Andrade-Barazarte, Hugo

Hernesniemi, Juha A.

Jahromi, Behnam Rezai

Kawamata, Takakazu

Kawashima, Akitsugu

English

Helsingin yliopiston digitaalinen arkisto

CORRESPONDENCEIn Reply: Superficial Temporal Artery: DistalPosterior Cerebral Artery Bypass Through theSubtemporal Approach: Technical Note andPilot Surgical CasesTo the Editor:We thank Verbraeken et al for their letter1 regarding our publi-cation.2 The authors recommended the occipital artery (OA)-posterior cerebral artery (PCA) bypass via infratentorial lateralsupracerebellar approach (ILSA) for surgical treatment of theP1/P2 aneurysms. There are some advantages and disadvantagesin each approach and we would like to discuss on them.Wewouldlike to focus on (1) specifics of surgical approaches for recon-struction of the distal PCA, (2) manipulation of the aneurysmand adjacent parent vessel parts while placing a bypass via thesame or different separate approaches, and (3) the properties ofthe required graft for treatment of complex P1/P2 aneurysms,ie, comparison between OA-PCA bypass via ILSA and superficialtemporal artery (STA)-PCA bypass via subtemporal approach.The distance of the surgical corridor to the PCA through theILSA is longer than the subtemporal approach. The surgical fieldobtained through the ILSA to manipulate the bypass procedureis also narrower and limited. The PCA runs supratentorially,thus only the posterior part of the P2 or anterior part of theP3 segments can be exposed even if the tent is divided. On theother hand, the main disadvantage of the subtemporal approachis the risk of temporal lobe injury during retraction. However, thetemporal lobe injury can be avoided by release of 50 to 100 mLcerebrospinal fluid by lumbar drainage, adequate exposure, andgood neuroanesthetic management that also improve the angle ofaccess.3,4For the treatment of complex P1/P2 aneurysms, the ILSArequires performing an additional procedure (endovasculartechnique or another craniotomy). The ILSA gives access to avery short segment of the PCA, and it is difficult to expose theproximal segment of the P2. Proximal control of the aneurysm,trapping, and/or thrombectomy cannot be achieved by theapproach. Performing 2 separate craniotomies for the treatmentof such aneurysms increases the risks of complications. Moreover,a bypass followed by an endovascular procedure carries higherrisks of complications related to the contradicting managementin endovascular and bypass procedures, and it is related to highercosts. As anticoagulation is used to minimize the risks of throm-boembolic events during endovascular interventions, increasingthe possibility to develop postoperative bleedings.5 Thrombosedaneurysms at the P1/P2 segment are one of the major indicationsfor revascularization of the distal PCA segment as indicated in ourpublication.2 Moreover, distal bypass without proximal controlfor the treatment of a ruptured aneurysm has serious risks of intra-operative rupture, even with intraoperative endovascular support.At the time of the distal PCA bypass placement via subtemporalapproach, the whole segment sequence from the P1 to the anteriorpart to of the P3 can be exposed, and that easily can includemanipulation on the aneurysm in the same surgical field. Thisfor us is the most important difference with the access providedby the ILSA.To the moment our experience consists of more than 1100extracranial-intracranial bypass operations, including more than50 cases using with the OA graft. Our observations indicatethat the OA as a donor vessel is inferior to the STA because ofits individual variability of development and the complexity ofharvesting due to its tortuosity, branching and tightness to thesurrounding connective tissue. Therefore we can expect that therisk of donor vessel occlusion using the OA graft is higher thanthe STA graft.If all the requirements for surgical technical management(proximal control, trapping, thrombectomy, and separate spacefor bypass) were obtained through the ILSA, the presentedtechnique by Verbraeken et al1 could be applicable. Therefore wesuppose that there are non-negligible risks associated with theirapproach for surgical treatment of complex P1/P2 aneurysms.We believe that the STA-PCA bypass through the subtemporalapproach has potentials advantages compared to the OA-PCAbypass through ILSA. After invoking the discussion on thiscomplex and controversial subject, we are grateful to Verbraekenet al1 for their suggestion and expect the mentioned approachto find well defined indications in the future in this complexpathology.DisclosureThe authors have no personal, financial, or institutional interest in any of thedrugs, materials, or devices described in this article.Akitsugu Kawashima, MD, PhD∗Hugo Andrade-Barazarte, MD, PhD‡Behnam Rezai Jahromi, MD‡Takakazu Kawamata, MD, PhD§Juha A. Hernesniemi, MD, PhD¶∗Department of NeurosurgeryYachiyo Medical CenterTokyo Women’s Medical UniversityChiba, Japan‡Department of NeurosurgeryUniversity of Helsinki and Helsinki University HospitalHelsinki, Finland§Department of NeurosurgeryTokyo Women’s Medical UniversityTokyo, Japan¶Juha Hernesniemi International Center for NeurosurgeryHenan Provincial People’s HospitalZhengzhou, ChinaE48 | VOLUME 15 | NUMBER 4 | OCTOBER 2018 www.operativeneurosurgery-online.comDownloaded from https://academic.oup.com/ons/article-abstract/15/4/48/5049299 by guest on 28 November 2018CORRESPONDENCEREFERENCES1. Verbraeken B, Aboukais R, Lejeune JP, Lukes A, Menovsky T. Letter: Superficialtemporal artery: Distal posterior cerebral artery bypass through the subtemporalapproach: Technical note and pilot surgical cases. Oper Neurosurg. 2018;15(4):E47.2. Kawashima A, Andrade-Barazarte H, Jahromi BR, et al. Superficial temporal artery:Distal posterior cerebral artery bypass through the subtemporal approach: Technicalnote and pilot surgical cases. Oper Neurosurg. 2017;13(3):309-316.3. Drake CG PS, Hernesniemi JA. Surgery of Vertebrobasilar Aneurysms. London,Ontario, Experience on 1767 Patients. Wien: Springer Ver lag; 1996.4. Hernesniemi J, Ishii K, Niemela M, Kivipelto L, Fujiki M, Shen H. Subtem-poral approach to basilar bifurcation aneurysms: advanced technique and clinicalexperience. Acta Neurochi Suppl. 2005;94(suppl):31-38.5. Chang SW, Abla AA, Kakarla UK, et al. Treatment of distal posterior cerebralartery aneurysms. Neurosurgery. 2010;67(1):16-26.10.1093/ons/opy169OPERATIVE NEUROSURGERY VOLUME 15 | NUMBER 4 | OCTOBER 2018 | E49Downloaded from https://academic.oup.com/ons/article-abstract/15/4/48/5049299 by guest on 28 November 2018

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In Reply: Superficial Temporal Artery: Distal Posterior Cerebral Artery Bypass Through the Subtemporal Approach: Technical Note and Pilot Surgical Cases

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In Reply : Superficial Temporal Artery: Distal Posterior Cerebral Artery Bypass Through the Subtemporal Approach: Technical Note and Pilot Surgical Cases

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