The main symptoms of motor neurons, also known as gradual freezing, are muscle weakness, muscle atrophy, muscle tremor and increased muscle tension.

Motor neuron disease is a chronic progressive neurodegenerative disease with unexplained decrease and apoptosis of motor neurons. Clinically, it can be divided into:

1. Progressive muscular atrophy: at the initial stage, it is characterized by weakness of upper limbs, muscle bundle tremor and muscle atrophy, and gradually develops into muscles of the whole body. In severe cases, it may lead to general paralysis and respiratory muscle paralysis, and the patient will eventually die of respiratory failure.

2. Progressive spinal muscular atrophy: the main manifestations are limb weakness, muscle tremor and muscle atrophy, which are related to the pathological segments of the spinal cord;

3. Progressive medullary atrophy: mainly manifested as dyspnea and dysarthria;

4. Primary lateral sclerosis: the lesion only involves pyramidal tract, which can be manifested as upper motor neuron paralysis and limb pseudobulbar paralysis.