Perspectives Commentary on: The Efficacy of Bypass Surgery Using a Short Interposition Graft for the Treatment of Intracranial Complex Aneurysm by Yang et al. pp. 197-202.
The Superficial Temporal Artery Trunk-to-M2 Middle Cerebral Artery Bypass with Short Radial Artery Interposition Graft: The Forgotten Bypass Adib A. Abla and Michael T. Lawton
O
ur bypass experience at the University of California, San Francisco, includes >350 cases over the past 16 years, and yet we have not done a bypass using the trunk of the superficial temporal artery (STA) and a radial artery interposition graft to the M2 segment of the middle cerebral artery (MCA). This is a curious fact. In the current issue of WORLD NEUROSURGERY, Yang et al. demonstrate the utility of using the STA trunk as a donor for a radial artery short interposition bypass graft to the M2 MCA in the treatment of 13 complex aneurysms, with all aneurysms occluded, all grafts patent, and good neurologic outcomes.
The rationale for using the STA trunk-to-M2 MCA bypass is sound. Complex aneurysms can be trapped and flow can be replaced without ischemic compromise. The larger caliber STA trunk donates more flow than smaller distal STA branches. The tapered STA branches have higher resistance than the STA trunk, and runoff to other STA branches can decrease flow to the distal STA bypass. The end-to-end anastomosis on the proximal end channels all STA flow through the graft to provide as much flow, if not more, than would be expected for a double-barrel STA-toM4 MCA bypass, without having to harvest both STA branches. There is no need for a cervical incision. Use of the STA trunk eliminates the need to harvest a long radial artery (or saphenous vein) graft for connection proximally to a cervical carotid artery donor site, shortening the incision in the arm or leg and eliminating the tunnel to the cervical carotid artery. The STA trunk-toM2 MCA bypass uses larger arteries with potentially higher patency rate than the STA branch-to-M4 MCA anastomosis. The large-caliber arteries are also easier to suture and have thicker
Key words Bypass surgery - Complex intracranial aneurysm - Short interposition graft - Superficial temporal artery -
Abbreviations and Acronyms MCA: Middle cerebral artery STA: Superficial temporal artery
WORLD NEUROSURGERY 83 [2]: 145-146, FEBRUARY 2015
walls that are better visualized. The problem of diminutive donor STA or recipient M4 MCA is eliminated. The STA trunk can be exposed more quickly than the long segment of the parietal STA branch that must be harvested for traditional STA-to-MCA bypass. In addition, harvest of the STA at the trunk spares the dissection of the STA from the galea, which leaves a healthier, more intact scalp flap for closure that might have a lower risk of wound complications. The trunk is more easily accessible than the internal maxillary artery, which some neurosurgeons have found appealing (1). Finally, the STA trunk is capable of enlarging to meet demands of the intracranial circulation, as demonstrated in this article with increased diameter of the STA after revascularization on postoperative angiography. These are all excellent reasons to embrace this STA trunk bypass. The advantages must be weighed against a deeper anastomosis in the sylvian fissure for an M2 bypass compared with a cortical M4 bypass. This bypass may require an incision that extends more inferiorly below the zygoma when the STA has a low bifurcation, which may place the facial nerve at risk during the procedure. The STA trunk bypass requires an extra incision in the arm or leg to harvest the interposition graft, and there can be ischemic complications to the hand if preoperative Allen tests have false-positive results. Use of the STA trunk for the bypass donor eliminates scalp flow, which might result in tissue ischemia and wound breakdown. This bypass is not novel, but the authors are championing it as an alternative to traditional STA-to-MCA bypass. Our reluctance to use it has to do with flow. It seems either you need more flow
Department of Neurological Surgery, University of California San Francisco, San Francisco, California, USA To whom correspondence should be addressed: Michael T. Lawton, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 83, 2:145-146. http://dx.doi.org/10.1016/j.wneu.2014.08.027
www.WORLDNEUROSURGERY.org
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PERSPECTIVES
and a cervical donor site is used, or you need less flow and a classic STA-to-MCA bypass is performed. The University of Illinois group previously reported that this bypass provides robust flow: 54e100 mL/min compared with 10e28 mL/min from STA branches (2). Yang et al. do not report flow measurements in their patients, and future studies should validate differences in volumetric flow with STA-to-M4 MCA bypasses, STA trunk-toM2 MCA bypasses, and cervical internal carotid artery/external carotid artery-to-M2 MCA bypasses. Another reason we have not done an STA trunk bypass is our preference for intracranial-to-intracranial bypass (3). Four excellent options exist for intracranial-to-intracranial bypass, including in situ bypass with side-to-side anastomosis, reimplantation with end-toside anastomosis, end-to-end reanastomosis, and short interposition bypasses using radial artery grafts to intracranial donor
REFERENCES 1. Abdulrauf SI, Sweeney JM, Mohan YS, Palejwala SK: Short segment internal maxillary artery to middle cerebral artery bypass: a novel technique for extracranial-to-intracranial bypass. Neurosurgery 68:804-808 [discussion 808-809], 2011.
arteries (3). The MCA territory is particularly favorable for these elegant bypasses because of the accessibility of the pathology, the availability of donor arteries such as the anterior temporal artery and the insular segments of the MCA, and superficial operative corridors. Intracranial-to-intracranial bypasses may be more technically challenging than extracranial-to-intracranial or STA trunk bypasses, but they provide solutions for a wide variety of aneurysms and can be tailored to the complexity of an individual aneurysm. This work by Yang et al. has not dampened our enthusiasm for these intracranial-to-intracranial bypasses, which are entirely intracranial and protected from external threats, require no harvest of donor arteries, are caliber-matched, avoid neck or additional incisions, and are amenable to short radial artery interposition grafts when necessary. Still, the STA trunk bypass is an excellent bypass to add to the armamentarium of choices when considering bypass options for complex aneurysms.
2. Alaraj A, Ashley WW Jr, Charbel FT, AminHanjani S: The superficial temporal artery trunk as a donor vessel in cerebral revascularization: benefits and pitfalls. Neurosurg Focus 24:E7, 2008.
Citation: World Neurosurg. (2015) 83, 2:145-146. http://dx.doi.org/10.1016/j.wneu.2014.08.027
3. Sanai N, Zador Z, Lawton MT: Bypass surgery for complex brain aneurysms: an assessment of intracranial-intracranial bypass. Neurosurgery 65:670-683 [discussion 683], 2009.
Available online: www.sciencedirect.com
Journal homepage: www.WORLDNEUROSURGERY.org
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD FEDERATION OF NEUROSURGICAL SOCIETIES Mission Statement To facilitate the personal association of neurological surgeons throughout the world. To aid in the exchange and dissemination of knowledge and ideas in the field of neurological surgery. To encourage research in neurological surgery and allied sciences. To address issues of neurosurgical demography. To address issues of Public Health. To implement, improve and promote the standards of neurosurgical care and training worldwide.
Membership Services (www.wfns.org) Teresa Chen Hsiao-Hui (Teresa) Chen Office Manager, WFNS Central Office World Federation of Neurosurgical Societies 5 Rue du Marché 1260 Nyon, Vaud, Switzerland Tel: +41 (0) 22 3624303 Fax: +41 (0) 22 3624352 Email: [email protected]
146
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.08.027
The Superficial Temporal Artery Trunk-to-M2 Middle Cerebral Artery Bypass with Short Radial Artery Interposition Graft: The Forgotten Bypass Adib A. Abla and Michael T. Lawton
O
ur bypass experience at the University of California, San Francisco, includes >350 cases over the past 16 years, and yet we have not done a bypass using the trunk of the superficial temporal artery (STA) and a radial artery interposition graft to the M2 segment of the middle cerebral artery (MCA). This is a curious fact. In the current issue of WORLD NEUROSURGERY, Yang et al. demonstrate the utility of using the STA trunk as a donor for a radial artery short interposition bypass graft to the M2 MCA in the treatment of 13 complex aneurysms, with all aneurysms occluded, all grafts patent, and good neurologic outcomes.
The rationale for using the STA trunk-to-M2 MCA bypass is sound. Complex aneurysms can be trapped and flow can be replaced without ischemic compromise. The larger caliber STA trunk donates more flow than smaller distal STA branches. The tapered STA branches have higher resistance than the STA trunk, and runoff to other STA branches can decrease flow to the distal STA bypass. The end-to-end anastomosis on the proximal end channels all STA flow through the graft to provide as much flow, if not more, than would be expected for a double-barrel STA-toM4 MCA bypass, without having to harvest both STA branches. There is no need for a cervical incision. Use of the STA trunk eliminates the need to harvest a long radial artery (or saphenous vein) graft for connection proximally to a cervical carotid artery donor site, shortening the incision in the arm or leg and eliminating the tunnel to the cervical carotid artery. The STA trunk-toM2 MCA bypass uses larger arteries with potentially higher patency rate than the STA branch-to-M4 MCA anastomosis. The large-caliber arteries are also easier to suture and have thicker
Key words Bypass surgery - Complex intracranial aneurysm - Short interposition graft - Superficial temporal artery -
Abbreviations and Acronyms MCA: Middle cerebral artery STA: Superficial temporal artery
WORLD NEUROSURGERY 83 [2]: 145-146, FEBRUARY 2015
walls that are better visualized. The problem of diminutive donor STA or recipient M4 MCA is eliminated. The STA trunk can be exposed more quickly than the long segment of the parietal STA branch that must be harvested for traditional STA-to-MCA bypass. In addition, harvest of the STA at the trunk spares the dissection of the STA from the galea, which leaves a healthier, more intact scalp flap for closure that might have a lower risk of wound complications. The trunk is more easily accessible than the internal maxillary artery, which some neurosurgeons have found appealing (1). Finally, the STA trunk is capable of enlarging to meet demands of the intracranial circulation, as demonstrated in this article with increased diameter of the STA after revascularization on postoperative angiography. These are all excellent reasons to embrace this STA trunk bypass. The advantages must be weighed against a deeper anastomosis in the sylvian fissure for an M2 bypass compared with a cortical M4 bypass. This bypass may require an incision that extends more inferiorly below the zygoma when the STA has a low bifurcation, which may place the facial nerve at risk during the procedure. The STA trunk bypass requires an extra incision in the arm or leg to harvest the interposition graft, and there can be ischemic complications to the hand if preoperative Allen tests have false-positive results. Use of the STA trunk for the bypass donor eliminates scalp flow, which might result in tissue ischemia and wound breakdown. This bypass is not novel, but the authors are championing it as an alternative to traditional STA-to-MCA bypass. Our reluctance to use it has to do with flow. It seems either you need more flow
Department of Neurological Surgery, University of California San Francisco, San Francisco, California, USA To whom correspondence should be addressed: Michael T. Lawton, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 83, 2:145-146. http://dx.doi.org/10.1016/j.wneu.2014.08.027
www.WORLDNEUROSURGERY.org
145
PERSPECTIVES
and a cervical donor site is used, or you need less flow and a classic STA-to-MCA bypass is performed. The University of Illinois group previously reported that this bypass provides robust flow: 54e100 mL/min compared with 10e28 mL/min from STA branches (2). Yang et al. do not report flow measurements in their patients, and future studies should validate differences in volumetric flow with STA-to-M4 MCA bypasses, STA trunk-toM2 MCA bypasses, and cervical internal carotid artery/external carotid artery-to-M2 MCA bypasses. Another reason we have not done an STA trunk bypass is our preference for intracranial-to-intracranial bypass (3). Four excellent options exist for intracranial-to-intracranial bypass, including in situ bypass with side-to-side anastomosis, reimplantation with end-toside anastomosis, end-to-end reanastomosis, and short interposition bypasses using radial artery grafts to intracranial donor
REFERENCES 1. Abdulrauf SI, Sweeney JM, Mohan YS, Palejwala SK: Short segment internal maxillary artery to middle cerebral artery bypass: a novel technique for extracranial-to-intracranial bypass. Neurosurgery 68:804-808 [discussion 808-809], 2011.
arteries (3). The MCA territory is particularly favorable for these elegant bypasses because of the accessibility of the pathology, the availability of donor arteries such as the anterior temporal artery and the insular segments of the MCA, and superficial operative corridors. Intracranial-to-intracranial bypasses may be more technically challenging than extracranial-to-intracranial or STA trunk bypasses, but they provide solutions for a wide variety of aneurysms and can be tailored to the complexity of an individual aneurysm. This work by Yang et al. has not dampened our enthusiasm for these intracranial-to-intracranial bypasses, which are entirely intracranial and protected from external threats, require no harvest of donor arteries, are caliber-matched, avoid neck or additional incisions, and are amenable to short radial artery interposition grafts when necessary. Still, the STA trunk bypass is an excellent bypass to add to the armamentarium of choices when considering bypass options for complex aneurysms.
2. Alaraj A, Ashley WW Jr, Charbel FT, AminHanjani S: The superficial temporal artery trunk as a donor vessel in cerebral revascularization: benefits and pitfalls. Neurosurg Focus 24:E7, 2008.
Citation: World Neurosurg. (2015) 83, 2:145-146. http://dx.doi.org/10.1016/j.wneu.2014.08.027
3. Sanai N, Zador Z, Lawton MT: Bypass surgery for complex brain aneurysms: an assessment of intracranial-intracranial bypass. Neurosurgery 65:670-683 [discussion 683], 2009.
Available online: www.sciencedirect.com
Journal homepage: www.WORLDNEUROSURGERY.org
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD FEDERATION OF NEUROSURGICAL SOCIETIES Mission Statement To facilitate the personal association of neurological surgeons throughout the world. To aid in the exchange and dissemination of knowledge and ideas in the field of neurological surgery. To encourage research in neurological surgery and allied sciences. To address issues of neurosurgical demography. To address issues of Public Health. To implement, improve and promote the standards of neurosurgical care and training worldwide.
Membership Services (www.wfns.org) Teresa Chen Hsiao-Hui (Teresa) Chen Office Manager, WFNS Central Office World Federation of Neurosurgical Societies 5 Rue du Marché 1260 Nyon, Vaud, Switzerland Tel: +41 (0) 22 3624303 Fax: +41 (0) 22 3624352 Email: [email protected]
146
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.08.027
