Application of negative pressure drain in cranial defect repair Since August 2012, our hospital has adopted the application of negative pressure drain in 48 cases of cranial defect repair with satisfactory results, which are reported as follows 1. Clinical data: 29 men and 19 women in this group of 48 patients; age 18-69 years old, average 40.3 years old. Cranial defects: 30 cases of frontotemporal, 8 cases of temporoparietal, 4 cases of occipital, 6 cases of bilateral defects. Causes of cranial defects: 29 cases after craniocerebral trauma (including 3 cases of open craniocerebral injury), 8 cases after aneurysm, 4 cases after arteriovenous malformation, and 6 cases after hypertensive cerebral hemorrhage. The area of the defect was 4cm×5cm~12cm×16cm, with an average of 8cm×10 cm, and the repair surgery was performed 2 months~15 years after the last surgery, except for 2 cases in which the repair was performed 2 years ago, the rest of the cases underwent the repair surgery within 24 months after the injury (average 6.0 months). The hospitalization time was 9~16d, average 10d. 2. Surgical method: The material used for cranial repair was Medtronic computerized three-dimensional molding titanium mesh. 48 patients were operated according to the routine surgery of cranial repair, using general anesthesia, entering from the original surgical incision, separating the scalp (or temporal muscle) from the pseudo meninges and separating the pseudo meninges carefully during the operation to avoid cutting the pseudo meninges, and using muscle or fascia to tightly protect the pseudo meninges from the injury during the operation. Should be used muscle or fascia tight suture repair, if necessary, with EC ear brain glue repair, titanium mesh covered with forming titanium nail fixation, such as large cavity can be in the center of the bone window position with a silk thread suspension dura mater and suspension of pseudo dura mater and titanium mesh, after the end of the cranial bone repair, in the skin flap and the titanium plate between the placement of the drainage tube, the external negative pressure drains (we use disposable gastrointestinal pressure reducer), incision with pressure bandage. In order to prevent retrograde infection, the negative pressure drain was changed every day, and the drain was continuously drained for 48h, during which the medication was not changed; the medication was changed on the 3rd postoperative day, the drain was removed, the wound continued to be bandaged under pressure, and the stitches were removed on the 8th postoperative day. Preoperative, intraoperative and postoperative antibiotics were used to prevent infection. 3.Results: 48 patients in this group, all of them recovered well after surgery, no subcutaneous effusion and epidural hematoma, and no infected patients were discharged from the hospital. Discussion: Cranial defect repair is one of the common neurosurgical procedures, although the surgical difficulty is not great, there are complications from time to time, and once the postoperative complications occur, it will definitely bring pain and burden to the patients and their families. Subcutaneous effusion is one of the common complications of cranial bone repair, and it has been reported in the literature that the incidence of subcutaneous effusion ranges from 7.6% to 12.9%. Once subcutaneous effusion occurs, it is often necessary to repeatedly pump out the effluent, which increases the patient’s pain and mental pressure, and it is easy to induce infections, which prolongs the use of antibiotics to prevent infections, prolongs the length of hospitalization, and increases the cost. In this group of patients with cranial defects, we placed homemade negative pressure drainage after surgery, and there was not a single case of subcutaneous effusion, which was much lower than the incidence of subcutaneous effusion in conventional normal pressure drainage. We used homemade negative pressure drain in the application of cranial defect repair, the negative pressure of the suction effect can make the dura mater and the repair material tightly, to a certain extent, reduce the liquid exudation of the planar surface, while the dura mater and the skin flap tightly and the titanium plate adhered to the together do not leave a dead space; and the oozing of blood and seepage can also be timely from the drainage tube into the negative pressure drainer. After 3d, the oozing of the wound basically stops, the granulation tissue starts to grow, and the granulation tissue of the dura and the skin flap starts to contact and bond through the small holes on the titanium plate. At this time, removing the negative pressure drainage tube and continuing the pressure bandage usually does not produce further effusion. We have been using this method since 2008, and have received good results, none of the patients had the above complications. The disposable gastrointestinal pressure reducer we use as a negative pressure drain is inexpensive and easy to obtain, and can be easily promoted in primary hospitals. We believe that this surgical method is simple, safe, effective, and worth using routinely in cranial bone repair without side injuries.