The exact cause of essential tremor is yet unknown. Tremors occur when there is a problem with the nerves supplying certain muscles. Some research suggests that the part of the brain that controls muscle movement does not work correctly in patients with essential tremor.

Essential tremor can also occur with other problems of the brain and nervous system such as dystonia, Parkinson’s disease and certain neurological diseases that are transmitted from parents to children.

If an essential tremor occurs in more than one member of a family is called familial tremor. This type of essential tremor is passed down through families (inherited), which suggests that genes play a role in its cause.

Familial tremor is usually a dominant trait, which means you only need to get the gene from one parent to develop tremor. It usually begins in early adulthood, but can be seen in older or younger people.

Rest tremor occurs when muscle is not voluntarily activated, while action tremor is present with voluntary contraction of muscle. Subtypes include postural, kinetic, and isometric tremor.

As the disease progresses, individuals with essential tremor experience varying degrees of functional disability and resultant handicap. 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.

While tremor is not medically dangerous, it is very disabling and affects mental status as well as functioning at home and in the work place.

The tremor is more likely to be noticed in the hands, but may affect the head, arms, eyelids, or other muscles. The tremor rarely turn affects the legs or feet. People with essential tremor may have trouble holding or using small objects such as silverware or a pen.

The doctor can make the diagnosis by performing a physical exam and asking questions about medical and personal history. A physical exam will show shaking with movement, usually small movements with a frequency greater than 5 times per second. Normally there are no problems with coordination or mental function.

Tremors can:

• Occur when you move (action-related tremor) or may be less noticeable with rest.

• Come and go, but generally get worse as you get older.
• Get worse with stress, caffeine and certain medications.
• Not affect both sides of the body in the same way.