Tympanicum, Jugulare, and Carotid Body
♦ Preoperative
Special Equipment
- 5 French (F) guide catheter
- 0.018 microcatheter
- 0.014 micro–guide wire
- Polyvinyl alcohol (PVA) particles (most commonly 100 to 300 and 300 to 500 microns)
- Platinum pushable coils
- Five 1-mL syringes for select angiography through the microcatheter
Anesthetic Issues
- General endotracheal anesthesia is the best because it limits patient movement during the procedure–especially important during roadmap guidance as well as microcatheterization
- A small percentage of glomus and carotid body tumors secrete catechol-amines that can be released as result of embolization. The anesthesiologist should be aware of the potential for blood pressure and heart rate fluctuations and be ready to promptly treat.
- Systemic heparinization is initiated at the start of the microcatheterization with a bolus of 4000 units of heparin.
- Heparinization is rebolused hourly with 1000 units. The target is a partial thromboplastin time two to two and a half times the standard values. Activated clotting time values can be monitored to ensure adequate anticoagulation.
Monitoring
- Aside from the strict monitoring of vital signs, no additional monitoring is required.
♦ Intraoperative
Positioning
- Patient is placed supine on the angiography table.
- General endotracheal anesthesia is performed.
- A Foley catheter is placed.
- The head is positioned in neutral position and secured within the head holder.
- Both groins are shaved and prepped with iodine solution.
- Sterile drape is placed over the entire angiography table.
- Five- and 10-mL syringes with 80% contrast solution or heparinized saline are prepared.
- Two pressure saline bags are prepared by removing all the air from tubing.
- All sheaths, catheters, and guide wires are flushed with heparinized saline.
Technique
- Femoral artery puncture is performed using 19-gauge single-wall puncture needle, Bentson wire, and 6F sheath, which is placed and attached to a continuous flush drip.
- Cerebral angiography is performed with a 5F catheter and with special attention to the region of tumor: middle ear for glomus tympanicum, jugular fossa for glomus jugulare, and carotid bifurcation for carotid body tumors.
- From the angiogram, the primary arterial feeders are determined. For glomus tympanicum and jugular tumors, the most common feeders are from branches of the ascending pharyngeal as well as the occipital and posterior auricular arteries. For carotid body tumors, the most common feeders are branches directly from the external carotid artery (ECA) as well as branches from the proximal ascending pharyngeal, lingual, or facial arteries. Most of the time, only feeders from the ECA are considered for embolization.
- Systemic heparinization is given, and a 5F guide catheter is placed into the proximal ECA.
- A high-magnification roadmap of the region of the tumor is performed to help visualize the arterial feeders that are to be embolized.
- The microcatheter is then advanced under roadmap guidance over a microguide wire into the arterial feeder that is to be embolized.
- A superselective angiogram of the feeding vessel is performed with a 1-mL syringe through the microcatheter to ensure that the blood supply is only to tumor and not normal tissue.
- One hundred to 300 micron PVA microspheres are the primary agent used. They are injected slowly after being diluted in contrast dye so they are better visualized. The injection is performed with a subtracted image. Small puffs of PVA are injected as the rate of contrast washout and degree of reflux is continually assessed. If the need arises, larger 300 to 500 micron particles can also be used later in the embolization to occlude larger feeding vessels.
- Frequent follow-up angiograms are performed during the procedure.
- Particle embolization is continued until stagnant flow is seen within the feeding artery.
- For larger caliber vessels, coil embolization can also be performed after particle embolization for proximal occlusion and to reduce the risk of recanalization.
- Embolization is stopped once no significant tumor blush exists or if no additional vessels can be microcatheterized.
- The microcatheter is removed and a final angiogram of the internal carotid artery (ICA) in the standard position is performed to exclude any distal thromboembolic vessel occlusions.
- The sheath can be removed by using either a femoral artery closure device if the sheath is within the common femoral artery or by using 15 minutes of manual pressure on the site of arterial puncture.
- Frequent follow-up angiograms are performed during the procedure.
♦ Postoperative
- Patients are commonly monitored overnight the in the neurosurgical intensive care unit.
- Neurologic examination should focus on cranial nerve function, especially for glomus tumors.
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