title: Fetal optic nerve sheath measurement as a non-invasive tool for assessment of increased intracranial pressure.
abstract: OBJECTIVE
  To describe the sonographic technique for assessment of the fetal optic nerve sheath and to report on three fetuses with intracranial lesions and enlarged optic nerve sheath diameter (ONSD) compared with normal controls matched for gestational age (GA).
  
  
  METHODS
  In this cross-sectional study ONSD was measured sonographically in three fetuses (aged 23, 24 and 35 gestational weeks) with intracranial findings associated with increased intracranial pressure (ICP; dural thrombosis and intracranial tumors) as well as 42 healthy controls matched for GA ± 1 week (aged 22-25 and 34-36 weeks). For fetal eye assessment, transabdominal and transvaginal routes and high-resolution transducers were used for optimal visualization depending on fetal position. Measurements were made using an axial view at the level of the orbits, with the fetal face positioned towards the transducer. The ONSD was measured 1.5 or 2 mm behind the papilla (depending on GA) in all fetuses. Mean ± 2 SD ONSD of controls were calculated for each GA and compared with data from the three fetuses with intracranial pathology.
  
  
  RESULTS
  In the 42 normal fetuses, ONSD increased from 1.2 mm at 23 weeks to 2.6 mm at 36 weeks. The measurements at 36 weeks correlated well with those observed in newborns. ONSD measurements of the three cases were above mean + 2 SD of values obtained from healthy controls at the same GA and also exceeded values of fetuses that were 1 week older.
  
  
  CONCLUSIONS
  Fetal ONSD measurement is feasible using a technique similar to that used in adults and children. ONSD enlargement was observed in all three fetuses with intracranial lesions and may be an early tool with which to diagnose increased ICP.
authors.affiliation: Fetal Neurology Clinic, Wolfson Medical Center, Holon, Israel.
authors.forename: K
authors.initials: K
authors.lastname: Haratz
authors.forename: F
authors.initials: F
authors.lastname: Viñals
authors.forename: D
authors.initials: D
authors.lastname: Lev
authors.forename: H
authors.initials: H
authors.lastname: Feit
authors.forename: L
authors.initials: L
authors.lastname: Ben-Sira
authors.forename: T
authors.initials: T
authors.lastname: Lerman-Sagie
authors.forename: G
authors.initials: G
authors.lastname: Malinger
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000196:embryology / Q000473:pathology; D003430:Cross-Sectional Studies; D003657:Decision Making; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D019586:Intracranial Hypertension / Q000000981:diagnostic imaging* / Q000196:embryology; D007427:Intracranial Pressure; D020767:Intracranial Thrombosis / Q000000981:diagnostic imaging* / Q000196:embryology / Q000473:pathology; D009186:Myelin Sheath / Q000000981:diagnostic imaging*; D020417:Nystagmus, Congenital / Q000000981:diagnostic imaging* / Q000196:embryology / Q000473:pathology; D009900:Optic Nerve / Q000000981:diagnostic imaging / Q000473:pathology; D011247:Pregnancy; D011379:Prognosis; D014463:Ultrasonography