title: Lateral Position of the External Carotid Artery: A Rare Variation to Be Recognized During Carotid Endarterectomy.
abstract: External carotid artery (ECA) positioned laterally to the internal carotid artery (ICA) at the level of the common carotid artery (CCA) bifurcation is occasionally encountered during carotid endarterectomy (CEA). This study aimed to determine the frequency of this phenomenon and provide technical tips for performing CEA.
  
  
  
  The study included 199 consecutive patients (209 carotid arteries) who underwent CEA at Otaru Municipal Medical Center in 2007-2014. The position of the ECA with respect to the ICA at the CCA bifurcation was preoperatively rated as either lateral or normal, using three-dimensional computerized tomographic angiography (3-D CTA) anteroposterior projections. Postoperative diffusion-weighted images (DWIs), and postoperative 3-D CTA images were reviewed.
  
  
  
  Among the 209 carotid arteries with atherosclerosis, 11 instances (5.3 %) of lateral position of the ECA were detected in 11 patients. Ten of these arteries (91 %) were right-sided (odds ratio 11.1; 95 % confidence interval 1.38-88.9). Wider longitudinal exposure of the arteries was used during CEA, and the CCA and ECA were rotated clockwise or counter clockwise. The ICA lying behind the ECA along the surgical access route was then pulled out laterally and moved to the shallow surgical field. Cross-clamping, arteriotomy, plaque removal, and wall suturing were performed as usual. No cerebral infarcts were detected on postoperative DWIs, and 3-D CTA revealed no CCA and ICA kinking.
  
  
  
  Lateral position of the ECA is not extremely rare in patients undergoing CEA for atherosclerosis and may be a congenital variation, although this is still controversial. CEA can be performed safely if the arteries from the CCA to the ICA are rotated, and the ICA is moved to the shallow surgical field under wider longitudinal exposure. Although no postoperative cerebral infarcts were detected, the risk of artery-to-artery embolism resulting from artery repositioning prior to plaque removal should be taken into consideration.
authors.affiliation: Department of Neurosurgery, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan. masakiitou-nsu@umin.ac.jp.|Department of Neurosurgery, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan. masakiitou-nsu@umin.ac.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ito
authors.affiliation: Department of Neurosurgery, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Niiya
authors.affiliation: Department of Radiology, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kojima
authors.affiliation: Department of Neurosurgery, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Itosaka
authors.affiliation: Department of Neurosurgery, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Iwasaki
authors.affiliation: Department of Neurosurgery, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Kazumata
authors.affiliation: Department of Neurosurgery, Otaru General Hospital, Wakamatsu 1-1-1, Otaru, 047-8550, Japan.
authors.forename: Shoji
authors.initials: S
authors.lastname: Mabuchi
authors.affiliation: Department of Neurosurgery, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Houkin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D063405:Anatomic Variation; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000601:surgery*; D017536:Carotid Artery, Common / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D002342:Carotid Artery, External / Q000002:abnormalities* / Q000000981:diagnostic imaging; D002343:Carotid Artery, Internal / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging / Q000601:surgery*; D002533:Cerebral Angiography; D002544:Cerebral Infarction / Q000000981:diagnostic imaging / Q000453:epidemiology; D000072226:Computed Tomography Angiography; D038524:Diffusion Magnetic Resonance Imaging; D016894:Endarterectomy, Carotid; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology
keywords: Atherosclerosis; Carotid artery; Carotid endarterectomy; External carotid artery abnormalities; Variation