Carotid body aneurysms are chemoreceptor tumors. They are found mainly in the carotid body and the aortic body. First described by VouHaller in 1743, carotid body aneurysms were reported and treated surgically by Marchond in 1891 and died 3 days after surgery. Nearly 1000 cases have been reported worldwide to date. About 150 cases have been identified in China. The carotid body is mostly located at the bifurcation of the common carotid artery, with a pericardium, variable in size, about 3 or 5 mm in diameter, and rich in blood vessels and nerves. The blood supply is provided by the small branches of the common carotid artery, and the nerves come from the cervical sympathetic ganglion, the glossopharyngeal nerve, the vagus nerve and the hypoglossal nerve. Carotid body tumors are reddish brown, round or ovoid, lobulated, and surrounded by an envelope. The cells are mainly polygonal, with eosinophilic staining of the cytoplasm and contain many vacuoles and microsomes. The tumor is most likely to occur between 30 and 40 years old, and the malignancy rate is 5% to 10%. It is rare clinically, but can cause severe cerebrovascular complications and death if not treated properly.
Symptoms and signs
The disease occurs in young adults. There is no conscious symptom in the early stage, but a slow growing mass may show symptoms when the tumor increases in size. In a few cases, carotid sinus syndrome occurs, in which the tumor compresses the carotid sinus due to the change of body position, causing upright vertigo, epigastric discomfort and transient loss of consciousness.
In a few cases of malignant carotid body tumor, tumor compression and infiltration of peripheral nerves may cause hoarseness, choking and coughing (vagus nerve invasion) and inferior lingual nerve invasion causing paralysis of the inferior lingual nerve, resulting in atrophy of the tongue muscle and limited tongue movement.
Carotid body tumor has 3 major signs.
1. The tumor is located slightly below the mandibular angle and superficial to the carotid triangle. In a few cases, it may protrude toward the lateral wall of the pharynx. The lesion is mostly unilateral. In the tumor site, there are obvious pulsations can be palpated.
2.Shift of carotid artery to superficial side Because the tumor is located in the medial part of carotid branch, the tumor may push the internal and external carotid artery to superficial side after enlargement.
3.Separation of internal and external carotid arteries As the carotid body tumor expands across the branches to the superficial surface, the internal and external carotid arteries are pushed to both sides. The outline of the artery may not be clearly palpable because the tumor wraps around the artery wall.
For carotid body aneurysm, biopsy is contraindicated. However, carotid artery angiography should be performed routinely, and digital subtraction arteriography (DSA) technique is commonly used nowadays. The typical carotid body aneurysm radiographic presentation is: the tumor displaces the carotid artery laterally; the carotid artery bifurcation widens or there is a small traffic branch from the carotid artery to the tumor.
Treatment with medicine
Surgical treatment is the only treatment method. If detected early, it should be treated promptly. The later the treatment, the more powerful the adhesion between the tumor and the branch of common carotid artery, the treatment is to peel off the tumor under the carotid artery. However, all the preparations of vessel rupture repair, transplantation of vessels and ligation of common carotid artery should be made before surgery.
1. Preoperative preparation: Carotid angiography must be done before surgery to understand the patency and compensation of Wills’ basal ring, so as to judge whether the common carotid artery can be blocked. Predict whether cerebrovascular complications may arise after surgery. If the preoperative indication is that the basilar ring of the brain (wills) is not compensated, carotid artery block training should be performed until the collateral circulation is established.
The training of blocking the flow of the affected common carotid artery was proposed by Matas as early as 1914, and a special compression device, the Matas clip, was used in clinical practice. However, the common method is still finger pressure on the affected common carotid artery, 4 to 6 times/d for more than 10 min each time. If the patient has no symptoms of cerebral ischemia, such as dizziness or fainting, for 30 min, it is considered safe to block the carotid artery and the procedure can be performed. To be more cautious, a second carotid angiogram is usually required to demonstrate that the Wills loop is indeed patent before the procedure can be performed. Because of the acupressure training, it is sometimes difficult to hold the pressure for a longer period of time and the pressure is not stable. The use of transcranial ultrasound flowmetry to measure the decline in blood flow before and after blockade can also be used as a primary monitoring indicator of cerebral blood supply. If the decline of blood supply after blocking does not exceed 25% is a safe value for surgery.
2.Intraoperative and postoperative treatment
Anesthesia: Generally, low temperature anesthesia is used to reduce the need for cerebral oxygen, to facilitate the intraoperative prolongation of blocked blood flow and to reduce brain damage.
Blood preparation: adequate blood volume should be prepared. Once the decision is made to ligate and remove the common carotid artery, sufficient blood volume must be replenished to maintain the blood pressure at a high level of normal value, which should not be lower than the patient’s original blood pressure level.
Application of vasodilator drugs: After ligation and resection, vasodilator drugs must be applied to dilate the cerebral blood vessels. Commonly used drugs include: low molecular dextran; compound danshen; nimodipine (nimoton) 1mg, 24h intravenous slow drip. Vasodilators are usually required to be used for 2 weeks, after 2 weeks they can be changed to oral vasodilators such as: niacin (NA), aspirin, etc.
Postoperatively, the patient is placed in a flat or head-down position at 15° with absolute bed rest for 2 weeks. If necessary, various preoperative cerebral blood flow checks can be repeated to understand the postoperative cerebral blood supply on the affected side.
3. Surgical precautions: strict hemostasis and avoidance of arterial injury are the keys to ensure successful surgery. Therefore, the operation should be performed gently and carefully, and in a planned and step-by-step manner. According to the experience of head and neck surgery of Tianjin Cancer Hospital, the peripheral area should be separated first and the tumor body should be dissociated later. The basic sequence is to cut off the proximal cranial end of the external carotid artery first; to cut off the common carotid artery; to cut off the proximal end of the external carotid artery; to cut off the internal carotid artery; and finally to cut off the branch of the carotid artery. The blood supply to the carotid body aneurysm comes from the external carotid artery. Therefore, in order to reduce intraoperative bleeding, complete dissection of the proximal cranial and proximal cardiac ends of the external carotid artery should be strived for as early as possible, followed by separation of the tumor base. In conclusion, according to the general operation order, the separation of the branch should be performed last, because this part has the tightest adhesion and is most likely to damage the arterial wall. In case of intraoperative rupture and bleeding of the internal artery of the common carotid artery, the vascular breach should be repaired with temporary blockage of blood flow; the duration of temporary blockage should generally not exceed 3 min each time.
For carotid body aneurysms that cannot be separated and completely resected, some advocate leaving a small portion of the aneurysm intact; others advocate resection of a branch of the carotid artery and anastomosis of the internal and external carotid artery stumps. Because of the possibility of cerebral complications after carotid artery resection, some people advocate vein or artificial vessel grafting and carotid artery reconstruction in cases where the superior segment of the internal carotid artery is isolated; however, in cases where sufficient internal carotid artery stumps cannot be preserved, only ligation and severance of the common carotid artery can be performed.
Dietary care
1. Soft and firm foods Jellyfish, kelp, seaweed, sea cucumber, abalone, etc. in seafood. The river products, such as Ulva, can also soften the firmness. The snapper, turtle, also has a soft effect, and a certain role in clearing heat and nourishing Yin.
2, blood activation food. According to Chinese medicine, many tumors can be manifested as blood stasis. The treatment is based on blood circulation and blood stasis medicine. Crab can relieve blood stasis and disperse blood, which is very suitable for cancer with blood stasis. Crab claws and shells also have the function of breaking blood. Hawthorn can help digestion and also has the function of invigorating blood.
3.Relief foods such as orange peel, kumquat, Buddha’s hand, lemon peel, etc.
4.Dissipative foods Radish can eliminate food and dissolve
Preventive care
This disease has no effective preventive measures, early detection and early diagnosis is the key to the prevention and treatment of this disease. Pathogenesis, etiology is currently unclear, unilateral lesions generally have no family history, but most bilateral carotid body aneurysms can have a family history. It has been found that the incidence of carotid body aneurysm is relatively higher in the plateau area of 2000-4000m above sea level; this may be due to the chronic hypoxic condition in the plateau area stimulating the carotid body to cause tissue proliferation, which gradually grows into a tumor.
Disease diagnosis
Carotid sympathetic nerve sheath tumor Carotid body tumor is most easily confused with carotid sympathetic nerve sheath tumor. Deep carotid body aneurysm can often compress the carotid sympathetic nerve, which can lead to Horner’s syndrome; while high carotid sympathetic nerve sheath aneurysm can also grow toward the pharynx; therefore, the two can be misdiagnosed each other, and carotid arteriogram is often required to confirm the diagnosis.
2. Carotid bifurcation dilatation This is a mild dilatation of the carotid bifurcation area, which is easily misdiagnosed as carotid body aneurysm or carotid artery aneurysm. This disease is mostly seen in middle-aged and elderly people, and can be identified by experienced vascular surgeons in general. When the proximal common carotid artery is compressed, the dilated area may immediately shrink or disappear. No special treatment is usually required.
Investigation methods
Laboratory tests.
Tumor morphology can be divided into 2 types, one is confined type, where the tumor is located in the outer sheath of the bifurcation of carotid artery; the other is encapsulated type, which is more common, where the tumor is located at the bifurcation of common carotid artery and grows around encapsulating the common, internal and external carotid arteries, and does not involve the middle layer and intima of carotid artery. However, the tumor may enlarge and compress the carotid artery and cause cerebral ischemia. Sometimes the tumor may involve the peripheral tissues such as the internal jugular vein and the Ⅸ, X, D and Ⅻ pairs of cerebral nerves and cause corresponding symptoms.
The tumor has no obvious envelope and is an oval or irregular shaped tiny pink tissue with medium texture and rich trophoblastic vessels. The blood supply mainly comes from the external carotid artery and returns through the pharyngeal and lingual veins, which are innervated by the glossopharyngeal nerve. Microscopically, the cells were nest-shaped and arranged around the vascular fibrous septum. Histological examination does not allow differentiation between malignant and benign. Lymphatic or distant metastases and local recurrence after resection are the main features of malignancy. Malignancy accounts for approximately 10% of cases.
Other ancillary tests.
Biopsy is contraindicated for carotid body aneurysms. However, carotid arteriography should be performed routinely, and digital subtraction arteriography (DSA) techniques are commonly used. The typical carotid body aneurysm radiographic manifestations are: the tumor displaces the carotid artery laterally; the carotid bifurcation widens or there is a small traffic branch from the carotid artery to the tumor.
Color ultrasonography can help detect this disease. And selective carotid angiography can make a definite diagnosis. The angiographic diagnosis of carotid body tumor has the following features: 1. The angle of bifurcation of internal and external carotid arteries is cup-shaped and enlarged. 2. There are abundant fine blood vessels inside the tumor. 3. The blood supply of the tumor mainly comes from the bifurcation area of external carotid artery and common carotid artery.
Carotid body aneurysm has rich blood supply and has its characteristic MRI and MRA manifestations. Reliable signs are: (1) a mass occurring at the bifurcation of carotid artery, MRI shows flow-space signal; (2) MRA shows tumor (trophoblastic) vessels; (3) Gd-DTPA dynamic enhancement examination, the tumor is obviously and continuously enhanced.
MRI has an important diagnostic value, and MRA and enhanced MRI are complementary examinations, which are important for showing the extent of the mass, the relationship between the mass and blood vessels, and preoperative planning, in addition to helping to confirm the diagnosis. The author believes that MRI and MRA can be used as routine examinations for carotid body aneurysms, and enhanced MRI can be used as a complementary examination method.
Complications
In a few cases, carotid sinus syndrome occurs, in which the tumor compresses the carotid sinus due to the change of body position, causing upright vertigo, epigastric discomfort and transient loss of consciousness. In a few cases of malignant carotid body tumor, tumor compression and infiltration of peripheral nerves may lead to hoarseness, choking and coughing (vagus nerve invasion) and inferior lingual nerve invasion causing paralysis of the inferior lingual nerve resulting in tongue muscle atrophy and limited tongue movement.
Prognosis
Surgery is the main treatment, because of the slow growth of this tumor, the risk of surgery is high, smaller ones can be followed up and observed, but the tumor increases, increasing the difficulty of surgery and mortality. Carotid body tumor is insensitive to radiotherapy, which makes the tumor shrink, but increases the possibility of malignancy and makes it difficult to separate the tumor during surgery. Most tumors can be removed from the common or internal carotid artery. The external carotid artery should be ligated to avoid damage to the Ⅸ, X, D and Ⅻ cerebral nerves. Injury to the common or internal carotid artery can be ligated or reconstructed, and the mortality rate of common carotid artery ligation is 30% to 50%.