The localization of paralysis can be based on the clinical location and extent of limb paralysis by monoplegia, bilateral lower limb paralysis, hemiplegia, and quadriplegia. Among them, monoplegia refers to the paralysis of one limb or a part of one limb. The diagnosis is based on the following: 1. Damage to the motor area of the cerebral cortex (anterior central gyrus): the pyramidal cells, which are responsible for the movement of various parts of the torso, are arranged in a special inverted shape in the anterior central gyrus, so the lower lesion appears as upper motor neuron paresis of the contralateral upper limb, and may be accompanied by motor aphasia if the lesion involves the Broca area in the posterior part of the inferior frontal gyrus in the dominant hemisphere. The superior lesion presents with upper motor neuron paresis of the contralateral lower extremity. When the lesion is confined to the cortex, the paresis is always flaccid, unlike the usual upper motor neuron paresis that is spastic in its later stages. When the lesion causes irritation, the paralyzed limb may also present with limited motor seizures without significant paralysis. It is often seen in tumors, vascular disease and trauma. The lesion involves both the posterior cord and the thalamic tract of the spinal cord, causing ipsilateral sensory and contralateral hyperalgesia below the level of damage, which is called “spinal cord hemimediastinum syndrome” (Brown-Sequard syndrome). Sequard syndrome). ②Lumbar segment lesions: damage to the ipsilateral anterior horn of the spinal cord, motor neuron paresis of the lower extremity on the side of the lesion, often accompanied by cauda equina symptoms such as radiating pain and hyperalgesia in the lower extremity, all of which are seen in the early stages of spinal cord compression disease. 3, spinal cord anterior horn lesions: cervical expansion (cervical 5 – thoracic 1) dominates the muscle movement of the upper limbs, lumbar expansion (lumbar 2 – sacral 2) dominates the muscle movement of the lower limbs, the above-mentioned parts of the lesion can cause motor neuron paresis in some muscles of the upper and lower limbs respectively, and because of the stimulation effect, accompanied by muscle fiber tremor of the paralyzed muscle. If the lesion is limited to the anterior horn, there is no sensory disturbance, which is mostly seen in the anterior horn of the spinal cord, such as gray matter inflammation. If there is a superficial sensory separation, it can be seen in the spinal cord cavity, etc. 4, anterior spinal nerve root lesions: the resulting paralysis is the same as the anterior horn damage, but the muscle fiber tremor is thicker, called muscle fiber bundle tremor, in addition, the lesion often involves the adjacent posterior roots, so it is accompanied by the corresponding root distribution of sensory disorders, such as upper and lower extremities of radiating pain, shallow sensory hypoesthesia, loss of ah allergy, etc.. Most commonly seen in radiculitis, proliferative spondylitis, and early intraspinal occupying lesions. 5, plexus damage: proximal damage with the corresponding symptoms of anterior spinal nerve damage, the distal end is manifested as its composition of the relevant nerve trunk damage symptoms. Take the proximal brachial plexus lesion as an example: ① upper brachial plexus trunk type damage (upper arm from paralysis, Erb-Du-chenne paralysis): for the cervical 5-6 nerve root damage, manifesting proximal upper limb and scapular band muscle paralysis, atrophy, upper limb can not be lifted, flexion and external rotation. The biceps tendon reflex and flexor pelvis reflex are absent, the upper limb flexor side has radiating pain and sensory impairment, and the forearm muscles and hand function are normal. It is mostly seen in trauma, birth injury, etc. ②Brachial plexus lower trunk type (lower brachial plexus paralysis, Klumpke-Dejerine paralysis) is a manifestation of cervical 7-thoracic 1 nerve root damage, muscle paralysis and atrophy mainly in the distal part of the upper limb including the hand, with radiating pain and sensory disturbance on the ulnar side, and may have Horner’s sign. It is mostly seen in apical lung tumors, clavicle fractures, and cervical ribs.