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|NI FEATURE: THE EDITORIAL DEBATE I-- PROS AND CONS
|Year : 2018 | Volume
| Issue : 3 | Page : 661-663
What is the current role of bypass surgery in the management of cerebral aneurysms?
Laligam N Sekhar1, Chun-Yu Cheng2, Harley Brito Da Silva1, Zeeshan Qazi1
1 Department of Neurological Surgery, University of Washington, Seattle, USA
2 Department of Neurosurgery, Chang Gung Memorial Hospital; College of Medicine, Chang Gung University, Chiayi, Taiwan
|Date of Web Publication||15-May-2018|
Dr. Laligam N Sekhar
Department of Neurological Surgery, University of Washington, Seattle
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sekhar LN, Cheng CY, Da Silva HB, Qazi Z. What is the current role of bypass surgery in the management of cerebral aneurysms?. Neurol India 2018;66:661-3
Brain bypasses have an established role in the management of complex aneurysms. But are they still relevant after the advent of flow diversion stents, and stent assisted coiling? There are circumstances during the management of complex aneurysms when bypasses may be used effectively, especially if parent vessel occlusion is being contemplated. In some circumstances, they may actually be preferred to endovascular techniques, or may be the only treatment possible.,
| » Unruptured Aneurysms|| |
- Replacement of a major intracranial artery: At present, flow diversion stents, such as the Pipeline Endovascular Stent Device, have established themselves as the treatment of first choice for unruptured petrous, cavernous, and paraclinoid internal carotid artery (ICA) aneurysms. Still in some patients, bypasses become necessary due to the difficulties with endovascular repair in a particular patient, the cost of the device, or concerns about the ability of a patient to take two anti-platelet drugs for an extended period of time. However, when the aneurysm involves the supraclinoid ICA, the middle cerebral artery (MCA), the anterior cerebral artery (ACA) or the anterior communicating artery (ACOM), the benefits are less certain. There is greater potential for complications; or both flow diversion stents, or stent assisted coiling may be ineffective, leading to the need for bypass in a patient with a poorer functional status., In the vertebral artery (VA), both stent assisted coiling and flow diversion are generally effective, but with fusiform aneurysms of the basilar artery (BA), the results of flow diversion stents have not been very impressive. On the other hand, a high flow bypass to the posterior cerebral artery, with trapping, may also yield a poor result due to the loss of perforators in the trapped segment, especially in older patients. The senior author has dealt with this issue by performing bypass followed by proximal occlusion of the main feeding vertebral artery acutely, with the goal of occluding the other vertebral artery at a later time, or allowing a spontaneous occlusion to take place. For all of these types of cases, a high flow bypass using the radial artery (RA), saphenous vein (SV), or the anterior tibial artery (ATA) remains a good treatment alternative
- Replacement of a branch artery arising from an aneurysm: When an arterial branch is arising from the sac of the aneurysm, an endovascular occlusion of the aneurysm may be difficult. Clip reconstruction may be attempted at microsurgery, and may be possible in some but not all cases, or may fail in some patients resulting in a stroke. In such patients, an extra-intracranial (EC-IC) bypass to the branch artery or an intracranial- intracranial (IC-IC) bypass technique can be successfully employed
- Replacement of a small intracranial artery: When one is faced with a fusiform aneurysm of a small intracranial artery such as the M4- MCA, or an A3-4 ACA, or a mycotic aneurysm of a similar vessel in a subacute stage after treatment with antibiotics, a bypass is a good option, and may be performed using a similar EC-IC or IC-IC technique. Again, flow diversion stents, which are very small in diameter, do not exist at present but may be devised successfully.
| » Ruptured Aneurysms|| |
The majority of ruptured intracranial aneurysms are treated presently by endovascular coiling, or microsurgical clipping. However, in situ ations where this is not possible, or as an adjunctive technique, a bypass may be used. A flow diversion stent, or stent assisted coiling may be used in some situations, but because of the need for dual anti-platelet therapy in a patient with acute subarachnoid hemorrhage who may need other procedures such as a shunt, this presents greater difficulties. Some endovascular surgeons have tried to overcome this problem by partially coiling the aneurysm, and placing a stent after 6 weeks. For aneurysms like ICA-blister aneurysms, or ICA-dissecting aneurysms, a high flow bypass with trapping seems to be definitely better than a flow diversion stent, which may fail to treat the aneurysm effectively.
| » Advances in Endovascular Techniques|| |
The endovascular field is steadily advancing, and new devices are being introduced which may make it possible to endovascularly treat aneurysms which cannot be so treated at present. However, these devices also need a critical evaluation by the neurovascular community, and need to be compared with existing microsurgical and endovascular techniques. It must be also kept in mind that many of these devices are necessarily expensive (because the companies which introduce them need to pay for their development costs, and also obtain profits associated with any product). This becomes an even more important issue in developing countries, wherein patients and systems may find microsurgical techniques and operations much cheaper. An additional issue to be considered is compliance, when repeated follow-up tests are required (as in patients whose aneurysms are coiled, who require periodic MRI scans or cerebral angiograms). In such cases, the microsurgical method may provide a definitive treatment, with a similar risk profile, although the initial morbidity is higher.
| » Bypass Techniques|| |
The preparations for a bypass must be made by a careful evaluation of the patient and his needs. The anesthesia, neuro-monitoring, perioperative antiplatelet and anticoagulation management, and intraoperative brain protection are very important maneuvers. Even more important are the surgeon and his team. All must have the right training, preparation, single mindedness of purpose, and steadfastness if there are difficulties, similar to the Pandavas facing the Kauravas (the patient's disease) in Kurukshethra (our operating rooms).
| » Training|| |
How does one train to become a surgeon adept in bypass surgery? This is a skill that is acquired steadily during and after residency training. It requires knowledge, training in the microsurgical lab (on chicken or turkey wing vessels, and cadavers, for example), observation and/or work with masters who perform these operations very well, and eventually, progressive experience.
| » The Senior Author's Experience|| |
The senior author's experience with bypass techniques for ischemic diseases, skull base tumors, and complex brain aneurysms are summarized in the [Table 1], [Table 2], [Table 3], [Table 4].
|Table 1: Department of Neurosurgery, University of Washington's bypass experience 2005-2017|
Click here to view
| » Conclusion|| |
Like any other field of Neurosurgery, bypass surgery for aneurysms is both a science and an art. Its role for the management of brain aneurysms is still evolving due to the advent of new endovascular techniques. However, it remains very relevant at present.
| » References|| |
Da Silva HB, Messina-Lopez M, Sekhar LN. Bypasses and reconstruction for complex brain aneurysms. Methodist DeBakey Cardiovascular Journal 2014;10:224-33.
Straus DC, Brito da Silva H, McGrath L, Levitt MR, Kim LJ, Ghodke BV, et al
. Cerebral revascularization for aneurysms in the flow-diverter era. Neurosurgery 2017;80:759-68.
Evans JJ, Sekhar LN, Rak R, Stimac D. Bypass grafting and revascularization in the management of posterior circulation aneurysms. Neurosurgery 2004;55:1036-49.
Nerva JD, Morton RP, Levitt MR, Osbun JW, Ferreira MJ, Ghodke BV, et al
. Pipeline embolization device as primary treatment for blister aneurysms and iatrogenic pseudoaneurysms of the internal carotid artery. J Neurointerv Surg 2015;7:210-6.
Schievink WI, Zabramski JM. Brain protection for cerebral aneurysm surgery. Neurosurg Clin N
[Table 1], [Table 2], [Table 3], [Table 4]