The following is a partial list of neurointerventional procedures which can be helpful adjuncts to an otolaryngologic practice:
Embolotherapy of Head and Neck Tumors
Preoperative embolization of head and neck tumors is a well-accepted technique for hypervascular tumors of the head and neck. Embolization results in decreased blood loss, diminished transfusion requirements, and shorter surgeries. In unresectable tumors, embolization can provide palliation. Tumors generally considered suitable for preoperative embolization include paragangliomas and juvenile nasopharyngeal angiomas. Less commonly embolized are hypervascular metastases, schwannomas, esthesioneuroblastomas, and hemangiopericytomas. Polyvinyl alcohol particles (PVA) and gelfoam are generally the embolic agents of choice in these procedures. Following embolization, surgery is delayed at least 24 hours to allow for maximum thrombosis. Delay longer than 7-10 days risks vessel recanalization and recruitment of collateral vasculature.
Many tumors are amenable to preoperative embolization, wherein their blood supply is reduced or eliminated transarterially so as to facilitate surgical resection. Embolization results in shorter surgeries, decreased blood loss, and diminished transfusion requirements. Juvenile angiofibromas, glomus tumors, meningiomas, and other vascular tumors of the head and neck, brain, and spinal column are amenable to this therapy.
Carotid Test Occlusion and Carotid Sacrifice
Carotid sacrifice for otolaryngologic disease is employed in the setting of extensive tumor involvement, when resection is contemplated but preservation of the carotid artery is not considered feasible, or more emergently in the setting of a carotid "blowout" syndrome. In the former, balloon test occlusion of the carotid artery (BTO) is performed in order to assess the adequacy of collateral flow to the brain. A compliant balloon is inflated within the carotid artery so as to produce temporary occlusion, and the patient is examined for signs of neurologic compromise. A hypotensive challenge and brain SPECT perfusion scan add to diagnostic accuracy. In emergent situations (carotid blowout) such a test is not possible, and an angiographic assessment of collateral flow is made before carotid occlusion.
For preoperative cases, once the patient has passed a BTO, endovascular carotid occlusion can be performed. This is generally done with detachable silicon balloons. The advantage of endovascular (as opposed to surgical) occlusion is that the highest balloon can be placed very close to the skull base, so as to shorten the residual arterial stump and lessen the risk of stump embolus. Occlusion can also be performed under full heparinization, which lessens the risk of stroke.
While epistaxis can usually be well controlled with nasal packing and cauterization, refractory cases are good candidates for embolization. Generally, angiography in cases of epistaxis is normal (does not show a site of extravasation), and so empiric embolization is performed. The ipsillateral distal internal maxillary artery and both facial arteries are occluded with small particulate material, usually PVA (polyvinyl alcohol) and gelfoam. The contrallateral internal maxillary artery is left open so as to prevent nasal necrosis. Treatment success is in the 90-95% range. Failures that do occur are often the result of prominent nasal supply from ethmoidal branches descending off the ophthalmic artery, which, due to its origin off the internal carotid artery, is not amenable to safe embolization.
Less common causes of epistaxis, such as posttraumatic, iatrogenic or tumoral, are also amenable to more targeted arterial occlusion.