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Tremors (cont.)

Tremors Causes

The causes of tremor are very diverse. However, even though the list of potential causes is very extensive, a few conditions are predominant. The most important will be discussed here.

Clinical Conditions Associated with Tremors

Familial and Essential Tremor

Familial and essential tremors are the most common conditions associated with action tremor. In the familial, or hereditary form, several members of the same family are affected. This is a genetically heterogeneous condition, and more than one gene might be involved.

The non-familial form is referred to as essential tremor because it is not associated with any other neurological condition. The term "benign essential tremor" has been used in reference to this tremor; however, this is misleading since the tremor can be very severe and disabling. The essential and the familial hereditary forms are similar in clinical presentation.

  • In some affected individuals the tremors start in infancy, however, more often they appear in the second and third decade of life and are most prevalent when a person is in his/her 60's.
  • It is seen in both sexes with similar frequency.
  • Most often, the first signs of tremors are seen in the arms, usually in both of them.
  • The condition is chronic and, in many instances, progressive; as time goes by, other regions are involved including the head, neck, chin, and mouth.
  • The tremor in the arms interferes with many activities such as eating and drinking.
  • Other clinical manifestations might be a tremulous voice, a continuous head movement in a vertical "yes, yes" or horizontal "no, no" pattern.
  • The legs are rarely affected.
  • The tremor might be severe enough to result in functional disability.
  • Tremors increase with anxiety and stimulant drugs and may decrease with the ingestion of alcohol.

There is no diagnostic test that confirms the condition. The diagnosis is based on clinical findings. However some tests might be indicated to rule out other conditions.

Parkinsonian (rest) Tremor

This type of tremor is predominant in the Parkinsonian syndrome

The better known of these conditions is Parkinson's disease, a degenerative progressive disorder of the brain that predominantly affects a deep structure of the brain called the substantia nigra, located in the basal ganglia. The cause of the disease is unknown, the strongest associated risk factor being age. In some individuals, genetic factors might be important.

In Parkinson's disease the tremor is the most common initial sign. This is followed by:

  • gait disturbances, characterized by a shuffling gait and stooped posture;
  • stiffness in the muscles;
  • a general slowness in motor activities;
  • muscle pain; and
  • lack of dexterity.

In addition, the patients present with loss of facial expression and slowed speech with repetition of words. The symptoms progress slowly, and as the disease progresses the tremors are more prominent.

Other conditions with Parkinsonian Tremors

Several conditions in which Parkinsonian tremor might be an important feature include:

Degenerative disorders


Vascular parkinsonism

  • Small ischemic infarcts in the brain (lacunar state)

Drug/Toxin induced

  • Neuroleptic agents
  • reserpine (Harmonyl)
  • Carbon monoxide intoxication
  • Manganese intoxication

Other disorders

  • Hydrocephalus
  • Brain tumors
  • Subdural hematomas
  • Post-traumatic
Last Reviewed 11/17/2017
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