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Cerebral Bypass Surgery

  • Saman SizdahkhaniEmail author
  • Jordan Lam
  • Shivani Rangwala
  • Jonathan Russin
Chapter
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Abstract

Cerebral bypass is an important option for the management of a variety of conditions. These include flow augmentation for cerebrovascular diseases such as atherosclerosis or moyamoya and flow replacement for proximal stenosis or aneurysms. Since the integration of fluorescent technology with microscopes, fluorescent videoangiography (VA) enables real-time intraoperative monitoring of graft patency. Furthermore, fluorescent VA is a safe, fast, cost-effective, and less invasive alternative to other intraoperative imaging methods including intraoperative digital subtraction angiography, doppler ultrasound, and intraoperative magnetic resonance imaging. Indocyanine green (ICG) and sodium fluorescein (FL) each offer their relative advantages and disadvantages, with ICG allowing for semi-quantification of flow using the FLOW 800 module, more frequent reinjections, and better visualization of large arteries; FL has been shown to be superior in visualizing deep structures and perforators and at higher magnifications. Pitfalls of VA pertain to those of optically based methods of imaging in general with areas visualized limited to those that can be seen through the microscope. Nevertheless, fluorescent VA is a key tool for routine intraoperative evaluation of cerebral blood flow in bypass surgery.

Keywords

Bypass Revascularization Fluorescent Videoangiography Indocyanine green Sodium fluorescein Stroke Atherosclerosis Aneurysm Moyamoya 

Supplementary material

Video 5.1

STA to SCA bypass for basilar insufficiency. This video demonstrates revascularization for basilar insufficiency utilizing a superficial temporal artery to superior cerebellar artery bypass (STA-SCA). The preoperative angiogram (0:09) demonstrates a left vertebral dissection, severe stenosis, and trace anterograde flow to the basilar artery. The parietal branch of the STA is dissected 8 cm from the root of the zygoma (0:23) and heparinized as described above. The temporal craniotomy (0:24) is completed, and the dural opening allowed for a subtemporal approach. The ambient cistern was opened sharply with brisk egress of cerebrospinal fluid and relaxation of the temporal lobe (0:30). The SCA was identified, with intraoperative indocyanine green to confirm the dissection and slow anterograde flow (1:11). We proceeded with microdissection of the SCA, mobilizing the portion distal to the dissection (1:20). The blue microgrid background was then placed, and the STA was mobilized intracranially, fish mouthed, and placed next to the recipient artery (1:26). Next, 3-mm AVM clips were placed on the recipient vessel in preparation for an arteriotomy. A running 10-0 nylon was utilized for the end-to-side anastomosis of the STA graft to the distal SCA vessel (1:28). Once the bypass was complete, the temporary clip was removed from the recipient artery, and the anastomosis was assessed for any leak. No leak was present (2:13); the background was removed followed by the proximal clip. At this time, there was good pulsatility noted, and intraoperative indocyanine green confirmed patency of the bypass (2:16). A postoperative angiogram also demonstrated a patent bypass graft. Postoperative perfusion studies also demonstrated a decrease in mismatch volume from 50 to 26 cc. (MP4 518855 kb) (MP4 367970 kb)

Video 5.2

STA to MCA bypass for moyamoya. This video demonstrates a right frontal craniotomy with STA to MCA bypass for revascularization in the setting of a right watershed stroke. The preoperative angiogram (0:08) demonstrates significantly bilateral ICA stenosis as well as occluded right MCA with diffuse moyamoya type vasculature. The right STA was mapped out using Doppler, and preoperative marking was completed with plans to end the base of the incision at the base of the STA. Once the STA dissection was completed, a temporary aneurysm clip was placed proximally (0:19), and the artery was prepared. The most distal 2 cm was circumferentially dissected free from the adventitia (0:32), and the artery was divided (0:25). The STA graft was flushed with a heparin milrinone solution to ensure no clots were formed, and it was subsequently elevated and removed from the field such that preparation for the craniotomy could commence. The incision was extended to create a musculocutaneous flap that could be reflected. As mentioned in the body of the text above, the dural opening was planned around the middle meningeal artery, to preserve its contributions to the middle meningeal branches (0:38). The arachnoid was carefully dissected (0:40) to prepare for mobilization of the recipient vessel. A microsurgical blue background was placed (0:43). The donor STA was then fish mouthed in preparation for an end-to-side anastomosis (1:00). Once the anastomotic site was marked, temporary AVM clips were then placed proximally and distally. The arteriotomy was placed at the planned site, and a 10-0 nylon suture was used to bypass the vessel in a standard running fashion (2:12). The temporary clips were then removed, and indocyanine green angiography (2:36) was performed to verify the patency of the bypass. Postoperative imaging showed improvement in perfusion mismatch volume (2:53) (MP4 420506 kb)

Video 5.3

STA to A2 bypass for trapping of giant aneurysm. Preoperative CT angiogram shown here (0:04) with 3D reconstruction of a giant 3 cm right-sided A1 aneurysm. The diagnostic angiogram is also shown (0:19). At 0:24, a glimpse of the final anastomosis is shown. A radial artery graft was utilized to anastomose the STA and A2 segment of the anterior cerebral artery, effectively trapping the giant aneurysm out of circulation. As mentioned above, not shown in this video is the proximal STA dissection, the pterional craniotomy with orbitozygomatic extension, sylvian dissection, and interhemispheric dissection. At this point, the A1 proximal to the aneurysm was directly visible (0:38) as well as the ipsilateral ICA. The dissection was further extended such that the bilateral optic nerves and A2 segments were also visible (1:15). The ipsilateral A2 was then circumferentially dissected out, and a microgrid background was placed behind the intended anastomosis site. The radial artery graft was stripped of adventitia distally and was placed adjacent to the ACA. Temporary aneurysm clips were then placed proximally and distally on the A2 segment in preparation for the end-to-side anastomosis. The bypass was performed with a 10-0 nylon in an interrupted manner, and the temporary clips were removed to assess for a leak. The graft was heparinized and occluded distally in preparation for the proximal anastomosis with the STA, which was once again completed with a 10-0 nylon suture in an interrupted manner. Once the extracranial anastomosis was completed, the clips were removed, confirming no anastomotic leak and good pulsatility in the graft. Next, intracranial clip trapping of the aneurysm was performed. First, a temporary clip was placed on the ICA (0:57). Then, the proximal ACA at the bifurcation from the ICA was occluded with a fenestrated clip around the ICA (1:05). The temporary clip was then removed, and ICG was used to confirm the ICA-MCA junction was patent. At this point, dissection was taken medially over the optic nerve and the outflow of the aneurysm was. A fenestrated clip placed around the recurrent artery of Heubner was used to trap the aneurysm (1:19). At this point, indocyanine green was again used to confirm patency of the bypass and the bilateral A2s (1:25). Once patency was confirmed, attention was turned to the aneurysm. There did seem to be some delayed filling in the aneurysm with indocyanine green; however, this was delayed. Given the delay, we felt the aneurysm was likely to thrombose. The aneurysm was not cut open, and the decision was made to close allow for thrombosis over time. A postoperative angiogram showed persistent, robust filling of the aneurysm through its neck (1:38); however, the decision was made to return to the operating room. A redo craniotomy and dissection were performed, with exposure of the ICA, and a temporary clip was placed. The previous permanent aneurysm clip on the origin of the ACA was removed (2:20). A slightly longer clip was then placed across the inflow to the aneurysm (2:38). The temporary clip was removed. At this point, ICG angiography was performed using the OR microscope (not shown). There was no filling appreciated in the aneurysm. Microscissors were then used to cut into the aneurysm, and there was still a small amount of bleeding coming from the aneurysm itself (3:15). After cutting more of the aneurysm wall and freeing it up to allow it to collapse, a second fenestrated clip was placed around the origin of the ACA (4:05). Once this was placed, there was a significant decrease in bleeding from the aneurysm; however, still a small amount of bleeding persisted. The posterior communicating and anterior choroidal artery were dissected out, and adhesions to the aneurysm wall were sharply dissected. A third fenestrated clip was placed between the posterior communicating and anterior choroidal arteries (5:24). At this point, there was no further bleeding from the aneurysm. A postoperative angiogram revealed no filling of the trapped giant anterior cerebral artery aneurysm (5:50) (MP4 518855 kb)

References

  1. 1.
    Yasargil MG, Yonekawa Y. Results of microsurgical extra-intracranial arterial bypass in the treatment of cerebral ischemia. Neurosurgery. 1977;1:22–4.CrossRefGoogle Scholar
  2. 2.
    Wessels L, Hecht N, Vajkoczy P. Bypass in neurosurgery-indications and techniques. Neurosurg Rev. 2018;42:389.  https://doi.org/10.1007/s10143-018-0966-9.CrossRefPubMedGoogle Scholar
  3. 3.
    Charbel FT, Meglio G, Amin-Hanjani S. Superficial temporal artery-to-middle cerebral artery bypass. Neurosurgery. 2005;56:186–90; discussion 186-190.PubMedGoogle Scholar
  4. 4.
    Tayebi Meybodi A, Huang W, Benet A, Kola O, Lawton MT. Bypass surgery for complex middle cerebral artery aneurysms: an algorithmic approach to revascularization. J Neurosurg. 2017;127:463–79.  https://doi.org/10.3171/2016.7.JNS16772.CrossRefPubMedGoogle Scholar
  5. 5.
    Matsukawa H, Miyata S, Tsuboi T, Noda K, Ota N, Takahashi O, Takeda R, Tokuda S, Kamiyama H, Tanikawa R. Rationale for graft selection in patients with complex internal carotid artery aneurysms treated with extracranial to intracranial high-flow bypass and therapeutic internal carotid artery occlusion. J Neurosurg. 2018;128:1753–61.  https://doi.org/10.3171/2016.11.JNS161986.CrossRefPubMedGoogle Scholar
  6. 6.
    Matsukawa H, Tanikawa R, Kamiyama H, Tsuboi T, Noda K, Ota N, Miyata S, Tokuda S. The valveless saphenous vein graft technique for EC-IC high-flow bypass: technical note. World Neurosurg. 2016;87:35–8.  https://doi.org/10.1016/j.wneu.2015.12.009.CrossRefPubMedGoogle Scholar
  7. 7.
    Esposito G, Fierstra J, Regli L. Distal outflow occlusion with bypass revascularization: last resort measure in managing complex MCA and PICA aneurysms. Acta Neurochir. 2016;158:1523–31.  https://doi.org/10.1007/s00701-016-2868-3.CrossRefPubMedGoogle Scholar
  8. 8.
    Alakbarzade V, Pereira AC. Cerebral catheter angiography and its complications. Pract Neurol. 2018;18:393–8.  https://doi.org/10.1136/practneurol-2018-001986.CrossRefPubMedGoogle Scholar
  9. 9.
    Hardesty DA, Thind H, Zabramski JM, Spetzler RF, Nakaji P. Safety, efficacy, and cost of intraoperative indocyanine green angiography compared to intraoperative catheter angiography in cerebral aneurysm surgery. J Clin Neurosci. 2014;21:1377–82.  https://doi.org/10.1016/j.jocn.2014.02.006.CrossRefPubMedGoogle Scholar
  10. 10.
    Pesce A, Frati A, D’Andrea G, Palmieri M, Familiari P, Cimatti M, Valente D, Raco A. The real impact of an intraoperative magnetic resonance imaging-equipped operative theatre in neurovascular surgery: the Sapienza University experience. World Neurosurg. 2018;120:190–9.  https://doi.org/10.1016/j.wneu.2018.08.124.CrossRefPubMedGoogle Scholar
  11. 11.
    Hecht N, Woitzik J, König S, Horn P, Vajkoczy P. Laser speckle imaging allows real-time intraoperative blood flow assessment during neurosurgical procedures. J Cereb Blood Flow Metab. 2013;33:1000–7.  https://doi.org/10.1038/jcbfm.2013.42.CrossRefPubMedPubMedCentralGoogle Scholar
  12. 12.
    Raabe A, Beck J, Gerlach R, Zimmermann M, Seifert V. Near-infrared indocyanine green video angiography: a new method for intraoperative assessment of vascular flow. Neurosurgery. 2003;52:132–9; discussion 139.PubMedGoogle Scholar
  13. 13.
    Balamurugan S, Agrawal A, Kato Y, Sano H. Intra operative indocyanine green video-angiography in cerebrovascular surgery: an overview with review of literature. Asian J Neurosurg. 2011;6:88–93.  https://doi.org/10.4103/1793-5482.92168.CrossRefPubMedPubMedCentralGoogle Scholar
  14. 14.
    Li J, Lan Z, He M, You C. Assessment of microscope-integrated indocyanine green angiography during intracranial aneurysm surgery: a retrospective study of 120 patients. Neurol India. 2009;57:453–9.  https://doi.org/10.4103/0028-3886.55607.CrossRefPubMedGoogle Scholar
  15. 15.
    Ma C-Y, Shi J-X, Wang H-D, Hang C-H, Cheng H-L, Wu W. Intraoperative indocyanine green angiography in intracranial aneurysm surgery: microsurgical clipping and revascularization. Clin Neurol Neurosurg. 2009;111:840–6.  https://doi.org/10.1016/j.clineuro.2009.08.017.CrossRefPubMedGoogle Scholar
  16. 16.
    Raabe A, Nakaji P, Beck J, Kim LJ, Hsu FPK, Kamerman JD, Seifert V, Spetzler RF. Prospective evaluation of surgical microscope-integrated intraoperative near-infrared indocyanine green videoangiography during aneurysm surgery. J Neurosurg. 2005;103:982–9.  https://doi.org/10.3171/jns.2005.103.6.0982.CrossRefPubMedGoogle Scholar
  17. 17.
    Woitzik J, Horn P, Vajkoczy P, Schmiedek P. Intraoperative control of extracranial-intracranial bypass patency by near-infrared indocyanine green videoangiography. J Neurosurg. 2005;102:692–8.  https://doi.org/10.3171/jns.2005.102.4.0692.CrossRefPubMedGoogle Scholar
  18. 18.
    Feletti A, Wang X, Tanaka R, Yamada Y, Suyama D, Kawase T, Sano H, Kato Y. Dual-image videoangiography during intracranial microvascular surgery. World Neurosurg. 2017;99:572–9.  https://doi.org/10.1016/j.wneu.2016.12.070.CrossRefPubMedGoogle Scholar
  19. 19.
    Shah KJ, Cohen-Gadol AA. The application of FLOW 800 ICG videoangiography color maps for neurovascular surgery and intraoperative decision making. World Neurosurg. 2019;122:e186–97.  https://doi.org/10.1016/j.wneu.2018.09.195.CrossRefPubMedGoogle Scholar
  20. 20.
    Jhawar SS, Kato Y, Oda J, Oguri D, Sano H, Hirose Y. FLOW 800-assisted surgery for arteriovenous malformation. J Clin Neurosci. 2011;18:1556–7.  https://doi.org/10.1016/j.jocn.2011.01.041.CrossRefPubMedGoogle Scholar
  21. 21.
    Rennert RC, Strickland BA, Ravina K, Bakhsheshian J, Russin JJ. Assessment of hemodynamic changes and hyperperfusion risk after extracranial-to-intracranial bypass surgery using intraoperative indocyanine green-based flow analysis. World Neurosurg. 2018;114:352–60.  https://doi.org/10.1016/j.wneu.2018.03.189.CrossRefPubMedGoogle Scholar
  22. 22.
    Rennert RC, Strickland BA, Ravina K, Bakhsheshian J, Fredrickson V, Carey J, Russin JJ. Intraoperative assessment of cortical perfusion after intracranial-to-intracranial and extracranial-to-intracranial bypass for complex cerebral aneurysms using flow 800. Oper Neurosurg (Hagerstown). 2018;16:583.  https://doi.org/10.1093/ons/opy154.CrossRefGoogle Scholar
  23. 23.
    Ye X, Liu X-J, Ma L, Liu L-T, Wang W-L, Wang S, Cao Y, Zhang D, Wang R, Zhao J-Z, Zhao Y-L. Clinical values of intraoperative indocyanine green fluorescence video angiography with Flow 800 software in cerebrovascular surgery. Chin Med J. 2013;126:4232–7.PubMedGoogle Scholar
  24. 24.
    Kobayashi S, Ishikawa T, Tanabe J, Moroi J, Suzuki A. Quantitative cerebral perfusion assessment using microscope-integrated analysis of intraoperative indocyanine green fluorescence angiography versus positron emission tomography in superficial temporal artery to middle cerebral artery anastomosis. Surg Neurol Int. 2014;5:135.  https://doi.org/10.4103/2152-7806.140705.CrossRefPubMedPubMedCentralGoogle Scholar
  25. 25.
    Uchino H, Kazumata K, Ito M, Nakayama N, Kuroda S, Houkin K. Intraoperative assessment of cortical perfusion by indocyanine green videoangiography in surgical revascularization for moyamoya disease. Acta Neurochir. 2014;156:1753–60.  https://doi.org/10.1007/s00701-014-2161-2.CrossRefPubMedGoogle Scholar
  26. 26.
    Uchino H, Nakamura T, Houkin K, Murata J, Saito H, Kuroda S. Semiquantitative analysis of indocyanine green videoangiography for cortical perfusion assessment in superficial temporal artery to middle cerebral artery anastomosis. Acta Neurochir. 2013;155:599–605.  https://doi.org/10.1007/s00701-012-1575-y.CrossRefPubMedGoogle Scholar
  27. 27.
    Munakomi S, Poudel D. A pilot study on assessing the role of intra-operative Flow 800 vascular map model in predicting onset of vasospasm following micro vascular clipping of ruptured intracranial aneurysms. F1000Res. 2018;7:1188.  https://doi.org/10.12688/f1000research.15627.1.CrossRefPubMedPubMedCentralGoogle Scholar
  28. 28.
    Prinz V, Hecht N, Kato N, Vajkoczy P. FLOW 800 allows visualization of hemodynamic changes after extracranial-to-intracranial bypass surgery but not assessment of quantitative perfusion or flow. Oper Neurosurg (Hagerstown). 2014;10:231–9.  https://doi.org/10.1227/NEU.0000000000000277.CrossRefGoogle Scholar
  29. 29.
    Lane B, Bohnstedt BN, Cohen-Gadol AA. A prospective comparative study of microscope-integrated intraoperative fluorescein and indocyanine videoangiography for clip ligation of complex cerebral aneurysms. J Neurosurg. 2015;122:618–26.  https://doi.org/10.3171/2014.10.JNS132766.CrossRefPubMedGoogle Scholar
  30. 30.
    Matano F, Mizunari T, Murai Y, Kubota A, Fujiki Y, Kobayashi S, Morita A. Quantitative comparison of the intraoperative utility of indocyanine green and fluorescein videoangiographies in cerebrovascular surgery. Oper Neurosurg (Hagerstown). 2017;13:361–6.  https://doi.org/10.1093/ons/opw020.CrossRefGoogle Scholar
  31. 31.
    Raabe A, Spetzler RF. Fluorescence angiography. J Neurosurg. 2008;108:429–30.  https://doi.org/10.3171/JNS/2008/108/2/0429.CrossRefPubMedGoogle Scholar
  32. 32.
    Moore GE, Peyton WT. The clinical use of fluorescein in neurosurgery; the localization of brain tumors. J Neurosurg. 1948;5:392–8.  https://doi.org/10.3171/jns.1948.5.4.0392.CrossRefPubMedGoogle Scholar
  33. 33.
    Ewelt C, Nemes A, Senner V, Wölfer J, Brokinkel B, Stummer W, Holling M. Fluorescence in neurosurgery: its diagnostic and therapeutic use. Review of the literature. J Photochem Photobiol B Biol. 2015;148:302–9.  https://doi.org/10.1016/j.jphotobiol.2015.05.002.CrossRefGoogle Scholar
  34. 34.
    Narducci A, Onken J, Czabanka M, Hecht N, Vajkoczy P. Fluorescein videoangiography during extracranial-to-intracranial bypass surgery: preliminary results. Acta Neurochir. 2018;160:767–74.  https://doi.org/10.1007/s00701-017-3453-0.CrossRefPubMedGoogle Scholar
  35. 35.
    Suzuki K, Kodama N, Sasaki T, Matsumoto M, Ichikawa T, Munakata R, Muramatsu H, Kasuya H. Confirmation of blood flow in perforating arteries using fluorescein cerebral angiography during aneurysm surgery. J Neurosurg. 2007;107:68–73.  https://doi.org/10.3171/JNS-07/07/0068.CrossRefPubMedGoogle Scholar
  36. 36.
    Chen SF, Kato Y, Oda J, Kumar A, Watabe T, Imizu S, Oguri D, Sano H, Hirose Y. The application of intraoperative near-infrared indocyanine green videoangiography and analysis of fluorescence intensity in cerebrovascular surgery. Surg Neurol Int. 2011;2:42.  https://doi.org/10.4103/2152-7806.78517.CrossRefPubMedPubMedCentralGoogle Scholar
  37. 37.
    Januszewski J, Beecher JS, Chalif DJ, Dehdashti AR. Flow-based evaluation of cerebral revascularization using near-infrared indocyanine green videoangiography. Neurosurg Focus. 2014;36:E14.  https://doi.org/10.3171/2013.12.FOCUS13473.CrossRefPubMedGoogle Scholar
  38. 38.
    Grubb RL, Derdeyn CP, Fritsch SM, Carpenter DA, Yundt KD, Videen TO, Spitznagel EL, Powers WJ. Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion. JAMA. 1998;280:1055–60.CrossRefGoogle Scholar
  39. 39.
    Klijn CJ, Kappelle LJ, Tulleken CA, van Gijn J. Symptomatic carotid artery occlusion. A reappraisal of hemodynamic factors. Stroke. 1997;28:2084–93.CrossRefGoogle Scholar
  40. 40.
    Amin-Hanjani S, Barker FG, Charbel FT, Connolly ES, Morcos JJ, Thompson BG, Cerebrovascular Section of the American Association of Neurological Surgeons, Congress of Neurological Surgeons. Extracranial-intracranial bypass for stroke-is this the end of the line or a bump in the road? Neurosurgery. 2012;71:557–61.  https://doi.org/10.1227/NEU.0b013e3182621488.CrossRefPubMedGoogle Scholar
  41. 41.
    Hänggi D, Steiger H-J, Vajkoczy P, Cerebrovascular Section of the European Association of Neurological Surgeons (EANS). EC-IC bypass for stroke: is there a future perspective? Acta Neurochir. 2012;154:1943–4.  https://doi.org/10.1007/s00701-012-1480-4.CrossRefPubMedGoogle Scholar
  42. 42.
    Jussen D, Zdunczyk A, Schmidt S, Rösler J, Buchert R, Julkunen P, Karhu J, Brandt S, Picht T, Vajkoczy P. Motor plasticity after extra-intracranial bypass surgery in occlusive cerebrovascular disease. Neurology. 2016;87:27–35.  https://doi.org/10.1212/WNL.0000000000002802.CrossRefPubMedGoogle Scholar
  43. 43.
    Yokota H, Yonezawa T, Yamada T, Miyamae S, Kim T, Takamura Y, Masui K, Aketa S. Transdural indocyanine green videography for superficial temporal artery-to-middle cerebral artery bypass-technical note. World Neurosurg. 2017;106:446–9.  https://doi.org/10.1016/j.wneu.2017.07.004.CrossRefPubMedGoogle Scholar
  44. 44.
    Dengler J, Kato N, Vajkoczy P. The Y-shaped double-barrel bypass in the treatment of large and giant anterior communicating artery aneurysms. J Neurosurg. 2013;118:444–50.  https://doi.org/10.3171/2012.11.JNS121061.CrossRefPubMedGoogle Scholar
  45. 45.
    Kato N, Prinz V, Finger T, Schomacher M, Onken J, Dengler J, Jakob W, Vajkoczy P. Multiple reimplantation technique for treatment of complex giant aneurysms of the middle cerebral artery: technical note. Acta Neurochir. 2013;155:261–9.  https://doi.org/10.1007/s00701-012-1538-3.CrossRefPubMedGoogle Scholar
  46. 46.
    Yang T, Tariq F, Chabot J, Madhok R, Sekhar LN. Cerebral revascularization for difficult skull base tumors: a contemporary series of 18 patients. World Neurosurg. 2014;82:660–71.  https://doi.org/10.1016/j.wneu.2013.02.028.CrossRefPubMedGoogle Scholar
  47. 47.
    Vajkoczy P, Roth H, Horn P, Lucke T, Thomé C, Hubner U, Martin GT, Zappletal C, Klar E, Schilling L, Schmiedek P. Continuous monitoring of regional cerebral blood flow: experimental and clinical validation of a novel thermal diffusion microprobe. J Neurosurg. 2000;93:265–74.  https://doi.org/10.3171/jns.2000.93.2.0265.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Saman Sizdahkhani
    • 1
    Email author
  • Jordan Lam
    • 1
  • Shivani Rangwala
    • 1
  • Jonathan Russin
    • 1
  1. 1.Department of NeurosurgeryKeck School of Medicine of USCLos AngelesUSA

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