Therapeutic Internal Carotid Artery Occlusion

Brian Hoh

Background

John Hunter is credited as the first to describe therapeutic proximal occlusion to treat an aneurysm. On December 12, 1785, Hunter successfully treated a patient with a popliteal aneurysm by ligating the superficial femoral artery.1 Hunterian ligation has been a primary therapy to treat peripheral aneurysms, and has been used as a treatment for cerebral aneurysms. Advancements in microsurgical techniques and endovascular therapies have led to direct clipping or coiling as the primary treatment for cerebral aneurysms, largely supplanting Hunterian proximal occlusion; in certain cerebral aneurysms, however, therapeutic proximal occlusion still plays an important role as a treatment option. Large and giant internal carotid artery (ICA) aneurysms are the most commonly treated aneurysms by this technique. Extracranial-intracranial (EC-IC) bypass is discussed in other chapters, so this chapter will limit discussion to therapeutic ICA occlusion as a stand-alone treatment.

Indications

Therapeutic ICA occlusion is most commonly employed to treat large and giant complex cerebral aneurysms of the ICA. Other indications include trauma, neoplastic invasion, and encasement of the carotid artery.

Giant cerebral aneurysms of the internal carotid artery portend a serious natural history, with a 40% risk of subarachnoid hemorrhage (SAH) over 5 years.² Large and giant ICA aneurysms can also cause significant cranial nerve dysfunction by mass effect. Therapeutic ICA occlusion is an effective treatment option in patients with ICA aneurysms that are not favorable for surgical clipping or endovascular coiling.³

Drake described using proximal “Hunterian” carotid artery occlusion to treat 160 patients with giant aneurysms of the anterior circulation, of which 90% of patients had a satisfactory outcome. Obliteration of the aneurysm by thrombosis was complete in all but four patients, and hemodynamic ischemic infarction occurred only after two of the carotid occlusions.⁴

Larson et al⁵ described long-term follow-up (mean 76 months) in 58 patients that they treated for ICA aneurysms (40 intracavernous, 5 petrous carotid, 3 cervical carotid, and 10 ophthalmic segment). Patients presented with symptoms of mass effect (n = 45), thromboembolic transient ischemia or stroke (n = 6), SAH (n = 4), and epistaxis (n = 3). Carotid occlusion was performed in 55 patients (with EC-IC bypass in three patients). Postoperatively and on long-term follow-up, six patients had transient ischemia that resolved, two patients had delayed infarction, one patient had aneurysm enlargement, two patients had delayed SAH, and three patients died from treatment.

Van Rooij and Sluzewski⁶ described the effects of therapeutic carotid occlusion on cranial nerve dysfunction in 31 patients they treated with cavernous ICA aneurysms. Cranial nerve dysfunction resolved in 19 patients, improved in 9 patients, and remained unchanged in 3 patients.

Test Occlusion

Before performing therapeutic ICA occlusion, tolerance to carotid occlusion must be determined. If a patient cannot tolerate carotid occlusion, EC-IC bypass is indicated. The method for determining tolerance to carotid occlusion is controversial. Several different techniques have been described. These include carotid balloon test occlusion with hypotensive challenge and clinical testing,⁷ carotid balloon test occlusion with single photon emission computed tomography (SPECT),8 carotid balloon test occlusion with stable xenon-enhanced CT,^9,10 carotid balloon test occlusion with transcranial Doppler ultrasonography,¹¹ carotid balloon test occlusion with measuring distal ICA stump pressure,¹² and carotid balloon test occlusion with venous phase timing.¹³ In our practice, we perform carotid balloon test occlusion with hypotensive challenge, clinical testing, and SPECT.

Technique

Our technique of therapeutic ICA occlusion consists of a staged procedure: (1) determining tolerance to carotid occlusion by carotid balloon test occlusion with hypotensive challenge, clinical testing, and SPECT; (2) this is followed at a later date by intentional endovascular sacrifice of the ICA with coil embolization. We perform occlusion in stages to allow time to evaluate the SPECT and to counsel the patient regarding the results of the SPECT and their therapeutic options, whether therapeutic ICA occlusion as a stand-alone treatment or in conjunction with EC-IC bypass.

Only gold members can continue reading. Log In or Register to continue