Essential tremor

Essential tremor is the most common type of pathologic tremor and the most common type of movement disorder. Although most clinicians agree on the major features, there is considerable controversy about several aspects of this condition. This stems from the lack of agreement concerning clinical diagnostic criteria, the difficulty in diagnosing the disease in its early stages, and the wide variety of tremors that are present in the population. Essential tremor should not be confused with physiological tremor, which is a normal phenomenon present in all muscle groups during waking hours and during some phases of sleep. Physiological tremors are not normally noticeable, but they can become exaggerated transiently during periods of anxiety, drug or alcohol withdrawal, and with certain metabolic disturbances.