Essential tremor: causes, symptoms and treatments

There are a large number of neurological disorders, all of them with different causes and that can produce a large number of symptoms, depending on the area or areas they affect. Some of them are linked to movement control. Among these, Parkinson's disease is especially known, but there are many problems with similar symptoms.

One of them, which is frequently confused with the previous disease and which is very frequent, is the tremor or essential tremor.

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Essential tremor: characteristics and symptoms

Essential tremor is a very common neurological disorder in the population, especially in those over 65 years of age, characterized by the presence of involuntary and persistent rhythmic tremors or shakes. These jerks occur especially in the hands and arms, generally in both extremities at the same time and symmetrically. It is also common for tremors to appear on the face, and can also affect the voice. Although it is not so frequent, sometimes the same happens in the legs.

These tremors occur when the subject is performing voluntary movements or maintaining certain postures such as when extending the arms, eating, writing or driving. These shocks can vary in intensity depending on the moment, and without treatment can get worse with age.

As a general rule and unless it overlaps with other disorders (it is possible that together with diseases such as Parkinson's), essential tremor is confined only to the motor field. In other words, essential tremor per se does not cause cognitive impairment or other disturbances. It is not a dementia or a neurodegenerative disease.

Although the main symptoms are the aforementioned tremors (although fatigue and weight loss may sometimes appear) when performing actions or maintaining postures, and it does not cause mental deterioration, this disease can be very disabling in different aspects of life.

For example, actions that require precision like sewing or even drinking from a glass can be greatly complicated. It is not strange that those who suffer from it may also have some depressive symptoms. Some people may have to quit their job (for example, a surgeon) or seek alternative methods of travel (driving is extremely dangerous).

This disease usually appears between 40 and 65 years of age. Despite this, cases have been detected in all ages, being able to appear even in childhood.

Causes of the disorder

In this disorder there are alterations in the nerve connections of the different nuclei that regulate movement, such as the cerebellum, the thalamus, or the nigrostriatal pathway. However, the causes of these alterations are currently not fully known.

The data and evidence show that there is a genetic origin in a high percentage of cases. In various families mutations have been located in the D3 receptor gene, but it does not occur in all cases. The genes involved vary from study to study. But there is also an environmental influence, since there are also sporadic cases in which there is no genetic inheritance.

Similarities and differences with Parkinson's

It has been previously commented that this disease is frequently confused with Parkinson's for various reasons. The causes of this confusion are based on the similarity of their symptoms and some neurological characteristics. Likewise, in some cases, people with essential tremor are predisposed to suffer from Parkinson's, which may or may not develop.

In both cases we found the presence of involuntary tremors. However, while in Parkinson's, tremors at rest stand outIn essential tremor, tremors occur when the subject is performing a movement or maintaining a posture.

Another common aspect is that in Parkinson's a great affectation of the nigrostriatal path is seen, with problems in the transmission of the neurotransmitter dopamine. In essential tremor there may also be an involvement, degeneration or hypofunction of this pathway, although it is not essential.

However, in Parkinson's, the presence of so-called Lewy bodies can be observed in this pathway. In many of the studies carried out to date they are not present in essential tremor, although in the literature Recently, cases have been found in which they were also present, generally in cases with a predisposition to Parkinson. In other cases they have been found in the cerebellum.

It also highlights the fact that regarding drug treatment, Substances that are helpful in one disorder usually do not have an effect on the other. For example, the L-dopa that is used in the case of Parkinson's is not usually useful in the case of essential tremor. There are exceptions such as some surgeries and drugs such as zonisamide, which in many cases is beneficial for both pathologies.

Common treatments for essential tremor

Essential tremor is a disease that does not currently have a curative treatmentInstead, the treatments are aimed at reducing the tremors present in it and improving the quality of life of the patient.

Essential tremor tends to be worse with the use of some exciting substances like coffee, which is why this substance is usually contraindicated. Alcohol in small doses can produce a certain decrease in tremor, but caution should be exercised with the doses and over time it can make it worse. It has been observed that the jerks can be less when carrying out the movements using elements that have a certain weight.

At the level of pharmacological treatment, different substances are usually used, such as primidone (an anticonvulsant) or beta-blockers such as propranolol. Sometimes they are also used antidepressants and anxiolytics. The choice of the drug in question will depend on the characteristics of the patient or its possible side and / or adverse effects (for example, propranolol lowers blood pressure).

Another treatment used is botulinum toxin or botox injections., especially in areas such as the hands or the head, which decrease the intensity of the tremors.

When the tremors are severe or very disabling, you can also choose to use surgery. In this sense, deep brain stimulation is usually used, in which a device is installed that stimulates by means of impulses. different electrical points of the brain in a similar way to how a pacemaker would act, or transcranial magnetic stimulation repetitive. In the most serious cases it is also possible to opt for the excision of part of the thalamus.

Bibliographic references:

• Bermejo, P.E.; Ruiz-Huete, C. and Terrón, C. (2007). Relationship between essential tremor, Parkinson's disease, and Lewy body dementia. Rev. Neurol. 45; 689-694.

• Labiano-Fontcuberta, A and Benito-León J. (2012) Tremor Essential: An Update. Clinical Medicine, 140 (3). 128-133.

• Lucotte, G.; Lagarde, J.P.; Funalot, B. & Sokoloff, P (2006). Linkage with the Ser9Gly DRD3 polymorphism in essential tremor families. Clin Genet; 69: 437-40.

• Schuurman, P.R.; Bosch, D.A.; Bossuyt, P.M.M. et al (2000).. A comparison of continuous thalamic stimulation and thalamotomy for suppression of severe tremor. N Engl J Med.; 342: 461-468.