A review of the current clinical applications of a variety of percutaneous and endovascular interventional procedures of the extracranial head and neck is presented. After a description of general principles and embolic agents for interventional procedures, management of specific disorders is presented and procedural steps are described for epistaxis, embolization of vascular head and neck tumors, high-flow and low-flow cervical vascular malformations, head and neck trauma and bleeding, radiofrequency ablation and cryoablation of tumors, along with percutaneous biopsy within the head and neck.
Key Points
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Interventional Neuroradiology can play a vital role in the diagnosis and treatment of vascular and non-vascular pathology in the head and neck. Continuing advancements in and increasing awareness of this field have allowed for the assessment and treatment of epistaxis, hypervascular tumors, vascular malformations, trauma, and bleeding in the head and neck. Percutaneous image guided interventions include biopsy and sclerosis. Radiofrequency ablation and cryoablation of head and neck tumors are evolving disciplines.
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The most common dangerous vascular anastomoses in the head and neck involve communications of the internal carotid artery and/or vertebral artery with the first-order and second-order branches of the external carotid artery; these anastomoses may not be evident on an initial angiogram but may reveal themselves as changes in local blood flow occur during embolization.
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Complications resulting from the described treatments are usually minor, including groin hematoma, facial numbness or pain, mucosal necrosis, and sinusitis. Serious major complications can be associated with head and neck embolization procedures if care is not taken to identify dangerous vascular anastomoses.
Introduction
Interventional neuroradiology is a rapidly evolving field encompassing several procedures that can be valuable assets in the diagnosis, treatment, and surgical management of a variety of disorders affecting the extracranial head and neck. Continuing advancements in medical imaging and devices have allowed the interventionalist to perform procedures not possible only 1 to 2 decades ago. New embolic materials, guide catheters, microcatheters, stents, and other devices have resulted in expanding applications of this discipline in treating both intracranial and extracranial vascular lesions of the head and neck. The minimally invasive nature of the field is a driving force for embracing novel methods to treat these abnormalities. With the use of high-quality imaging and meticulous technique, the incidence of major complications can be very low.
Interventions in the head and neck can be performed via a percutaneous, endovascular, or combination approach. Procedures that typically require percutaneous access include biopsies, aspirations, sclerotherapy, and relatively newer techniques, such as radiofrequency ablation and cryoablation. An endovascular approach is used to treat vascular pathology, such as dissection, pseudoaneurysm, arteriovenous fistula, and bleeding, as well as in the presurgical treatment of hypervascular tumors of the head and neck, such as paragangliomas, juvenile nasopharyngeal angiofibroma, and other tumors. Transarterial chemotherapy administration for head and neck neoplasms is another growing application. A combination percutaneous and endovascular approach may be needed in the embolization of high-flow craniofacial vascular malformations (VMs) and hypervascular tumors. This article provides a review of the current clinical applications of a variety of percutaneous and endovascular interventional procedures of the extracranial head and neck.
General principles
A thorough understanding of cross-sectional and vascular anatomy with a keen awareness of collateral pathways and potential collateral pathways between the extracranial and intracranial vessels is essential for ensuring safe and successful endovascular procedures in the head and neck. Anastomotic pathways exist between the external carotid artery (ECA), internal carotid artery (ICA), vertebral artery (VA), ophthalmic artery, ascending cervical artery, deep cervical artery, and spinal arteries. The most common dangerous anastomoses involve communications of the ICA and/or VA with the first-order and second-order branches of the ECA, such as the ascending pharyngeal artery, occipital artery, middle meningeal artery, accessory meningeal artery, and internal maxillary artery. These anastomoses may not be evident on an initial angiogram but may reveal themselves as changes in local blood flow occur during embolization. Moreover, branches of the ECA serve as the primary blood supply to many of the cranial nerves; palsies of cranial nerves V, VII, IX, X, XI, and/or XII may result from inadvertent embolization of feeding branches to the vasa nervorum. The middle meningeal artery supplies the vasa nervorum of cranial nerve VII. The ascending pharyngeal artery provides supply to the vasa nervorum of cranial nerves IX, X, XI, and XII via its posteriorly directed neuromeningeal trunk. Appropriate selection of embolic agents, and, if necessary, provocative testing before embolization, may help avoid damage to the cranial nerves.
Embolic Agents
Embolic agents are classified into the categories of mechanical devices, particles, and liquids. The optimal embolic agent may be chosen depending on hemodynamic and angioarchitectural factors.
Mechanical devices
Mechanical devices include balloons, which are useful in the permanent occlusion of large vessels, such as the carotid and vertebral arteries, and are useful in transarterial embolization of large direct arteriovenous fistulas. Detachable coils can be deployed by means of electrolysis and are primarily used for embolization of intracranial aneurysms. They can also be used in the embolization of arteriovenous fistulas to safely form the initial meshwork into which pushable coils will be placed. Pushable coils tend to be more thrombogenic and less expensive than detachable coils and can be used to occlude relatively larger vessels, such as the ICA or VA, which may be desirable in certain clinical scenarios, such as trauma.
Particles
Particles, such as polyvinyl alcohol particles, embospheres, or gelfoam, can be used for the embolization of hypervascular tumors and in the treatment of epistaxis, as they are able to penetrate into the small vascular interstices of these lesions while allowing for delayed recanalization of embolized tissue and, thereby, also diminishing the risks of nontarget tissue embolization. The tendency to recanalize can be advantageous in the setting of nontarget embolization, as opposed to nontarget embolization with permanent embolic agents. Choosing particulate size is dependent on multiple factors. Larger particles tend to embolize more proximally than smaller particles and, thereby, may avoid ischemic complications to nontarget tissue seen with smaller particles and with permanent liquid embolics. This is because small particles or liquid embolic agents can penetrate capillaries, such as the vasa nervorum beyond the point of effective anastomoses and, therefore, induce nerve ischemia. Small particles, on the other hand, by penetrating into the tiny vascular interstices of target hypervascular lesions, can more optimally embolize target tissue. If an arteriovenous shunt within an arteriovenous malformation (AVM), fistula, and/or hypervascular mass is larger than the particle diameter being used, the particles may travel through the lesion and embolize to the lungs.
Liquids
Liquid embolic agents include cyanoacrylates, ethylene vinyl alcohol copolymer (EVAC), dehydrated ethanol, Ethibloc (Ethnor Laboratories, Norderstedt, Germany), and sodium tetradecyl sulfate. Cyanoacrylates, such as N-butyl cyanoacrylate ( n -BCA), also commonly referred to as “glue,” are not entirely permanent but are one of the longest lasting embolic agents and are generally referred to as “permanent” agents. Glue polymerizes on contact with ionic solutions, such as saline or blood, and can be difficult to use for a nonexperienced operator. Polymerization time can be controlled by the addition of various concentrations of ethiodol. Nevertheless, delivery of glue demands extensive familiarity with the substance and with the procedure and careful control of polymerization time, velocity of injection, and microcatheter manipulation. Inherent in the use of glue is the risk of gluing the microcatheter in place in the vessel with the associated risks of thrombosis or vessel rupture. To avoid gluing the microcatheter into the vessel, the operator must inject glue relatively quickly and continuously, thereby often sacrificing precise control.
Onyx
EVAC, also known by its trade name of “Onyx,” is a liquid embolic agent that was approved by the Food and Drug Administration in 2005 for the use of endovascular embolization. Similar to glue, Onyx polymerizes when injected into the vasculature. It is delivered as a mixture in solution with dimethyl sulfoxide (DMSO). It is radiopaque and is manufactured in established concentrations and viscosities. The least-concentrated Onyx solution is the least viscous and is expected to have the most distal penetration.
Onyx has several advantages over glue. Onyx carries a lower risk of gluing the catheter into the vessel because of its cohesive and yet nonadhesive properties. Injection of Onyx can be performed slowly for precise delivery. Injection of EVAC can be and is often stopped intermittently to check the degree of embolization. In contrast to glue, Onyx is advanced as a single column, thereby lowering the risk of involuntary venous migration. Onyx has less tendency to fragment in high-flow lesions. These characteristics of Onyx make embolization with this material more controllable and, according to many users, safer in comparison with glue.
Onyx does have its own drawbacks. Long injection times require prolonged exposure to xray fluoroscopy. Rapid injection of DMSO or Onyx can induce vasospasm, which can hinder Onyx penetration or even trap the catheter within the vessel. DMSO is angiotoxic if not used appropriately. Onyx cannot always be injected a long distance in a small-diameter or slow-flow vessel. Onyx injection into a large arteriovenous fistula does entail risk of unwanted venous migration, although glue and particles carry this risk as well. To overcome this limitation in high-flow lesions, partial embolization can first be performed with coils to slow the blood flow and provide a meshwork before embolization with other agents. Embolization with DMSO and Onyx can be painful, and general anesthesia is often recommended to provide patient comfort and prevent patient movement. Onyx embolization requires the use of special DMSO-compatible microcatheters. The microcatheter cannot be reused and has to be changed after each vessel embolization. Microcatheters for the use of glue also have to be changed after each vessel embolization. Embolization with particles, on the other hand, does not require the changing of microcatheters after each embolization.
Endovascular management of epistaxis
Epistaxis is a common clinical problem, with 60% of individuals in the normal population experiencing an episode of varying severity in their lifetime. Epistaxis can be managed conservatively in most cases; only 6% of cases require medical or surgical attention. Intractable epistaxis is relatively uncommon. The idiopathic or spontaneous form of epistaxis is the most common cause, accounting for at least 70% of cases and is often related to cigarette use, hypertension, and atherosclerotic disease. Other causes of epistaxis include hereditary hemorrhagic telangiectasia (HHT), craniofacial trauma, infections, tumors, bleeding disorders, vascular abnormalities, and anticoagulation therapy.
In most of these cases, findings of angiography will be normal. Although hypervascularity is commonly seen, angiographic demonstration of the point of extravasation is rare. This normal initial angiographic finding may relates in part to the nasal packing material that is generally in place to tamponade bleeding.
The arterial supply to the nasal fossa involves branches from both the ECA and ICA. The terminal branch of the internal maxillary artery (IMA), the sphenopalatine artery, provides the dominant supply to the nasal cavity. The roof of the nasal cavity is supplied by the anterior ethmoidal artery (AEA) and posterior ethmoidal artery, which branch off the ophthalmic artery. The floor of the nasal cavity is supplied by the ascending palatine artery and decending palatine artery, branches of the facial artery and IMA, respectively. Minor supply is provided anteriorly by the superior labial artery, a branch of the facial artery, and posteriorly by branches from the ascending pharyngeal artery ( Fig. 1 ).
Epistaxis in Anterior Septal Area (Little Area)
Most cases of epistaxis arise from the anterior septal area, also known as the Little area. This area is vascularized by the Kiesselbach plexus, which is supplied by second-order branches of the ECA, including the sphenopalatine artery, descending palatine artery, and superior labial artery, as well as the anterior and posterior ethmoidal arteries (see Fig. 1 ). Hemorrhage from this region can usually be managed by applying pressure to the nostrils, chemical or electrocautery, topical hemostatic or vasoconstricting agents, cryotherapy, hot water irrigation, or anterior nasal packing together with the management of underlying risk factors, such as hypertension and oral anticoagulation.
Epistaxis from Posterior Nasal Cavity
In only approximately 5% of cases, the origin of the epistaxis lies more posteriorly on the nasal cavity, causing these initial measures to fail. In most cases, an attempt will be made to control such posterior bleeding with the application of anterior and posterior packs. These packs should be applied with care because they can lead to nasal trauma, cartilage necrosis, vagal response, aspiration, infection, sepsis, and airway obstruction, which can lead to hypoxia, cardiac arrhythmia, myocardial infarction, and, rarely, even death. The success rate of nasal packs in this setting has been reported to lie between 48% and 83%. In the remaining patients, bleeding either continues despite packing or recurs after removal of the packs. Subsequent treatment can consist of either surgical ligation or endovascular embolization of the arteries supplying the posterior nasal fossa. Historically, the definitive treatment for intractable posterior epistaxis consisted of transantral surgical ligation of branches of the IMA, with or without ligation of the AEA. A failure rate of up to 24% has been described with this technique. Endoscopic surgical procedures have been described more recently for direct cauterization of the active bleeding site or ligation of the sphenopalatine artery.
Endovascular Embolization for Epistaxis
Endovascular embolization for epistaxis is an effective alternative to surgery and is associated with few complications. The procedure was first presented as an alternative to surgery by Sokoloff and colleagues in 1974 and consisted of particle embolization of the ipsilateral IMA. The technique was later refined by Lasjaunias and colleagues, stressing the need for a standardized angiographic and therapeutic approach. It has gained increased acceptance, and several large series have been reported.
Reported success rates range from 71% to 100%. The ability to halt bleeding with embolization therapy immediately following the procedure has been reported to be between 93% and 100%. When early rebleeds were taken into account, the success rate dropped to 77% to 95%. Retrospective reviews that took late rebleeds into account reported a further drop in the success rate to 71% to 89%. In general, these success rates best represent the results in idiopathic posterior epistaxis. Failure of endovascular treatment of epistaxis is often related to continued bleeding from the ethmoidal branches of the ophthalmic artery ( Fig. 3 A). Embolization of these branches is relatively contraindicated because ophthalmic artery embolization carries a risk of blindness ( Fig. 2 ). The ethmoidal vessels can, however, be surgically ligated, as they perforate the medial wall of the orbit. In comparison, the failure rate of surgical ligation to treat intractable epistaxis has been reported to be between 4.3% and 33.0%. Success rates are comparable between surgical ligation and embolization.
Endovascular Embolization Procedure
The endovascular embolization procedure can often be done safely using either conscious sedation or general anesthesia.
Selective angiography of the bilateral ICAs and ECAs is first performed with 4F or 5F catheters. In a minority of cases, this may reveal specific abnormalities indicating the cause and location of the hemorrhage. These include contrast extravasation, a tumor blush, a vascular malformation, a traumatic pseudoaneurysm, or another unusual ICA source of epistaxis ( Figs. 2 , 3 and 4 ). Furthermore, angiography enables identification of vascular anomalies, variants, or anastomoses between the ECA and ICA and/or ophthalmic artery that could increase the risk of complications, such as stroke or blindness during embolization. Embolization through the ICA, ophthalmic artery, and ascending pharyngeal artery is not considered safe. Although uncommon, embolization of the ophthalmic artery can occur if it is supplied by the ECA instead of the ICA. Therefore, one can confirm the choroidal blush from the ICA before embolization. The angiographic findings may influence the embolization protocol or even lead to aborting the procedure.
In idiopathic cases of bleeding, a routine embolization protocol is used, with the goal of diminishing flow to the bleeding mucosa but allowing sufficient collateral flow to avoid mucosal necrosis. The most important vessel to embolize is the ipsilateral IMA and its branches. Because of anastomoses between the ICA and ECA described previously, embolization should be performed only with a stable microcatheter position sufficiently distal to the origins of the accessory meningeal artery and the middle meningeal artery. Placing the microcatheter distal to the middle deep temporal artery also may avoid postembolization pain and trismus. Additional embolization of the ipsilateral facial artery has been reported to increase the success rate. In this case, the catheter should be placed beyond the submandibular artery to avoid embolization of the submandibular gland. Some investigators will also embolize the contralateral IMA and even the contralateral facial artery, especially when these show substantial collateral supply.
The microcatheter is positioned just proximal to the branches supplying the nasal mucosa, and care is taken to avoid nontargeted vessel embolization. Embolization is performed by injecting a suspension of embolic and contrast material under fluoroscopic guidance until significant flow reduction is noted in the artery and its branches. Injection of embolic material should be gentle to avoid reflux of embolic material into dangerous anastomoses. A wedged catheter position should also be avoided, as this may allow buildup of injection pressure with the subsequent opening of potential dangerous anastomoses.
Embolization is generally performed using particles sized 150 to 500 μm. If smaller particles (50–150 μm) are chosen, they are typically used in small quantities because aggressive embolization with small particles is associated with a risk of necrosis of the embolized territory, owing to the greater degree of distal penetration of particles into tiny mucosal vessels; smaller particles are also more likely to enter dangerous anastomoses. Gelfoam pledgets may be placed in the vessel lumen after completing embolization with particulate agents. Permanent occlusion of vessels with mechanical devices, such as coils, is avoided in patients with epistaxis unless the bleeding is related to trauma, pseudoaneurysm, or nasal AVMs, because permanent occlusion of vessels in epistaxis will not allow the operator access for reembolization of the target territory should bleeding recur because of collateral flow and/or intrinsic regrowth of vascular pathology.
Complications with Endovascular Embolization
Complications resulting from the treatment are usually minor, including groin hematoma, facial numbness or pain, mucosal necrosis, and sinusitis. A cerebrovascular accident or blindness can occasionally occur as a complication of the treatment, although the incidence of this complication is very low. Serious major complications can be associated with embolization if care is not taken to identify dangerous vascular anastomoses. Larger series report minor transient complications in 25% to 59% of cases, major transient complications in 0% to 1% of cases, and persistent complications in 2% or fewer cases. With the advent of endoscopic surgery, complication rates of surgery have decreased, with only minor complications being reported. Thus, success and complication rates are comparable between surgical ligation and embolization.
Hereditary Hemmorhagic Teleangiectasia
Recurrent bleeding is not uncommon in patients with HHT; however, embolization often decreases the severity of hemorrhage and improves the quality of life in these patients. The difficulty in treating recurrent epistaxis in patients with HHT is reflected by the multitude of reported treatment options, including chemical, electrical, or ultrasonic cauterization; local or systemic hormone therapy; topical application of fibrin glue; photocoagulation; transarterial embolization; brachytherapy; septal dermoplasty; vessel ligation; bleomycin injections; and the use of nasal obturators. Because none of these provide a definite cure, treatment is aimed at reducing the number and severity of epistaxis episodes. Although transarterial embolization may achieve this goal, recurrence rates requiring reembolization or surgery are generally higher in patients with HHT than in patients without HHT. Therefore, permanent proximal occlusion with coils is not advised because this may preclude reembolization when distal collaterals result in recurrent bleeding episodes. Embolization at a time when the patient is not actively bleeding will generally not yield long-term control.
Embolization of vascular head and neck tumors
The tumors that most frequently require embolization in the head and neck include glomus tumors, angiofibromas, and meningiomas. Other tumors that may benefit from preoperative embolization include hypervascular metastases, esthesioneuroblastomas, schwannomas, rhabdomyosarcomas, plasmacytomas, chordomas, and hemangiopericytomas.
Preoperative embolization has been shown to be cost-effective and tends to shorten operative time by reducing blood loss and the period of recovery. Moulin and colleagues demonstrated a statistically significant difference in blood loss between embolized and nonembolized surgical groups of patients with high-grade tumors. The benefit is less clear for smaller, less vascular tumors. Embolization is ideally performed 24 to 72 hours before surgical resection to allow maximal thrombosis of the occluded vessels and to prevent recanalization of the occluded arteries or formation of collateral arterial channels.
Blood supply to tumors of the head and neck is derived primarily from branches of the ECA, which can vary greatly in size depending on local tumoral influences. Additional recruitment of vascular supply may develop from the VA, ICA, and thyrocervical and costocervical trunks.
Treatment consists of performing detailed angiography, including selective injections of the ICA and the ECA. A microcatheter is advanced into the artery supplying the tumor and angiography is performed to assess flow dynamics and to identify any potentially dangerous vascular anastomoses. The embolic agent is then injected under constant fluoroscopic monitoring, making sure to avoid both reflux of embolic material and possibly opening of previously occult potential anastomoses. Ideally, the embolic material is deposited at the arteriolar/capillary level. If there is arteriovenous shunting, particle size may need to be increased to prevent passage into the venous side. Proximal arterial occlusion alone is inadequate because it allows arterial collateralization into the tumor bed between the time of embolization and surgery and may make surgical resection more difficult. If critical anastomoses are present, the anastomotic connection may first be occluded with coils followed by particulate embolization of the tumor.
Embolization of Vascular Head and Neck Tumors with Particles
Particles are most frequently used at our institution for the embolization of hypervascular head and neck tumors. Small particles, such as those in the 100-um to 300-um range, allow more distal penetration into the tumor bed and better devascularization. One should always be aware of the possible risk of devascularizing the cranial nerves with small particles that may penetrate into the tiny vasa nervorum, however. Therefore, when embolizing the arterial pedicles that might also supply the cranial nerves (for example, the stylomastoid branch of the occipital artery or neuromeningeal trunk of the ascending pharyngeal artery), increasing particle size to 300 to 500 μm is generally preferred. Smaller particles may also increase the risk of tumoral hemorrhage and swelling. In addition, undesired embolization of normal ECA territory tissue can cause harm to mucosa, tongue, larynx, and orbit. Anastomoses to the ophthalmic and central retinal arteries may exist from the IMA, middle meningeal artery, facial artery, and superficial temporal artery. Of utmost concern during embolization of a juvenile nasopharyngeal angiofibroma, for example, is central retinal artery occlusion secondary to the presence of dangerous collaterals from the IMA into the orbit via nasal to ethmoidal and/or other potential collateral pathways.
Embolization of Vascular Head and Neck Tumors with Liquids
Liquid embolic agents are generally not used in this setting via a transarterial approach because liquid has greater potential to occlude the vasa nervorum of the cranial nerves and may also pass through tiny anastomoses into the intracranial circulation. Moreover, the advantageous permanent quality of liquid embolics need not be used in this setting if surgical resection of the embolized tumor is planned to be within 24 to 72 hours postembolization.
Embolization of Vascular Head and Neck Tumors with Percutaneous Puncture
Direct percutaneous puncture under fluoroscopic guidance, computed tomography (CT), or sonography has also been described to embolize head and neck tumors. This method was initially reported for use in tumors in which conventional transarterial embolization was technically impossible because of the small size of the arterial feeders or in the setting of dangerous vascular anastomoses to the ICA or VA. Excellent results obtained by this technique have extended its application to smaller and less complex tumors. Direct and easy access to the vascular tumor bed that is not hampered by arterial tortuosity, small size of the feeders, atherosclerotic disease, or catheter-induced vasospasm is the main advantage of this direct percutaneous technique. Complete or near complete devascularization of the tumor can be obtained with decreased risk to the patient by direct tumoral injection of n -BCA or Onyx ( Fig. 5 ). Serious complications occur in fewer than 2% of patients and include dangerous nontarget migration of embolic material. These are usually related to particle reflux, poor technique, or nonvisualization of dangerous anastomoses resulting in blindness or irreversible neurologic deficits.
