Each year, there are 600 new cases of essential tremor per 100,000 people. This condition appears in childhood and can evolve over time. We take stock.
The essential tremor is a still unrecognized neurological and genetic disease, which affects around 300,000 individuals in France. The first tremors can appear in childhood and get worse with age. About 14% of patients with essential tremor are over 65 years of age.
The tremors affect the upper limbs such as the hands, arms, neck, voice or face. The trunk or legs are rarely affected. There are two types of tremors: postural tremor which affects posture maintenance and action tremor which is triggered when muscle contraction.
Four characteristics make it possible to detect the first signs of an essential tremor:
- typographical extension: tremors evolve in areas that were not yet affected.
- progression from the distal end to the proximal regions: when the tremor begins at the tips of the upper limbs (fingers and hands) and progresses to the proximal ends (the shoulders).
- increase in amplitude with decrease in frequencies: this form of the disease intensifies the amplitude of tremors and decreases the frequency of attacks. However, it leads to increasingly severe disability situations.
- the increase in volitional component: the tremors are accentuated during the execution of the gestures. They increase in intensity over time.
What are the causes of essential tremor?
Essential tremor is not a serious illness as it does not cause paralysis in patients, but it can progress over the years. The tremors can therefore be very disabling for patients who sometimes have to give up their studies or quit their jobs.
This neurological disease is caused by genetic mutations. Recently, a new mutation has been detected in a gene located on chromosome 3. In the body, this gene is responsible for producing a membrane receptor (D3) sensitive to dopamine. The genetic alteration makes this receptor hypersensitive to dopamine and triggers tremors. However, this mutation in the D3 gene is not the only cause of essential tremor. Other mutations can be responsible for this pathology.
Essential tremor: how is this neurological disease diagnosed?
No specific test can diagnose this genetic disease. When a patient presents tremors, the neurologist can ask them about their occurrence, the part (s) of the body that are affected, the conditions of onset (at rest, sitting, limbs stretched, standing) , his family and medical history.
During the consultation, the neurologist often ask the patient to write, draw certain shapes or hold a glass of water in order to identify the action tremors. Tests are also possible to spot postural tremors.
The neurologist also makes sure that the tremors are not symptoms of another pathology such as Parkinson’s disease or thyroid conditions. Chronic alcoholism, too much caffeine or the side effects of certain medicines can also cause tremors.
What are the treatments for essential tremor?
For the moment, no treatment cures essential tremor. Health professionals sometimes prescribe drugs (beta-blockers, anxiolytics, antiepileptics) to soothe the tremors.
In some cases, patients experience deep brain stimulation. This surgical operation consists of implanting brain stimulation electrodes connected to electrical stimulators. According to the Association of people affected by essential tremor (Aptes), 80% of patients observe an improvement in tremor one year after the operation. However, this surgery can sometimes make the tremors worse.
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