General Description

Carotid blowout syndrome (CBS) refers to the signs and symptoms associated with the rupture of the extracranial carotid artery or one of its branches. It can be a life-threating complication of head and neck cancer and radiation therapy. CBS typically occurs in cases of head and neck cancers, with an estimated incidence of 4.3% in patients undergoing radical neck dissection. Risk factors for CBS include previous radiotherapy (particularly radiation-induced necrosis), recurrent tumors, and the presence of pharyngocutaneous fistulae. Symptoms of CBS are usually related to oral, nasal, or peritracheal acute bleeding or mass effect from a hematoma on laryngeal structures (e.g., respiratory compromise).

Prior to the advent of endovascular technology, treatment of CBS consisted of neck exploration and carotid artery ligation. Surgical exploration in the setting of a previously irradiated field, as is often the case in patients with CBS, is challenging and has been associated with unacceptably high rates of perioperative morbidity and mortality, reaching 40% and 60%, respectively. As such, surgical treatment of CBS has largely been abandoned in favor of endovascular techniques. The most common endovascular treatment strategies include carotid occlusion with coil and/or Onyx (Medtronic) embolization and carotid stent grafting. Technical success rates for both procedures are similar with comparable rates of periprocedural morbidity and mortality. Regardless of technique, the most frequent complication is carotid rebleeding, which occurs in roughly 25% of patients within 1 week of the procedure, although delayed rebleeding is not uncommon. Rebleeding may be more common in patients treated with stenting, whereas coil embolization may be associated with higher rates of postprocedure cerebral infarction, although the latter assertion is controversial. Reflected by an estimated median survival time of 3 months, the overall prognosis after treatment of CBS remains poor.

Indications

In general, presentations of CBS have been subdivided into one of three categories: (1) a self-limited, or sentinel, hemorrhage, (2) an exposed carotid artery representing a potential carotid blowout, and (3) uncontrolled hemorrhage resulting in hemorrhagic shock. The former two presentations are high risk for a subsequent life-threatening hemorrhage and warrant urgent endovascular intervention.

Neuroendovascular Anatomy

The internal carotid artery (ICA) normally originates from the common carotid artery (CCA) at the C3-4 or C4-5 level of the cervical spine. In general, the ICA is the larger of the two CCA branches. However, in the presence of neck or face malignancies, the external carotid artery (ECA) or one of its branches could be abnormally enlarged. The proximal ICA initially lays posterolateral to the ECA, then courses medial to the ECA as it advances upward. In pathological circumstances (e.g., neck cancer), the natural course, size, and overall anatomical characteristics of the ICA or the ECA can be altered and an arterial cerebral angiogram should be carefully studied. One must always be vigilant for aberrant anatomy (i.e., proatlantal persistent vessels) that could be disrupted during coil embolization, resulting in posterior circulation stroke.

The site of carotid blowout should be carefully identified, and it should be determined whether it is at the CCA, ICA, ECA, or one of the branches. The endovascular treatment varies according to the location of the arterial injury. The ECA or branches of the ECA can be endovascularly sacrificed without impunity and the need for further testing. If the site of carotid injury is at the CCA or ICA, further evaluation is needed, including the presence of collateral blood supply from the ECA and the contralateral and posterior circulation. A balloon test occlusion (BTO) should always be done before CCA or ICA sacrifice. If the patient passes the BTO, the CCA or ICA can be sacrificed; otherwise, an endovascular or bypass reconstruction procedure is an alternative.

Periprocedure Medications

Systemic heparinization is administered during the endovascular procedure because of the risk of intraprocedural thrombus formation. A weight-based intravenous bolus of heparin aimed at an activated coagulation time of 250–300 seconds may limit thromboembolic complications. Heparin should be administered once the active bleeding of the carotid artery has been stopped.

For carotid artery reconstruction with stenting, dual antiplatelet therapy with aspirin (325 mg daily) and clopidogrel (75 mg daily) is prescribed to prevent platelet aggregation on the stent that can result in the formation of an intraluminal thrombus during or after the stenting procedure (see carotid artery stenting and angioplasty chapters).

Specific Technique and Key Steps

1. 
   

   Carotid occlusion via coil embolization ( Fig. 39.1, Video 39.1 ).

   
   
   
   
   1. 
      

      After obtaining femoral artery access using modified Seldinger technique, a 6 or 8 French (F) sheath is placed within the femoral artery.

      
      
   2. 
      

      A guide catheter is then advanced into the aorta over a curved wire (0.035-inch angled Glidewire, Terumo).

      
      
   3. 
      

      The guide catheter is then navigated into the CCA over a 4–5F intermediate diagnostic catheter, such as a Vitek (Cook Medical) or Berenstein catheter (Cook Medical) ( Fig. 39.1, Video 39.1 ).

      
      
   4. 
      

      Cerebral angiography is then performed to assess for active extravasation through the ruptured carotid artery and for contribution of the affected carotid artery to the intracranial circulation ( Video 39.1 ).

      
      
   5. 
      

      If technically feasible, a BTO should be performed prior to carotid artery occlusion (see Chapter 9).

      
      
   6. 
      

      A microcatheter is then placed distal to the desired site of occlusion ( Video 39.1 ).

      
      
   7. 
      

      Under roadmap guidance, occlusion can be performed either with liquid embolic agent, coils, or a combination of both.

      
      
   8. 
      

      The use of a balloon or a balloon-guide catheter is recommended to cause flow arrest to prevent intracranial migration of coils or liquid embolic agent ( Fig. 39.1, Video 39.1 ).

      
      
   9. 
      

      Coil embolization above and below the point of rupture is performed to create a framework for liquid embolic agents ( Fig. 39.1, Video 39.1 ).

      
      
   10. 
       

       Final angiographic runs should be performed to confirm carotid occlusion and to assess for complications.

   
   
2. 
   

   Carotid artery stent reconstruction.

The technique of carotid artery stent reconstruction for CBS is similar to carotid artery stenting for stenotic disease. Please refer to Chapters 10–12.