Vascular Emergencies of the Head and Neck
Michele H. Johnson
Vascular emergencies can generally be divided into those with neurologic/neurosurgical implications (head, cervical spine, and brain) and those with otorhinolaryngologic (ear, nose, and throat [ENT]) considerations. As one would expect, there can be considerable overlap, such as in those patients with facial and skull base trauma and those with carotid blowout syndrome. Emergent intervention for stroke is discussed in a separate chapter. Diagnostic angiographic protocols vary with the indication for intervention. As in other areas of the vascular system, selectivity is the key to safe and successful diagnostic angiography and intervention.
Neurologic and Neurosurgical Disorders
Intracranial Subarachnoid Hemorrhage
1. Trauma is the most common cause of subarachnoid hemorrhage and is not usually associated with major vascular injury. Identification of the distribution of the blood and the presence of associated intracranial and soft tissue injury permits differentiation from aneurysmal subarachnoid hemorrhage in most cases.
2. Ruptured saccular (“berry aneurysm”) is the second most common cause of subarachnoid hemorrhage. Giant, fusiform and dissecting intracranial aneurysms represent the smaller subset of aneurysm pathologies. Other causes of subarachnoid hemorrhage include pial and mixed pial-dural arteriovenous malformation (AVM), dural arteriovenous fistula (DAVF), vasculitis, and moyamoya disease. The incidence of ruptured aneurysm varies by location (Table 7.1).
3. Clinical presentation: headache (worst headache of life [WHOL]), nausea, vomiting, stiff neck, photophobia. The presentation is usually acute, although some may present subacutely with a few days of intractable headache.
4. Noncontrast computed tomography (CT) demonstrates blood within the subarachnoid spaces in the basal cisterns, sulci, and ventricles; the distribution of blood varies with the location of the aneurysm (Table 7.2).
5. Computed tomographic angiography (CTA) at the time of initial CT often permits identification of the aneurysm and characterization sufficient for triage to open surgery or endovascular treatment. CTA may circumvent the need for digital subtraction angiography (DSA) or may reduce the number of injections required for evaluation with DSA (3,4).
1. Clinical and imaging (noncontrast CT) criteria for suspect nontraumatic subarachnoid hemorrhage
Table 7.1 Incidence of Ruptured Aneurysms by Location | ||||||||||||||||||||||||||||
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2. CTA is usually performed following the noncontrast CT in patients with subarachnoid hemorrhage in order to define the source of the subarachnoid hemorrhage and inform triage to surgical or endovascular treatment.
Contraindications to Cerebral Angiography
1. Stabilization of the patient’s clinical condition should precede angiography.
2. Relative contraindications to cerebral angiography include renal failure, uncontrolled hypertension, and clinical instability.
3. Standard renal protection measures should precede contrast administration when possible.
4. Standard premedication for contrast allergy should be employed in appropriate patients.
Preprocedure Preparation
Standard preangiographic workup, preparation, and monitoring are used in addition to intracranial pressure (ICP) monitoring and central venous lines and/or arterial lines and Swan-Ganz catheters as dictated by the patient’s clinical condition.
Table 7.2 Distribution of Subarachnoid Hemorrhage (SAH) by Aneurysm Location | ||||||||||
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1. Standard heparin bolus is often administered at the time of angiography (approximately 2,000 units intravenously [IV] for an average adult vs. a weightbased dose to achieve an activated clotting time or ACT of 200 to 250 seconds).
2. Bilateral common, internal and external carotid injections or bilateral common carotid injections (when catheterization is difficult or when significant common carotid bifurcation disease precludes safe catheterization)
3. Bilateral vertebral injections or one vertebral injection with reflux into the contralateral vertebral artery proximal to the posterior inferior cerebellar artery origin
4. Angiography should include anteroposterior (AP), lateral, and at least one oblique view of the intracranial circulation in order to facilitate visualization of the branching points where aneurysms usually arise (1,2).
5. Digital rotational angiography with three-dimensional (3D) reconstruction images may be performed in addition to the above or in lieu of oblique images and can provide multiple projection images with reduction of contrast and radiation as compared to conventional orthogonal imaging. It is important to survey these rotational images carefully to avoid missing tandem lesions (6).
6. Adjunctive maneuvers to improve visualization of communicating arteries
a. Multiple projections, rotational angiography, rapid frame rates, and increasing injection volumes are simple tools to improve communicating artery and aneurysm visualization.
b. Carotid cross-compression—manual compression of the contralateral carotid in the neck during injection and filming to increase flow through the anterior communicating artery to improve visualization
c. Alcock’s test—bilateral manual carotid compression during vertebral injection and filming to increase flow through the posterior communicating arteries to improve visualization
d. Negative cerebral angiography: In order to exclude the possibility that a ruptured aneurysm is obscured by spasm or thrombus, a follow-up angiogram has traditionally been performed in 7 to 10 days following the initial examination. More recently, this follow-up has been performed using CTA within 1 week and prior to discharge. Magnetic resonance imaging (MRI) with magnetic resonance angiography (MRA) may also be performed (7,8).
e. Intraoperative and/or postoperative angiography is often performed in order to optimize clip placement and assess patency of adjacent vessels. Sheaths are placed in the operating room (OR) and sterile access to the sheath established. Rapid recognition and revision of clip placement, when needed, may improve outcome.
7. Spinal subarachnoid hemorrhage
a. Spinal subarachnoid hemorrhage often presents with headache or cervical pain. Blood may be demonstrated at the skull base and in the upper cervical region.
b. Cross-sectional imaging with MRI +/- MRA should be performed prior to spinal arteriography. Spinal CTA may be useful when MRI is contraindicated. Cross-sectional imaging may allow for more limited spinal angiography.
c. Additions to the cerebral angiographic protocol include both cervical vertebral arteries, and bilateral ascending cervical, costocervical, and thyrocervical trunks should be examined.
d. Spinal radicular arteries must be selectively catheterized in turn, in order to exclude a spinal source for subarachnoid hemorrhage. When the cerebral arteriogram is negative and a spinal source is suspected, complete spinal angiography is often done in a separate session due to contrast considerations.
Postprocedure Management
1. Hemostasis achieved at the puncture site in standard fashion with manual compression or vascular closure device.
2. Neurologic checks are included in the postprocedural nursing order set.
1. CTA demonstrates cerebral aneurysm in the majority of cases and aids in triage of patients to surgical clipping or endovascular treatment (1,2,3).
2. DSA is performed for CTA negative subarachnoid hemorrhage, for those patients triaged for endovascular therapy, and for intraoperative or postoperative assessment (5).
3. Diagnostic arteriography demonstrates cerebral aneurysm in the majority of circumstances (>85%). Repeat angiography (DSA, CTA) improves the yield to greater than 95% (8).
Treatment for Ruptured Intracranial Saccular Aneurysm (5)
Surgical Clipping
1. Intraoperative angiography is adjunctive to confirm clip placement and patency of adjacent vessels.
2. Proximal control with surgical access to the carotid in the neck is sometimes utilized for temporarily reducing the flow in the internal carotid artery at the time of clip placement for treatment of large paraclinoid or supraclinoid aneurysms.
3. Balloon suction decompression (rarely performed today): A nondetachable balloon catheter is inserted into the internal carotid artery in the operating room and inflated at the time of clip placement. Gentle suction is applied on the catheter through the central lumen during occlusion, which serves to decompress the aneurysm and facilitate clip placement.
Endovascular Aneurysm Treatment by Detachable Platinum Coil Embolization
Indications
1. Anatomical criteria that favor successful coil placement
a. Aneurysm morphology; shape size relationship to adjacent branches, relationship to critical structures, that is, cranial nerves
b. Small neck of the aneurysm compared to the dome; aneurysms with neck to dome ratio >0.5, or neck of 4 mm, will likely require balloon or stent assist for endovascular management.
c. Absence of perforators or branches arising from the aneurysm
2. Posterior circulation aneurysms such as basilar summit, superior cerebellar and posterior inferior cerebellar artery aneurysms
3. Balloon-assisted techniques and stent-assisted coiling have expanded the range of aneurysms that can be successfully treated by endovascular means.
Contraindications and Relative Contraindications
1. Severely tortuous atherosclerotic vessels with inadequate access to the aneurysm may require open surgery.
2. Fusiform or dissecting aneurysms: may require stent assist or flow diversion (see the following discussion)
3. Vasospasm that inhibits adequate catheterization and deployment of the coils may require endovascular treatment of vasospasm and the aneurysm in the same session.
Preprocedure Preparation
1. General anesthesia, arterial line, ventriculostomy, and central venous catheters as needed for patient care
2. Preparation similar to diagnostic cerebral angiography
Procedure
1. Detachable coil systems for endovascular treatment of aneurysms (available through multiple vendors)
2. Coils are available in a wide variety of diameters, lengths, shapes, and degrees of softness. New technologies include stretch resistance.
3. Platinum microcoils are introduced through a microcatheter placed into the aneurysm using at least a 5 Fr. or 6 Fr. guiding catheter platform.
4. For balloon-assisted coiling, larger internal diameter (ID) guiding catheters are needed, and the balloon is inflated across the neck of the aneurysm to protect the parent artery during coil placement. The balloon is deflated just prior to coil detachment in order to look for coil prolapse, although the coil can still be removed. A balloon can also provide some protection in the case of intraprocedural rupture and may be lifesaving.
5. Heparin administration is titrated to an ACT level of approximately 200 to 300 seconds, following the standard heparin bolus administered at initiation of angiography (2,000 U IV for an average 70-kg adult).
6. Stent-assisted coiling is reserved for unruptured aneurysm patients who can be electively treated with antiplatelet agents prior to treatment. The stent is placed crossing the aneurysm neck and the aneurysm accessed through the stent mesh. Alternatively, the aneurysm can be catheterized and the catheter “jailed” by the stent. The aneurysm is coiled, and the microcatheter removed.
Postprocedure Management
1. Intensive care unit (ICU) management, vasospasm monitoring
2. Systemic heparinization (partial thromboplastin time [PTT] 40 to 60 seconds) is maintained for at least 48 hours. Antiplatelet therapy, usually aspirin, is added after 24 hours.
3. Follow-up CTA to assess for vasospasm and coil stability
1. With endovascular coil techniques, the International Subarachnoid Aneurysm Trial (ISAT) study of treatment for ruptured saccular aneurysms demonstrated an absolute risk reduction for endovascular versus surgery of 7.4%. The metric was death and disability at 1 year. Although there are many criticisms of the study, the basic conclusion has been supported by extended ISAT follow-up and other studies.
2. Aneurysms with smaller sacs will have a higher rate of total occlusion.
1. Complications of diagnostic cerebral angiography include contrast allergy, TIA, stroke (0.5% to 2%), hematoma, and dissection.
2. Risk of aneurysm rupture is low during diagnostic angiography and approximately 1% to 3% during endovascular coiling.
3. Risk of TIA/stroke during endovascular coiling (thromboembolic complications) is 3% to 5% depending on the series. Some authors feel the risk of stroke during diagnostic or endovascular procedures is reduced by the administration of heparin during the procedure and for 48 hours following endovascular coiling.
4. Compaction of coils within the aneurysm may result in aneurysm recurrence requiring placement of additional coils, stent, or flow diverter treatment, or surgical clipping.
5. Perforation or vascular injury with hemorrhage; compromise of adjacent or parent vessel by thrombus or due to compression by the coil mass
Endovascular Aneurysm Treatment: Parent Vessel Occlusion
Indications
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