Essential tremor

Essential tremor
Other names	Idiopathic tremor
Archimedean spiral drawings from a man with a unilateral essential tremor. The spiral on the left was drawn by the subject using the left hand, and the one on the right using the right hand.
Medical specialty	Neurology
Usual onset	Any age, but typically after 40
Causes	Unknown
Risk factors	Family history, exposure to particular toxins
Diagnostic method	Based on symptoms
Differential diagnosis	Cerebellar tremor, dystonic tremor, multiple sclerosis, Parkinson's disease
Treatment	Medications, surgery
Medication	propranolol, beta blockers, primidone, anticonvulsants, topiramate, gabapentin
Frequency	Annual incidence of 23.7 per 100,000 (2010)

Essential tremor (ET), also called benign tremor, familial tremor, and idiopathic tremor, is a disorder of the nervous system that causes the patient to experience involuntary and rhythmic jerking movements. It often affects the hands, although it can sometimes affect the voice or the head.

Although essential tremor is the most common type of medical tremor, its causes have not yet been identified. It is not usually a dangerous condition, but essential tremor is sometimes a worsening condition over time.

Essential tremor is a progressive neurological disorder, and the most common movement disorder. The most common age of onset is usually after age 40, although it can occur at any age. The cause is unknown. Diagnosis is by observing the typical pattern of the tremor coupled with the exclusion of known causes of such a tremor.

Causes

During maturation, a process occurs that involves progressive neurodegeneration and/or the death of neurons. This process, which can be normal and natural during normal aging, involves the fundamental cells of the nervous tissue and its internal components (which are the ones that prevent effectiveness in conducting information in the human brain) in the development of tremors, such as in Parkinson's disease.

Essential tremor is the result of abnormal communication between certain areas of the brain, including the cerebellum, thalamus, and brainstem.

Features

Essential tremor affects men and women. It commonly does not occur until aged 40 or older, and occurs most often in people over 65 years of age.

Although the exact cause of essential tremor is unknown, some work indicates that the part of the brain that controls muscle movements does not work correctly in patients with essential tremor.

Half of all attributed cases of essential tremor are the consequence of a genetic mutation, although the specific gene has not been identified; this is called familial (as in family) tremor. It is unknown what causes essential tremor in people who do not have a genetic mutation.

Diagnosis

The diagnosis is usually made clinically. Tremors may begin at any age, from birth to old age (senile tremor). Any voluntary muscle in the body can be affected, although tremor is most common in the hands and the arms, and slightly less common in the legs, the neck (which makes the person's head move), and the tongue. A resting tremor of the hands is sometimes present. Tremor occurring in the legs may be diagnosed as orthostatic tremor.

Essential tremor occurs as a part of many neurological disorder complexes, in addition to Parkinson's disease. This includes migraine disorders, where co-occurrences between essential tremor and migraines have been examined.

References