title: Fetal eye movements on magnetic resonance imaging.
abstract: OBJECTIVE
  Eye movements are the physical expression of upper fetal brainstem function. Our aim was to identify and differentiate specific types of fetal eye movement patterns using dynamic MRI sequences. Their occurrence as well as the presence of conjugated eyeball motion and consistently parallel eyeball position was systematically analyzed.
  
  
  METHODS
  Dynamic SSFP sequences were acquired in 72 singleton fetuses (17-40 GW, three age groups [17-23 GW, 24-32 GW, 33-40 GW]). Fetal eye movements were evaluated according to a modified classification originally published by Birnholz (1981): Type 0: no eye movements; Type I: single transient deviations; Type Ia: fast deviation, slower reposition; Type Ib: fast deviation, fast reposition; Type II: single prolonged eye movements; Type III: complex sequences; and Type IV: nystagmoid.
  
  
  RESULTS
  In 95.8% of fetuses, the evaluation of eye movements was possible using MRI, with a mean acquisition time of 70 seconds. Due to head motion, 4.2% of the fetuses and 20.1% of all dynamic SSFP sequences were excluded. Eye movements were observed in 45 fetuses (65.2%). Significant differences between the age groups were found for Type I (p = 0.03), Type Ia (p = 0.031), and Type IV eye movements (p = 0.033). Consistently parallel bulbs were found in 27.3-45%.
  
  
  CONCLUSIONS
  In human fetuses, different eye movement patterns can be identified and described by MRI in utero. In addition to the originally classified eye movement patterns, a novel subtype has been observed, which apparently characterizes an important step in fetal brainstem development. We evaluated, for the first time, eyeball position in fetuses. Ultimately, the assessment of fetal eye movements by MRI yields the potential to identify early signs of brainstem dysfunction, as encountered in brain malformations such as Chiari II or molar tooth malformations.
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria.
authors.forename: Ramona
authors.initials: R
authors.lastname: Woitek
authors.forename: Gregor
authors.initials: G
authors.lastname: Kasprian
authors.forename: Christian
authors.initials: C
authors.lastname: Lindner
authors.forename: Fritz
authors.initials: F
authors.lastname: Stuhr
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Veronika
authors.initials: V
authors.lastname: Schöpf
authors.forename: Peter C
authors.initials: PC
authors.lastname: Brugger
authors.forename: Ulrika
authors.initials: U
authors.lastname: Asenbaum
authors.forename: Julia
authors.initials: J
authors.lastname: Furtner
authors.forename: Dieter
authors.initials: D
authors.lastname: Bettelheim
authors.forename: Rainer
authors.initials: R
authors.lastname: Seidl
authors.forename: Daniela
authors.initials: D
authors.lastname: Prayer
mesh_terms: D001933:Brain Stem / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005333:Fetus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*