GENERAL SCIENTIFIC SESSION 2 GENERAL SCIENTIFIC SESSION 2
Tackling Technical Challenges for Microsurgical Clip Ligation of Complex Aneurysms During the Endovascular Era: A Personal Perspective Aaron A. Cohen-Gadol, MD, MSc Indiana University Department of Neurological Surgery and Goodman Campbell Brain and Spine, Indianapolis, Indiana This article is based on the author’s presentation given during the 2013 CNS Annual Meeting in San Francisco, California. Correspondence: Aaron A. Cohen-Gadol, MD, MSc, Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, 355 W 16th St, Ste 5100, Indianapolis, IN 46202. E-mail: [email protected] Copyright © 2014 by the Congress of Neurological Surgeons.
The 2013 CNS Annual Meeting presentation on which this article is based is available at: http://bit.ly/RuWKgx.
CLINICAL NEUROSURGERY
N
eurosurgeons dedicated to the art of microsurgery have undergone a significant evolution in the past decade as a result of advances in endovascular neurosurgery. These neurosurgeons are tackling more technically formidable aneurysm surgeries with ever-increasing expectations for better results. The heightened pressure associated with this evolution demands an intense passion for continual refinement in the art, skill, and craft of microsurgery. Passion for technical excellence is the foundation on which the microvascular neurosurgeon evolves in response to the ever-changing pressures exerted by alternative, potentially lower-risk options afforded by endovascular routes. Because endovascular techniques are still fairly new, the long-term durability of these techniques has been only partly proven. Nonetheless, in some institutions, up to 90% of aneurysms are managed through endovascular procedures. So, how does the microvascular surgeon justify a potentially higherrisk operative intervention if endovascular options are available? Every postoperative complication reminds the microsurgeon that the patient may have been spared some agony if an endovascular route had been chosen. These momentums have promoted the evolution in our profession. We have adapted by careful preoperative patient selection and a passionate pursuit of technical excellence. The normal cerebrovascular structures are respected and left untouched, and every intraoperative maneuver is carefully executed to preserve important perforators. The future of microvascular aneurysm surgery demands neurosurgeons who tackle the most difficult problems; their passion for achieving outcomes comparable to those of other treatment options will lead to survival of their art.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.neurosurgery-online.com).
Technical excellence requires a lifetime desire to advance patients’ outcomes. It is achieved through rigorous discipline combined with mastering technical proficiency. Here, I review 3 ingredients that have been paramount in the evolution of my own microsurgical skills and a series of cases to illustrate my personal perspectives in managing complex aneurysms.
FIRST, OBJECTIVE SELF-REFLECTION AND RESPECT FOR CONSTRUCTIVE FEEDBACK FROM COLLEAGUES AND A DETERMINATION TO LEARN FROM EXPERIENCE In my own journey of self-reflection, the video recordings of my cases have been a tremendous guidance. Passion for continual improvement and microsurgical proficiency can be facilitated by watching yourself operate after the surgery is complete. During the first 2 years of my career, I was very surprised when I reviewed my operative videos. These videos demonstrated an operator who executed operative maneuvers that were precise and accurate during a single moment. However, my transitions between surgical movements were somewhat not deliberate and, most important, not efficient. A critical review of these videos was humbling and taught me lessons for improving my surgical techniques. I paid particular attention to the last few minutes of each video to analyze the chosen operative corridor and any unnecessary exposure. With time, my craniotomies became smaller and more tailored to the pathology at hand. Most important, I critically assessed the degree of injury to the adjacent normal cerebrovascular structures. I made a special effort to prevent these collateral injuries during subsequent cases by using different patient positions to take advantage of gravity retraction, by avoiding fixed retractors, and by more judiciously
VOLUME 61 | NUMBER 1 | AUGUST 2014 | 43
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COHEN-GADOL
choosing the operative corridors. The protection of normal structures was my priority, not the technical ease of the approach or working length of the instruments. Fixed retractors were minimized but used when necessary only briefly to ensure adequate visibility of important structures to prevent their inadvertent injury during final clip placement. Every step of the operation was preplanned to avoid intraoperative surprises. If clip ligation was considered too risky on exposure of the aneurysm, further operative intervention was aborted, and delayed endovascular treatment was then contemplated. Careful patient selection and minimal operative morbidity were the priority over an intense “enthusiasm” to clip the exposed aneurysm.
SECOND, A PASSIONATE SENSE OF CONFIDENCE THAT WE WILL REFINE OUR TECHNIQUES ONLY BY TACKLING MORE DIFFICULT CASES THAT PUSH THE BOUNDARIES OF OUR “COMFORT” By my third year in practice, I had become intimately familiar with how to “get out of trouble” to protect the most important result of our work: the welfare of the patient. I therefore tackled more unfamiliar operative territories and complex revascularization procedures. A review of operative videos from colleagues with adequate expertise facilitated undertaking these procedures. A telephone conversation with the colleague whose video I had reviewed provided a more in-depth understanding and avoidance of pitfalls. Supportive senior colleagues helped by referring their “inoperable” cases to me while providing guidance and a supportive environment. A passion for lifelong learning and technical development beyond residency and fellowship has remained an important part of my philosophy.
THIRD, A KEY INGREDIENT IN THE EVOLUTION OF THE SURGEON’S MICROSURGICAL SKILLS IS AN INNOVATIVE SPIRIT I commented on this last element during a discussion of operative approaches for difficult-to-reach tumors. We must challenge dogma and resist the temptation to believe that the procedures we were taught as residents are the only ways to perform an operation. An innovative spirit will enable us to innovate safer ways to expose and treat risky vascular lesions. Consultation with more senior colleagues both locally and nationally further fosters the safety and refinement of an operation. Through the following case examples, I briefly discuss my personal evolutionary journey for tackling technical challenges in the microsurgical treatment of complex aneurysms during the past decade. During this decade, of course, we have witnessed tremendous advances in endovascular therapies. I have focused my discussion on the treatment of anterior circulation aneurysms.
44 | VOLUME 61 | NUMBER 1 | AUGUST 2014
HIGH-FLOW RADIAL ARTERY INTERPOSITION GRAFT REVASCULARIZATION FOR THE MANAGEMENT OF GIANT ANEURYSMS A 26-year-old woman presented with progressive right-sided hemiparesis caused by a giant .5-cm partially thrombosed and calcified left-sided internal carotid artery (ICA) bifurcation aneurysm (Figure 1A). Although flow diverters may have been an option, I decided to trap this aneurysm by occlusion of the ICA and A1 with high-flow revascularization of the middle cerebral artery tree (Figure 1B). In my opinion, the superficial temporal artery often does not provide adequate flow after acute ICA occlusion to revascularize the entire middle cerebral artery territory. Figure 1C demonstrates anastomosis of radial interposition graft to the M2 temporal trunk, and Figure 1D confirms good flow within the graft. Compared with clip ligation, revascularization techniques offer flexibility in managing giant aneurysms and provide the microsurgeon with robust alternative methods to treat aneurysms. In this case, the very broad and calcified base of the aneurysm defeated the conventional methods of clip ligation.
CLIP LIGATION OF PARTIALLY COILED WIDE-NECK ATHEROSCLEROTIC ANEURYSMS This 62-year-old woman underwent partial coil embolization of 1 of the lobes of her ruptured bilobed posterior communicating artery (P-Comm) aneurysm at another hospital and was subsequently transferred to our institution for clip ligation of her remaining aneurysm lobe. Partially coiled aneurysms offer daunting challenges in their exclusion because the coils often prevent closure of the clip blades and place the aneurysm neck at risk of a tear during blade closure. Figure 2A demonstrates preoperative imaging, including 3-dimensional arteriogram of this partially coiled aneurysm. In these situations, the clip blades must close parallel to the long axis of the parent vessel (in this case, the ICA). Any other clip application technique will place the neck of the aneurysm at risk of injury because of the resistance provided by the coils during blade closure. In the present case, a fenestrated straight clip was applied across the neck of the aneurysm while incorporating the clip mass within the fenestration of the clip (Figure 2B). A second tandem clip allowed complete exclusion of this atherosclerotic aneurysm. I have experienced serious aneurysm tears with any attempt to remove the coil mass from within the sac. Therefore, I do not recommend mobilization of the coils from the aneurysm. Alternative clipping strategies such as the one discussed above and aneurysm trapping and revascularization remain the most reasonable options in these cases.
MANAGEMENT OF TORRENTIAL INTRAOPERATIVE ANEURYSM RUPTURE Intraoperative aneurysm rupture remains one of the most disruptive events in microsurgery, especially when torrential
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CLIP LIGATION OF COMPLEX ANEURYSMS
FIGURE 1. A, a 26-year-old woman with progressive right-sided hemiparesis caused by a giant .5-cm partially thrombosed and calcified left-sided internal carotid artery bifurcation aneurysm. B, aneurysm trapping and middle cerebral artery revascularization through a radial artery high-flow bypass graft was completed. The image in C demonstrates anastomosis of radial interposition graft to the M2 temporal trunk, and the image in D confirms good flow within the graft. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
CLINICAL NEUROSURGERY
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FIGURE 2. A, a 62-year-old woman underwent partial coil embolization of 1 of the lobes of her ruptured bilobed posterior communicating artery aneurysm elsewhere. B, a fenestrated straight clip was applied across the neck of the aneurysm while incorporating the clip mass within the fenestration of the clip. A second clip allowed complete exclusion of this atherosclerotic aneurysm.
bleeding originates directly from the high-flow ICA. A short period of dramatic blood flow in the surgical field is often of minimal risk to the patient, but an emotionally charged, hasty, and indiscreet response by the operator can place the patient at significant risk. The operator must act deliberately and decisively because his or her decision will make the biggest difference in the outcome of the patient. This next case describes the operative details of a 62-year-old woman who presented with a 15-mm broad-neck right-sided P-Comm aneurysm (Figure 3A). The preoperative images demonstrated a highly calcified carotid artery at the skull base, and we were unable to secure proximal control on exposure of the aneurysm because of this calcification. As discussed above, clip ligation parallel to the axis of ICA was considered most effective in aneurysm neck closure (Figure 3B). Aneurysm deflation was necessary to prevent the clips from migrating proximally and stenosing the ICA lumen (Figure 3C). The retrograde suctiondecompression technique was not effective in providing sac deflation. A small hole in the aneurysm sac led to a larger tear in the midbody of the aneurysm by a piece of calcium at the wall protruding through and enlarging the pinhole (Figure 3D). This unfortunate situation led to a massive intraoperative rupture without proximal control. The use of 2 large-bore suctions cleared the field, and the single suction on the bleeding point freed my other hand to apply 3 clips on a completely deflated aneurysm (Figure 3E). Luckily, these timely operative maneuvers led to control of bleeding with immediate exclusion of the aneurysm at minimal risk to the patient (Figure 3F). Hasty maneuvers, including blind placement of clips, often lead to larger tears and a potential need for ICA sacrifice.
REPAIR OF INTRAOPERATIVE TEARS ALONG ANEURYSM NECKS Another unsettling and potentially disastrous event in surgery is inadvertent generation of a tear at the aneurysm neck during
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aneurysm blunt dissection, clip application, or manipulation. The following case describes the technique for cotton-clipping repair of neck tears.1 Using this technique, the surgeon covers the tear site with a small piece of cotton and places the clip across the cotton, just above the tear, allowing the cotton to act as a bolster to seal the tear without compromising the lumen of the parent vessel (Figure 4A). A 56-year-old patient who harbored a 7-mm ruptured PComm aneurysm underwent clip ligation of her aneurysm. During removal of the temporary clip, inadvertent torsion of the permanent clip by the clip applier led to a tear along the superior axilla of the aneurysm neck. A piece of cotton was subsequently placed across the tear, and a permanent clip held the cotton in place without any compromise of the ICA lumen (Figure 4B).
CLIP LIGATION OF RECURRENT/ RESIDUAL ANEURYSMS Previous scarring and the location of previous clip blades can obstruct and complicate clip ligation of recurrent or residual aneurysms. Sharp dissection of the aneurysm neck through the scar and complete mobilization of the previous clip adherent to the surrounding structures are necessary. However, if possible, the previous clip should not be removed; it should be left attached to the aneurysm. During closure of the new clip blades, the previous clip often needs to be mobilized for complete clip blade closure. Again, new clip blades should be implanted parallel to the axis of the parent artery to prevent future aneurysm regrowth or displacement of the clip blades. In the following case, a 42-year-old woman presented with a recurrent/residual right-sided P-Comm aneurysm managed years ago at a different institution. Preoperative angiogram demonstrated the location of the clip in relationship to the aneurysm (Figure 5A). The chance of clip slippage or aneurysm recurrence could have been decreased if the clip blades had initially been applied parallel to the carotid artery. Exploration of the aneurysm required complete mobilization of the aneurysm dome and disconnection
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CLIP LIGATION OF COMPLEX ANEURYSMS
FIGURE 3. A, a 62-year-old woman with a 15-mm broad-neck right-sided posterior communicating artery aneurysm. B, in these situations, clip ligation parallel to the axis of the internal carotid artery (ICA) is most effective in aneurysm neck closure. C, aneurysm deflation was necessary to prevent the clips from migrating proximally and stenosing the ICA lumen. D, a small hole in the aneurysm sac led to a larger tear in the midbody of the aneurysm by a piece of calcium at the wall protruding through and enlarging the pinhole. This unfortunately led to a massive intraoperative rupture without proximal control. E, after blood was cleared from the surgical field, 3 clips were applied on a completely deflated aneurysm neck. F, luckily, these timely maneuvers led to control of bleeding with immediate exclusion of the aneurysm at minimal risk to the patient. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
CLINICAL NEUROSURGERY
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FIGURE 4. A, the cotton clipping technique may be used for repair of tears at the aneurysm neck. A 56-year-old patient who harbored a 7-mm ruptured posterior communicating artery aneurysm underwent clip ligation of her aneurysm. During removal of the temporary clip, inadvertent torsion of the permanent clip by the clip applier led to a tear along the superior axilla of the aneurysm neck. B, a piece of cotton was subsequently placed across the tear, and a permanent clip held the cotton in place without any compromise of the internal carotid artery lumen. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
of the old aneurysm blades from the tentorium and oculomotor nerve to allow closure of the new clip blades applied parallel to the parent vessel (Figure 5B).
ALTERNATIVE CLIP LIGATION OF COMPLEX ANTERIOR COMMUNICATING ARTERY ANEURYSMS Clip exclusion of anterior communicating artery (A-Comm) aneurysms is challenging and requires several maneuvers to protect
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surrounding perforating and branching vessels (Figure 6A). A small subset of A-Comm aneurysms are associated with blister aneurysms along the A-Comm and aneurysm neck. Clip ligation of large A-Comm aneurysms with such associated blister aneurysms can be difficult without compromising the lumen of the A-Comm. Figure 6B demonstrates a complex 10-mm ruptured A-Comm aneurysm in a 42-year-old woman with associated blister aneurysms along the A-Comm. In these situations, as in the case of neck tears, a piece of cotton bolstered by the clip blades can be used to cover the blister aneurysm while maintaining the patency
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CLIP LIGATION OF COMPLEX ANEURYSMS
FIGURE 5. A, a 42-year-old woman presented with recurrent/residual right-sided posterior communicating artery aneurysm managed years ago at an outside institution. A preoperative angiogram demonstrated the location of the clip in relationship to the aneurysm. B, exploration of the aneurysm required complete mobilization of the aneurysm dome to allow closure of the new clip blades applied parallel to the parent vessel.
of the A-Comm (Figure 6C). A postoperative 3-dimensional arteriogram reveals adequate clip ligation of the aneurysm and associated blister aneurysms (Figure 6D).
ANEURYSMORRHAPHY FOR WIDE-NECK MIDDLE CEREBRAL ARTERY ANEURYSMS Complete clip exclusion of wide neck aneurysms incorporating a portion of the parent and branching vessels while
CLINICAL NEUROSURGERY
preventing a parent vessel stenosis can be challenging. Bipolar aneurysmorrhaphy along the midbody of the aneurysm will allow effective clip application by “gathering” the aneurysm neck (Figure 7A). Anterior temporal artery (ATA) aneurysms are often very broad based and substantially incorporate the proximal part of the ATA. To illustrate technical nuances for management of such aneurysms, I review the case of a 42-yearold woman who presented with an incidental 6-mm ATA aneurysm. Preoperative 3-dimensional arteriogram (Figure 7B)
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FIGURE 6. A, clip exclusion of anterior communicating artery (A-Comm) aneurysms is challenging and requires several maneuvers to protect surrounding perforating and branching vessels based on the aneurysm projection. B, a 42-year-old woman presented with a complex 10-mm ruptured A-Comm aneurysm with associated blister aneurysms along the A-Comm. C, in these situations, the use of a piece of cotton bolstered by the clip blades can cover the blister aneurysm while maintaining the patency of the A-Comm. D, postoperative 3-dimensional arteriogram reveals adequate clip ligation of the aneurysm and associated blister aneurysms. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
demonstrated incorporation of the proximal ATA within the aneurysm base. Such aneurysms are often not readily amenable to endovascular techniques. Exposure of this aneurysm through a right-sided transsylvian route is depicted in Figure 7C. Temporary occlusion of M1 allowed deflation of the sac. Bipolar coagulation of the aneurysm midbody (the neck should be spared to preserve its integrity) gathered the aneurysm sac. A tentative clip was then placed across the aneurysm while the temporary M1 clip was removed. Further aneurysmal bipolar coagulation distal to the tentative clip shrunk the sac and allowed repositioning of the clip and definitive clip application (Figure 7D). Gentle handling of the brain and meticulous sylvian fissure opening allowed minimal injury to the frontotemporal opercula
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(Figure 7E). Complete aneurysm exclusion was verified on a postoperative arteriogram (Figure 7F).
CLIP LIGATION OF LARGE, PARTIALLY THROMBOSED ANEURYSMS PRESENTING WITH MASS EFFECT A 42-year-old man presented with a large, partially thrombosed A-Comm aneurysm causing significant chiasmal compression (Figure 8A and 8B). Because of the symptomatic mass effect of the aneurysm, endovascular routes may not be effective, and microsurgical clip ligation and sac decompression are indicated. Exposure of the aneurysm through a right-sided transsylvian approach revealed its significant adherence to and
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CLIP LIGATION OF COMPLEX ANEURYSMS
FIGURE 7. A, bipolar aneurysmorrhaphy along the midbody of wide-based aneurysms will allow effective clip application by “gathering” the aneurysm neck. A 42-year-old woman presented with an incidental 6-mm anterior temporal artery (ATA) aneurysm. B, a preoperative 3-dimensional arteriogram demonstrated incorporation of the proximal ATA within the aneurysm base. C, this aneurysm was exposed through a right-sided transsylvian route. D, bipolar coagulation of the aneurysm midbody gathered the aneurysm sac and allowed definitive clip application. E, gentle handling of the brain and meticulous sylvian fissure opening allowed minimal injury to the frontotemporal opercula. F, complete aneurysm exclusion was verified on postoperative arteriogram. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
erosion through the chiasm (Figure 8C). Because of the presence of significant atherosclerosis at the neck, I placed 1 fenestrated clip (ipsilateral A2 through fenestration) to close the distal neck (Figure 8D), while a straight clip closed the proximal neck just anterior to A2 (Figure 8E). Intraoperative fluorescence angiography ensured cessation of flow within the sac. Subsequent opening of the aneurysm and its decompression (Figure 8F) provided the patient with relief of his preoperative visual deficits.
CLINICAL NEUROSURGERY
INTRAOPERATIVE FLUORESCENCE IMAGING Intraoperative fluorescence imaging with indocyanine green has been helpful for immediate assessment of flow within branching/ perforating arteries and aneurysms. Certain infrared optical imaging properties have limited the use of this mode of fluorescence in deep surgical fields, partly as a result of the phenomenon of apochromatic aberration. During imaging of deep operative fields at high magnification, the indocyanine green fluorescence signal can be attenuated
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FIGURE 8. A and B, a 42-year-old man presented with a large, partially thrombosed anterior communicating artery aneurysm causing significant chiasmal compression. C, exposure of the aneurysm through a right-sided transsylvian approach revealed its significant adherence to and erosion through the chiasm. D, because of the presence of significant atherosclerosis at the neck, 1 fenestrated clip (ipsilateral A2 through fenestration) was applied to close the distal neck, while a straight clip closed the proximal neck just anterior to A2 (E). F, subsequent opening of the aneurysm and its decompression provided the patient with relief of his preoperative visual deficits.
FIGURE 9. This figure demonstrates the advantages of fluorescein fluorescence compared with indocyanine green fluorescence in the assessment of flow within A2 branches after clip ligation of an anterior communicating artery (A-Comm) aneurysm. The former (top left) allows a more succinct assessment of flow within the adjacent vasculature, whereas the latter (bottom right) is degraded in its signal quality.
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CLIP LIGATION OF COMPLEX ANEURYSMS
and appear out of focus, limiting its use for flow evaluation within the smaller branching and perforating arteries. The use of intravenous fluorescein fluorescence signal detected by a microscope-integrated module (YELLOW 560; Zeiss Meditech, Oberkochen, Germany) has provided an alternative option to resolve some of these issues. Figure 9 demonstrates the advantages of fluorescein fluorescence compared with indocyanine green fluorescence in the assessment of flow within A2 branches after clip ligation of an A-Comm aneurysm. The former allows a more succinct assessment of flow within the adjacent vasculature, whereas the latter is degraded in its signal quality. Future intraoperative fluorescence technologies will allow more quantitative evaluation of flow within the vessels exposed in the surgical field.
CONCLUSION Microsurgery for aneurysms is a dynamic evolving field and will transform on the basis of advances in endovascular intervention.
CLINICAL NEUROSURGERY
Microsurgery remains a very adaptable and flexible modality for the management of complex aneurysms that are not currently amenable to other treatment options. Disclosure Dr Cohen-Gadol has a consulting agreement with Carl Zeiss Meditec AG. The compensation from this arrangement is donated to a not-for-profit educational organization, The Neurosurgical Atlas. No funding was received for this work.
REFERENCE 1. Barrow DL, Spetzler RF. Cotton clipping technique to repair intraoperative aneurysm neck tear. Neurosurgery. 2011;68(2 suppl operative):294-299.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.neurosurgery-online.com).
VOLUME 61 | NUMBER 1 | AUGUST 2014 | 53
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
Tackling Technical Challenges for Microsurgical Clip Ligation of Complex Aneurysms During the Endovascular Era: A Personal Perspective Aaron A. Cohen-Gadol, MD, MSc Indiana University Department of Neurological Surgery and Goodman Campbell Brain and Spine, Indianapolis, Indiana This article is based on the author’s presentation given during the 2013 CNS Annual Meeting in San Francisco, California. Correspondence: Aaron A. Cohen-Gadol, MD, MSc, Goodman Campbell Brain and Spine, Department of Neurological Surgery, Indiana University School of Medicine, 355 W 16th St, Ste 5100, Indianapolis, IN 46202. E-mail: [email protected] Copyright © 2014 by the Congress of Neurological Surgeons.
The 2013 CNS Annual Meeting presentation on which this article is based is available at: http://bit.ly/RuWKgx.
CLINICAL NEUROSURGERY
N
eurosurgeons dedicated to the art of microsurgery have undergone a significant evolution in the past decade as a result of advances in endovascular neurosurgery. These neurosurgeons are tackling more technically formidable aneurysm surgeries with ever-increasing expectations for better results. The heightened pressure associated with this evolution demands an intense passion for continual refinement in the art, skill, and craft of microsurgery. Passion for technical excellence is the foundation on which the microvascular neurosurgeon evolves in response to the ever-changing pressures exerted by alternative, potentially lower-risk options afforded by endovascular routes. Because endovascular techniques are still fairly new, the long-term durability of these techniques has been only partly proven. Nonetheless, in some institutions, up to 90% of aneurysms are managed through endovascular procedures. So, how does the microvascular surgeon justify a potentially higherrisk operative intervention if endovascular options are available? Every postoperative complication reminds the microsurgeon that the patient may have been spared some agony if an endovascular route had been chosen. These momentums have promoted the evolution in our profession. We have adapted by careful preoperative patient selection and a passionate pursuit of technical excellence. The normal cerebrovascular structures are respected and left untouched, and every intraoperative maneuver is carefully executed to preserve important perforators. The future of microvascular aneurysm surgery demands neurosurgeons who tackle the most difficult problems; their passion for achieving outcomes comparable to those of other treatment options will lead to survival of their art.
Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.neurosurgery-online.com).
Technical excellence requires a lifetime desire to advance patients’ outcomes. It is achieved through rigorous discipline combined with mastering technical proficiency. Here, I review 3 ingredients that have been paramount in the evolution of my own microsurgical skills and a series of cases to illustrate my personal perspectives in managing complex aneurysms.
FIRST, OBJECTIVE SELF-REFLECTION AND RESPECT FOR CONSTRUCTIVE FEEDBACK FROM COLLEAGUES AND A DETERMINATION TO LEARN FROM EXPERIENCE In my own journey of self-reflection, the video recordings of my cases have been a tremendous guidance. Passion for continual improvement and microsurgical proficiency can be facilitated by watching yourself operate after the surgery is complete. During the first 2 years of my career, I was very surprised when I reviewed my operative videos. These videos demonstrated an operator who executed operative maneuvers that were precise and accurate during a single moment. However, my transitions between surgical movements were somewhat not deliberate and, most important, not efficient. A critical review of these videos was humbling and taught me lessons for improving my surgical techniques. I paid particular attention to the last few minutes of each video to analyze the chosen operative corridor and any unnecessary exposure. With time, my craniotomies became smaller and more tailored to the pathology at hand. Most important, I critically assessed the degree of injury to the adjacent normal cerebrovascular structures. I made a special effort to prevent these collateral injuries during subsequent cases by using different patient positions to take advantage of gravity retraction, by avoiding fixed retractors, and by more judiciously
VOLUME 61 | NUMBER 1 | AUGUST 2014 | 43
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
COHEN-GADOL
choosing the operative corridors. The protection of normal structures was my priority, not the technical ease of the approach or working length of the instruments. Fixed retractors were minimized but used when necessary only briefly to ensure adequate visibility of important structures to prevent their inadvertent injury during final clip placement. Every step of the operation was preplanned to avoid intraoperative surprises. If clip ligation was considered too risky on exposure of the aneurysm, further operative intervention was aborted, and delayed endovascular treatment was then contemplated. Careful patient selection and minimal operative morbidity were the priority over an intense “enthusiasm” to clip the exposed aneurysm.
SECOND, A PASSIONATE SENSE OF CONFIDENCE THAT WE WILL REFINE OUR TECHNIQUES ONLY BY TACKLING MORE DIFFICULT CASES THAT PUSH THE BOUNDARIES OF OUR “COMFORT” By my third year in practice, I had become intimately familiar with how to “get out of trouble” to protect the most important result of our work: the welfare of the patient. I therefore tackled more unfamiliar operative territories and complex revascularization procedures. A review of operative videos from colleagues with adequate expertise facilitated undertaking these procedures. A telephone conversation with the colleague whose video I had reviewed provided a more in-depth understanding and avoidance of pitfalls. Supportive senior colleagues helped by referring their “inoperable” cases to me while providing guidance and a supportive environment. A passion for lifelong learning and technical development beyond residency and fellowship has remained an important part of my philosophy.
THIRD, A KEY INGREDIENT IN THE EVOLUTION OF THE SURGEON’S MICROSURGICAL SKILLS IS AN INNOVATIVE SPIRIT I commented on this last element during a discussion of operative approaches for difficult-to-reach tumors. We must challenge dogma and resist the temptation to believe that the procedures we were taught as residents are the only ways to perform an operation. An innovative spirit will enable us to innovate safer ways to expose and treat risky vascular lesions. Consultation with more senior colleagues both locally and nationally further fosters the safety and refinement of an operation. Through the following case examples, I briefly discuss my personal evolutionary journey for tackling technical challenges in the microsurgical treatment of complex aneurysms during the past decade. During this decade, of course, we have witnessed tremendous advances in endovascular therapies. I have focused my discussion on the treatment of anterior circulation aneurysms.
44 | VOLUME 61 | NUMBER 1 | AUGUST 2014
HIGH-FLOW RADIAL ARTERY INTERPOSITION GRAFT REVASCULARIZATION FOR THE MANAGEMENT OF GIANT ANEURYSMS A 26-year-old woman presented with progressive right-sided hemiparesis caused by a giant .5-cm partially thrombosed and calcified left-sided internal carotid artery (ICA) bifurcation aneurysm (Figure 1A). Although flow diverters may have been an option, I decided to trap this aneurysm by occlusion of the ICA and A1 with high-flow revascularization of the middle cerebral artery tree (Figure 1B). In my opinion, the superficial temporal artery often does not provide adequate flow after acute ICA occlusion to revascularize the entire middle cerebral artery territory. Figure 1C demonstrates anastomosis of radial interposition graft to the M2 temporal trunk, and Figure 1D confirms good flow within the graft. Compared with clip ligation, revascularization techniques offer flexibility in managing giant aneurysms and provide the microsurgeon with robust alternative methods to treat aneurysms. In this case, the very broad and calcified base of the aneurysm defeated the conventional methods of clip ligation.
CLIP LIGATION OF PARTIALLY COILED WIDE-NECK ATHEROSCLEROTIC ANEURYSMS This 62-year-old woman underwent partial coil embolization of 1 of the lobes of her ruptured bilobed posterior communicating artery (P-Comm) aneurysm at another hospital and was subsequently transferred to our institution for clip ligation of her remaining aneurysm lobe. Partially coiled aneurysms offer daunting challenges in their exclusion because the coils often prevent closure of the clip blades and place the aneurysm neck at risk of a tear during blade closure. Figure 2A demonstrates preoperative imaging, including 3-dimensional arteriogram of this partially coiled aneurysm. In these situations, the clip blades must close parallel to the long axis of the parent vessel (in this case, the ICA). Any other clip application technique will place the neck of the aneurysm at risk of injury because of the resistance provided by the coils during blade closure. In the present case, a fenestrated straight clip was applied across the neck of the aneurysm while incorporating the clip mass within the fenestration of the clip (Figure 2B). A second tandem clip allowed complete exclusion of this atherosclerotic aneurysm. I have experienced serious aneurysm tears with any attempt to remove the coil mass from within the sac. Therefore, I do not recommend mobilization of the coils from the aneurysm. Alternative clipping strategies such as the one discussed above and aneurysm trapping and revascularization remain the most reasonable options in these cases.
MANAGEMENT OF TORRENTIAL INTRAOPERATIVE ANEURYSM RUPTURE Intraoperative aneurysm rupture remains one of the most disruptive events in microsurgery, especially when torrential
www.neurosurgery-online.com
Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited
CLIP LIGATION OF COMPLEX ANEURYSMS
FIGURE 1. A, a 26-year-old woman with progressive right-sided hemiparesis caused by a giant .5-cm partially thrombosed and calcified left-sided internal carotid artery bifurcation aneurysm. B, aneurysm trapping and middle cerebral artery revascularization through a radial artery high-flow bypass graft was completed. The image in C demonstrates anastomosis of radial interposition graft to the M2 temporal trunk, and the image in D confirms good flow within the graft. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
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FIGURE 2. A, a 62-year-old woman underwent partial coil embolization of 1 of the lobes of her ruptured bilobed posterior communicating artery aneurysm elsewhere. B, a fenestrated straight clip was applied across the neck of the aneurysm while incorporating the clip mass within the fenestration of the clip. A second clip allowed complete exclusion of this atherosclerotic aneurysm.
bleeding originates directly from the high-flow ICA. A short period of dramatic blood flow in the surgical field is often of minimal risk to the patient, but an emotionally charged, hasty, and indiscreet response by the operator can place the patient at significant risk. The operator must act deliberately and decisively because his or her decision will make the biggest difference in the outcome of the patient. This next case describes the operative details of a 62-year-old woman who presented with a 15-mm broad-neck right-sided P-Comm aneurysm (Figure 3A). The preoperative images demonstrated a highly calcified carotid artery at the skull base, and we were unable to secure proximal control on exposure of the aneurysm because of this calcification. As discussed above, clip ligation parallel to the axis of ICA was considered most effective in aneurysm neck closure (Figure 3B). Aneurysm deflation was necessary to prevent the clips from migrating proximally and stenosing the ICA lumen (Figure 3C). The retrograde suctiondecompression technique was not effective in providing sac deflation. A small hole in the aneurysm sac led to a larger tear in the midbody of the aneurysm by a piece of calcium at the wall protruding through and enlarging the pinhole (Figure 3D). This unfortunate situation led to a massive intraoperative rupture without proximal control. The use of 2 large-bore suctions cleared the field, and the single suction on the bleeding point freed my other hand to apply 3 clips on a completely deflated aneurysm (Figure 3E). Luckily, these timely operative maneuvers led to control of bleeding with immediate exclusion of the aneurysm at minimal risk to the patient (Figure 3F). Hasty maneuvers, including blind placement of clips, often lead to larger tears and a potential need for ICA sacrifice.
REPAIR OF INTRAOPERATIVE TEARS ALONG ANEURYSM NECKS Another unsettling and potentially disastrous event in surgery is inadvertent generation of a tear at the aneurysm neck during
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aneurysm blunt dissection, clip application, or manipulation. The following case describes the technique for cotton-clipping repair of neck tears.1 Using this technique, the surgeon covers the tear site with a small piece of cotton and places the clip across the cotton, just above the tear, allowing the cotton to act as a bolster to seal the tear without compromising the lumen of the parent vessel (Figure 4A). A 56-year-old patient who harbored a 7-mm ruptured PComm aneurysm underwent clip ligation of her aneurysm. During removal of the temporary clip, inadvertent torsion of the permanent clip by the clip applier led to a tear along the superior axilla of the aneurysm neck. A piece of cotton was subsequently placed across the tear, and a permanent clip held the cotton in place without any compromise of the ICA lumen (Figure 4B).
CLIP LIGATION OF RECURRENT/ RESIDUAL ANEURYSMS Previous scarring and the location of previous clip blades can obstruct and complicate clip ligation of recurrent or residual aneurysms. Sharp dissection of the aneurysm neck through the scar and complete mobilization of the previous clip adherent to the surrounding structures are necessary. However, if possible, the previous clip should not be removed; it should be left attached to the aneurysm. During closure of the new clip blades, the previous clip often needs to be mobilized for complete clip blade closure. Again, new clip blades should be implanted parallel to the axis of the parent artery to prevent future aneurysm regrowth or displacement of the clip blades. In the following case, a 42-year-old woman presented with a recurrent/residual right-sided P-Comm aneurysm managed years ago at a different institution. Preoperative angiogram demonstrated the location of the clip in relationship to the aneurysm (Figure 5A). The chance of clip slippage or aneurysm recurrence could have been decreased if the clip blades had initially been applied parallel to the carotid artery. Exploration of the aneurysm required complete mobilization of the aneurysm dome and disconnection
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FIGURE 3. A, a 62-year-old woman with a 15-mm broad-neck right-sided posterior communicating artery aneurysm. B, in these situations, clip ligation parallel to the axis of the internal carotid artery (ICA) is most effective in aneurysm neck closure. C, aneurysm deflation was necessary to prevent the clips from migrating proximally and stenosing the ICA lumen. D, a small hole in the aneurysm sac led to a larger tear in the midbody of the aneurysm by a piece of calcium at the wall protruding through and enlarging the pinhole. This unfortunately led to a massive intraoperative rupture without proximal control. E, after blood was cleared from the surgical field, 3 clips were applied on a completely deflated aneurysm neck. F, luckily, these timely maneuvers led to control of bleeding with immediate exclusion of the aneurysm at minimal risk to the patient. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
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FIGURE 4. A, the cotton clipping technique may be used for repair of tears at the aneurysm neck. A 56-year-old patient who harbored a 7-mm ruptured posterior communicating artery aneurysm underwent clip ligation of her aneurysm. During removal of the temporary clip, inadvertent torsion of the permanent clip by the clip applier led to a tear along the superior axilla of the aneurysm neck. B, a piece of cotton was subsequently placed across the tear, and a permanent clip held the cotton in place without any compromise of the internal carotid artery lumen. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
of the old aneurysm blades from the tentorium and oculomotor nerve to allow closure of the new clip blades applied parallel to the parent vessel (Figure 5B).
ALTERNATIVE CLIP LIGATION OF COMPLEX ANTERIOR COMMUNICATING ARTERY ANEURYSMS Clip exclusion of anterior communicating artery (A-Comm) aneurysms is challenging and requires several maneuvers to protect
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surrounding perforating and branching vessels (Figure 6A). A small subset of A-Comm aneurysms are associated with blister aneurysms along the A-Comm and aneurysm neck. Clip ligation of large A-Comm aneurysms with such associated blister aneurysms can be difficult without compromising the lumen of the A-Comm. Figure 6B demonstrates a complex 10-mm ruptured A-Comm aneurysm in a 42-year-old woman with associated blister aneurysms along the A-Comm. In these situations, as in the case of neck tears, a piece of cotton bolstered by the clip blades can be used to cover the blister aneurysm while maintaining the patency
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FIGURE 5. A, a 42-year-old woman presented with recurrent/residual right-sided posterior communicating artery aneurysm managed years ago at an outside institution. A preoperative angiogram demonstrated the location of the clip in relationship to the aneurysm. B, exploration of the aneurysm required complete mobilization of the aneurysm dome to allow closure of the new clip blades applied parallel to the parent vessel.
of the A-Comm (Figure 6C). A postoperative 3-dimensional arteriogram reveals adequate clip ligation of the aneurysm and associated blister aneurysms (Figure 6D).
ANEURYSMORRHAPHY FOR WIDE-NECK MIDDLE CEREBRAL ARTERY ANEURYSMS Complete clip exclusion of wide neck aneurysms incorporating a portion of the parent and branching vessels while
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preventing a parent vessel stenosis can be challenging. Bipolar aneurysmorrhaphy along the midbody of the aneurysm will allow effective clip application by “gathering” the aneurysm neck (Figure 7A). Anterior temporal artery (ATA) aneurysms are often very broad based and substantially incorporate the proximal part of the ATA. To illustrate technical nuances for management of such aneurysms, I review the case of a 42-yearold woman who presented with an incidental 6-mm ATA aneurysm. Preoperative 3-dimensional arteriogram (Figure 7B)
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FIGURE 6. A, clip exclusion of anterior communicating artery (A-Comm) aneurysms is challenging and requires several maneuvers to protect surrounding perforating and branching vessels based on the aneurysm projection. B, a 42-year-old woman presented with a complex 10-mm ruptured A-Comm aneurysm with associated blister aneurysms along the A-Comm. C, in these situations, the use of a piece of cotton bolstered by the clip blades can cover the blister aneurysm while maintaining the patency of the A-Comm. D, postoperative 3-dimensional arteriogram reveals adequate clip ligation of the aneurysm and associated blister aneurysms. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
demonstrated incorporation of the proximal ATA within the aneurysm base. Such aneurysms are often not readily amenable to endovascular techniques. Exposure of this aneurysm through a right-sided transsylvian route is depicted in Figure 7C. Temporary occlusion of M1 allowed deflation of the sac. Bipolar coagulation of the aneurysm midbody (the neck should be spared to preserve its integrity) gathered the aneurysm sac. A tentative clip was then placed across the aneurysm while the temporary M1 clip was removed. Further aneurysmal bipolar coagulation distal to the tentative clip shrunk the sac and allowed repositioning of the clip and definitive clip application (Figure 7D). Gentle handling of the brain and meticulous sylvian fissure opening allowed minimal injury to the frontotemporal opercula
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(Figure 7E). Complete aneurysm exclusion was verified on a postoperative arteriogram (Figure 7F).
CLIP LIGATION OF LARGE, PARTIALLY THROMBOSED ANEURYSMS PRESENTING WITH MASS EFFECT A 42-year-old man presented with a large, partially thrombosed A-Comm aneurysm causing significant chiasmal compression (Figure 8A and 8B). Because of the symptomatic mass effect of the aneurysm, endovascular routes may not be effective, and microsurgical clip ligation and sac decompression are indicated. Exposure of the aneurysm through a right-sided transsylvian approach revealed its significant adherence to and
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FIGURE 7. A, bipolar aneurysmorrhaphy along the midbody of wide-based aneurysms will allow effective clip application by “gathering” the aneurysm neck. A 42-year-old woman presented with an incidental 6-mm anterior temporal artery (ATA) aneurysm. B, a preoperative 3-dimensional arteriogram demonstrated incorporation of the proximal ATA within the aneurysm base. C, this aneurysm was exposed through a right-sided transsylvian route. D, bipolar coagulation of the aneurysm midbody gathered the aneurysm sac and allowed definitive clip application. E, gentle handling of the brain and meticulous sylvian fissure opening allowed minimal injury to the frontotemporal opercula. F, complete aneurysm exclusion was verified on postoperative arteriogram. Copyright © The Neurosurgical Atlas, Aaron A. Cohen-Gadol, MD, MSc. Used with permission.
erosion through the chiasm (Figure 8C). Because of the presence of significant atherosclerosis at the neck, I placed 1 fenestrated clip (ipsilateral A2 through fenestration) to close the distal neck (Figure 8D), while a straight clip closed the proximal neck just anterior to A2 (Figure 8E). Intraoperative fluorescence angiography ensured cessation of flow within the sac. Subsequent opening of the aneurysm and its decompression (Figure 8F) provided the patient with relief of his preoperative visual deficits.
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INTRAOPERATIVE FLUORESCENCE IMAGING Intraoperative fluorescence imaging with indocyanine green has been helpful for immediate assessment of flow within branching/ perforating arteries and aneurysms. Certain infrared optical imaging properties have limited the use of this mode of fluorescence in deep surgical fields, partly as a result of the phenomenon of apochromatic aberration. During imaging of deep operative fields at high magnification, the indocyanine green fluorescence signal can be attenuated
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FIGURE 8. A and B, a 42-year-old man presented with a large, partially thrombosed anterior communicating artery aneurysm causing significant chiasmal compression. C, exposure of the aneurysm through a right-sided transsylvian approach revealed its significant adherence to and erosion through the chiasm. D, because of the presence of significant atherosclerosis at the neck, 1 fenestrated clip (ipsilateral A2 through fenestration) was applied to close the distal neck, while a straight clip closed the proximal neck just anterior to A2 (E). F, subsequent opening of the aneurysm and its decompression provided the patient with relief of his preoperative visual deficits.
FIGURE 9. This figure demonstrates the advantages of fluorescein fluorescence compared with indocyanine green fluorescence in the assessment of flow within A2 branches after clip ligation of an anterior communicating artery (A-Comm) aneurysm. The former (top left) allows a more succinct assessment of flow within the adjacent vasculature, whereas the latter (bottom right) is degraded in its signal quality.
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and appear out of focus, limiting its use for flow evaluation within the smaller branching and perforating arteries. The use of intravenous fluorescein fluorescence signal detected by a microscope-integrated module (YELLOW 560; Zeiss Meditech, Oberkochen, Germany) has provided an alternative option to resolve some of these issues. Figure 9 demonstrates the advantages of fluorescein fluorescence compared with indocyanine green fluorescence in the assessment of flow within A2 branches after clip ligation of an A-Comm aneurysm. The former allows a more succinct assessment of flow within the adjacent vasculature, whereas the latter is degraded in its signal quality. Future intraoperative fluorescence technologies will allow more quantitative evaluation of flow within the vessels exposed in the surgical field.
CONCLUSION Microsurgery for aneurysms is a dynamic evolving field and will transform on the basis of advances in endovascular intervention.
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Microsurgery remains a very adaptable and flexible modality for the management of complex aneurysms that are not currently amenable to other treatment options. Disclosure Dr Cohen-Gadol has a consulting agreement with Carl Zeiss Meditec AG. The compensation from this arrangement is donated to a not-for-profit educational organization, The Neurosurgical Atlas. No funding was received for this work.
REFERENCE 1. Barrow DL, Spetzler RF. Cotton clipping technique to repair intraoperative aneurysm neck tear. Neurosurgery. 2011;68(2 suppl operative):294-299.
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