What is the reason for shaking hands and legs?

Everyone has some little habits in daily life. For example, some people like to eat certain things, some people like to play games, and some people have developed the habit of shaking their hands and legs. This seems normal, but there may be other reasons behind it. Take shaking hands and legs for example. Such behavior is not only related to psychology, but may also be related to the body. So, what causes shaking hands and legs?

Essential tremor (ET) is the most common movement disorder, mainly postural and movement tremors in the hands, head and other parts of the body. Essential tremor has a contradictory clinical nature. On the one hand, it is a mild, monosymptomatic disease, but on the other hand, it is a common, progressive disease with significant clinical variability. The tremor of this disease worsens when one is concentrating, mentally stressed, tired, or hungry. In most cases, it disappears temporarily after drinking and worsens the next day. This is also the clinical feature of essential tremor. The cause of essential tremor is unclear and it is easy to be confused with tremors caused by other diseases.

Disease classification

Essential tremor is also called familial tremor, and about 60% of patients have a family history. No cross-generational phenomenon has been found in multiple families with essential tremor, and the gender distribution is balanced. It is generally believed that this is an autosomal dominant inheritance, which is fully penetrant before the age of 65 to 70 years. Incomplete penetrance and sporadic cases have also been reported. The clinical features of sporadic and hereditary cases are exactly the same, and it is usually considered to be the same disease, but the related gene abnormalities have not yet been identified. The bimodal characteristics of the age of onset of essential tremor suggest the possibility of two different abnormal genes. The age of onset of familial tremor is earlier than that of sporadic cases, suggesting that early-onset essential tremor is more strongly affected by genetic susceptibility, which can significantly affect the clinical subtype characteristics.

Pathogenesis and Pathophysiology

The exact cause of this disease is still unclear. Its generation may be the result of the combined action of peripheral muscle spindle afferents and central autonomic oscillators. ventro-intermediate nucleus of the thalamus

The VIM nucleus is the nucleus that receives proprioceptive input, and the rhythmic burst discharge activity of its neurons may play a key role, which has been confirmed by both neurophysiological recordings and stereotactic surgery. PET studies using CO2 labeled with oxygen (15[O]) revealed selective hypermetabolic function in the bilateral cerebellum and inferior olive. Functional magnetic resonance imaging (FMRI) showed increased activity in the contralateral cortical motor and sensory areas, globus pallidus, and thalamus, as well as hyperactivity in the bilateral dentate nuclei, cerebellar hemispheres, and red nucleus. These suggest that tremor is the result of oscillations in the cerebellar-olivary nucleus loop in the pathway from the thalamus and motor cortex to the spinal cord. Because there are no specific changes in the pathological anatomy, the location of the abnormally vibrating central nervous system "pacemaker" is unclear, so it is speculated that the central oscillator is enhanced or inhibited by peripheral reflexes to regulate the generation and amplitude of tremor.