The essential tremor is a type of tremor that occurs isolated and not as a symptom of a disease. It is one of the most common movement disorders in the world. The essential tremor, also known as familial tremor, often manifests in the upper extremities, especially in the hands. It can manifest in the head, the tongue or the legs too, but this is not as common as the hand tremor. Patients with a head tremor often seem as if they were constantly nodding or shaking their heads.
The shaking of the essential tremor is, in contrast to the Parkinsonian tremor, usually not present in rest position but starts if a movement is implemented. Another form of the essential tremor is the postural tremor where the shaking starts when patients hold objects.
The essential tremor can occur at all ages; about 0,9% of the Austrian population suffers from essential tremor1. Within the age group over 65 years are 4,6% suffering from this tremor type2. This means that the disease occurs twice times more often than the Parkinson’s disease.
The cause of essential tremor is not known. It is assumed that the nerve cells in the cerebellum change and cause the tremor. A genetic cause is also possible; children of patients diagnosed with essential tremor have a 50% risk to develop this movement disorder. Which genetic defect causes the essential tremor within families is unknown. There are also patients without any family members who are shaking. Because of that also environmental influences are discussed to be co-responsible for the essential tremor but in this area of research also no proof was found until today.
The essential tremor often starts in one side of the body, in later states of the disease the tremor spreads onto the other side of the body too. Very interesting is the fact that the essential tremor’s force decreases after the consumption of alcohol (e.g. a glas of wine) within most patients. During the first evaluation of the shaking, this reaction to alcohol can give doctors a hint that the patient suffers from essential tremor.
In the beginning, the severity of the tremor is most of the time lesser than in the later course of disease. The frequency is higher and the amplitude lower – later, it can turn around and the frequency decreases while the amplitude increases. That means the shaking becomes slower but stronger.
Depending on the tremor severity the essential tremor can impede patients in their everyday lives. But not all patients suffer from an impairment, some can live their lives without problems because the tremor has manifested not that strongly. There is no cure for essential tremor but there are some effective treatments available to calm the shaking if it becomes a burden.
Essential tremor is mostly treated with beta blockers. Beta blockers are a group of substances that are commonly used to treat high blood pressure. Due to the intake of beta blockers the shaking calms and daily activities become much easier for patients. The two most used drugs are Propranolol and Primidon. Propranolol is often prescribed to younger patients and Primidon to the elder ones. Another possibility is the intake of medication that are used to treat epilepsy; but every medication can have side effects like fatigue.
When the essential tremor reaches a level where medication has no effect anymore, patients can get the treatment of deep brain stimulation. In this surgical procedure tiny electrodes are inserted into the areas of the brain, where the tremor has its origin. A trigger is implanted under the skin near the collarbone and is wired with these electrodes. The functioning is similar to the one of a pacemaker: the trigger emits impulses to the thalamus. This brain area is responsible for the involuntary management of arbitrary movements; the thalamus is also responsible for the overactivity of the muscles – this overactivity then manifests as tremor.
1Louis ED. Clinical Practice. Essential tremor. N Engl J Med 2001;345:887-91
2see FN 1
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