Carotid body tumors

Abstract

Carotid body tumors are rare, slow-growing, hypervascular neuroendocrine tumors. Although these tumors are benign neoplasm, they also have a tendency to malignant transformation. Complete surgical excision is the gold standard therapeutic modality for the treatment of carotid body tumors. Early surgical removal is recommended to prevent the development of larger and more advanced tumors, which are associated with higher morbidity and mortality. In this report, we presented three cases of carotid body tumor which were successfully treated with complete surgical excision, and reviewed the current literature. Furthermore, it was emphasized the necessity of early surgical management regardless of patient age and tumor size.

1. carotid surgery Carotid Body Tumors E dited by KARAR A.ALI

2. The carotid body is the largest mass of chemoreceptor tissue in the body. It is located within the periadventitia of the posterior surface of the carotid bifurcation. The normal carotid body is ovoid in shape and approximately 5 mm in its longest dimension. It usually receives its blood supply through branches of the external carotid artery. Blood returns through tributaries of the lingual and laryngopharyngeal veins. The carotid body derives sensory innervation through small nerve fibers from the glossopharyngeal nerve

3. Abstract Carotid body tumors are rare paragangliomas that arise from the chemoreceptive tissue located at the carotid bifurcation. Most carotid body tumors are benign ; although, aggressive local invasion or malignant transformation have been observed . Carotid body tumors are typically discovered as asymptomatic neck masses. Diagnosis is confirmed with imaging studies, such as duplex ultrasound, computed tomography scanning, magnetic resonance imaging, and conventional angiography. Surgical resection is the recommended treatment for patients with acceptable perioperative risk

4. PATHOLOGY Carotid body tumors are also known as carotid chemodectomas, carotid paragangliomas, and glomus tumors. They represent neoplastic growths of the chemoreceptive tissue. These tumors belong to the family of paragangliomas, which are neoplastic tumors that occur along the autonomic ganglion chain from the head to pelvis. Within the head and neck, carotid body tumors are the most common type. Other cervical paragangliomas include the glomus tympanicum, glomus vagale, and glomus jugulare

5. Carotid body tumors belong to the family of paragangliomas, which are neoplastic tumors that occur along the autonomic ganglion chain from the head to pelvis. Carotid body tumors are the most common of the cervical paragangliomas. Others include the glomus tympanicum, glomus vagale, and glomus jugulare. The circles represent the relative incidences of these cervical paragangliomas.

6. As carotid body tumors enlarge, they distort the carotid bifurcation and splay the internal and external carotid arteries, known as the “lyre sign” seen on angiography. Large tumors often encase the external carotid artery, but rarely wrap around the internal carotid artery.

7. CLINICAL PRESENTATION Carotid body tumors most commonly present as asymptomatic neck masses located below the angle of mandible. On palpation, the lesions are firm, smooth, and lobulated, and are characteristically mobile laterally but fixed longitudinally due to their association with the carotid artery. Carotid pulsation may be transmitted through the mass, and approximately 30% to 40% of patients may have an audible bruit over the tumor. Very large carotid tumors may cause compression or local invasion, leading patients to present with nonspecific symptoms, such as localized tenderness, fullness, numbness, dysphagia, hoarseness, chronic cough, and tinnitus. Tumors rarely produce cranial nerve dysfunction, and if there is involvement, symptoms are typically associated with the vagal, hypoglossal, and cervical sympathetic nerves. Occasionally, Horner syndrome has been reported with this tumor. Patients may complain of dizziness, but lateralizing neurologic signs are uncommon

8. The differential diagnosis for neck masses is broad, and includes congenital lesions (vascular malformations, branchial cleft cysts, hygromas), inflammatory disorders (chronic lymphadenitis, reactive lymphadenopathy), infection (viral, bacterial, and parasitic lymphadenopathy ), benign lesions (lipomas, cysts, parotid,and salivary tumors), and malignancies (metastatic head and neck cancer, lymphoma). Other vascular lesions (carotid artery aneurysms, kinks, and coils) and cervical paragangliomas (glomus jugulare and glomus vagale) may also present as neck masses.

9. Vascular malformations can cause cosmetic deformities of the head and neck and can interfere with normal function in these areas. They also occur in other areas of the body and can cause pain, swelling, and bleeding

10. A cystic hygroma is a fluid-filled sac that results from a blockage in the lymphatic system . It is most commonly located in the neck or head area,

11. chronic cervical lymphadenitis in children

12. Due to the highly vascular nature of the carotid body tumor, percutaneous needle biopsy and incisional biopsies are contraindicated . Risks include hemorrhage, hematoma, pseudoaneurysm, and injury to adjacent neurovascular structures. Furthermore, the ability to confirm the diagnosis with high-quality imaging renders further diagnostic tests, including biopsy, unnecessary

13. Carotid body tumors radiology

14. Radiographic features Carotid body tumors are located at the carotid bifurcation with characteristic splaying of the ICA and ECA , described as the lyre sign . In all modalities, the dense vascularity of these tumors is manifested as prominent contrast enhancement. CT Contrast-enhanced CT is excellent at depicting these lesions. Typical appearances are: soft tissue density on non-contrast CT (similar to muscle) bright and rapid (faster than schwannoma) enhancement splaying of the ICA and ECA circumferential angle of contact of tumor with ICA could also be categorized under the Shamblin group system as group I : <180 degrees of encasement group II : 180-270 degrees of encasement group III : >270 degrees of encasement helps in deciding the risk of ICA adventitial involvement and possible need of ICA resection followed by grafting required in group III cases

15. There is a highly vascular mass measuring 3.6 x 3.3 cm in the left carotid space situated between and splaying the external and internal carotid arteries (the lyre sign ).  The external carotid artery is totally encased by the tumor, the internal carotid artery is not completely encased.Albeit that, both arteries do not show signs of narrowing of their lumens.

16. MRI T1 iso to hypointense compared to muscle salt and pepper appearance when larger, representing a combination of punctate regions of hemorrhage or slow flow (salt) and flow voids (pepper) 3 intense enhancement following gadolinium T2 hyperintense compared to muscle salt and pepper appearance

17. MR T2-weighted sequential STIR images for carotid splaying

18. Carotid body tumor Ultrasonography: Round to oval well define heterogeneously hypoechoic mass in the lateral neck with splaying of the common carotid artery. Small vessels can be demonstrated within the mass Differential diagnosis:   Nerve sheath tumors, nodal metastasis, abscess, vascular thrombosis. Rarely lipoma, liposarcoma, hibernoma. Treatment:  Surgical excision.

19. TREATMENT Surgical resection is the mainstay of treatment for carotid body tumors. Although these lesions tend to be small and slow growing, they are best treated early for several reasons: smaller tumors are easier to remove; most tumors can become locally invasive; lesions may grow distally into the skull or involve cranial nerves, complicating resection; and these tumors may develop malignant behavior. In the absence of prohibitive comorbidities, perioperative risks, or limited life expectancy, patients with carotid body tumors should undergo surgical resection as soon as the diagnosis is made.

20. Radiation therapy is another treatment modality for carotid body tumors, although its use as a primary or adjunct therapy remains controversial due to conflicting studies and lack of long-term follow-up. Carotid body tumors are traditionally considered not radiosensitive, and radiation is used for suppression. Preoperative radiation may render surgery more difficult due to fibrosis. Radiation therapy is usually reserved for patients deemed poor operative candidates, and for bulky, unresectable, or recurrent tumors. There are currently no effective chemotherapy treatments for carotid body tumors

21. The senior author does not advocate preoperative embolization. The disadvantages include the risk of inadvertent cerebral embolization and stroke. It also adds an additional invasive procedure with associated patient discomfort and increases the overall cost of care.

22. Percutaneous Embolization of Carotid Paragangliomas Using Solely Onyx

23. Anesthesia for this operation could potentially be either cervical block or general anesthesia, as is the case for other carotid artery operations. However, resection of carotid body tumors usually requires more time than carotid endarterectomy and tends to be more invasive, particularly with large tumors. As a result, it is difficult to maintain patient comfort and compliance during a technically demanding operation that requires all of the surgical teams’ attention to the operative field without the distraction that can occur with patient discomfort and restless movement. Therefore most surgeons prefer the more controlled setting of general anesthesia, with better airway management and reduced patient movement during the operation

24. pruitt-inahara shunt

25. Cerebral monitoring and protection should be used for carotid body tumor resection due to potential or planned internal carotid artery occlusion or reconstruction. The choices are to use EEG monitoring or routine shunting of the internal carotid artery. Internal carotid artery back pressure is not an option due to the inability to clamp the external carotid artery due to tumor involvement. If continuous EEG monitoring shows ischemic changes with clamping of the carotid artery, a Pruitt-Inahara shunt can be inserted

26. anatomy

27. Hypoglossal nerve

28. For larger tumors that are adherent to the external carotid artery (Shamblin group II), the vessel can be divided at its origin, and the proximal stump is oversewn at the point where it was circumferentially mobilized. This maneuver is useful in reducing blood loss, and it provides a handle to rotate the tumor and aid in the dissection. The external carotid artery is resected en bloc with the tumor For tumors that cannot be dissected from the bifurcation (Shamblin group III), the bifurcation and possibly the internal and external carotid arteries must be removed with the tumor. Vascular reconstruction for the internal carotid can be performed

29. it is our preference to use a 6-mm PTFE graft, because long-term patency in this position is well documented as opposed to vein grafts. If a carotid shunt is required, the vascular reconstruction can be performed by passing the shunt through the graft and removing the shunt before the second anastomosis is completed. In addition, if clamping of the common or internal carotid arteries must be performed, the patient should receive systemic heparin . If the neoplasm adheres to or encases nerves, attempts should be made to preserve the nerves, even by splitting the tumor. If it is necessary to split the tumor to preserve a cranial nerve, use of bipolar forceps is helpful for hemostasis.

30. A, Dissection of the carotid body tumor with the central carotid body tumor. B, The loop is around the common carotid A (arrow) and vessel loops around the internal carotid artery B (arrow), external carotid artery C (arrow), and superior thyroid D (arrow). The cranial nerves are also identified vagus X (arrow ), accessory XI (arrow), and hypoglossal XII (arrow). Postremoval of the tumor noting the splayed configuration of the carotid arteries. C, Gross specimen of the resected carotid body tumor. Note the anterior indentation (right to left) that represents the location of the carotid bulb location when the tumor was in situ.

31. Preoperative Preparation • Duplex ultrasound scans show a highly vascular mass that widens the carotid bifurcation. Concomitant carotid occlusive disease may be identified in patients at risk of atherosclerosis. • Fine needle aspiration or open biopsy of a suspected CBT are contraindicated because of the risks of hemorrhage or injury to the carotid artery. • Computed tomography (CT) and magnetic resonance imaging (MRI) scanning can be used to identify a CBT and estimate its size and extent. Proximity to other vital neck structures can be ascertained. CT scanning is particularly valuable in demonstrating the presence or absence of a plane between the internal carotid artery (ICA) and the tumor. CT may assist in the preoperative assessment as to whether the tumor can be removed without disruption of the ICA. Both CT and MRI scanning are useful in determining bilaterality, which occurs in approximately 5% of patients. • Angiography demonstrates the tumor’s blood supply and its relationship to neighboring vascular structures . CT angiography may be preferred over conventional angiography because of the lack of embolic risk . However, angiography has been used in conjunction with peroperative embolization of large tumors and balloon occlusion testing to determine whether the ICA can be ligated during resection, if required and reconstruction is not possible. • Prophylactic antibiotics should be administered. Invasive arterial blood pressure monitoring and intraoperative cerebral monitoring are recommended

32. Pitfalls and Danger Points • Cranial nerve injury is the most common complication and occurs most often with larger tumors. 8 • Stroke • Hematoma • Horner syndrome • First bite syndrome • Baroreflex failure

33. AVOIDING CRANIAL NERVE INJURIES Particularly with Shamblin’s Group II/III tumors, cranial nerve injury may be unavoidable and sacrifice of a cranial nerve may be required to facilitate a complete resection. However, steps should be taken to minimize injury by carefully identifying adjacent cranial nerves. To do so, comprehensive understanding of the regional anatomy is essential. The hypoglossal nerve (cranial nerve XII) exits the skull base via the hypoglossal canal and courses caudally between the internal jugular vein and the ICA . It passes medially over the ICA and ECA and posterior to the digastric muscle . There may be significant variability in the course of the hypoglossal nerve. Although typically found crossing the ICA and ECA about 2 to 4 cm cephalad to the carotid bifurcation, it can be found as caudal as the bifurcation or sometimes adherent to the posterior surface of the common facial vein.10 During CBT resection, the hypoglossal nerve is frequently encountered in the fascia overlying the superior aspect of the tumor

34. The vagus nerve (cranial nerve X) normally lies in a posterolateral position relative to the ICA, though occasionally it may be found in an anteromedial position, putting it at greater risk for injury. During CBT resection, the vagus nerve may be identified at its junction with the hypoglossal nerve and then followed caudally. As the vagus nerve courses inferiorly, it must be carefully dissected away from its intimate association with the tumor and the carotid artery. The superior laryngeal nerve can be found in the fascia posterior to the tumor. It courses posterior to the internal carotid artery with the external branch lying posterior to the superior thyroid artery. Injury to the external branch may cause impaired phonation and easy voice fatiguability . The recurrent laryngeal nerve courses in the tracheoesophageal groove and is typically well removed from the surgical field . Vocal cord dysfunction may result from vagal trunk injury.

35. The spinal accessory nerve (cranial nerve XI) and glossopharyngeal nerve (cranial nerve IX) are at risk during a resection that extends near the skull base . The spinal accessory nerve lies anterior to the most distal portion of the ICA and posterior to the stylohyoid muscle. It should be identified as it enters the sternocleidomastoid muscle. The glossopharyngeal nerve crosses anterior to the internal jugular vein and ICA near the skull base. The deep fascia of the tumor may be intimately associated with the sympathetic trunk. Sacrifice of this structure during resection may lead to Horner syndrome.

36. AVOIDING INTRAOPERATIVE STROKE A “no touch” technique should be used in handling the carotid bifurcation, particularly when atherosclerosis is present. With large tumors, this may not be possible. Heparin is used if carotid replacement is required

37. PREOPERATIVE EMBOLIZATION Preoperative embolization may reduce intraoperative blood loss,11 but improvement in clinical outcome has not been demonstrated.12 With the possible exception of tumors exceeding 4 to 5 cm in size preoperative embolization is not performed because the risk of embolism outweighs the benefit of reduced intraoperative blood loss. BIPOLAR ELECTROCAUTERY The use of bipolar electrocautery minimizes risk of injury to adjacent cranial nerves and is of particular value while separating the tumor from cranial nerves. Combined with a meticulous dissection, bipolar electrocautery can reduce intraoperative blood loss.

38. Countertension between the carotid body tumor (CBT) and the carotid bifurcation reveal the periadventitial white line, shown here as the tumor is dissected initially off the external carotid artery ( ECA ). The common facial vein is divided and ligated, and the internal jugular vein ( IJV ) has been retracted both posteriorly and laterally. The dissection proceeds circumferentially, cauterizing or ligating the vessels feeding the CBT as necessary. ICA , Internal carotid artery

39. A, The hypoglossal nerve (cranial nerve XII) (single arrow) and ansa cervicalis (double arrow) identified anterior to a carotid body tumor (CBT). The left portion of the image indicates the superior extent of the surgical field

40. This CBT has been dissected completely free (dashed line) and left in situ to demonstrate its anatomic relationship to the surrounding tissue. The hypoglossal nerve (single arrow) and vagus nerve (double arrow) have been dissected away from the tumor.

41. Resection of the Shamblin Type II/III Carotid Body Tumor As with resection of a Shamblin type I tumor, dissection is begun in the periadventitial plane and proceeds circumferentially when dealing with resection of a Shamblin type II/III tumor. As the tumor is mobilized and can be retracted with greater ease, feeder vessels are exposed and should be divided. With large tumors, early ligation and division of the ECA may aid resection. The devascularized ECA can then be clamped to serve as a “handle” to facilitate retraction of the CBT.

42. Resection should be limited to the periadventitial tissue and not extend through the media of the ICA. A compromised arterial wall puts the patient at risk for a postoperative carotid rupture. When the arterial wall is involved, or with a Shamblin type III tumor that envelops the ICA, dissection of the tumor should be continued, but its attachments to the ICA are preserved in anticipation of a carotid vein graft interposition. The sacrifice of cranial nerves is often unavoidable with larger Shamblin type II/III tumors, though unnecessary cranial nerve injury should be avoided. The hypoglossal nerve is frequently on the anterior surface of the CBT and at particular risk

43. When the tumor has been mobilized save the ICA, attention is turned to performing a carotid vein interposition graft. Size mismatch should be taken into account but is generally well accommodated by either a saphenous vein or a superficial femoral vein. The saphenous vein is the preferred conduit as long as it is judged to be of acceptable quality. The vein graft is harvested in the standard fashion, a straight carotid shunt may be placed through the graft, and systemic heparin is administered in preparation of carotid clamping. A clamp is placed on the common carotid artery caudal to the site chosen for resection, and the distal ICA is occluded with a bulldog clamp. The vessels are transected, and the specimen is submitted with the proper orientation clearly indicated for pathologic analysis. The vein graft, with the indwelling shunt, is introduced into the open ICA. The bulldog clamp is replaced with a Rummel tourniquet, and as backbleeding is allowed through the shunt, the proximal end is introduced into the common carotid artery. The proximal clamp is then removed, and a Rummel tourniquet is used for control.

44. The ICA and the adjacent end of the vein graft are both spatulated. Anastomoses are performed end to end, with the last several sutures in the anterolateral portion omitted to allow for later flushing. The vein graft is cut to length and spatulated to allow for the proximal end-to-end anastomosis to the common carotid artery. The vein graft should be shortened and stretched to the point of some tension in order to avoid having a redundant graft upon release of the clamps. The proximal anastomosis is subtotally completed to allow for shunt removal. The shunt is removed and the ICA and common carotid artery are again clamped. The proximal anastomosis is completed and the vein graft is flushed. The ICA is vented via the incomplete distal anastomosis, which is then completed ( Fig. 9-6 ). Because the saphenous vein graft is reversed, the final flushing is performed through the distal anastomosis to accommodate for the presence of valves. With more extensive tumor resections, placement of a closed suction drain may be considered. The platysma is closed with a running absorbable suture and the skin closed with a running subcuticular layer.

45. Postoperative Care • The patient should be observed overnight for development of a hematoma at the surgical site. Depending on the size of the tumor resection, the patient may be hospitalized for as little as 1 day or as many as 3 days. • The patient may resume a regular diet and is encouraged to ambulate on the first postoperative day. • Blood pressure is typically monitored via an arterial line for several hours in the recovery room. Systemic hypertension may require management in an intensive care unit (ICU) setting. • If the patient has had a previous CBT resection on the contralateral side, monitoring in the ICU is necessary because of the risk of baroreflex failure.

46. Postoperative Complications • Nerve injury. When cranial nerve injury has occurred, the patient should be evaluated by otolaryngology and a swallowing study. If unable to swallow safely, placement of a gastrostomy tube may be necessary. Cranial nerve recovery is expected over time, especially if the primary insult is a traction- or stretchrelated injury. • Stroke. Neurologic deficits may indicate a technical problem with the interposition graft. Urgent duplex imaging or operative reexploration should be undertaken in an effort to avoid permanent neurologic sequelae. • Hematoma. Any sizable hematoma requires reexploration in the operating room. • Horner syndrome. Operative injury to the carotid sympathetic chain can result in an ipsilateral Horner syndrome. If portions of the sympathetic chain remain intact, symptoms may improve over time.

47. • First bite syndrome. The first bite entity is characterized by severe cramping in the parotid region after the first bite of a meal and can be particularly severe in the early postoperative period. The pain typically improves with subsequent bites. A likely mechanism is damage to the cervical sympathetics that innervate the parotid gland.14 A diet of “bland” food may reduce symptoms. Refractory symptoms may warrant botulinum toxin injections into the parotid gland. • Baroreflex failure. The carotid sinus consists of baroreceptor tissue innervated via the nerve of Hering, which is a branch of the glossopharyngeal nerve. Bilateral CBT resection may disrupt the negative feedback mechanism of the carotid baroreceptor tissue, resulting in baroreflex failure. This entity can result in a life-threatening hypertensive crisis.15 Patients should be monitored in an ICU setting for 24 to 48 hours after bilateral CBT resection. Hypertensive episodes should be managed aggressively. In some patients continued blood pressure lability can be a significant detriment to the quality of life. Clonidine may reduce the “peaks” of the hypertensive episodes and with less of an effect during periods of normotension