Essential Tremor

Essential tremor (ET) is considered the most common neurologic movement disorder. It can be 20 times more prevalent than Parkinson's disease. ET is a chronic condition characterized by involuntary, rhythmic tremor of a body part, most typically the hands and arms. In most patients, ET is considered a slowly progressive disorder and, in some patients, may eventually involve the head, voice, tongue (with associated dysarthria), legs, and trunk. However, in many people, the disease may be relatively non-progressive and the tremor may be mild throughout life.


Hand tremor is the most common form of essential tremor. It is typically biphasic and involves agonist and antagonist muscles. It is usually present in both hands (bilateral); however, in about 10% to 15% of patients, tremor is first noted in the dominant hand. The frequency of the tremor is between 4 to 12 Hz.


Tremor may be most visible while the patient is voluntarily maintaining a fixed position against gravity (e.g., outstretched arms, etc.). This type of tremor, termed a "postural tremor," is a major component of classic ET. The tremor is apparent while holding the body part in a fixed position. In some patients, the tremor may worsen upon performance of self-directed tasks or goal-directed movements. This component of essential tremor is termed as an "intention tremor" meaning that it is present with targeted actions, a form of "kinetic tremor". ET sometimes results in what is referred to as an "internal tremor." Patients most often describe this feeling as a general "shakiness" or a vibrating sensation in the body. All tremors usually disappear during sleep. Unlike the resting tremor associated with Parkinson's disease during which muscles are not voluntarily activated, the symptoms of essential tremor are either absent or minimal during periods of rest.


As the disease progresses, individuals with ET experience varying degrees of functional disability and resultant handicap based on the severity of the tremor. Affected individuals may have difficulty performing everyday tasks requiring fine motor manipulation skills. Holding or manipulating small objects, such as small tools or utensils, may be difficult. Hand tremor may cause difficulties with writing, drinking fluids from a glass or cup, eating, sewing, applying makeup, shaving, or dressing, for example.


In individuals with ET, the next most frequently affected area of the body is the head, followed by the voice, tongue, legs, or trunk. These tremors may occur in isolation or along with tremor of the hands, arms, etc. The movements associated with head tremor usually occur in a horizontal "no-no" pattern (in about 75%); however, in some patients, head tremors may occur in a vertical "yes-yes" pattern. In advanced cases, tremor of the voice, tongue, and palate may lead to dysarthria. In these patients, the voice is usually "shaky" or has a "trembling" quality. Such tremors are uncommon in individuals under the age of 65 years.


The psychosocial effects of ET may be embarrassing and debilitating. ET may eventually affect the patient's ability to perform certain work-related tasks; interfere with activities of daily living; or lead to withdrawal from social activities and interactions due to embarrassment.


In some patients with ET, other neurologic symptoms may also be present such as unsteady, uncoordinated manner of walking (tandem gait disturbance [ataxia]). This finding may be more common than previously believed; however, its occurrence seems to be more frequent in older patients or those with long-standing disease ( >5 years' duration). In many people, the disease may be relatively non-progressive and the tremor may be mild throughout life.


Source - www.wemove.org