title: Primary tumours of the optic nerve and its sheath.
abstract: OBJECTIVE
  To describe the clinical, neuroimaging, and pathologic features of primary tumours of the optic nerve and its sheath.
  
  
  METHODS
  Review of published cases and personal series.
  
  
  RESULTS
  The most common primary tumour of the optic nerve is the benign glioma. This low-grade astrocytoma usually can be followed without intervention. Progression of visual symptoms and signs may necessitate either surgery to remove the tumour or radiation therapy. The most common tumour of the optic nerve sheath is the meningioma. The optimum treatment for this lesion is stereotactic or three-dimensional conformal fractionated radiation therapy, which generally results in stabilization or improvement in vision. A variety of other primary tumours may mimic, in both manifestations and imaging appearance, the more common glioma or meningioma. In such cases, the correct diagnosis may not be made until a biopsy is performed or the nerve is removed.
  
  
  CONCLUSIONS
  Primary tumours of the optic nerve and its sheath are not uncommon. Diagnosis can often but not always be made by the results of a complete examination combined with imaging studies, particularly CT scanning and MR imaging. Management depends on the presumed or histologically verified nature of the tumour.
authors.affiliation: Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, MD 21287, USA.
authors.forename: N R
authors.initials: NR
authors.lastname: Miller
mesh_terms: D018303:Ganglioglioma / Q000473:pathology; D018325:Hemangioblastoma / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008577:Meningeal Neoplasms / Q000473:pathology; D008579:Meningioma / Q000473:pathology; D009442:Neurilemmoma / Q000473:pathology; D018242:Neuroectodermal Tumors, Primitive / Q000473:pathology; D017253:Neurofibromatoses / Q000150:complications / Q000473:pathology; D020339:Optic Nerve Glioma / Q000473:pathology; D019574:Optic Nerve Neoplasms / Q000150:complications / Q000473:pathology*; D011379:Prognosis; D014056:Tomography, X-Ray