Orbital Tumors - Optic Nerve Glioma

 

 

  • Clinical Symptoms

    • decreased visual acuity
    • minimal proptosis
    • restricted, decreased eye movement 
    • strabismus 
  • Etiology

    • neoplasm of {the} optic nerve
    • may also be called juvenile pilocytic astrocytoma 
    • Optic nerve glioma in adults are glioblastoma 
    • Optic nerve glioma is {the} most common cause of optic nerve enlargement
      • it accounts for 80% of optic nerve tumors
      • 1% of all intracranial tumors
      • 2% of childhood intraorbital masses
  • Demographics

    • 80% are in children under 10 years old
    • peak age is 5-8
    • 90% of patients are under {the} age of 20
    • more common in females
    • 10-50% are in neurofibromatosis patients, especially if bilateral
    • 15% of NF patients have an optic glioma
  • Clinical Course

    • Optic nerve gliomas grow very slowly and have similar pathology as juvenile pilocytic astrocytomas of {the} cerebellum. 
    • typically intraorbitally and grow in a fusiform shape 
    • 25% are limited to {the} orbit
    • malignant degeneration is very rare in children
    • if {the} tumor begins in {the} chiasm, it is likely to invade surrounding parenchyma regardless of age
  • Imaging

    • On MRI, there is usually mild contrast enhancement. The affected optic nerve should be greater than 3 mm in diameter, or 1 mm wider than {the} unaffected side. It should be hypo- to isointense to muscle on T1 and hyperintense on T2. Fat supression sequences should be performed to see {the} entire extent of {the} lesion since it could appear to be more extensive than it is on T2-weighted images secondary to edema
  • Differential Diagnosis

    • Sarcoidosis
    • Infiltration by leukemia or lymphoma
    • Optic neuritis
    • Perineural hematoma
    • Papilledema of intracranial hypertension
    • Patulous subarachnoid space
Procedures
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