title: Risk of optic pathway glioma in children with neurofibromatosis type 1 and optic nerve tortuosity or nerve sheath thickening.
abstract: OBJECTIVE
  Optic nerve tortuosity and nerve and sheath thickening are observed on MRI in some patients with neurofibromatosis type 1 (NF-1). This study aimed to determine if tortuosity and thickening are associated with the development of optic pathway glioma (OPG) and subsequent vision loss.
  
  
  METHODS
  Children with NF-1 who underwent brain MRI between 1992 and 2005, and had at least 1 year of subsequent visual acuity (VA) follow-up, were identified retrospectively. The baseline MRI was independently reviewed by three neuroradiologists for consensus assessment. Tortuosity was identified using validated operational criteria. Optic nerve and sheath thicknesses and VA at last follow-up were directly measured.
  
  
  RESULTS
  Of 132 evaluable children, seven (5%) had tortuosity on baseline MRI. 20 subjects (15%) ultimately developed OPG at a median of 1.9 years (range 7 months-8.0 years) following the baseline MRI. Subjects with tortuosity were significantly more likely to develop OPG than those without tortuosity (57% vs 13%, p=0.01). In subjects who developed OPG, the prevalence of tumour-related vision loss was not significantly different between those with and without baseline tortuosity (14% vs 4%, p=0.28). No difference existed between mean baseline optic nerve (2.3 vs 2.2 mm) or sheath (5.2 vs 5.4 mm) thicknesses comparing subjects who did and did not develop OPG.
  
  
  CONCLUSIONS
  Optic nerve tortuosity at baseline is associated with OPG development among patients with NF-1, but does not predispose to aggressive OPG with associated vision loss. Neither nerve nor sheath thickening at baseline is associated with OPG development.
authors: Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Department of Ophthalmology, University of California San Francisco, San Francisco, California, USA.
authors: Marc H
authors: MH
authors: Levin
authors: Department of Epidemiology and Cancer Control, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Gregory T
authors: GT
authors: Armstrong
authors: Division of Oncology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors: Julian H
authors: JH
authors: Broad
authors: The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors: Robert
authors: R
authors: Zimmerman
authors: The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Division of Oncology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors: Larissa T
authors: LT
authors: Bilaniuk
authors: The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA Department of Radiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors: Tamara
authors: T
authors: Feygin
authors: Department of Biostatistics and Epidemiology, The University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors: Yimei
authors: Y
authors: Li
authors: Division of Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors: Grant T
authors: GT
authors: Liu
authors: Department of Epidemiology and Cancer Control, St. Jude Children's Research Hospital, Memphis, Tennessee, USA Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors: Michael J
authors: MJ
authors: Fisher
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009186:Myelin Sheath / Q000473:pathology*; D009456:Neurofibromatosis 1 / Q000150:complications* / Q000175:diagnosis; D009900:Optic Nerve / Q000473:pathology*; D020339:Optic Nerve Glioma / Q000175:diagnosis / Q000209:etiology*; D019574:Optic Nerve Neoplasms / Q000175:diagnosis / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D014792:Visual Acuity; D014795:Visual Pathways / Q000473:pathology*
keywords: Imaging; Neoplasia; Optic Nerve; Vision; Visual pathway