s nose. Lesions or damage to the cerebellum on one side of the brain (resulting from stroke, tumor or disease such as multiple sclerosis) produce a tremor in that same side of the body that worsens with directed movement. Cerebellar tremor may be accompanied by speech problems, nystagmus (rapid involuntary movements of the eyes) and gait problems.
- Orthostatic tremor involves rhythmic muscle contractions that occur in the legs and trunk immediately after standing. The person typically perceives that he/she is unsteady rather than experiencing an actual tremor. No other clinical signs or symptoms are present and the unsteadiness ceases when the person sits or starts walking.
Tremor can result from other conditions as well, including alcoholism, excessive alcohol consumption, or alcohol withdrawal. In addition, tremor in peripheral neuropathy may occur when the nerves that supply the body’s muscles are traumatized by injury, disease, abnormality in the central nervous system, or as the result of systemic illnesses.
During a physical exam a doctor can determine whether the tremor occurs primarily during action or at rest. The doctor will also check for tremor symmetry, sensory loss, weakness, muscle atrophy or a decrease in reflexes. The physician will take a detailed family history to determine if the tremor is inherited. In some cases, blood or urine tests can detect thyroid malfunction or other metabolic causes of tremor. These tests may also help to identify contributing causes, such as drug interaction, chronic alcoholism, or another condition or disease.
Diagnostic imaging using computerized tomography or magnetic resonance imaging may help determine if there is a lesion or other damage in the brain causing the tremor.
In addition to a general physical examination, a neurological exam may be conducted to assess nerve function and motor and sensory skills. These tests help determine any functional limitations, such as difficulty with handwriting or the ability to hold a small item. An EMG (electromyogram) may also be ordered to diagnose muscle or nerve problems.
There is no cure for most tremors, but there may be treatment to relieve them. This treatment depends on their cause. Medicines and some surgical procedures can reduce or stop tremors and improve muscle control, but the appropriate treatment depends on accurate diagnosis of the cause.
Diet and physical therapy may also help as well. For example, eliminating tremor “triggers,” such as caffeine and other stimulants from the diet, is often recommended. Furthermore, physical therapy may help to reduce tremor and improve coordination and muscle control for some individuals.