title: Comparative analysis of bleeding risk by the location and shape of arachnoid cysts: a finite element model analysis.
abstract: OBJECTIVE
  Although arachnoid cysts (ACs) are observed in various locations, only sylvian ACs are mainly regarded to be associated with bleeding. The reason for this selective association of sylvian ACs with bleeding is not understood well. This study is to investigate the effect of the location and shape of ACs on the risk of bleeding.
  
  
  METHODS
  A developed finite element model of the head/brain was modified for models of sylvian, suprasellar, and posterior fossa ACs. A spherical AC was placed at each location to compare the effect of AC location. Bowl-shaped and oval-shaped AC models were developed to compare the effect by shape. The shear force on the spot-weld elements (SFSW) was measured between the dura and the outer wall of the ACs or the comparable arachnoid membrane in the normal model.
  
  
  RESULTS
  All AC models revealed higher SFSW than comparable normal models. By location, sylvian AC displayed the highest SFSW for frontal and lateral impacts. By shape, small outer wall AC models showed higher SFSW than large wall models in sylvian area and lower SFSW than large ones in posterior fossa. In regression analysis, the presence of AC was the only independent risk of bleeding.
  
  
  CONCLUSIONS
  The bleeding mechanism of ACs is very complex, and the risk quantification failed to show a significant role of location and shape of ACs. The presence of AC increases shear force on impact condition and may be a risk factor of bleeding, and sylvian location of AC may not have additive risks of AC bleeding.
authors.affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.|Department of Neurosurgery, Ilsan Paik Hospital, Inje University College of Medicine, 170, Juhwaro, Ilsan-seogu, Goyang, Gyeonggi, 10380, Republic of Korea.
authors.forename: Chang-Hyun
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Dankook University, 126, Jukjeon-dong, Suji-gu, Yongin, Gyeonggi, 16891, Republic of Korea.
authors.forename: In Seok
authors.initials: IS
authors.lastname: Han
authors.affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.|Department of Anatomy, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
authors.forename: Ji Yeoun
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Phi
authors.affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
authors.forename: Seung-Ki
authors.initials: SK
authors.lastname: Kim
authors.affiliation: Department of Mechanical Engineering, Dankook University, 126, Jukjeon-dong, Suji-gu, Yongin, Gyeonggi, 16891, Republic of Korea. yekim@dankook.ac.kr.
authors.forename: Young-Eun
authors.initials: YE
authors.lastname: Kim
authors.affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, Seoul National University College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea. kcwang@snu.ac.kr.
authors.forename: Kyu-Chang
authors.initials: KC
authors.lastname: Wang
mesh_terms: D016080:Arachnoid Cysts / Q000150:complications*; D002543:Cerebral Hemorrhage / Q000209:etiology*; D020342:Finite Element Analysis; D006801:Humans; D008959:Models, Neurological
keywords: Arachnoid cyst; Bleeding; Finite element; Location; Mechanism; Shape