Hearing impairment Hearing impairment is the most common complication of apparent microvascular decompression, with an incidence of 3%, and it is more difficult to recover from hearing impairment, so reducing hearing impairment during surgery is the focus. The causes of hearing impairment are as follows; 1, mechanical injury in surgery of the auditory nerve: microscopic instruments used during surgery, such as nerve splitting ion, microscopic scissors, brain pressure plate and other direct contact with the auditory nerve, this contact and collision can easily cause edema and damage to the auditory nerve, this condition generally has a small impact, the patient can have vertigo, tinnitus and other symptoms after surgery, with the recovery of the auditory nerve injury and edema, hearing The hearing will gradually improve. 2. High-temperature burns of the auditory nerve: During the surgery, due to the treatment of bleeding too close to the auditory nerve, the nerve is burned due to heat conduction, especially the cochlear hair cells are very sensitive to heat, and once they are damaged by heat, it is difficult to recover. 3. Secondary arterial injury: The internal auditory artery and the inferior arch artery that nourishes the inner and middle ears suffer from varying degrees of hearing impairment due to vasospasm or direct injury. Wang et al. believe that the main cause of internal auditory artery injury is that most of the internal auditory arteries originate from the anterior inferior cerebellar artery (AICA), of which about 10% are direct continuations of the AICA, and the rest start near the collaterals of the AICA. The AICA is one of the main vessels that compress the facial nerve root and cause HFS. When the AICA is padded, it will cause excessive pulling of the internal auditory artery or angulation of the vessel, which will cause the impaired blood supply to the auditory nerve. Secondly, the stimulation during the use of the suction device and the nerve splitting ion causes spasm or branch dissection of the internal auditory artery. The dissection of the internal auditory artery is characterized by an immediate loss of hearing and a permanent and complete loss of hearing. The internal auditory artery is also prone to reflex vasospasm, which leads to impaired blood supply to the inner ear and auditory nerve. The hearing impairment due to arterial spasm is mostly delayed and occurs within 1 day to 1 week after surgery, and can occur up to 1 month after surgery. Severe spasm may also lead to permanent hearing impairment. 4, cerebrospinal fluid ear leakage caused by middle ear sound conduction abnormalities: during surgery because of the opening of the affected side of the mastoid humeri, very few patients have cerebrospinal fluid ear leakage, cerebrospinal fluid from the sinus mouth into the middle ear, causing sound conduction disorders, resulting in hearing loss on the affected side of the ear, but this situation can be completely self-healing with the improvement of cerebrospinal fluid ear leakage. I personally believe that the measures to prevent hearing impairment are as follows: 1. The internal auditory artery should never be mistaken as the responsible vessel for compression of the facial nerve, and should not be separated or padded with cotton pads away from the nerve. When the AICA is the responsible vessel for facial spasm compressing the nerve root, the arachnoid membrane attached to the internal auditory artery should be completely loosened before cushioning away, thus avoiding angulation or hypertonicity of the internal auditory artery caused by cushioning away the AICA. The most effective method is to apply a cotton pad infiltrated with poppy base solution to the surface of the spastic internal auditory artery and its branches to prevent prolonged ischemia of the vessel. 4, the use of micro-suction device head, the suction force of the suction device should be properly adjusted to prevent serious injury caused by accidental aspiration of the auditory nerve and blood vessels. 5.When applying bipolar electrocoagulation, the power of the electrocoagulator should be adjusted moderately and water should be dripped in time to reduce the heat damage to the auditory nerve and blood vessels, especially to the hair cells. 6, the use of brainstem auditory evoked potential real-time monitoring during surgery can reduce hearing damage. If there are conditions to use brainstem auditory evoked potential real-time monitoring during surgery, it can effectively reduce the occurrence of hearing impairment and guarantee the safety of surgery. Real-time monitoring of brainstem auditory evoked potentials during surgery found that the incidence of hearing impairment in patients after surgery has been reduced from 7.1% to 2.5%.