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380 Revascularization techniques for complex aneurysms and skull base tumor
This document discusses revascularization techniques for complex aneurysms and skull base tumors. It covers when bypass is necessary due to inadequate collateral circulation, planning for bypass procedures, types of procedures including interposition grafts and direct arteriotomy, management during and after surgery, and complications. Revascularization techniques are used to treat complex aneurysms when coiling or clipping is not possible or to sacrifice arteries during tumor removal when normal blood flow must be restored. Careful planning and patient management are required due to risks of graft occlusion, hemorrhage, and ischemia.
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380 Revascularization techniques for complex aneurysms and skull base tumor
- 1. Revascularization Techniques for ComplexAneurysms and Skull Base Tumors Youmans Chapter 380 Joshua R. Dusick Nestor R. Gonzalez Neil A. Martin
- 2. Outline • Revascularization forthe Treatment of Aneurysms • Revascularization for the Treatment of Skull Base Tumors • When Is the Collateral Circulation Inadequate and Bypass Necessary? • Preoperative Planning and Preparation for Bypass Procedures • Intraoperative Monitoring and Management • Type of revascularization procedures • Postoperative Management • Complication • Long-Term Graft Patency
- 3. Revascularization for theTreatment of Aneurysms • Clipping or coiling of complex, giant, and fusiform aneurysms • Calcification or atherosclerotic thickening of the aneurysm neck or the parent artery • Recurrent aneurysms after endovascular coil embolization
- 4. Revascularization for theTreatment of Skull Base Tumors • Petrous and cavernous ICA • Benign • Meningioma, schwannoma, pituitary adenoma, angiofibroma, chordomas : benign nature, should not resect artery • Stereotactic radiosurgery or fractionated stereotactic radiotherapy • Malignant head and neck • Radical tumor with ICA sacrifice
- 5. When Is theCollateral Circulation Inadequate and Bypass Necessary? • Anterior circulation • Posterior circulation • Distal arterial braches
- 6. Anterior circulation • Selectiveapproach • angiographic evaluation of the competence of the circle of Willis • balloon test occlusion coupled with measurement of cerebral blood flow • patient pass balloon occlusion test : 20% chance of stroke with complete occlusion without a bypass • Universal approach • advocate bypass for all patients who undergo ICA occlusion
- 7. Posterior circulation • Unclipableand uncoilable posterior circulation • Unilateral vertebral artery occlusion is well tolerated when • the contralateral vertebral artery is not hypoplastic • does not terminate in the posterior inferior cerebellar artery (PICA) • Bilateral vertebral artery or basilar artery occlusion is associated with a much higher risk for ischemia and should be considered only if blood flow through both posterior communicating arteries is sufficient (>1 mm)
- 8. Distal arterial braches •Proximal occlusion : ICA, VA • Occlusion of branch : MCA, PICA, AICA
- 9. Preoperative Planning andPreparation for Bypass Procedures • Optimal site of arterial occlusion, the collateral circulation, and the size and location of the intended recipient and donor bypass vessels • Anticonvulsants • Aspirin (325 mg daily)
- 10. Intraoperative Monitoring andManagement • EEG : monitor burst suppression • Evoked potential : activity of the sensory cortex and subcortical and brainstem pathways during bypass procedures • Mild hypothermic : 34-36 C • Thiopental : cerebral protection during transient focal ischemia • Local intraluminal anticoagulant irrigation is used • Do not use systemic heparin
- 11. Type of revascularizationprocedures Interposition Vein Grafts Extracranial-to-Intracranial Bypass with a Saphenous Vein Graft or Radial Artery Graft Scalp Artery (Superficial Temporal or Occipital) Extracranial-to-Intracranial Bypass Direct Intracranial Revascularization
- 12. Type I Bypasses—InterpositionVein Grafts • Interposition graft from the parent artery proximal to the site of the occlusion to the point immediately distal to the parent artery • Purely intracranial petrous carotid–to–supraclinoid carotid saphenous vein interposition graft • Remove skull base tumors and to treat giant intracavernous carotid aneurysms • Disadvantage • Technically complex • Lengthy procedure • Prolonged period of ICA occlusion
- 13. Type II Bypasses—Extracranial-to-IntracranialBypass with a Saphenous Vein Graft or Radial Artery Graft • Extracranial Carotid Artery–to–Middle Cerebral Artery Saphenous Vein Interposition Graft • External Carotid Artery–to–Posterior Cerebral Artery Saphenous Vein Interposition Graft
- 14. Type II Bypasses—Extracranial-to-IntracranialBypass with a Saphenous Vein Graft or Radial Artery Graft • Normal blood flow MCA : 250 mL/min, PCA moderate less • STA graft position • 15-30 mL/min, may increase with time • not adequate to the circulation of major artery • Saphenous vein graft • 70-140 mL/min,can exceed 250 mL/min, 4-5 mm • Lower longterm patency rate, higher risk of kinking, caliber mismatch • Radial artery graft • Smaller diameter, 3.5 mm • 40-70 mL/min
- 15. Type II Bypasses—Extracranial-to-IntracranialBypass with a Saphenous Vein Graft or Radial Artery Graft • Substiture for STA-MCA bypass • scalp artery is hypoplastic, diseased, or occluded • aneurysm that can be occluded only proximally, as in the case of some dolichoectatic and fusiform aneurysms • type II bypass may supply too much flow and can be dangerous
- 16. Extracranial Carotid Artery–to–MiddleCerebral Artery Saphenous Vein Interposition Graft
- 17. External Carotid Artery–to–PosteriorCerebral Artery Saphenous Vein Interposition Graft • Basilar artery or bilateral vertebral arteries are occluded to treat an unclippable basilar artery aneurysm • Subtemporal approach • The proximal 20 to 25 mm of the P2 segment is isolated, and a segment free of brainstem perforating vessels is chosen for the anastomosis • Subdural hygroma : suggest routine subtemporal subdural-peritoneal (or atrial) shunt
- 18. Type III Bypasses—ScalpArtery (Superficial Temporal or Occipital) Extracranial-to-Intracranial Bypass • Used • a giant aneurysm requires occlusion of a single, crucial arterial branch • carotid occlusion is required (for an aneurysm or tumor) and the circle of Willis is only marginally inadequate • Donor vessel : STA, occipital artery • STA 15 – 30 mL/min • STA-PCA, STA-SCA • OA-PICA, OA-AICA
- 19. Superficial Temporal Artery–to–MiddleCerebral Artery Bypass • Parietal branch : Charter’s point (center, 6 cm, above EAC) • Frontal branch : a second, vertically oriented incision above the ear is required over Chater’s point
- 20. Superficial Temporal Artery–to–Middle CerebralArtery Bypass • In patients who have two separate MCA branches that arise from the dome of an aneurysm : double-barrel STA bypass • Recipient a. ,> 1 mm diameter, 10 mm length • Adventitia over the distal end of STA is removed • Off temporary clip : distal MCA, proximal MCA, STA
- 21. Occipital Artery–to–Posterior InferiorCerebellar Artery Bypass
- 22. Superficial Temporal Artery–to–SuperiorCerebellar Artery Bypass and Superficial Temporal Artery–to– Posterior Cerebral Artery Bypass • Substituted for the saphenous vein graft–to-PCA bypass when some collateral blood flow is available through small posterior communicating arteries
- 23. Type IV Bypasses—DirectIntracranial Revascularization • Anastomosis between two adjacent cerebral arteries • Primary Reanastomosis • intracranial arterial reconstruction involves excision of the aneurysm with primary reconstruction of the parent artery • Pericallosal-to-Pericallosal Bypass • used to treat fusiform aneurysms of the proximal pericallosal artery or for giant anterior communicating artery aneurysms that require trapping • side-to-side anastomosis
- 24. Type IV Bypasses—DirectIntracranial Revascularization • Posterior Inferior Cerebellar Artery–to–Posterior Inferior Cerebellar Artery Anastomosis • used when the occipital artery is small or has been damaged during a previous surgical procedure • side-to-side anastomosis
- 25. Techniques for Occludingor Trapping an Aneurysm after Bypass • Trapping • combined proximal and distal parent artery occlusion • it isolates the aneurysm from the circulation • avoids the risk of rupture from retrograde filling • allows immediate decompression of the aneurysm to relieve any mass effect. • Proximal occlusion • induce aneurysmal thrombosis • Used in giant intracavernous aneurysms and large fusiform or dolichoectatic vertebrobasilar aneurysms
- 26. Postoperative Management • Palpatingbypass pulse or by using a Doppler probe • Continue ASA • Euvolemia • Normal SBP • CTA
- 27. Complications • Early graftocclusion • careful avoidance of twisting, kinking, stretching, or tension of the graft • avoidance of graft spasm by adventitial papaverine irrigation • administration of perioperative antiplatelet therapy • Post operative aneurysmal rupture • High flow graft • Emphasize the need to isolate the aneurysm completely from the circulation by trapping whenever possible
- 28. Complications • Ischemic neurologicaldeficits • Temporary arterial occlusion while the bypass anastomosis • Cerebral protection with moderate hypothermia, induced arterial hypertension, and barbiturate administration • Subdural or epidural hematomas (or both) developed postoperatively • given heparin in addition to aspirin
- 29. Long-Term Graft Patency •Superior temporal artery graft • Radial artery graft • Saphenous vein graft
Editor's Notes
- #11 Burst suppression is an electroencephalography (EEG) pattern that is characterized by periods of high-voltage electrical activity alternating with periods of no activity in the brain. The pattern is found in patients with inactivated brain states, such as from general anesthesia, coma, orhypothermia.[1] This pattern can be physiological, as during early development, or pathological, as in diseases such as Ohtahara syndrome