Having recently performed several consecutive cases of carotid body aneurysms, I feel compelled to reproduce here an article I published in 2004. In addition, in clinical practice, if the carotid body aneurysm is bilateral, it is strongly recommended to operate in different times, because the carotid body aneurysm is locally invasive and often invades the vagus nerve, which will cause respiratory difficulty due to vocal cord paralysis after separation. The harder the tumor is, the more it invades the vascular nerve, and the less the possibility of separation. [Abstract] Objective To explore the surgical methods and related techniques for the safe and efficient treatment of carotid body paraganglioma. Methods We retrospectively analyzed the relationship between different surgical methods and intraoperative and postoperative complications in 33 cases of 35 lateral carotid body paragangliomas, and the follow-up observation of postoperative efficacy. Results All 33 cases were clinically cured, one case of temporary paralysis of the mandibular rim branch of facial nerve and two cases of vagus nerve, and two cases of postoperative thrombosis. 19 cases were followed up and all were alive, except for one case in which the swelling was slightly enlarged in those who were not excised, and no recurrence or surgery-related complications were observed. Conclusion For tumors of small size, simple tumor dissection under the extravascular membrane can be performed. For those with severe neurovascular encapsulation, preoperative determination, monitoring and establishment of cerebral blood flow collateral circulation are the keys to ensure surgical safety and strive for complete removal of tumors. Vascular suturing and graft repair of injury or defect must be supplemented with anticoagulants to prevent thrombosis. Since von Haller first described carotid body in 1743, carotid body paraganglioma has been highly valued for its low morbidity and high surgical mortality. A search of 35 patients with carotid body paraganglioma admitted to our hospital from June 1988 to December 2003 showed that 33 cases and 35 sides were treated surgically. The surgical treatment is now reviewed and analyzed to provide reference for future clinical management of this disease. Clinical data: 14 males and 21 females, male to female ratio: 1:1.5; age: 23-73 years old, average 39.31±13.02; 32 unilateral cases, 3 bilateral cases, 22 left-sided cases, 16 right-sided cases, left-right ratio: 1.38:1.0; two elderly patients (70, 73 years old) were discharged due to general health condition, and one bilateral patient underwent surgery on only one side. There were 4 cases with clinical manifestations of malignancy and 1 case with pathologically confirmed malignancy; there was 1 case of suspected familial inheritance and the rest were disseminated cases. There were 29 cases of substantial painless masses under the mandibular angle of the neck, 2 cases of local tenderness with dizziness and tinnitus, 1 case of Honner’s sign, 2 cases of dysphagia with hoarseness, 2 cases of hoarseness with Honner’s sign, 2 cases of hoarseness with sublingual nerve palsy; 8 cases had a history of local surgery outside the hospital; 1 case had a history of local surgery in our hospital; the medical history ranged from 1 month to 9 years, with an average of 4.23 years The history of the disease ranged from 1 month to 9 years, with an average of 4.23 years. Preoperative imaging diagnosed the disease in 31 cases: 21 with enhanced CT, 7 with MRI, and 16 with ultrasound or digital subtraction angiography (DSA); in 9 cases with a history of surgery, DSA was performed again to determine the extent of the lesion and blood supply to the tumor regardless of any imaging diagnosis. Four cases with obvious tumor blood supply arteries were identified during DSA, and the supply vessels were permanently embolized with polyvinyl acetate immediately. The diagnosis was not clearly established before surgery in 4 cases. Matas training was performed in 16 patients with large aneurysms (>5 cm in diameter) to prevent ligation of the common carotid artery as a last resort during surgery. General anesthesia was used for all procedures. Skin incision: 6 cases had transverse incision on the surface of the mass, and the rest had oblique incision on the anterior border of the sternocleidomastoid muscle, from the mastoid process upwards to the level of the cricoid cartilage downwards. During the operation, the common, external and internal carotid arteries around the tumor were firstly freed and wrapped with a thin soft rubber tube (thin catheter around the vessel twice), and the rubber tube was fixed with hemostatic forceps to stop bleeding by lifting the rubber tube immediately when bleeding occurred. In the last two years, after exposing the common and internal carotid arteries, the blood flow was completely blocked for 5 minutes, released for 5-10 minutes, blocked again for 5 minutes, and so on, with effective and reliable intraoperative training to promote compensation of the contralateral cerebral blood supply. A new INVOS5100 non-invasive cerebral oxygen saturation (rSO2) monitor was also selectively used to determine the oxygen supply and demand balance of the brain, which sensitively reflects the altered cerebral blood flow. The tumors ranged in size from 2.5X2X2cm to 11X6X4cm; 12 cases were confined type, 21 cases were encapsulated type, and 23 sides were exposed to the blood vessels and the surrounding tissues were separated first. After resection, it was found that the internal jugular vein was completely occluded, the internal carotid artery was largely occluded, and the vagus nerve, sympathetic nerve and hypoglossal nerve were indistinguishable, but no enlarged lymph nodes were seen, and the boundary with the surrounding area was still clear. In the nine cases of secondary surgery, one case was confined type and eight cases were encapsulated type. In one case, during intraoperative stimulation of the tumor, there were three sudden increases in blood pressure up to 24-27/19-21 KPa (180-200/140-160 mmHg), which decreased to normal within a few minutes after cessation of stimulation as well as deepening of anesthesia. There were 15 cases and 17 sides of subarterial separation and simple tumor resection, 8 cases of tumor combined with external carotid artery segmental resection, 5 cases of tumor resection and repair of arterial bifurcation and internal carotid artery suture, 4 cases of resection of mass, internal and external carotid artery and vagus nerve, 1 case of major tumor resection, and 1 case each of saphenous vein and artificial vessel graft to repair internal carotid artery. One case was found to be hemiplegic on the day after vascular suture repair, and immediate imaging showed thrombosis at the carotid artery bifurcation suture, but the contralateral blood supply was partially compensated, and the muscle strength was completely restored after two weeks and one month. In the other case, he was able to move freely in bed on the second day after surgery, but suddenly fell down and had sudden onset of aphasia and hemiparesis. In addition to the neurological symptoms such as hoarseness, tongue muscle palsy and Horner syndrome that had occurred before surgery, temporary injury to the mandibular branch of the facial nerve occurred in one case and vagus nerve injury in two cases after surgery, which recovered at 1 month and 6 months after surgery, respectively. All 33 cases were clinically cured at the time of discharge. The follow-up period ranged from 3 months to 16 years, with an average of 5 years, and only 19 cases were available, with a follow-up rate of 57.58%. 19 cases were alive, including one patient who had a major tumor resection, and the mass grew slowly for 6 years without any conscious symptoms; one bilateral patient had only one side of the tumor surgically removed, and the other side had a mildly enlarged tumor for 2 years without any obvious discomfort. Four cases were clinically diagnosed as malignant, three cases were lost to follow-up, and one case was 7 months postoperative with no significant local changes and no distant metastases. Discussion Ultrasound, enhanced CT and MRI are all effective noninvasive diagnostic tools for carotid body paraganglioma, but DSA is not only the most useful diagnostic tool, but can also be used to assess the cerebral blood supply collateral circulation by selective internal carotid artery balloon embolization and to establish cerebral blood supply collateral circulation by this exercise. The vast majority of carotid body paragangliomas are treated by surgical resection. However, due to their special location and close relationship with important vascular nerves, there is a real risk of important neurovascular damage and surgical mortality is as high as 3-9%. The most influential factor is the size of the tumor, with surgical complications being as high as 67% for diameters greater than 5 cm, compared to 15% for diameters < 5 cm. Most scholars believe that carotid body aneurysms should be treated with early surgery. The longer the disease, the more closely it adheres to the artery, and the more chances of sacrificing the carotid artery. Preoperative embolization of the artery supplying the aneurysm can shrink the mass and significantly reduce intraoperative bleeding. However, preoperative embolization was successfully performed in only 4 cases during DSA in this group, and no obvious blood supply artery for embolization was seen in most patients. Shamblin classified tumors according to their size and the difficulty of resection. One category includes tumors that are small and easily separated from the vascular dissection. Another category includes paragangliomas that are closely associated with blood vessels and of moderate size, but can be dissected out by subepithelial dissection. The third category is tumors that are large and typically encase the carotid artery, requiring partial or complete vascular resection and replacement. In our group, 17 patients had tumors less than 5 cm in length, of which 13 cases had subepithelial dissection of 15 sides and complete resection of the tumor. In the remaining cases, 8 cases had aneurysm removal and segmental resection of the external carotid artery without any cerebral ischemic complications. Generally, the adhesion between the tumor and the internal carotid artery is slightly loose, and it is easier to separate the internal carotid artery posteriorly and laterally first. Once the internal carotid artery is separated, the risk of blocking cerebral blood flow caused by ligating the internal carotid artery is eliminated. Once the internal carotid artery is separated, the risk of blocking cerebral blood flow by ligating the internal carotid artery is eliminated. In order to reduce intraoperative bleeding, after the internal carotid artery is isolated, the external carotid artery is separated and the vessels supplying the aneurysm are ligated. It is also possible to first cut the distal segment of the tumor in the external carotid artery and then separate the base of the tumor. Thereafter, the surgeon can hold the tumor in his hand and can dissociate it whenever needed, which is helpful to control bleeding. The separation is slightly easier, and after separating the internal carotid artery, then try to cut the external carotid artery. When the internal carotid artery needs to be resected, the timely and reasonable application of vascular surgery techniques is required. Recent advances in vascular surgery have resulted in a significant decrease in operative mortality. In cases where the tumor is large, tightly wrapped around the carotid bifurcation, difficult or impossible to dissect outside the arterial sheath, or where the arterial wall is very weakly compressed or the tumor is suspected to be malignant, resection of the tumor, resection of the carotid bifurcation, and reconstruction of the carotid artery with an autologous vein or artificial vessel are generally required. In addition to head cooling to reduce cerebral metabolism and oxygen consumption, the duration of cerebral blood flow blockage should be minimized during the operation. In our group, this method was used in 2 cases, and no serious complications occurred in any of them. Although some people advocate leaving part of the tumor in order to ensure the safety of surgery for those with large tumors and close adhesions to the carotid bifurcation, the authors believe that this is mainly the result of failure to confirm the diagnosis before surgery and insufficient preparation for ligation of blood vessels. The preoperative diagnosis rate should be improved and preoperative preparation should be perfected to ensure that the surgery is clean. In addition, resection of tumor and ligation of the common and internal carotid arteries is often safe for tumors that have invaded the blood vessels and nerves. During the slow growth of tumor, cerebral blood flow collateral circulation has been established. In our group, four cases were treated with common carotid artery ligation and segmental common and internal carotid artery and peripheral nerve resection, and none of them had cerebral ischemic symptoms after surgery. Matas training is a simple and effective method that has been preferred by clinicians, but there is a lack of scientific verification of its effectiveness. The authors have used interstitial direct blockade of internal carotid artery flow to further promote the formation of collateral circulation and intraoperative monitoring of cerebral blood flow changes in the past two years. Nerve injury The incidence of nerve injury varies widely between domestic and international reports, and is mainly related to the size and extent of tumor invasion and surgical operation. In patients with familial paraganglioma or in the presence of catecholamine-related symptoms, urine epinephrine and vanillylmandelic acid (VMA) tests, as well as serum catecholamines, are required. For well diagnosed, metabolically active tumors, timely preoperative, intraoperative, and postoperative testing of these indicators can be helpful in obtaining a variety of relevant information, considering the risk of tumor irritation during surgery. Perioperative a- and b-adrenergic blockers should be used in patients with catecholamine-secreting carotid body paragangliomas. Thrombosis and cerebral artery embolism are also a cause of surgical failure or cerebral ischemia. Intraoperative protection of the intima is required as much as possible, and intraoperative and postoperative intravenous application of anticoagulant drugs. Thrombosis of the anastomosis occurred in 2 patients in this group after surgery, both of which were not on anticoagulant drugs at that time, and although cerebral blood flow was compensated in all cases, a small embolus detachment occurred in 1 case causing hemiparesis. Generally, heparin is applied intraoperatively, low molecular dextrose and oral aspirin are applied postoperatively, and if arterial embolism occurs, thrombolytic drugs should be applied in sufficient quantity as soon as possible. Carotid body paraganglioma is more often disseminated, with less genetic factors and slightly more in women. The literature reports that more cases live in the plateau, but this group of cases is more concentrated in northern and central China, none of them live in the plateau or have a history of living in the plateau. Genetic factors account for 7-9% of all cases of carotid body paraganglioma and 30-40% of multicentric occurrence, with no significant gender differences. Autosomal dominant inheritance is subject to genomic imprinting modifications. Although alleles may be passed on to the next generation through both parents, only inheritance from the father results in paraganglioma manifestations in the child. This is due to the fact that activation of the allele occurs only during spermatogenesis and not during oogenesis. Because of the low mortality and risk associated with hourly treatment of the tumor and because of the autosomal dominant inheritance profile, periodic MRI examinations have been recommended every two years for children over 16 years of age. In our group, there was only one case with suspected genetic factors. The patient's brother had an upper neck mass excision 1 year ago, which was reported to be a carotid body aneurysm, with no pathology report. There were no other similar cases in the family. Carotid body paraganglioma is malignant in 6-12.5% of cases and is the most malignant lesion of head and neck paraganglioma. However, histologically, it is difficult to differentiate between benign and malignant. In fact, there are no clear signs of peripheral tissue invasion and no clear malignant features microscopically. It needs to be considered in the clinical context.