Definition
The term “tremor” is derived from the Latin word “tremere”, which means trembling in German. Tremor is a movement disorder that describes an over-mobility of the affected part of the body. It is caused by repeated contractions of muscle groups that have an opposite effect, resulting in rapid movement first in one direction and then in the other. A tremor is classified according to various aspects: According to the amplitude of the rash (coarse or fine), according to the frequency (high or low frequency), according to the time of occurrence (at rest, during movement, when holding out the hands) and according to the regularity (regular or irregular).
Causes
In principle, a slight tremor is absolutely normal: The structure of the nervous system is based on various control circuits, and the activity of the nerve cells is subject to regular fluctuations. These fluctuations lead to a slight tremor of the hands, for example, when the arms are held out. This physiological tremor is caused by fine, involuntary, rhythmic muscle movements in the sub-millimeter to millimeter range and is intensified by stress, excitement or caffeine.
A tremor when you are under strong tension is therefore (in most cases) completely harmless and represents only the intensification of the tremor that is always present. A tremor only becomes pathological when it is very severe, i.e. when the tremor is very large, or when the back and forth tremor occurs very quickly. A tremor can be caused by various diseases.
In Parkinson’s disease, the cells that are responsible for suppressing involuntary movements perish. The result is a tremor at rest and possibly also when action is taken, which is more pronounced on one side than the other. If the cerebellum is damaged, the coordination of all movements is disturbed.
The result is an irregular tremor that becomes more pronounced when approaching the target (target or intention tremor). Larger amounts of alcohol temporarily incapacitate the cerebellum, resulting in intention tremor, uncoordinated gait and unsafe movements. Chronic alcohol abuse destroys cells of the cerebellum and thus leads to permanent cerebellar damage.
The cause of a more severe tremor than is common can be essential tremor, which almost always affects the hands and arms symmetrically and can occur both at rest and in action. It is inherited in 60% of cases and otherwise occurs spontaneously due to unexplained causes. It affects about 1% of the population.
A rare form of tremor is orthostatic tremor, which affects mainly women over 60 years of age. After prolonged standing, the leg muscles tremble, resulting in unsteady standing and falls. Psychogenic tremor affects the hands or the head and is the physical symptom of mental overload.
It is interesting to note that the psychogenic tremor disappears completely when distracted. Other causes of tremor include chronic mercury poisoning, Wilson’s disease (copper storage disease), hyperthyroidism or fibromyalgia syndrome. Various drugs can also cause tremor: Theophylline (for COPD), cyclosporine A (immunosuppressive agent), cortisone (immunosuppressive agent), amiodarone (for cardiac arrhythmia), calcium antagonists (e.g. for high blood pressure), valproate (for epilepsy) and neuroleptics are among them.
Tremor is one of the four main symptoms of Parkinson’s disease, along with a lack of movement, holding stability and increased muscle stiffness. In Parkinson’s disease, cells in the substantia nigra (black substance) in the midbrain are destroyed. This region of the brain, together with other regions of the brain, controls the execution of voluntary motor activity and the suppression of unwanted movements.
Cell death in the substantia nigra upsets the mechanisms of movement control, which is why unwanted tremor, for example, can occur. Parkinson’s tremor is a resting and holding tremor, which becomes stronger when nervous. It usually affects the hands, typically one side is more affected than the other.
The frequency of the Parkinson’s tremor is about 4-7 per second, the amplitude is of medium amplitude. The so-called pill-twisting phenomenon is a specific form of the resting tremor of the hands: the Parkinson’s patient repeatedly rubs his thumb and index finger together, as in pill-twisting or coin counting. In rare cases, the head, legs, or chin are also affected by the Parkinson’s tremor.
If the chin is affected in Parkinson’s disease, doctors refer to it as the “rabbit” phenomenon.There are some drugs that can cause tremors, especially if taken over a long period of time or even incorrectly (e.g. too high a dosage). These include, for example, so-called cholinesterase inhibitors, which ensure that the neurotransmitter acetylcholine (a substance that mediates the transmission of information via nerves) can work for longer. This group of drugs is used, for example, in the treatment of Alzheimer’s disease.
Other possible drugs that can cause tremor are neuroleptics and antidepressants, which are used to treat psychosis, depression and anxiety disorders. Adrenaline, amphetamines or caffeine can also cause tremor due to their activating effect. Conversely, the withdrawal of tremor-reducing drugs can also be a possible cause.
These include above all beta-blockers, which are used to treat so-called essential tremor, but also primidone or gabapentin. Thyroid disease can also lead to tremor. If the thyroid gland is overactive (hyperthyroidism), the thyroid gland produces too many hormones (especially the so-called T3 and T4).
This leads to increased activity of many organs in the body, such as the heart and also the muscles. As a result, those affected can become fidgety and restless. This often leads to twitching of the hands and fingers.
Many forms of tremor have as yet unexplained causes. However, there are studies that show that the form of essential tremor in particular is related to heredity. It has been shown that in about 60% of people who suffer from tremor, the condition is also a family trait and is therefore probably inherited. It is not yet clear whether this is solely due to heredity.
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