title: Finite element modeling of optic chiasmal compression.
abstract: BACKGROUND
  The precise mechanism of bitemporal hemianopia is still not clear. Our study investigated the mechanism of bitemporal hemianopia by studying the biomechanics of chiasmal compression caused by a pituitary tumor growing below the optic chiasm.
  
  
  METHODS
  Chiasmal compression and nerve fiber interaction in the chiasm were simulated numerically using finite element modeling software. Detailed mechanical strain distributions in the chiasm were obtained to help understand the mechanical behavior of the optic chiasm. Nerve fiber models were built to determine the relative difference in strain experienced by crossed and uncrossed nerve fibers.
  
  
  RESULTS
  The central aspect of the chiasm always experienced higher strains than the peripheral aspect when the chiasm was loaded centrally from beneath. Strains in the nasal (crossed) nerve fibers were dramatically higher than in temporal (uncrossed) nerve fibers.
  
  
  CONCLUSIONS
  The simulation results of the macroscopic chiasmal model are in agreement with the limited experimental results available, suggesting that the finite element method is an appropriate tool for analyzing chiasmal compression. Although the microscopic nerve fiber model was unvalidated because of lack of experimental data, it provided useful insights into a possible mechanism of bitemporal hemianopia. Specifically, it showed that the strain difference between crossed and uncrossed nerve fibers may account for the selective nerve damage, which gives rise to bitemporal hemianopia.
authors: School of Engineering and Information Technology (XW, AJN, MT, TPL), University of New South Wales, Canberra, Australia; Department of Ophthalmology, Queen's University Belfast (GGM), Belfast, United Kingdom; Belfast Health and Social Care Trust (GGM), Belfast, United Kingdom; Department of Neurology, The Canberra Hospital (TPL, CJL), Canberra, Australia; and Medical School, Australian National University (TPL, CJL), Canberra, Australia.
authors: Xiaofei
authors: X
authors: Wang
authors: Andrew J
authors: AJ
authors: Neely
authors: Gawn G
authors: GG
authors: McIlwaine
authors: Murat
authors: M
authors: Tahtali
authors: Thomas P
authors: TP
authors: Lillicrap
authors: Christian J
authors: CJ
authors: Lueck
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008959:Models, Neurological; D009408:Nerve Compression Syndromes / Q000473:pathology*; D009897:Optic Chiasm / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000473:pathology* / Q000503:physiopathology; D015203:Reproducibility of Results