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Treatment of Unruptured Middle Cerebral Artery Aneurysms: The Risk Factors and Surgical Safety
Perspectives Commentary on: Microsurgical Clipping of Unruptured Middle Cerebral Artery Bifurcation Aneurysms: Incidence of and Risk Factors for Procedure-Related Complications by Chung et al. World Neurosurg 83:666-672, 2015
Treatment of Unruptured Middle Cerebral Artery Aneurysms: The Risk Factors and Surgical Safety Wei Zhu and Ying Mao
S
ince the publication of the results of the International Subarachnoid Aneurysm Trial, the management of intracranial aneurysms has significantly changed (2). A better clinical outcome was observed in patients who underwent endovascular treatment compared with microsurgical clipping. However, microsurgical clipping has long been considered the primary treatment modality of middle cerebral artery (MCA) aneurysms. MCA aneurysms are located close to the brain surface, making them accessible with little or no brain retraction. Conversely, these aneurysms usually have dysmorphic shapes, broad necks, or angiographically undecipherable perforators, which make them less favorable for endovascular treatment compared with aneurysms in other locations. It is debatable whether or not to treat an unruptured MCA aneurysm because most patients with unruptured aneurysms are asymptomatic, and risk assessment for future hemorrhage is usually difficult to determine for regularly sized MCA aneurysms. The safety of treatment should be seriously evaluated before a recommendation is made to the patient. Although surgical series with unruptured MCA aneurysms consistently demonstrate good results with a complete aneurysm obliteration rate >90% and a favorable outcome rate >88%, results from published studies showed the surgical mortality and morbidity rates of unruptured MCA aneurysms were variable. Regli et al. (3) reported their surgical mortality and morbidity rates were 0% and 3%, respectively. The series by Rodrı´guez-Herna´ndez et al. (4) of 261 surgically treated unruptured MCA aneurysms showed that 16 patients (6.1%) had poor outcomes, 3 patients with giant aneurysms died after surgery, and 2 died during long-term
Key words Middle cerebral artery aneurysm - Risk factor - Surgery -
Abbreviations and Acronyms MCA: Middle cerebral artery
follow-up. These studies indicated that some complicated MCA aneurysms remain challenging even in experienced hands. The decision whether to treat unruptured MCA aneurysms should be made based on the natural history and the surgical risks. Studies on surgical difficulties of MCA aneurysms focused on the angioarchitectural characteristics, including projection of the aneurysm dome and its relationship to the lenticulostriate arteries. The inferior projection type in Yasargil’s classification or the insular middle cerebral artery bifurcation aneurysm (MbifA) type in Hernesniemi’s classification presents the closest relationship between the aneurysm base and the lenticulostriate arteries. Clear visualization and meticulous dissection of these perforators before deploying a clip is important to prevent ischemic complications. The surgical difficulties of an unruputured MCA bifurcation aneurysm also depend on the size of the aneurysm. Giant MCA bifurcation aneurysms are challenging because of the diversity of aneurysm morphology, intraluminal thrombus, severe calcification on the aneurysm neck, and involvement of perforators. In addition to direct neck clipping, some special surgical techniques, such as reconstructive clipping and bypass, are needed to obliterate the aneurysm. In addition, as the temporary occlusion time increases, greater surgical skills are required to facilitate these techniques. In our series of 59 complex MCA aneurysms, including 57 giant or large MCA aneurysms, 12% of cases resulted in poor outcomes (7). Similarly, in the series by Rodrı´guez-Herna´ndez et al. (4), the 3 perioperative deaths reported all were patients with giant aneurysms. In addition to the morphologic characteristics and the size of the aneurysm, the patient’s clinical status, age, and comorbidities
Department of Neurosurgery, Huashan Hospital of Fudan University, and Shanghai Neurosurgical Center, Shanghai, China To whom correspondence should be addressed: Ying Mao, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 84, 3:618-619. http://dx.doi.org/10.1016/j.wneu.2015.04.006
618
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.006
PERSPECTIVES
affect the surgical outcome. Aging is associated with an increasing prevalence of multiple diseases and disabilities, a decline of the functional reserve of multiple organ systems, and a progressive restriction in personal and social resources. Advanced age has been demonstrated as a risk factor for cancer (1) and cardiac surgery (5). Rodrı´guez-Herna´ndez et al. (4) reported that patients with MCA aneurysms who were elderly (65 years old) tended to have poor surgical outcomes. We believe that it is important to implement the use of geriatric markers such as comorbidities and nutritional status to assess the surgical risks of elderly patients with unruptured MCA aneurysms. Surgical safety of an unruptured MCA aneurysm is based on careful preoperative assessment including the angioarchitectural features of the aneurysm, clinical status of the patient, appropriate application of surgical techniques and strategies, use of intraoperative motor and sensory evoked potential monitoring (6), and available postoperative care.
carotid artery bifurcation and MCA bifurcation, and a large horizontal angle between the vertical line and the skull base were factors predictive of surgical risks. Although this was a retrospective trial with similar results as previous publications, the authors pointed out the objective parameters that showed a significant association with surgical outcomes by appropriate statistical methods. Some bias was unavoidable in this study because it included very few giant MCA aneurysms. Apart from the limitations that the authors mentioned, no explanation was offered for why 20 patients were lost to follow-up 1 year postoperatively, which could have affected the results when analyzing the clinical outcome and its predictive factors. The authors also needed to explain why only the angioarchitectural factors were associated with surgical risks. The patients’ ages and their comorbidities were not addressed and may have affected surgical outcomes, even if they did not show any significant difference in this study.
In their study, Chung J et al. reviewed their large series of 416 patients with surgically treated unruptured bifurcation MCA aneurysms. The postoperative complication rate was 3.6%, with only 1.2% of cases being symptomatic. Results from multivariate logistic regression analysis showed that posterior-inferior projection of the aneurysm dome, short distance between internal
In conclusion, this study provided helpful information regarding the surgical safety of unruptured MCA aneurysms. The results remind us to pay more attention to the architectural characteristics of the MCA aneurysm despite the fact that it has been long considered the aneurysm most amenable to surgery.
REFERENCES 1. Kristjansson SR, Nesbakken A, Jordhøy MS, Skovlund E, Audisio RA, Johannessen HO, Bakka A, Wyller TB: Comprehensive geriatric assessment can predict complications in elderly patients after elective surgery for colorectal cancer: a prospective observational cohort study. Crit Rev Oncol Hematol 76:208-217, 2010. 2. Molyneux AJ, Kerr RS, Yu LM, Clarke M, Sneade M, Yarnold JA, Sandercock P; International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet 366: 809-817, 2005.
3. Regli L, Uske A, de Tribolet N: Endovascular coil placement compared with surgical clipping for the treatment of unruptured middle cerebral artery aneurysms: a consecutive series. J Neurosurg 90: 1025-1030, 1999. 4. Rodríguez-Hernández A, Sughrue ME, Akhavan S, Habdank-Kolaczkowski J, Lawton MT: Current management of middle cerebral artery aneurysms: Surgical results with a “clip first” policy. Neurosurgery 72:415-427, 2013.
monitoring during surgery of middle cerebral artery aneurysms: a cohort study. World Neurosurg 82:1091-1099, 2014. 7. Zhu W, Liu P, Tian Y, Gu Y, Xu B, Chen L, Zhou L, Mao Y: Complex middle cerebral artery aneurysms: a new classification based on the angioarchitecture and surgical strategies. Acta Neurochir (Wien) 155: 1481-1491, 2013.
5. Sündermann S, Dademasch A, Praetorius J, Kempfert J, Dewey T, Falk V, Mohr FW, Walther T: Comprehensive assessment of frailty for elderly high-risk patients undergoing cardiac surgery. Eur J Cardiothorac Surg 39:33-37, 2011.
Citation: World Neurosurg. (2015) 84, 3:618-619. http://dx.doi.org/10.1016/j.wneu.2015.04.006
6. Yue Q, Zhu W, Gu Y, Xu B, Lang L, Song J, Cai J, Xu G, Chen L, Mao Y: Motor evoked potential
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY 84 [3]: 618-619, SEPTEMBER 2015
Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
www.WORLDNEUROSURGERY.org
619
Treatment of Unruptured Middle Cerebral Artery Aneurysms: The Risk Factors and Surgical Safety Wei Zhu and Ying Mao
S
ince the publication of the results of the International Subarachnoid Aneurysm Trial, the management of intracranial aneurysms has significantly changed (2). A better clinical outcome was observed in patients who underwent endovascular treatment compared with microsurgical clipping. However, microsurgical clipping has long been considered the primary treatment modality of middle cerebral artery (MCA) aneurysms. MCA aneurysms are located close to the brain surface, making them accessible with little or no brain retraction. Conversely, these aneurysms usually have dysmorphic shapes, broad necks, or angiographically undecipherable perforators, which make them less favorable for endovascular treatment compared with aneurysms in other locations. It is debatable whether or not to treat an unruptured MCA aneurysm because most patients with unruptured aneurysms are asymptomatic, and risk assessment for future hemorrhage is usually difficult to determine for regularly sized MCA aneurysms. The safety of treatment should be seriously evaluated before a recommendation is made to the patient. Although surgical series with unruptured MCA aneurysms consistently demonstrate good results with a complete aneurysm obliteration rate >90% and a favorable outcome rate >88%, results from published studies showed the surgical mortality and morbidity rates of unruptured MCA aneurysms were variable. Regli et al. (3) reported their surgical mortality and morbidity rates were 0% and 3%, respectively. The series by Rodrı´guez-Herna´ndez et al. (4) of 261 surgically treated unruptured MCA aneurysms showed that 16 patients (6.1%) had poor outcomes, 3 patients with giant aneurysms died after surgery, and 2 died during long-term
Key words Middle cerebral artery aneurysm - Risk factor - Surgery -
Abbreviations and Acronyms MCA: Middle cerebral artery
follow-up. These studies indicated that some complicated MCA aneurysms remain challenging even in experienced hands. The decision whether to treat unruptured MCA aneurysms should be made based on the natural history and the surgical risks. Studies on surgical difficulties of MCA aneurysms focused on the angioarchitectural characteristics, including projection of the aneurysm dome and its relationship to the lenticulostriate arteries. The inferior projection type in Yasargil’s classification or the insular middle cerebral artery bifurcation aneurysm (MbifA) type in Hernesniemi’s classification presents the closest relationship between the aneurysm base and the lenticulostriate arteries. Clear visualization and meticulous dissection of these perforators before deploying a clip is important to prevent ischemic complications. The surgical difficulties of an unruputured MCA bifurcation aneurysm also depend on the size of the aneurysm. Giant MCA bifurcation aneurysms are challenging because of the diversity of aneurysm morphology, intraluminal thrombus, severe calcification on the aneurysm neck, and involvement of perforators. In addition to direct neck clipping, some special surgical techniques, such as reconstructive clipping and bypass, are needed to obliterate the aneurysm. In addition, as the temporary occlusion time increases, greater surgical skills are required to facilitate these techniques. In our series of 59 complex MCA aneurysms, including 57 giant or large MCA aneurysms, 12% of cases resulted in poor outcomes (7). Similarly, in the series by Rodrı´guez-Herna´ndez et al. (4), the 3 perioperative deaths reported all were patients with giant aneurysms. In addition to the morphologic characteristics and the size of the aneurysm, the patient’s clinical status, age, and comorbidities
Department of Neurosurgery, Huashan Hospital of Fudan University, and Shanghai Neurosurgical Center, Shanghai, China To whom correspondence should be addressed: Ying Mao, M.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 84, 3:618-619. http://dx.doi.org/10.1016/j.wneu.2015.04.006
618
www.SCIENCEDIRECT.com
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2015.04.006
PERSPECTIVES
affect the surgical outcome. Aging is associated with an increasing prevalence of multiple diseases and disabilities, a decline of the functional reserve of multiple organ systems, and a progressive restriction in personal and social resources. Advanced age has been demonstrated as a risk factor for cancer (1) and cardiac surgery (5). Rodrı´guez-Herna´ndez et al. (4) reported that patients with MCA aneurysms who were elderly (65 years old) tended to have poor surgical outcomes. We believe that it is important to implement the use of geriatric markers such as comorbidities and nutritional status to assess the surgical risks of elderly patients with unruptured MCA aneurysms. Surgical safety of an unruptured MCA aneurysm is based on careful preoperative assessment including the angioarchitectural features of the aneurysm, clinical status of the patient, appropriate application of surgical techniques and strategies, use of intraoperative motor and sensory evoked potential monitoring (6), and available postoperative care.
carotid artery bifurcation and MCA bifurcation, and a large horizontal angle between the vertical line and the skull base were factors predictive of surgical risks. Although this was a retrospective trial with similar results as previous publications, the authors pointed out the objective parameters that showed a significant association with surgical outcomes by appropriate statistical methods. Some bias was unavoidable in this study because it included very few giant MCA aneurysms. Apart from the limitations that the authors mentioned, no explanation was offered for why 20 patients were lost to follow-up 1 year postoperatively, which could have affected the results when analyzing the clinical outcome and its predictive factors. The authors also needed to explain why only the angioarchitectural factors were associated with surgical risks. The patients’ ages and their comorbidities were not addressed and may have affected surgical outcomes, even if they did not show any significant difference in this study.
In their study, Chung J et al. reviewed their large series of 416 patients with surgically treated unruptured bifurcation MCA aneurysms. The postoperative complication rate was 3.6%, with only 1.2% of cases being symptomatic. Results from multivariate logistic regression analysis showed that posterior-inferior projection of the aneurysm dome, short distance between internal
In conclusion, this study provided helpful information regarding the surgical safety of unruptured MCA aneurysms. The results remind us to pay more attention to the architectural characteristics of the MCA aneurysm despite the fact that it has been long considered the aneurysm most amenable to surgery.
REFERENCES 1. Kristjansson SR, Nesbakken A, Jordhøy MS, Skovlund E, Audisio RA, Johannessen HO, Bakka A, Wyller TB: Comprehensive geriatric assessment can predict complications in elderly patients after elective surgery for colorectal cancer: a prospective observational cohort study. Crit Rev Oncol Hematol 76:208-217, 2010. 2. Molyneux AJ, Kerr RS, Yu LM, Clarke M, Sneade M, Yarnold JA, Sandercock P; International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group: International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion. Lancet 366: 809-817, 2005.
3. Regli L, Uske A, de Tribolet N: Endovascular coil placement compared with surgical clipping for the treatment of unruptured middle cerebral artery aneurysms: a consecutive series. J Neurosurg 90: 1025-1030, 1999. 4. Rodríguez-Hernández A, Sughrue ME, Akhavan S, Habdank-Kolaczkowski J, Lawton MT: Current management of middle cerebral artery aneurysms: Surgical results with a “clip first” policy. Neurosurgery 72:415-427, 2013.
monitoring during surgery of middle cerebral artery aneurysms: a cohort study. World Neurosurg 82:1091-1099, 2014. 7. Zhu W, Liu P, Tian Y, Gu Y, Xu B, Chen L, Zhou L, Mao Y: Complex middle cerebral artery aneurysms: a new classification based on the angioarchitecture and surgical strategies. Acta Neurochir (Wien) 155: 1481-1491, 2013.
5. Sündermann S, Dademasch A, Praetorius J, Kempfert J, Dewey T, Falk V, Mohr FW, Walther T: Comprehensive assessment of frailty for elderly high-risk patients undergoing cardiac surgery. Eur J Cardiothorac Surg 39:33-37, 2011.
Citation: World Neurosurg. (2015) 84, 3:618-619. http://dx.doi.org/10.1016/j.wneu.2015.04.006
6. Yue Q, Zhu W, Gu Y, Xu B, Lang L, Song J, Cai J, Xu G, Chen L, Mao Y: Motor evoked potential
1878-8750/$ - see front matter ª 2015 Elsevier Inc. All rights reserved.
WORLD NEUROSURGERY 84 [3]: 618-619, SEPTEMBER 2015
Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
www.WORLDNEUROSURGERY.org
619