Endovascular neurosurgery is the discipline of direct treatment of central nervous system disorders under X-ray surveillance. Endovascular interventions for cerebrovascular disease are the most important component of endovascular neurosurgery.
Section I. Intracranial aneurysms
The development of endovascular intervention for intracranial aneurysms includes several stages such as detachable balloon technique, free spring coil, mechanically detachable spring coil (MDS) and electrolytic detachable spring coil (GDC, EDC) technique. In particular, the introduction of GDC has led to a historical breakthrough in endovascular intervention for intracranial aneurysms. On this basis, special endovascular interventions such as remodeling have emerged to further improve the therapeutic effect of aneurysms. Currently, endovascular interventions are preferred for 80% of aneurysms in Europe, 40% in North America, and 15% to 20% in China. In a multicenter collaborative (ISAT) prospective study including a large number of cases, a comparison of surgical clamping (1070 cases) and endovascular intervention (1073 cases) showed that both were effective in preventing aneurysm rebleeding, but the mortality and disability rates were significantly lower with endovascular intervention than with surgical clamping.
I. Indications
1. Almost all aneurysms can be treated by endovascular intervention. Especially for elderly patients, patients with serious diseases of heart, liver and kidney, and other patients who are not suitable for surgical treatment. Endovascular intervention should be preferred for aneurysms of the vertebrobasilar system.
2.Wide carotid aneurysm, shuttle aneurysm, or clogged aneurysm can be treated by remodeling technique or stent placement technique.
3.The aneurysm to neck ratio is greater than 1.5, and small aneurysms (<15mm) are most suitable for endovascular intervention.
Contraindications
1.Patients with very poor clinical condition (Hunt&Hess classification of IV or V).
2.Patients with coagulation disorders or adverse reactions to heparin.
3.Patients with history of allergy to contrast agent.
III. Embolization method
The endovascular intervention technique is used to insert the microcatheter into the aneurysm neck super-selectively and place the corresponding embolic material to completely occlude the aneurysm. For specific operation techniques, please refer to relevant professional books.
IV. Postoperative treatment
1.Preserve the arterial sheath (heparin seal) and heparinization for 24 hours.
2. Compress the puncture site for 10-15 minutes. After no active bleeding, manually compress or apply pressure bandage for more than 40 minutes and lie flat for at least 8 hours.
3. Observe the pulsation of the dorsalis pedis artery.
V. Complications and treatment
1.Cerebral infarction: Mostly caused by thrombosis, thrombolytic treatment can be performed.
2.Ruptured aneurysm bleeding: mostly caused by microcatheter or microguide wire piercing the aneurysm, do not remove the microcatheter at this time, and continue to fill the aneurysm.
3.Unspin, fracture and displacement of the spring coil: To prevent unspin and fracture of the spring coil, try to avoid repeatedly pushing and pulling the spring coil, especially when there is resistance. To prevent displacement, the diameter of the selected spring coil should not be smaller than the aneurysm neck.
Recommendations.
(1) In general, endovascular intervention is mostly used for aneurysms of the posterior circulation, while surgical treatment is mostly chosen for aneurysms of the posterior communicating artery or middle cerebral artery. The choice of endovascular intervention or surgical treatment depends on the surgeon’s mastery of endovascular treatment techniques and surgical techniques.
(2) After subarachnoid hemorrhage, cerebral angiography should be arranged as early as possible, and if there is no very severe vasospasm, embolization should be performed at the same time of angiography.
Section 2: Cerebral arteriovenous malformation
At present, the treatment of cerebral arteriovenous malformation (AVM) is still mainly surgical. For those who are not suitable for surgery, endovascular intervention or gamma knife treatment can be chosen. With the development of catheter materials and embolization materials, endovascular interventions have occupied an increasingly important position in the comprehensive treatment of cerebral arteriovenous malformations.
I. Indications
1.AVM located in the functional area or deep, and the risk of surgical resection is large.
2.Vascular malformation is large and difficult to be surgically resected.
3.Patients who are not willing to accept surgical treatment.
II. Contraindications
The same as endovascular intervention for aneurysm.
Embolization method
An appropriate microcatheter is inserted into the malformation and the corresponding embolic material, such as NBCA or ONYX, is injected to occlude the malformed vascular mass.
IV. Postoperative treatment
1. Compress the puncture site for 10-15 minutes, and after no active bleeding, manually compress or apply pressure bandage for more than 40 minutes and lie flat for at least 8 hours.
2. Observe the pulsation of the dorsalis pedis artery.
V. Complications and treatment
1.Normal vessel embolism: caused by embolic agent entering normal vessels. Therefore, the operation requires the head end of the microcatheter to enter into the malformed vascular mass.
2.Adhesion of the catheter to the vessel wall: It is seen when NBCA is injected, and the use of dilute NBCA (concentration less than 25%) can reduce this complication. When using ONYX embolization, the catheter tip should be avoided to be buried in ONYX for too long.
3, cerebral hemorrhage: caused by vascular rupture, so the microcatheter should be operated gently.
4, normal perfusion pressure breakthrough: seen in high flow or huge AVM. for AVM with severe blood theft, staged embolization or post-embolization blood pressure lowering can be performed.
Recommendations.
(1) Endovascular intervention is generally not recommended for AVMs that are easily resected by surgery.
(2) When AVM is treated by endovascular technique alone, solid embolic material is not recommended, but liquid embolic material should be used.
(3) For AVM with arteriovenous fistula, a spring coil can be used to reduce the blood flow before injecting liquid embolic material.
Section 3: Atherosclerotic cerebrovascular disease
Stent placement for carotid artery atherosclerotic stenosis is a newly introduced technique in recent years. Long-term follow-up results of large number of cases are still lacking, so it should be selected with caution. Recently, Wholey published the results of 5210 carotid artery stent placements at 36 medical centers in Europe, the United States, and Asia, with a 30-day perioperative mortality rate of 0.86%, severe stroke of 1.49%, and mild stroke of 2.72%, and restenosis rates of 1.99% and 3.46% at 6 and 12 months, respectively. This outcome is still significantly better than carotid endarterectomy. From the current data, carotid stenting has several advantages over carotid endarterectomy: there is no risk of cerebral nerve injury with stenting, compared with 2% to 12.5% with carotid endarterectomy. It can treat lesions that are difficult to reach surgically, such as intracranial segmental artery stenosis; it does not require general anesthesia, and the patient’s neurological function can be observed at any time during the operation, and the treatment can be terminated at any time in case of accidents; the postoperative recovery is fast.
I. Indications
(A) Carotid artery stenosis
1.Carotid artery stenosis >70%, patients have neurological symptoms related to stenosis.
2. Patients with ischemic imaging of the brain parenchyma associated with stenosis.
3.For a small number of carotid stenosis <70%, but with obvious related neurological symptoms, endovascular intervention can also be considered in hospitals with conditions.
(B) Angioplasty of the extracranial segment of the vertebral artery
1. Ischemic symptoms of the vertebrobasilar system or recurrent posterior circulation strokes, where medical anticoagulation or antiplatelet therapy is ineffective.
2. Stenosis of more than 70% of the opening of one vertebral artery and dysplasia or complete occlusion of the other side.
3. Bilateral vertebral artery opening stenosis of more than 50%.
Contraindications
1, Stenosis with soft thrombus.
2. Combined Ehlers-Danlos syndrome (a rare hereditary connective tissue disease characterized by vascular fragility and bleeding tendency).
3.Severe vascular tortuosity.
4, Coagulation disorder or contrast allergy.
5, Combination of serious systemic organic diseases such as heart, liver and kidney dysfunction.
6.Bilateral carotid artery occlusion or bilateral vertebral artery occlusion.
7.CT or MRI shows severe infarct foci.
8.Severe stroke attack within 3 weeks.
9.Severe neurological dysfunction.
III. Treatment
1. Carotid stenosis can be performed under local anesthesia, while vertebral stenosis is usually performed under general anesthesia.
2.Select the appropriate guiding catheter to be placed in the common carotid artery or vertebral artery, pass the corresponding finger guiding wire through the stenosis, and place the appropriately selected stent along the finger guiding wire at the stenosis site; after the position is satisfactory, release the stent and evaluate the treatment effect by imaging.
3. The specific operating protocol of stent placement has not been unified. It is generally recommended that antiplatelet therapy, such as oral aspirin 325 mg/d or clopidogrel 75 mg/d, should be given for at least 3 days before the procedure. some people suggest that systemic heparinization therapy should be continued for 2-3 days after stent placement.
IV. Postoperative treatment
1.Postoperative observation in the intensive care unit for 12 to 24 hours is desirable.
2.Oral clopidogrel for 4-6 weeks, 75mg/d; lifelong aspirin, 325mg/d.
V. Complications and treatment
1.Cerebral infarction: mostly due to atherosclerotic plaque detachment. Placement of a protective umbrella before stent placement can reduce its incidence. Thrombolytic therapy can be performed.
2. Cerebral hemorrhage: Mostly due to breakthrough of normal perfusion pressure. In severe stenosis with hypertension, appropriate antihypertensive treatment should be given after stent placement.
3.Acute vascular occlusion: if necessary, balloon dilation is performed.
4. Bradycardia with decreased blood pressure: give atropine and, if necessary, antihypertensive drugs.
Recommendations.
(1) Carotid artery stenosis >70%, patients with neurological symptoms associated with stenosis, endovascular intervention can be considered.
(2) Carotid artery stenosis <70%, but there are obvious clinical symptoms associated with it, endovascular intervention can also be considered in hospitals that have the conditions.
(3) For arteries less than 3 mm in diameter, the restenosis rate is higher with stent placement, and special stents (such as coated stents) are recommended to reduce the incidence of restenosis.
(4) Stenting for arterial stenosis is a newly introduced technique and should be chosen with caution due to the lack of long-term follow-up results of large numbers of cases.