[쉬운 신경질환사전] Both hands tremble… What is the most common tremor, essential tremor?

[쉬운 신경질환사전]is a series of articles designed by neurologist Hanseung Lee (Herb Neurology Clinic) and Hidak on the topic of neurological diseases in everyday life. Common but vague symptoms such as ‘eyelid tremors’, ‘dizziness’, ‘numbness of hands and feet’, and ‘various headaches’ are explained in an easy-to-understand manner for the general public.

Tremor is one of the basic neurological symptoms. Essential tremor (essential tremor) is the most common cause of tremor, affecting 3 to 4 people out of 1,000 people. Roughly speaking, if the population of Korea is 50 million, it can be estimated that about 150,000 to 200,000 people have essential tremor. To help readers understand, I will introduce a case of essential tremor.

“A 34-year-old office worker, ‘A’, started to shake his hands from middle school. Then, the tremors got noticeably worse in high school. Through a series of incidents, I even developed fear of public speaking. Even now, even as an office worker, I am having a lot of trouble due to hand shaking every time I give a presentation. Even when dating a woman, my hand shakes, so I take illegal drugs to the other person. In addition, on days when I drink a lot of coffee, my hand tremors get worse and I am suffering. “When the patient came to the hospital and had a physical examination and a brief examination, the possibility of essential tremor was high. So, I started drug treatment with a ‘beta blocker’. Now, the symptoms of hand tremor have improved a lot.”

What is essential tremor?

The meaning of the word essential has the meaning of ‘the cause may be unclear or constitutional’. Essential tremor, as the name suggests, is not completely curable because the exact cause has not yet been found. However, as shown in the introduced case, symptoms can be controlled through appropriate drug treatment.

According to the international diagnostic criteria revised in 2018, for the diagnosis of essential tremor, it must not worsen for at least 3 years and must not be accompanied by other forms of tremor. In other words, if only the head, voice, or lower body trembles without hand tremors, other tremors or diseases should be considered first rather than essential tremors. As I said, most of the symptoms appear on both hands. However, the intensity of the tremors varies from side to side, and the rate of tremors is usually around 5-7 Hz. Occasionally, tremors are found in the ‘head’, ‘face’, and ‘legs’ along with hand tremors.

Symptoms are more pronounced when moving or holding certain positions. Typical examples are ‘when using a laser pointer for a presentation’, ‘when using a spoon for a meal’, and ‘when pouring a drink into a cup’. In addition, symptoms may worsen when you consume ‘coffee’, ‘various energy drinks’, and ‘drugs’ that contain arousing ingredients that excite the nervous system. On the other hand, when alcohol is consumed, symptoms are temporarily relieved. This is a characteristic that distinguishes essential tremor from other common tremors, and is diagnostically significant.

Essential tremor is most often found in people in their teens or 40s. Of course, there is a possibility that the disease can develop in other age groups, but most of the patients under the age of 40 responded that they had already had symptoms since they were in their teens. It is extremely rare that the onset occurs in the 20s and 30s, and the first onset after the 40s, especially in the 40s and 60s, is common. If an elderly person over the age of 70 develops unprecedented tremor, Parkinson’s disease should be suspected.

Another characteristic of essential tremor is that it occurs 50 to 60% more often in men than in women. In addition, the influence of family history is strong. If a family member or relative has essential tremor, 25% of all relatives are likely to experience essential tremor or other tremors. If there is a family history from generation to generation, there is a tendency for autosomal dominant inheritance, so 50% of children can inherit the disease.

What is essential tremor treatment?

Although it is not a curable disease, most symptoms can be controlled by using beta-blockers as the response to drug treatment is good. In the past, propranolol was mainly used. However, while the effects are broad, side effects can also be widespread. Typically, there is a drop in blood pressure and pulse, and 1~2% of users may experience side effects such as ‘insomnia’, ‘weight gain’, and ‘nightmares’. For this reason, I personally do not use propranolol as a first-line treatment for female patients.

Recently, the use of Arotinolol, which is slightly less effective but has a significantly lower risk of side effects, is increasing. However, since the amount of the drug is different for each patient, it is necessary to start with a small dose and gradually increase the amount to find the appropriate dose. If symptoms cannot be controlled with beta blockers alone, other drugs may be used in combination. Examples include Primidone, Gabapentin, Topiramate, and Zonisamide. According to overseas academic journals, primidone is effective, but it can make you quite sleepy when you take it, and it is difficult to find medicine, so I do not use it often. If essential tremor suddenly worsens and causes major problems with daily life, deep brain stimulation may be tried.

Essential tremor is often exacerbated when a medical or psychiatric disorder is present. Among internal medical diseases, ‘hyperthyroidism’ is typical, and in psychiatric diseases, ‘anxiety’ greatly worsens symptoms. If essential tremor, which has not changed for more than several years, suddenly worsens, it must be corrected by examining the accompanying disease.

Essential tremor seems to be a very common and simple disease. In fact, it is not a life-threatening disease, and research is lacking because in many cases it does not worsen over a long period of time. Therefore, the pathophysiology, including the cause, has not yet been fully elucidated. However, based on the studies done so far, academia believes that intrinsic muscle tremor caused by dysfunction of GABA receptors in the cerebellar-thalamus-cerebral motor control network is de-suppressed, resulting in essential tremor.

The problem is what causes disinhibition. This is because there is a difference between the onset group in adolescence and the onset group in middle age. Unlike the adolescent onset group, the middle-aged and later onset group is often accompanied by degenerative changes in the central nervous system, so the possibility is very low, but it may develop into Parkinson’s or dystonia in the future.

Recently, various papers have questioned essential tremor as a single disease. Although further research is needed, the opinion is that there are many complex causes that appear as a symptom of essential tremor. In addition, essential tremor often appears together with a ‘soft neurologic sign’, which is referred to as ‘Essential tremor plus’. In my personal opinion, the pathophysiology of essential tremor will become clear in the near future. When that time comes, I am hoping that a better treatment will come out than now.

Help = Hidak Consulting Doctor Hanseung Lee (Neurologist at Herb Neurology Clinic)

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