Essential tremor

Introduction to idiopathic tremor Essential tremor (ET), also known as familial or benign essential tremor, is a common clinical dyskinesia with autosomal dominant inheritance. Postural or motor tremor is the only manifestation, slow progression or long-term No progress. It is currently believed that age is an important risk factor for ET and the prevalence increases with age. The onset is slow and can occur at any age, but it usually starts in adults. There are reports in the literature that men are slightly more than women. basic knowledge The proportion of illness: 0.002%-0.005% Susceptible people: no specific population Mode of infection: non-infectious Complications: speech disorders writing spastic torticollis restless legs syndrome migraine

Cause of idiopathic tremor

Causes:

Ageing (15%):

This is the main reason why idiopathic tremor prefers the onset of the elderly. In general, people are prone to various diseases due to the decline in physical fitness. Idiopathic tremor syndrome is one of them.

Environmental factors (25%):

The occurrence of a disease is more or less related to environmental factors. The same is true for idiopathic tremor. The reason for the prevalence of idiopathic tremor is regional. The reason may be that there may be some toxic substances in the environment. The brain's neurons.

Family inheritance (35%):

In the follow-up survey of some patients with essential tremor, it is found that the senile disease of idiopathic tremor seems to have a certain tendency to family aggregation, and the family members of patients with idiopathic tremor have a higher incidence than the normal population. For idiopathic tremor, although the main cause of the disease is age aging associated with environmental toxins, not all elderly people live in the same environment, even people who also consume large amounts of pollutants will develop idiopathic tremors. disease. Therefore, our relevant experts concluded that idiopathic tremor also has a certain family agglomeration phenomenon, but so far no clear pathogenic genes have been found in patients with sporadic tremors, so the etiology of idiopathic tremor syndrome is proved. There are many kinds, so don't take it lightly.

Pathogenesis:

Current research suggests that essential tremor (ET) is caused by abnormal oscillations in the reticular formation or nucleus scattered in the central nervous system. The location of the pacemaker is unclear, and the primate induced by the harmaline The tremor model is similar to human idiopathic tremor and is a commonly used ET animal model; harmin is a canine-like -carboline analog that can cause tremor in humans.

Animal model studies have found that camelids-induced nucleus neurons produce synchronous rhythmic discharges, which are transmitted to cerebellar Purkinje cells and cerebellar nuclei, and then activate spinal motor neurons via Deiter's nucleus and reticular nucleus. The most common hypothesis of tremor is the olivine-cerebellar rhythm change. The lower olive-cerebellar nerve pathway oscillates through the thalamus and cortex to the spinal cord, eventually causing tremors. PET detection found that ET patients had no tremor when the thalamus and medulla (mainly under The olive nucleus) increased the metabolic rate of glucose, and the H215O blood flow measured the increase of bilateral cerebellar blood flow; the cerebral nucleus and cerebellum metabolic rate and blood flow increased further during tremor, and the blood flow of thalamus, striatum and motor cortex also increased, ethanol (alcohol) May act on the cerebellum, thus improving tremor, increasing cerebellar blood flow, increasing metabolic rate; cerebellar infarction can eliminate ipsilateral idiopathic tremor; animal models treated with Hamelin can be found abnormalities in cerebellar pathway Oscillation; these all suggest that the cerebellum also plays an important role in the development of essential tremor.

It is assumed that the vibration originates from the brainstem (olive nucleus), through the cerebellum to the thalamus, and the damage of the cerebellum can cause the ipsilateral tremor to disappear. PET scanning studies using radionuclide-labeled CO2 revealed selective bilateral cerebellum and lower olive metabolism. Hyperfunction, functional magnetic resonance imaging (FMRI) showed the contralateral cortical movement and sensory area of the affected limb, globus pallidus, thalamic activity, bilateral dentate nucleus, cerebellar hemisphere and red nucleus hyperactivity, these suggestive tremor The production is the result of oscillation of the cerebellar-olive nucleus loop in the thalamus and motor cortex to spinal cord pathway. Because the pathological anatomy has no specific changes, the exact location of the abnormally vibrating central nervous system "pacemaker" is still unclear. The central oscillator is enhanced or suppressed by peripheral reflections to adjust the generation of tremor and the amplitude of the tremor.

Electromyography (EMG) can record 4~8 Hz evoked muscle-antagonistic muscle synchronous continuous release activity, and about 10% of patients show agonist muscle-antagonistic muscle alternating contraction. Single motion unit analysis shows electric impulse It is aggregated or synchronized. During the recruitment phase during the tremor episode, the newly recruited motion unit has an abnormally high instantaneous 20 to 50 Hz discharge frequency.

The tremor is often maintained by impulse. Peripheral afferent impulse changes can affect tremor, depending on the size of the disturbance and the time course of the tremor cycle. Secondly, the interfering impulse of the peripheral afferent can also affect the rhythm of the central autonomous pacemaker. The tremor caused by the discharge.

In summary, essential tremor may be caused by a central oscillator, which may explain the clinical features of some essential tremors, such as tremors exacerbate in rapid activity and relatively lack of resting tremor.

Idiopathic tremor prevention

1, mostly based on light food, pay attention to the law of diet.

2. Eat properly according to the doctor's advice.

3, the disease does not have too much taboo on the diet, a reasonable diet can be.

Idiopathic tremor complications Complications speech disorder writing spasmodic torticollis restless legs syndrome migraine

Some elderly patients with essential tremor have speech problems, and EF patients with dystonia account for 6% to 47%. Positional tremor is also common in dystonia, especially in writing stenosis. In dystonia, 7% to 23% of patients with idiopathic tremors, spastic torticollis often accompanied by head and torso tremor.

In the family of essential tremors, a small number of members can also find other dyskinesias such as Tourette's Syndrome and Restless Leg Syndrome. The presence of typical migraine in patients with confirmed essential tremor is common. Report of malignant hyperthermia.

Symptoms of idiopathic tremor Common symptoms Fatigue and anxiety hand sputum-like action Resting tremor Neonatal tremor High fever Elderly slow-moving Involuntary movement Muscle fiber tremors Postural tremor

1. Typical idiopathic tremor can be found in children, adolescents, middle-aged and elderly people. There are two views on the peak age of onset. One thinks that the age of onset is bimodal, that is, 20 to 30 years old. And 50 to 60 years old; another view that idiopathic tremor is rarely in juvenile onset, with an increase in the number of people with age, the average onset age is 37 to 47 years old.

2. The only symptom of idiopathic tremor is tremor. Occasionally, there are reports of tone and slight gait abnormalities. Patients usually start with the upper limbs, mainly affecting the upper limbs, bilateral upper limbs with symmetric onset, and unilateral upper limbs. Once the upper limbs are affected, they often develop upward to the head, face, tongue, and lower jaw, and the torso and bilateral lower limbs are rare. They appear only in the late stage of the disease and are lighter than the upper limbs.

Mainly manifested as positional tremor, which can contain both motility, intentional or resting tremor components. The tremor may be aggravated in the movement toward the target. The frequency of tremor is 4-8 Hz, and the frequency at onset is 8-12 Hz. As the disease course and age increase, the frequency gradually decreases and the amplitude gradually increases.

The typical symptom is the rhythmic abduction of the hand, which is endogenous tremor and flexion and extensor tremor. Pre-rotation tremor (similar to Parkinson's disease) is very rare. The written words may be deformed, but they will not appear to be too small. Another frequently affected part is the craniocerebral muscle group, which can be involved in the head, tongue or vocal muscles. It is characterized by severe tremor and head tremor in the patient's hand, including vertical "nodding" movement and horizontal "Shaking his head" movement, soft sputum, tremor of the tongue can cause difficulty in vocalization.

3. The tremor will affect the activity after 10 to 20 years of onset, and the severity will increase with age, so that the ability to complete fine activities will be impaired, reaching the peak in the sixth 10 years after the onset, 86% to 60-70 years old. Can affect social activities and living ability, including writing, drinking, eating, dressing, speech and operation, the greater the tremor, the greater the impact on the ability to move, the impact of tremor on gender is no different.

4. Many factors can affect tremor, hunger, fatigue, emotional and temperature (high fever, hot water bath), etc. will aggravate tremor. Like most involuntary movements, idiopathic tremors are relieved during sleep, and there have been some reports. Tremors persist in the light sleep.

The response to alcohol (alcohol) in patients with essential tremor is characteristic. Many patients can reduce tremor even if they only consume a small amount of alcohol (alcohol), and 42% to 75% of patients have reduced tremor after drinking, but only temporarily, generally maintained 2 to 4 hours, the next day, the tremor was aggravated. It was rarely reported that ethanol (alcohol) had a similar effect on other types of tremor. Ethanol (alcohol) acts through the central nervous system.

5. Idiopathic tremor can be associated with other dyskinesias. Idiopathic tremor with Parkinson's disease is well known. It is reported that in patients with essential tremor, the incidence of Parkinson's disease is higher than that of normal controls. Much, even in patients with idiopathic tremors older than 60 years, the risk of Parkinson's disease is 24 times that of randomized individuals in the same age group. Lou and Jankovic have reported 350 cases of idiopathic tremor, 20% of which are With Parkinson's disease, it is considered that essential tremor may be an important risk factor for Parkinson's disease.

Postural tremor is common in many dyskinesias including Parkinson's disease, and even the only symptom in the early stage. Some patients develop postural tremors that develop Parkinson's disease several years later, and idiopathic tremors. The incidence of Jinsen's disease is higher, and there may be a special subgroup.

Examination of idiopathic tremor

Blood electrolytes, drugs, trace elements and biochemical tests help to differentiate the diagnosis.

1. CT, MRI, positron emission tomography (PET) or single photon emission tomography (SPECT), meaningful for differential diagnosis.

2. Electromyography (EMG) can record 4~8 Hz evoked muscle-antagonistic muscle synchronous continuous release activity, and about 10% of patients show agonist muscle-antagonistic muscle contraction, single motion unit analysis shows The electrical impulses are collective or synchronized, and the newly recruited motion units in the recruiting phase during the episode of tremor have an abnormally high instantaneous 20 to 50 Hz discharge frequency.

3. Genetic analysis is important for the diagnosis of certain hereditary dystonia.

Diagnosis and diagnosis of idiopathic tremor

Diagnostic criteria

According to the patient's frequent posture and/or action tremor, after drinking, the family history, without other symptoms and signs of the nervous system, should consider the possibility of idiopathic tremor.

1. Clinical grading of tremors The clinical grading of tremors proposed by the National Institutes of Health (NIH) Idiopathic Tremor Research Group in 1996 was five grades.

Level 0: No tremor.

Class I: Very slight tremor (not easy to find).

Class II: Easy to find amplitude less than 2cm without disabling tremor.

Grade III: Significant amplitude 2 to 4 cm partial disabling tremor.

Grade IV: a severe amplitude of more than 4 cm of disabling tremor.

2. Diagnostic criteria for essential tremors Diagnostic criteria for essential tremors proposed by the American College of Motion Disorders and the World Tremor Research Institute.

(1) Core diagnostic criteria:

1 Both hands and forearms are tremors.

2 In addition to the gear phenomenon, without other signs of the nervous system.

3 or only head tremor, without dystonia.

(2) Secondary diagnostic criteria:

1 The course of disease is more than 3 years.

2 has a family history.

3 After the drinking, the tremor is reduced.

(3) Exclusion criteria:

1 with other signs of the nervous system, or a history of trauma shortly before the occurrence of tremor.

2 Physiological hyperactivity caused by drugs, anxiety, depression, hyperthyroidism, etc.

3 has a history of mental (cardiac) tremor.

4 sudden onset or segmentation progress.

5 primary erectile tremor.

6 only location-specific or target-specific tremors, including occupational tremors and primary writing tremors.

7 only words, tongue, sputum or leg tremors.

Differential diagnosis

The differential diagnosis of idiopathic tremor is very important, mainly identified with the following diseases.

1. Parkinson's disease Parkinson's disease is mostly in the elderly, this period is also the multiple age of idiopathic tremor, so many idiopathic tremors are misdiagnosed as Parkinson's disease, the incidence of PD in patients with essential tremor is higher than the general population. The study found that the tremors of relatives of PD patients were at least 2.5 times that of the normal control group, and the relatives of PD patients with essential tremors had a tremor rate of 10 times, indicating that idiopathic tremor and PD are two independent diseases, but both. There may be a certain relationship between them. PD tremor is mainly static, and can be combined with action tremor, often accompanied by slow movement, rigidity, abnormal gait and less expression.

2. Hyperthyroidism and adrenal hyperfunction cause hyperactivity tremor. When a large inertia load is applied to the limb, the frequency of tremor can be reduced by more than 1 time/s. The characteristic tremor does not have this performance, which may be accompanied by excessive appetite, hyperhidrosis and increased heart rate. , weight loss, increased neurological excitability and goiter, and hyperthyroidism with full moon face, central obesity, high blood pressure and multi-blood.

3. erect tremor performance posture tremor of the trunk and lower limbs when standing, can affect the upper limbs, with body instability and calf sputum (muscle high-frequency tonic contraction), ease after sitting or lying on the back, reduce when walking, familial posture Patients with tremor have a higher incidence of orthostatic tremor. Both PET have bilateral cerebellum, contralateral lenticular nucleus and thalamic dysfunction, suggesting that there may be a relationship between the two, compared with idiopathic tremor, erectile tremor The frequency (14 to 18 times / s) is faster, with clonazepam (clonazepam), gabapentin (gabapentin) can be significantly relieved.

4. Cerebellar efferent pathway lesions are mainly cerebellar nucleus and combined arm lesions, showing upper and lower limbs intentional tremor, often accompanied by other cerebellar signs such as ataxia.

5. Poisoning or drug-induced tremor is usually posture tremor combined with exercise tremor, static tremor and intentional tremor may also occur, depending on the type of drug and the severity of poisoning, most tremors affect the whole body, irregular rhythms, flapping wings Quiver, accompanied by myoclonus.

6. Cortical tremor is irregular high frequency (>7 times / s) posture and exercise tremor, often accompanied by exercise myoclonus, electrophysiological examination can find large somatosensory evoked potential and somatosensory reflex.

7. Red nucleus and midbrain tremor are a mixture of static, postural and intentional tremor. The frequency of tremor is 2 to 5 times/s, usually caused by lesions near the red nucleus (stroke or trauma), affecting one side of the black. The striatum and the binding arm pathway lead to tremor of the contralateral limb, which is often accompanied by other signs of brain stem and cerebellar lesions.

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