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Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery
9
Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery BRIAN M. HOWARD, DANIEL L. BARROW
HIGHLIGHTS
Anatomic Insights
• Intraoperative rupture during intracranial aneurysm surgery is a stressful but manageable event. • Successful management of intraoperative rupture requires the operator to stay calm and employ steps to clear the field of blood, limit continued bleeding, and clip the aneurysm. • The neurologic outcome after aneurysm surgery complicated by intraoperative rupture is related to the reaction of the surgeon. If the surgeon rushes to blindly place clips on the aneurysm before the aneurysm is sufficiently dissected in an attempt to stop heavy bleeding, the tear may be made worse or the parent vessel may be irreparably damaged.
Comprehensive understanding of the anatomy of IAs is imperative for prevention and management of IOR/PVI. The location of the aneurysm within the intracranial circulation determines the safest and most easily accessed sites of proximal control. The size and geometry of the aneurysm drive clipping strategy may increase the risk of IOR or PVI, and can dramatically influence the surgeon’s ability to safely apply clips without injuring or occluding the parent artery, nearby perforators, or en passage vessels. Specific anatomic insights are noted throughout the ensuing text where appropriate.
Background
Prevention of IOR begins with patient selection. Surgical treatment of IAs is higher risk in many patient populations, including the elderly, those with multiple medical comorbidities, and those with subarachnoid haemorrhage and poor neurologic status or vasospasm. Atherosclerotic neck calcification makes IA surgery more difficult. Certain aneurysms are better treated endovascularly. With the advent of flow diversion, many surgically challenging IAs are successfully treated in this manner with less risk.11 Ultimately, patient selection is the first line of defense against any surgical complication, including IOR. Adequate bony exposure and a craniotomy that provides the most direct route to the aneurysm limit the need for brain retraction and provide adequate proximal control and maximal degrees of freedom to maximize clip application angle (Fig. 9.1). The pterional craniotomy is the workhorse of cerebrovascular surgery. When completed appropriately, the pterional approach provides a direct working corridor to most anterior circulation aneurysms as well as aneurysms that arise from the basilar artery apex (BAA) and superior cerebellar artery (SCA) origin. The entire anterior sylvian fissure is exposed, and the need for brain retraction is limited if the lesser wing of sphenoid is drilled completely flat. The modified orbito-zygomatic approach is sometimes necessary to visualize the BAA and distal basilar artery when the BAA is above the level of the posterior clinoid. A “half-and-half ” approach provides the most versatile combination of angles of attack for many BAA and SCA aneurysms. In addition to performing a standard pterional craniotomy, the squamosal temporal bone is drilled flush with the floor of the middle fossa in the half-and-half approach, thereby granting access to the BAA through the optico-carotid cistern or
As the proportion of intracranial aneurysms (IAs) treated by endovascular therapies rises, surgically treated patients will harbor more complex aneurysms.1 Although the role of open microsurgical treatment of IAs remains, trainees and younger vascular neurosurgeons will be less experienced than their mentors. Experience is the ultimate tool in the surgeon’s armamentarium to avoid complications and mitigate their potentially deleterious effects. Vascular neurosurgeons must develop strategies to hone microsurgical skills to keep the surgical treatment of IAs minimally disruptive in the combined microsurgical and endovascular era.2 Intraoperative rupture (IOR) and/or parent vessel injury (PVI) are among the most nerve-wracking and potentially devastating complications in the treatment of IAs. IOR occurs in as many as one-third of cases of microsurgically treated IAs and is more common when operating on ruptured aneurysms.3–8 Aneurysm size, location, and morphology and the adherence of the fundus to surrounding structures are associated with IOR.2,5,7,9 Patient outcomes after IOR are varied.3–6,8,10 Rupture before opening the dura or arachnoid dissection is predictive of unfavorable outcomes.3,6,10 Surgeon experience has been shown to have no effect on the rate of IOR,5,7 but it is positively associated with improved outcomes, indicating “mental anticipation and technical repetition over time transform into efficiency, confidence and insight in the management of [IOR].”7 IOR is inevitable; however, with adequate preparation and calm and decisive action, the surgeon can limit the possibility of IOR but also effectively manage the rupture while mitigating complications.
Prevention
37
38
SE C T I O N 2
Cranial Complications
A
B
C
D • Fig. 9.1
Insufficient drilling of the lesser wing of sphenoid for pterional approach limits exposure of the sylvian fissure and cisterns associated with the vessels of the circle of Willis (A and B). Extensive drilling of the sphenoid wing exposes the entire sylvian fissure, provides a subfrontal corridor to the opticocarotid and oculomotor cisterns, limits the need for brain retraction, provides adequate proximal control, and maximizes degrees of freedom for clip application (C and D).
oculomotor triangle, a subtemporal approach, or a combination. Liberal drilling of the occipital condyle provides wide exposure to visualize posterior inferior cerebellar artery (PICA) aneurysms. Meticulous arachnoid dissection is vital in the prevention of IOR/ PVI. Adequate dissection of the arachnoid releases cerebrospinal fluid (CSF) from the cisterns. Egress of CSF in addition to administration of osmotic diuretics provides brain relaxation sufficient to limit the need for fixed retractors, which not only cause white matter injury, but also may lead to a tear in the dome of an aneurysm that is adherent to surrounding brain if retraction is overly aggressive. Microdissection should be completed sharply whenever possible, particularly when dissecting the neck of an IA. Forceful or blind blunt dissection of the neck of the aneurysm, the parent artery, and surrounding structures increases the risk of IOR/PVI. Temporary clipping of the parent artery proximal to the inlet of an IA softens the aneurysm and can make final dissection and clip application safer. Temporary clipping is particularly useful in the setting of large or turgid aneurysms or for aneurysms where the orientation of the aneurysm neck and the origin of branch vessels, small perforating arteries, or surrounding cranial nerves is complicated and extensive dissection is required to define the anatomy. The surgeon must be mindful of the duration of parent
vessel temporary occlusion to limit the possibility of irreversible ischemic injury. Several strategies can be employed, typically in concert, to protect the brain during temporary clipping, including hypothermia and pharmacologic burst suppression to limit metabolic demand from ischemic brain, and induced hypertension to maximize pial collateralization to the ischemic territory. Modern aneurysm clips are available in a wide range of sizes and configurations, which makes clipping of IAs a versatile and durable treatment. Selection of the permanent clip(s) can have a profound effect on the likelihood of IOR/PVI. The risk of IOR increases each time an aneurysm clip is removed and reapplied. The most parsimonious combination of clips to completely occlude the IA should be used. The long axes of clip application and the parent vessel should be aligned as well as possible. Application of an aneurysm clip(s) parallel to the long axis of the parent artery limits stress on the arterial wall at the neck and increases the likelihood that the entire neck is obliterated, which limits the need for additional clip application. Additionally, angled, bayonetted, and right-angle clips all have lower closing force than straight clips and may lead to incomplete occlusion.12 A well-thought-out, simple clipping strategy, executed deftly, maximizes the potential for complete occlusion and limits manipulation of the aneurysm, IOR,
CHAPTER 9 Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery
and PVI. Overall, IOR is better prevented than managed. Although IOR is inevitable, keeping to the principles of cerebrovascular surgery will limit the risk.
RED FLAGS Patient-related: • Atherosclerotic vessels • Large and giant aneurysms • Blister aneurysms • Adherent en passage vessels Surgeon-related: • Inadequate exposure • Failure to gain proximal control • Clipping perpendicular to the long axis of the parent vessel • Blind clipping • Blunt arachnoid dissection • Aggressive brain retraction
Management Arguably, the most important attribute of the surgeon in the successful management of an IOR is unwavering calm. When IOR/PVI occurs, effective treatment relies on achieving two goals. First, the field must be cleared of blood. Second, the aneurysm must be definitively treated. The timing of aneurysm rupture in the course of surgery and the anatomic location of rupture also are important determinants of treatment. When IOR or PVI occurs, burst suppression should be induced to provide cerebral protection by lowering oxygen demand. IOR before exposure of the aneurysm is uncommon but is potentially devastating and is associated with a high rate of morbidity and mortality.3,6,10 Unfortunately, strategies to manage IOR before aneurysm exposure are limited. The surgeon must first clear the field of blood. This is best achieved using two large-bore suctions, one in the surgeon’s nondominant hand and the other controlled by an assistant. Frequently, a jet of blood can be traced to the site of rupture. If possible, proximal control of the parent vessel should be achieved and a temporary clip placed to stem torrential hemorrhage. Once the site of IOR is located, cotton is placed over the ruptured portion of the aneurysm to control the extravasation of blood. As a consequence of its absorbency, loosely packed cotton serves as an ideal tamponade. Gentle pressure should be applied to the cotton, either with a suction tip or a retractor blade. Excessive force during tamponade may worsen the tear in the aneurysm or parent vessel and should be avoided. Although fixed retractors are almost never used in aneurysm surgery, we routinely set one up to assist in the event of an IOR. The self-retaining retractor can serve as a “third hand” to hold the cotton in place on the rent in the aneurysm, while the surgeon gains full use of both hands to complete microdissection and clip application. If the flow of blood is too brisk to clear effectively with suction alone, intravenous adenosine can be administered to induce temporary asystole, which typically lasts between 30 and 60 seconds and can yield enough time to locate and control the source of bleeding. Once relative hemostasis and proximal control have been achieved, the surgeon must efficiently dissect and apply permanent clips to the neck of the aneurysm. IOR/PVI that occurs after proximal control has been achieved may occur for multiple reasons. Management of IOR/PVI after exposure of the aneurysm has been completed is directed toward
39
the cause. IOR/PVI may occur before clip application, and the most common inciting events at this stage include excessive retraction on structures to which the dome of the aneurysm is affixed, or overly aggressive blunt or blind microdissection of the aneurysm neck or en passage vessels. If IOR/PVI occurs during dissection of the aneurysm and temporary parent vessel occlusion has not yet been utilized, a temporary clip should be placed on the parent vessel, if this is necessary to assist in controlling the hemorrhage. Temporary clipping to reduce the rate of extravasation followed by directed cotton tamponade and suction often easily controls the bleeding after proximal control is established. These actions give the surgeon adequate visualization to dissect the neck of the aneurysm and place permanent clips. IOR/PVI may occur during clip application. Anecdotally, the most common reason for aneurysm rupture during clip application is inadequate neck dissection. When the neck has not been completely dissected, the operator uses the tips of the clip blades to bluntly dissect the remaining neck that was not previously freed. Moreover, this is often a blind maneuver by virtue of the fact that incomplete neck dissection occurs most often at the deepest aspect of the neck, which is difficult to visualize. Blind clipping in this scenario may lead to direct injury of the aneurysm neck, a tear in the parent vessel, laceration of a daughter sack, or avulsion or injury to an adjacent perforator. IOR can also occur with incomplete aneurysm occlusion. If the blades of the permanent clip do not completely cross the entire neck of the aneurysm, the hemodynamics change, sometimes producing an “inflow jet” that can lead to IOR. Incomplete clipping is often the result of blind clipping, or of the clipping of an aneurysm perpendicular to the long access of the parent vessel, in which case the length of the blades required to close the entire inlet of the aneurysm is underestimated. Particularly in the setting of aneurysms and parent vessels with extensive atherosclerosis, the rigidity of the walls of the aneurysm prevents complete closure of the clip blades, which can result in altered blood flow characteristics and IOR. The treatment of IOR/PVI at the time of clip placement is focused on the cause. If the neck is incompletely obliterated, the clip can be opened slightly and advanced to span the entire neck. Alternatively, if the clip applied earlier to the aneurysm cannot be advanced further, an additional clip can be stacked parallel to the first clip to occlude the more distal neck. In the case of wide-necked or atherosclerotic aneurysms, if the clip does not close completely, a fenestrated clip can be applied to the distal neck to increase the closing pressure, and a shorter clip can then be placed within the fenestration to occlude the proximal neck. If the clip blades still do not close entirely, a clip with the strongest closing force should be used—i.e., straight rather than angled or bayonetted clips. IOR/PVI rarely occurs after application of permanent clips. At this stage, IOR/PVI is the direct result of excessive torqueing of the clips to gain a view of relevant anatomy. After final clip placement, the aneurysm, parent artery, and surrounding neurovascular structures must be inspected to assure that the aneurysm is completely obliterated and that no perforating or en passage vessels or adjacent cranial nerves are impinged by the aneurysm clips. However, any manipulation of the permanent clips transmits force to the neck of the aneurysm and the interface with the parent vessel that can lead to injury. Care must be taken to limit manipulation of permanent clips when examining clip placement. Once the aneurysm is secured after IOR/PVI, the temporary clip should be slowly opened, but not removed. The surgeon should pause briefly after the temporary clip has been opened to assure that no additional bleeding from the aneurysm is noted. If bleeding
40
SE C T I O N 2
Cranial Complications
does occur when the temporary clip is released, it should be immediately reapplied and the aneurysm should be inspected.
Specific Anatomic Considerations Most IA ruptures occur at the dome and, particularly after adequate aneurysm exposure, are easily controlled with the previously described methods. Sometimes, particularly during treatment of larger aneurysms, the fundus can be partially clipped below the site of rupture to control bleeding and to allow the surgeon to proceed to final clipping. Ruptures at the neck or at the interface of the neck and parent vessel are more difficult to manage. Often, the tissue is extremely fragile, and attempts to adjust clips either worsens the tear or occludes the parent vessel. Cotton-clipping is an effective way to occlude the aneurysm, but parent artery patency should be salvaged when the point of rupture is at the neck or the parent artery is injured at the interface with the aneurysm inlet.13 A small piece of cotton is placed at the point of rupture, and a permanent clip is placed at the superior margin of the cotton, cheating toward the aneurysm side. The cotton distributes the closing force of the clip over a larger surface area than the clip alone, while leaving the parent vessel patent. Blister aneurysms can be particularly treacherous to treat. The wall of the aneurysm and associated parent vessel is extremely thin, making these aneurysms prone to IOR and nearly impossible to occlude with standard clips. A Sundt-Kees clip (S-KC) can be applied to the parent vessel to treat such aneurysms. The S-KC is an encircling clip that envelops the aneurysm and parent artery. Although useful in emergent situations, S-KCs have several disadvantages. Pragmatically, the perfect size and length S-KC to adequately protect the aneurysm, while maintaining parent vessel patency and not overlapping perforators, is often lacking. An alternative strategy to treat blister aneurysms is Gor-Tex clip wrapping.14 A piece of Gor-Tex is cut to span the exact length of parent artery required. If needed, slits can be cut into the Gor-Tex to allow unencumbered egress of essential perforators or branch vessels through the graft. The entire circumference of the parent vessel and blister aneurysm is surrounded by Gor-Tex, the tails are pulled snugly, and a 90-degree aneurysm clip is applied to secure the sling. The parent vessel should be slightly narrowed to ensure adequate protection from additional rupture of the blister aneurysm. Posterior communicating artery (PCommA) aneurysms, particularly larger ones, can pose a challenge if IOR occurs. The space within the oculomotor triangle is often limited. IOR is likely to occur during dissection of the neck or surrounding structures. Often, the anterior choroidal artery (AchorA) is draped over the backside of PCommA aneurysms, and IOR may occur as a consequence of dissection of the AchorA from the aneurysm. IOR may also occur if the surgeon attempts to use a straight clip applied perpendicular to the long axis of the internal carotid artery (ICA). PCommA aneurysms project laterally or posterolaterally,
and the surgeon’s angle of approach to the oculomotor triangle via pterional craniotomy entices him or her to use a straight clip, which may lead to incomplete neck occlusion and IOR. Instead, an angled clip, or fenestrated angled clip for aneurysms that arise more ventrally, is favored to achieve parallel clipping. To effectively control IOR when clipping anterior communicating artery (AcommA) aneurysms requires full understanding of the surrounding anatomy. The anatomy of the ACommA complex is highly variable, and bilateral inflow from the ipsi- and contralateral A1 segments can make achieving proximal control difficult, particularly for inferiorly directed aneurysms that may obscure the contralateral A1. Extensive dissection of the neck is often required to clip ACommA aneurysms to avoid injuring or occluding the recurrent artery of Heubner, other smaller medial lenticulostriate arteries, or hypothalamic and chiasmal perforators. The extent of dissection increases the risk of IOR/PVI. IOR may occur during clip placement, which can be partially blind as a result of obscuration by the ipsilateral A2 segment and gyrus rectus. If IOR occurs, proximal control of both A1 segments best mitigates the amount of extravasation. Removal of the inferomedial aspect of the gyrus rectus can aid in visualization and is well tolerated clinically. Resection of the gyrus rectus should be completed with suction and bipolar cautery and should be limited to the minimum necessary to avoid thermal injury to surrounding structures. IOR when clipping middle cerebral artery (MCA) aneurysms is often easily controlled. Provided the sylvian fissure is widely opened, the proximal M1 segment should be readily accessible for temporary clipping. Premature rupture of MCA aneurysms often occurs when dissecting en passage vessels from the aneurysm neck or dome. MCA aneurysms are often nestled within the branches of the candelabra, making navigating to the aneurysm confusing, particularly when IOR occurs and the sylvian fissure fills with blood. Proximal control and cotton tamponade are effective tools to control IOR of MCA aneurysms, but the key to clipping in this location is careful and broad exposure of the sylvian fissure. IOR may occur while approaching PICA aneurysms due to several factors. The fundus may be adherent to the cerebellar tonsils or clival dura depending on the direction the aneurysm points. Excessive retraction of the cerebellum should be avoided to avoid an avulsion tear of the dome. Bony exposure via a far lateral craniotomy allows for outstanding visualization of the foramen magnum, anterior medulla, lower clivus, lower cranial nerves, and PICA origin. IOR/PVI may occur during neck dissection if the aneurysm is entwined with the lower cranial nerves. Standard principles of proximal control and cotton tamponade apply to the management of PICA aneurysm IOR. The surgeon must remember that temporary clips must be placed on the vertebral artery both proximal and distal to the PICA origin to curtail the bleeding. Additionally, the surgeon must be sensitive to the directionality and precise location of final clip placement because the PICA is small and easily occluded by the clip.
SURGICAL REWIND
My Worst Case The patient was a 32-year-old female who presented with subarachnoid haemorrhage. Angiography revealed a BAA aneurysm and a low-lying basilar artery. The interventional neuroradiologist felt that he could not safely and
completely treat the aneurysm. Therefore the patient was brought to the operating room for a pterional craniotomy for microsurgical clip ligation of the aneurysm. The posterior clinoid was drilled to gain proximal control of
CHAPTER 9 Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery
the basilar artery. The posterior clinoid was cored using a high-speed drill and diamond burr. The supraclinoid ICA was accidentally severed with a curette that slipped off the posterior clinoid during removal of the remaining bone. The anterior clinoid was drilled, the distal dural ring opened sharply, and temporary aneurysm clips were placed on the proximal and distal stumps of the torn ICA. The ICA was repaired directly using 9-0 suture. ICG video angiography revealed patency of the ICA after repair. The BAA
41
aneurysm was clipped without difficulty. The patient did well postoperatively. However, 48 hours after surgery the patient developed a right MCA syndrome. Computed tomography revealed a holohemispheric infarction from occlusion of the repaired ICA. Despite aggressive medical therapy to control cerebral edema and a large decompressive hemicraniectomy, the patient progressed to brain death (Fig. 9.2).
A’
A
B
C
• Fig. 9.2 Preoperative 3-D rotational angiography of a basilar artery apex aneurysm and a low-lying basilar artery (A and A′). The supraclinoid internal carotid artery (ICA) was inadvertently severed when a curette slipped off the posterior clinoid during removal. The ICA was repaired, and ICG video angiography revealed patency. The basilar artery apex aneurysm was clipped without difficulty. The patient did well postoperatively, and a computed tomography scan within 24 hours of surgery demonstrated expected postoperative changes, but no stroke (B). However, 48 hours after surgery, the patient developed a right middle cerebral artery syndrome. Computed tomography revealed a holohemispheric infarction from occlusion of the repaired ICA (C).
NEUROSURGICAL SELFIE MOMENT IOR/PVI is a stressful but manageable event. Complication avoidance in the setting of IOR/PVI requires the operator to stay calm and employ steps to clear the field of blood, limit continued bleeding, and clip the aneurysm. The neurologic outcome after aneurysm surgery complicated by IOR is related less to the rupture and more to the reaction of the surgeon. If the surgeon rushes to blindly place clips on the aneurysm before the aneurysm is sufficiently dissected in an attempt to stop heavy bleeding, the tear may be made worse, or the parent vessel may be irreparably damaged.
References 1. Barrow DL, Cawley CM. Surgical management of complex intracranial aneurysms. Neurol India. 2004;52(2):156–162. 2. Schuette AJ, Barrow DL, Cohen-Gadol AA. Strategies to minimize complications during intraoperative aneurysmal hemorrhage: a personal experience. World Neurosurg. 2015;83(4):620–626. 3. Batjer H, Samson D. Intraoperative aneurysmal rupture: incidence, outcome, and suggestions for surgical management. Neurosurgery. 1986;18(6):701–707. 4. Elijovich L, Higashida RT, Lawton MT, et al. Predictors and outcomes of intraprocedural rupture in patients treated for ruptured
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intracranial aneurysms: the CARAT study. Stroke. 2008;39(5):1501– 1506. 5. Fridriksson S, Saveland H, Jakobsson KE, et al. Intraoperative complications in aneurysm surgery: a prospective national study. J Neurosurg. 2002;96(3):515–522. 6. Giannotta SL, Oppenheimer JH, Levy ML, Zelman V. Management of intraoperative rupture of aneurysm without hypotension. Neurosurgery. 1991;28(4):531–535, discussion 5–6. 7. Lawton MT, Du R. Effect of the neurosurgeon’s surgical experience on outcomes from intraoperative aneurysmal rupture. Neurosurgery. 2005;57(1):9–15, discussion 9. 8. Sandalcioglu IE, Schoch B, Regel JP, et al. Does intraoperative aneurysm rupture influence outcome? Analysis of 169 patients. Clin Neurol Neurosurg. 2004;106(2):88–92. 9. Leipzig TJ, Morgan J, Horner TG, Payner T, Redelman K, Johnson CS. Analysis of intraoperative rupture in the surgical treatment of 1694 saccular aneurysms. Neurosurgery. 2005;56(3):455–468, discussion 455–68.
10. Schramm J, Cedzich C. Outcome and management of intraoperative aneurysm rupture. Surg Neurol. 1993;40(1):26–30. 11. Becske T, Brinjikji W, Potts MB, et al. Long-term clinical and angiographic outcomes following Pipeline Embolization Device treatment of complex internal carotid artery aneurysms: five-year results of the Pipeline for Uncoilable or Failed Aneurysms Trial. Neurosurgery. 2017;80(1):40–48. 12. Horiuchi T, Rahmah NN, Yanagawa T, Hongo K. Revisit of aneurysm clip closing forces: comparison of titanium versus cobalt alloy clip. Neurosurg Rev. 2013;36(1):133–137, discussion 7–8. 13. Barrow DL, Spetzler RF. Cotton-clipping technique to repair intraoperative aneurysm neck tear: a technical note. Neurosurgery. 2011;68(Operative suppl 2):294–299, discussion 9. 14. Barrow DL, Pradilla G, McCracken DJ. Intracranial blister aneurysms: clip reconstruction techniques. Neurosurg Focus. 2015;39(Video suppl 1): V20.
Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery BRIAN M. HOWARD, DANIEL L. BARROW
HIGHLIGHTS
Anatomic Insights
• Intraoperative rupture during intracranial aneurysm surgery is a stressful but manageable event. • Successful management of intraoperative rupture requires the operator to stay calm and employ steps to clear the field of blood, limit continued bleeding, and clip the aneurysm. • The neurologic outcome after aneurysm surgery complicated by intraoperative rupture is related to the reaction of the surgeon. If the surgeon rushes to blindly place clips on the aneurysm before the aneurysm is sufficiently dissected in an attempt to stop heavy bleeding, the tear may be made worse or the parent vessel may be irreparably damaged.
Comprehensive understanding of the anatomy of IAs is imperative for prevention and management of IOR/PVI. The location of the aneurysm within the intracranial circulation determines the safest and most easily accessed sites of proximal control. The size and geometry of the aneurysm drive clipping strategy may increase the risk of IOR or PVI, and can dramatically influence the surgeon’s ability to safely apply clips without injuring or occluding the parent artery, nearby perforators, or en passage vessels. Specific anatomic insights are noted throughout the ensuing text where appropriate.
Background
Prevention of IOR begins with patient selection. Surgical treatment of IAs is higher risk in many patient populations, including the elderly, those with multiple medical comorbidities, and those with subarachnoid haemorrhage and poor neurologic status or vasospasm. Atherosclerotic neck calcification makes IA surgery more difficult. Certain aneurysms are better treated endovascularly. With the advent of flow diversion, many surgically challenging IAs are successfully treated in this manner with less risk.11 Ultimately, patient selection is the first line of defense against any surgical complication, including IOR. Adequate bony exposure and a craniotomy that provides the most direct route to the aneurysm limit the need for brain retraction and provide adequate proximal control and maximal degrees of freedom to maximize clip application angle (Fig. 9.1). The pterional craniotomy is the workhorse of cerebrovascular surgery. When completed appropriately, the pterional approach provides a direct working corridor to most anterior circulation aneurysms as well as aneurysms that arise from the basilar artery apex (BAA) and superior cerebellar artery (SCA) origin. The entire anterior sylvian fissure is exposed, and the need for brain retraction is limited if the lesser wing of sphenoid is drilled completely flat. The modified orbito-zygomatic approach is sometimes necessary to visualize the BAA and distal basilar artery when the BAA is above the level of the posterior clinoid. A “half-and-half ” approach provides the most versatile combination of angles of attack for many BAA and SCA aneurysms. In addition to performing a standard pterional craniotomy, the squamosal temporal bone is drilled flush with the floor of the middle fossa in the half-and-half approach, thereby granting access to the BAA through the optico-carotid cistern or
As the proportion of intracranial aneurysms (IAs) treated by endovascular therapies rises, surgically treated patients will harbor more complex aneurysms.1 Although the role of open microsurgical treatment of IAs remains, trainees and younger vascular neurosurgeons will be less experienced than their mentors. Experience is the ultimate tool in the surgeon’s armamentarium to avoid complications and mitigate their potentially deleterious effects. Vascular neurosurgeons must develop strategies to hone microsurgical skills to keep the surgical treatment of IAs minimally disruptive in the combined microsurgical and endovascular era.2 Intraoperative rupture (IOR) and/or parent vessel injury (PVI) are among the most nerve-wracking and potentially devastating complications in the treatment of IAs. IOR occurs in as many as one-third of cases of microsurgically treated IAs and is more common when operating on ruptured aneurysms.3–8 Aneurysm size, location, and morphology and the adherence of the fundus to surrounding structures are associated with IOR.2,5,7,9 Patient outcomes after IOR are varied.3–6,8,10 Rupture before opening the dura or arachnoid dissection is predictive of unfavorable outcomes.3,6,10 Surgeon experience has been shown to have no effect on the rate of IOR,5,7 but it is positively associated with improved outcomes, indicating “mental anticipation and technical repetition over time transform into efficiency, confidence and insight in the management of [IOR].”7 IOR is inevitable; however, with adequate preparation and calm and decisive action, the surgeon can limit the possibility of IOR but also effectively manage the rupture while mitigating complications.
Prevention
37
38
SE C T I O N 2
Cranial Complications
A
B
C
D • Fig. 9.1
Insufficient drilling of the lesser wing of sphenoid for pterional approach limits exposure of the sylvian fissure and cisterns associated with the vessels of the circle of Willis (A and B). Extensive drilling of the sphenoid wing exposes the entire sylvian fissure, provides a subfrontal corridor to the opticocarotid and oculomotor cisterns, limits the need for brain retraction, provides adequate proximal control, and maximizes degrees of freedom for clip application (C and D).
oculomotor triangle, a subtemporal approach, or a combination. Liberal drilling of the occipital condyle provides wide exposure to visualize posterior inferior cerebellar artery (PICA) aneurysms. Meticulous arachnoid dissection is vital in the prevention of IOR/ PVI. Adequate dissection of the arachnoid releases cerebrospinal fluid (CSF) from the cisterns. Egress of CSF in addition to administration of osmotic diuretics provides brain relaxation sufficient to limit the need for fixed retractors, which not only cause white matter injury, but also may lead to a tear in the dome of an aneurysm that is adherent to surrounding brain if retraction is overly aggressive. Microdissection should be completed sharply whenever possible, particularly when dissecting the neck of an IA. Forceful or blind blunt dissection of the neck of the aneurysm, the parent artery, and surrounding structures increases the risk of IOR/PVI. Temporary clipping of the parent artery proximal to the inlet of an IA softens the aneurysm and can make final dissection and clip application safer. Temporary clipping is particularly useful in the setting of large or turgid aneurysms or for aneurysms where the orientation of the aneurysm neck and the origin of branch vessels, small perforating arteries, or surrounding cranial nerves is complicated and extensive dissection is required to define the anatomy. The surgeon must be mindful of the duration of parent
vessel temporary occlusion to limit the possibility of irreversible ischemic injury. Several strategies can be employed, typically in concert, to protect the brain during temporary clipping, including hypothermia and pharmacologic burst suppression to limit metabolic demand from ischemic brain, and induced hypertension to maximize pial collateralization to the ischemic territory. Modern aneurysm clips are available in a wide range of sizes and configurations, which makes clipping of IAs a versatile and durable treatment. Selection of the permanent clip(s) can have a profound effect on the likelihood of IOR/PVI. The risk of IOR increases each time an aneurysm clip is removed and reapplied. The most parsimonious combination of clips to completely occlude the IA should be used. The long axes of clip application and the parent vessel should be aligned as well as possible. Application of an aneurysm clip(s) parallel to the long axis of the parent artery limits stress on the arterial wall at the neck and increases the likelihood that the entire neck is obliterated, which limits the need for additional clip application. Additionally, angled, bayonetted, and right-angle clips all have lower closing force than straight clips and may lead to incomplete occlusion.12 A well-thought-out, simple clipping strategy, executed deftly, maximizes the potential for complete occlusion and limits manipulation of the aneurysm, IOR,
CHAPTER 9 Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery
and PVI. Overall, IOR is better prevented than managed. Although IOR is inevitable, keeping to the principles of cerebrovascular surgery will limit the risk.
RED FLAGS Patient-related: • Atherosclerotic vessels • Large and giant aneurysms • Blister aneurysms • Adherent en passage vessels Surgeon-related: • Inadequate exposure • Failure to gain proximal control • Clipping perpendicular to the long axis of the parent vessel • Blind clipping • Blunt arachnoid dissection • Aggressive brain retraction
Management Arguably, the most important attribute of the surgeon in the successful management of an IOR is unwavering calm. When IOR/PVI occurs, effective treatment relies on achieving two goals. First, the field must be cleared of blood. Second, the aneurysm must be definitively treated. The timing of aneurysm rupture in the course of surgery and the anatomic location of rupture also are important determinants of treatment. When IOR or PVI occurs, burst suppression should be induced to provide cerebral protection by lowering oxygen demand. IOR before exposure of the aneurysm is uncommon but is potentially devastating and is associated with a high rate of morbidity and mortality.3,6,10 Unfortunately, strategies to manage IOR before aneurysm exposure are limited. The surgeon must first clear the field of blood. This is best achieved using two large-bore suctions, one in the surgeon’s nondominant hand and the other controlled by an assistant. Frequently, a jet of blood can be traced to the site of rupture. If possible, proximal control of the parent vessel should be achieved and a temporary clip placed to stem torrential hemorrhage. Once the site of IOR is located, cotton is placed over the ruptured portion of the aneurysm to control the extravasation of blood. As a consequence of its absorbency, loosely packed cotton serves as an ideal tamponade. Gentle pressure should be applied to the cotton, either with a suction tip or a retractor blade. Excessive force during tamponade may worsen the tear in the aneurysm or parent vessel and should be avoided. Although fixed retractors are almost never used in aneurysm surgery, we routinely set one up to assist in the event of an IOR. The self-retaining retractor can serve as a “third hand” to hold the cotton in place on the rent in the aneurysm, while the surgeon gains full use of both hands to complete microdissection and clip application. If the flow of blood is too brisk to clear effectively with suction alone, intravenous adenosine can be administered to induce temporary asystole, which typically lasts between 30 and 60 seconds and can yield enough time to locate and control the source of bleeding. Once relative hemostasis and proximal control have been achieved, the surgeon must efficiently dissect and apply permanent clips to the neck of the aneurysm. IOR/PVI that occurs after proximal control has been achieved may occur for multiple reasons. Management of IOR/PVI after exposure of the aneurysm has been completed is directed toward
39
the cause. IOR/PVI may occur before clip application, and the most common inciting events at this stage include excessive retraction on structures to which the dome of the aneurysm is affixed, or overly aggressive blunt or blind microdissection of the aneurysm neck or en passage vessels. If IOR/PVI occurs during dissection of the aneurysm and temporary parent vessel occlusion has not yet been utilized, a temporary clip should be placed on the parent vessel, if this is necessary to assist in controlling the hemorrhage. Temporary clipping to reduce the rate of extravasation followed by directed cotton tamponade and suction often easily controls the bleeding after proximal control is established. These actions give the surgeon adequate visualization to dissect the neck of the aneurysm and place permanent clips. IOR/PVI may occur during clip application. Anecdotally, the most common reason for aneurysm rupture during clip application is inadequate neck dissection. When the neck has not been completely dissected, the operator uses the tips of the clip blades to bluntly dissect the remaining neck that was not previously freed. Moreover, this is often a blind maneuver by virtue of the fact that incomplete neck dissection occurs most often at the deepest aspect of the neck, which is difficult to visualize. Blind clipping in this scenario may lead to direct injury of the aneurysm neck, a tear in the parent vessel, laceration of a daughter sack, or avulsion or injury to an adjacent perforator. IOR can also occur with incomplete aneurysm occlusion. If the blades of the permanent clip do not completely cross the entire neck of the aneurysm, the hemodynamics change, sometimes producing an “inflow jet” that can lead to IOR. Incomplete clipping is often the result of blind clipping, or of the clipping of an aneurysm perpendicular to the long access of the parent vessel, in which case the length of the blades required to close the entire inlet of the aneurysm is underestimated. Particularly in the setting of aneurysms and parent vessels with extensive atherosclerosis, the rigidity of the walls of the aneurysm prevents complete closure of the clip blades, which can result in altered blood flow characteristics and IOR. The treatment of IOR/PVI at the time of clip placement is focused on the cause. If the neck is incompletely obliterated, the clip can be opened slightly and advanced to span the entire neck. Alternatively, if the clip applied earlier to the aneurysm cannot be advanced further, an additional clip can be stacked parallel to the first clip to occlude the more distal neck. In the case of wide-necked or atherosclerotic aneurysms, if the clip does not close completely, a fenestrated clip can be applied to the distal neck to increase the closing pressure, and a shorter clip can then be placed within the fenestration to occlude the proximal neck. If the clip blades still do not close entirely, a clip with the strongest closing force should be used—i.e., straight rather than angled or bayonetted clips. IOR/PVI rarely occurs after application of permanent clips. At this stage, IOR/PVI is the direct result of excessive torqueing of the clips to gain a view of relevant anatomy. After final clip placement, the aneurysm, parent artery, and surrounding neurovascular structures must be inspected to assure that the aneurysm is completely obliterated and that no perforating or en passage vessels or adjacent cranial nerves are impinged by the aneurysm clips. However, any manipulation of the permanent clips transmits force to the neck of the aneurysm and the interface with the parent vessel that can lead to injury. Care must be taken to limit manipulation of permanent clips when examining clip placement. Once the aneurysm is secured after IOR/PVI, the temporary clip should be slowly opened, but not removed. The surgeon should pause briefly after the temporary clip has been opened to assure that no additional bleeding from the aneurysm is noted. If bleeding
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Cranial Complications
does occur when the temporary clip is released, it should be immediately reapplied and the aneurysm should be inspected.
Specific Anatomic Considerations Most IA ruptures occur at the dome and, particularly after adequate aneurysm exposure, are easily controlled with the previously described methods. Sometimes, particularly during treatment of larger aneurysms, the fundus can be partially clipped below the site of rupture to control bleeding and to allow the surgeon to proceed to final clipping. Ruptures at the neck or at the interface of the neck and parent vessel are more difficult to manage. Often, the tissue is extremely fragile, and attempts to adjust clips either worsens the tear or occludes the parent vessel. Cotton-clipping is an effective way to occlude the aneurysm, but parent artery patency should be salvaged when the point of rupture is at the neck or the parent artery is injured at the interface with the aneurysm inlet.13 A small piece of cotton is placed at the point of rupture, and a permanent clip is placed at the superior margin of the cotton, cheating toward the aneurysm side. The cotton distributes the closing force of the clip over a larger surface area than the clip alone, while leaving the parent vessel patent. Blister aneurysms can be particularly treacherous to treat. The wall of the aneurysm and associated parent vessel is extremely thin, making these aneurysms prone to IOR and nearly impossible to occlude with standard clips. A Sundt-Kees clip (S-KC) can be applied to the parent vessel to treat such aneurysms. The S-KC is an encircling clip that envelops the aneurysm and parent artery. Although useful in emergent situations, S-KCs have several disadvantages. Pragmatically, the perfect size and length S-KC to adequately protect the aneurysm, while maintaining parent vessel patency and not overlapping perforators, is often lacking. An alternative strategy to treat blister aneurysms is Gor-Tex clip wrapping.14 A piece of Gor-Tex is cut to span the exact length of parent artery required. If needed, slits can be cut into the Gor-Tex to allow unencumbered egress of essential perforators or branch vessels through the graft. The entire circumference of the parent vessel and blister aneurysm is surrounded by Gor-Tex, the tails are pulled snugly, and a 90-degree aneurysm clip is applied to secure the sling. The parent vessel should be slightly narrowed to ensure adequate protection from additional rupture of the blister aneurysm. Posterior communicating artery (PCommA) aneurysms, particularly larger ones, can pose a challenge if IOR occurs. The space within the oculomotor triangle is often limited. IOR is likely to occur during dissection of the neck or surrounding structures. Often, the anterior choroidal artery (AchorA) is draped over the backside of PCommA aneurysms, and IOR may occur as a consequence of dissection of the AchorA from the aneurysm. IOR may also occur if the surgeon attempts to use a straight clip applied perpendicular to the long axis of the internal carotid artery (ICA). PCommA aneurysms project laterally or posterolaterally,
and the surgeon’s angle of approach to the oculomotor triangle via pterional craniotomy entices him or her to use a straight clip, which may lead to incomplete neck occlusion and IOR. Instead, an angled clip, or fenestrated angled clip for aneurysms that arise more ventrally, is favored to achieve parallel clipping. To effectively control IOR when clipping anterior communicating artery (AcommA) aneurysms requires full understanding of the surrounding anatomy. The anatomy of the ACommA complex is highly variable, and bilateral inflow from the ipsi- and contralateral A1 segments can make achieving proximal control difficult, particularly for inferiorly directed aneurysms that may obscure the contralateral A1. Extensive dissection of the neck is often required to clip ACommA aneurysms to avoid injuring or occluding the recurrent artery of Heubner, other smaller medial lenticulostriate arteries, or hypothalamic and chiasmal perforators. The extent of dissection increases the risk of IOR/PVI. IOR may occur during clip placement, which can be partially blind as a result of obscuration by the ipsilateral A2 segment and gyrus rectus. If IOR occurs, proximal control of both A1 segments best mitigates the amount of extravasation. Removal of the inferomedial aspect of the gyrus rectus can aid in visualization and is well tolerated clinically. Resection of the gyrus rectus should be completed with suction and bipolar cautery and should be limited to the minimum necessary to avoid thermal injury to surrounding structures. IOR when clipping middle cerebral artery (MCA) aneurysms is often easily controlled. Provided the sylvian fissure is widely opened, the proximal M1 segment should be readily accessible for temporary clipping. Premature rupture of MCA aneurysms often occurs when dissecting en passage vessels from the aneurysm neck or dome. MCA aneurysms are often nestled within the branches of the candelabra, making navigating to the aneurysm confusing, particularly when IOR occurs and the sylvian fissure fills with blood. Proximal control and cotton tamponade are effective tools to control IOR of MCA aneurysms, but the key to clipping in this location is careful and broad exposure of the sylvian fissure. IOR may occur while approaching PICA aneurysms due to several factors. The fundus may be adherent to the cerebellar tonsils or clival dura depending on the direction the aneurysm points. Excessive retraction of the cerebellum should be avoided to avoid an avulsion tear of the dome. Bony exposure via a far lateral craniotomy allows for outstanding visualization of the foramen magnum, anterior medulla, lower clivus, lower cranial nerves, and PICA origin. IOR/PVI may occur during neck dissection if the aneurysm is entwined with the lower cranial nerves. Standard principles of proximal control and cotton tamponade apply to the management of PICA aneurysm IOR. The surgeon must remember that temporary clips must be placed on the vertebral artery both proximal and distal to the PICA origin to curtail the bleeding. Additionally, the surgeon must be sensitive to the directionality and precise location of final clip placement because the PICA is small and easily occluded by the clip.
SURGICAL REWIND
My Worst Case The patient was a 32-year-old female who presented with subarachnoid haemorrhage. Angiography revealed a BAA aneurysm and a low-lying basilar artery. The interventional neuroradiologist felt that he could not safely and
completely treat the aneurysm. Therefore the patient was brought to the operating room for a pterional craniotomy for microsurgical clip ligation of the aneurysm. The posterior clinoid was drilled to gain proximal control of
CHAPTER 9 Intraoperative Rupture and Parent Artery Injury During Aneurysm Surgery
the basilar artery. The posterior clinoid was cored using a high-speed drill and diamond burr. The supraclinoid ICA was accidentally severed with a curette that slipped off the posterior clinoid during removal of the remaining bone. The anterior clinoid was drilled, the distal dural ring opened sharply, and temporary aneurysm clips were placed on the proximal and distal stumps of the torn ICA. The ICA was repaired directly using 9-0 suture. ICG video angiography revealed patency of the ICA after repair. The BAA
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aneurysm was clipped without difficulty. The patient did well postoperatively. However, 48 hours after surgery the patient developed a right MCA syndrome. Computed tomography revealed a holohemispheric infarction from occlusion of the repaired ICA. Despite aggressive medical therapy to control cerebral edema and a large decompressive hemicraniectomy, the patient progressed to brain death (Fig. 9.2).
A’
A
B
C
• Fig. 9.2 Preoperative 3-D rotational angiography of a basilar artery apex aneurysm and a low-lying basilar artery (A and A′). The supraclinoid internal carotid artery (ICA) was inadvertently severed when a curette slipped off the posterior clinoid during removal. The ICA was repaired, and ICG video angiography revealed patency. The basilar artery apex aneurysm was clipped without difficulty. The patient did well postoperatively, and a computed tomography scan within 24 hours of surgery demonstrated expected postoperative changes, but no stroke (B). However, 48 hours after surgery, the patient developed a right middle cerebral artery syndrome. Computed tomography revealed a holohemispheric infarction from occlusion of the repaired ICA (C).
NEUROSURGICAL SELFIE MOMENT IOR/PVI is a stressful but manageable event. Complication avoidance in the setting of IOR/PVI requires the operator to stay calm and employ steps to clear the field of blood, limit continued bleeding, and clip the aneurysm. The neurologic outcome after aneurysm surgery complicated by IOR is related less to the rupture and more to the reaction of the surgeon. If the surgeon rushes to blindly place clips on the aneurysm before the aneurysm is sufficiently dissected in an attempt to stop heavy bleeding, the tear may be made worse, or the parent vessel may be irreparably damaged.
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intracranial aneurysms: the CARAT study. Stroke. 2008;39(5):1501– 1506. 5. Fridriksson S, Saveland H, Jakobsson KE, et al. Intraoperative complications in aneurysm surgery: a prospective national study. J Neurosurg. 2002;96(3):515–522. 6. Giannotta SL, Oppenheimer JH, Levy ML, Zelman V. Management of intraoperative rupture of aneurysm without hypotension. Neurosurgery. 1991;28(4):531–535, discussion 5–6. 7. Lawton MT, Du R. Effect of the neurosurgeon’s surgical experience on outcomes from intraoperative aneurysmal rupture. Neurosurgery. 2005;57(1):9–15, discussion 9. 8. Sandalcioglu IE, Schoch B, Regel JP, et al. Does intraoperative aneurysm rupture influence outcome? Analysis of 169 patients. Clin Neurol Neurosurg. 2004;106(2):88–92. 9. Leipzig TJ, Morgan J, Horner TG, Payner T, Redelman K, Johnson CS. Analysis of intraoperative rupture in the surgical treatment of 1694 saccular aneurysms. Neurosurgery. 2005;56(3):455–468, discussion 455–68.
10. Schramm J, Cedzich C. Outcome and management of intraoperative aneurysm rupture. Surg Neurol. 1993;40(1):26–30. 11. Becske T, Brinjikji W, Potts MB, et al. Long-term clinical and angiographic outcomes following Pipeline Embolization Device treatment of complex internal carotid artery aneurysms: five-year results of the Pipeline for Uncoilable or Failed Aneurysms Trial. Neurosurgery. 2017;80(1):40–48. 12. Horiuchi T, Rahmah NN, Yanagawa T, Hongo K. Revisit of aneurysm clip closing forces: comparison of titanium versus cobalt alloy clip. Neurosurg Rev. 2013;36(1):133–137, discussion 7–8. 13. Barrow DL, Spetzler RF. Cotton-clipping technique to repair intraoperative aneurysm neck tear: a technical note. Neurosurgery. 2011;68(Operative suppl 2):294–299, discussion 9. 14. Barrow DL, Pradilla G, McCracken DJ. Intracranial blister aneurysms: clip reconstruction techniques. Neurosurg Focus. 2015;39(Video suppl 1): V20.