The main clinical manifestations of brachial plexus neuropathy include muscle weakness and atrophy of the shoulder girdle, upper extremity and thoracic back muscles, numbness, pain and hyperalgesia in the sensory areas of the skin corresponding to the affected brachial plexus nerve branches. Brachial plexus neuropathy has a complex etiology, what are the examination methods? 1.Electromyography It is now widely used as a means of measuring the function of the motor system to distinguish between weak muscle strength and myasthenia, whether due to myopathy, or neuropathy, or other causes. By needle polar electromyography, the measurement of different parts of the muscles of the torso, it is possible to understand: (1) whether the muscle lesion is neurogenic damage or myogenic damage; (2) the site of neurogenic damage (anterior horn cells or nerve roots, plexuses, trunks, and terminals); (3) whether the lesion is active or chronic; (4) the regenerative capacity of the nerve; and (5) to provide a basis for the diagnosis and differential diagnosis of myotonicity and its classification. It should be used for qualitative and localized diagnosis of unexplained muscle atrophy, numbness, weakness, limb movement disorders, etc. It can also be used as a monitoring tool after surgery or treatment of nerve injury, as well as providing objective indicators for rehabilitation, disability and forensic identification. 2.Nerve conduction velocity is a diagnostic technique to assess the conduction function of peripheral motor and sensory nerves. It is mainly used for the diagnosis of peripheral neuropathies such as polyneuropathy, hereditary peripheral neuropathy, Green-Barre syndrome, carpal tunnel syndrome, peripheral nerve trauma, etc. Combined with EMG, it can identify anterior horn cells, nerve roots, peripheral nerves and myogenic diseases, etc. 3.Visual evoked potential It is mainly used to detect visual pathway lesions. It is widely used in ophthalmology for optic neuritis, retrobulbar neuritis, optic nerve atrophy, optic nerve compression lesions, multiple sclerosis, visual cortex lesions, ocular trauma, hysteria and other diseases; in internal medicine, it is mainly used for visual pathway lesions caused by diabetes, etc. It is important for early diagnosis, localization, prognosis estimation and assessment of treatment effect. 4.Brainstem auditory evoked potential is mainly used to check the audiology of auditory nerve injury, episodic vertigo, auditory neuroma, multiple neurosclerosis, ototoxic tau and peripheral injury; it can objectively evaluate whether there is auditory dysfunction in uncooperative people, infants and hysterical patients. 5.Sensory evoked potential is mainly used to detect the functional status of peripheral nerves, nerve roots, spinal cord, brainstem, thalamus and brain. It is applied to Green-Barre syndrome, cervical spondylosis, posterior lateral sclerosis syndrome, multiple sclerosis, cerebrovascular disease, neurogenic bladder, sexual dysfunction, etc. 6.Event-related potentials Clinically used for diagnosis and efficacy judgment of dementia, brain injury, chronic brain diseases such as hepatic encephalopathy, psychiatric diseases and evaluation of brain development in children.