Introduction
Background
Optic nerve glioma (also known as optic pathway glioma) is the most common primary neoplasm of the optic nerve. Along with reducing visual acuity in the affected eye, the tumor sometimes produces additional symptoms as it grows. A low-grade form of this neoplasm, benign optic glioma, occurs most often in pediatric patients. Another form, aggressive glioma, is most common in adults; it is frequently fatal, even with treatment.1
Coronal noncontrast T1-weighted MRI reveals a large intraorbital mass (arrow) centered on the optic nerve.
Axial T2-weighted MRI in a 46-year-old man demonstrates a mass in the lateral geniculate nucleus of the thalamus resulting from contiguous extension of the patient's known optic nerve glioma.
Contrasted computed tomography (CT) scanning can be used to characterize local involvement of optic nerve glioma within the orbit. However, magnetic resonance imaging (MRI) better demonstrates the extent of the lesion's intracranial growth.2,3
Many children with optic nerve glioma are also known to have neurofibromatosis type 1 (NF-1) or, in some cases, hybrid phakomatosis.4
Pathophysiology
The World Health Organization classifies optic nerve gliomas as grade I astrocytomas (pilocytic astrocytomas) because they are slow growing and tend not to metastasize. Development of optic nerve gliomas occurs in stages, from generalized hyperplasia of glial cells in the nerve to complete disorganization with loss of neural landmarks in the nerve and nerve sheath. A reactive meningeal hyperplasia may be incited, making optic nerve glioma difficult to distinguish from a perioptic meningioma. It is unclear which glial cells give rise to benign optic glioma.
From 10 to 38% of pediatric patients with optic nerve glioma have NF-1; conversely, 15-40% of children with NF-1 have optic nerve glioma. Bilateral optic nerve gliomas are almost pathognomonic for NF-1.5
In the aggressive form of the disease, the glioma is either an anaplastic astrocytoma or a glioblastoma multiforme, arising from abnormal astrocytes. Prominent features of this neoplasm include nuclear pleomorphism, numerous mitoses, and vascular endothelial proliferation.
Frequency
United States
- Optic nerve gliomas represent 4% of orbital tumors, 4% of intracranial gliomas, and 2% of intracranial tumors. They also constitute two thirds of all primary optic nerve tumors.6
- Aggressive glioma is rare. According to Millar et al, it is an unusual presentation of a more common adult disease, astrocytoma.7
Mortality/Morbidity
Benign optic glioma grows relatively slowly, if at all, over extended periods. However, some lesions can progress, causing visual impairment, so ongoing follow-up has been recommended.8
Twenty percent of optic gliomas that extend to the optic chiasm or beyond, into the optic radiations, demonstrate a more aggressive course.
Local surgical therapy for large lesions may cause significant morbidity, including hypothalamic dysfunction. Stereotactic radiation or gamma-knife therapy also can produce complications, including decreased visual acuity, radiation-induced optic neuritis, and ophthalmic artery vasculopathy.
Despite aggressive radiation, chemotherapeutic, or surgical treatment, aggressive glioma is an almost uniformly fatal disease.
Race
There is no distinct racial predilection to sporadic optic nerve glioma. Benign optic glioma has the same distribution as NF-1.
Sex
In pediatric patients, there is a slight female predominance, whereas in adult patients, the opposite is true.6
Age
In the pediatric population, the median patient age is 5 years, with 80% of patients presenting before age 15.6
In adult patients, the age ranges from 22-79 years, with a mean age of 52 years.7
Anatomy
The optic nerve is divided into 4 parts: (1) intraocular, (2) intraorbital, (3) intracanalicular, and (4) intracranial. Within the orbit, the nerve usually is approximately 5 mm in diameter and is surrounded by fat. The intracanalicular portion passes through the lesser wing of the sphenoid and is surrounded by a muscular cone. The cerebrospinal fluid (CSF) of the subarachnoid space surrounding the nerve is contiguous with the CSF of the intracranial compartment.
In 66% of NF-1 patients with optic nerve glioma, the growth involves the intraorbital optic nerve. In 10-20%, the tumor is confined to the orbit, with the remainder of these patients showing involvement of the intracranial compartment. In the absence of NF-1, the optic chiasm is most commonly involved, as is, less often, the intraorbital optic nerve.9 Optic nerve glioma may involve various portions of the retrobulbar visual pathway, including the optic nerve, chiasm, tracts, and radiations. Malignant lesions can invade the hypothalamus, basal ganglia, and internal capsule directly, or they may spread to the leptomeninges or subpial surfaces.
Presentation
In most young patients with optic glioma, the presenting symptom is painless proptosis. Optic atrophy is common, as is reduced visual acuity, although the latter may be a late symptom. A large lesion may compress the optic chiasm, causing nystagmus or other symptoms. Hypothalamic symptoms, such as changes in appetite or sleep, also may occur. Massive lesions may compress the third ventricle, resulting in obstructive hydrocephalus accompanied by headache, nausea, and vomiting.10,11
In adult patients, bilateral vision loss is a common early finding because most lesions involve the optic chiasm.
Preferred Examination
When the diagnosis is in question, the presence of an intraconal mass can often be detected through CT scanning.
MRI, however, is the preferred method for definitive evaluation of optic nerve glioma. Both the intraorbital lesion and its intracranial extent can be effectively characterized through MRI. When evaluating the orbit, gadolinium-enhanced T1-weighted images with fat saturation can define the extent of aggressive glioma. Intracranially, MRI allows better evaluation of the optic nerve, chiasm, tracts, geniculate body, and optic radiations than does CT.12,13,14
Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans.
NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.
Limitations of Techniques
Although MRI may reveal even subtle lesions of the optic nerve, CT scanning can detect a subtle erosion or expansion of the optic canal. In addition, fine calcification, which may help to identify a lesion as a meningioma rather than a glioma, is visualized best through CT scanning.
Differential Diagnoses
Other Problems to Be Considered
Optic nerve meningioma
Lymphoma, soft tissue
Optic nerve sheath ectasia
More on Optic Nerve Glioma |
Overview: Optic Nerve Glioma |
| Imaging: Optic Nerve Glioma |
| Follow-up: Optic Nerve Glioma |
| Multimedia: Optic Nerve Glioma |
| References |
| Further Reading |
| Next Page » |
References
Wilhelm H. Primary optic nerve tumours. Curr Opin Neurol. Feb 2009;22(1):11-8. [Medline].
Aoki S, Barkovich AJ, Nishimura K, et al. Neurofibromatosis types 1 and 2: cranial MR findings. Radiology. Aug 1989;172(2):527-34. [Medline].
Hendrix LE, Kneeland JB, Haughton VM, et al. MR imaging of optic nerve lesions: value of gadopentetate dimeglumine and fat-suppression technique. AJNR Am J Neuroradiol. Jul-Aug 1990;11(4):749-54. [Medline].
Messori A, Salvolini U. Hybrid phakomatosis: from initial CT observation to molecular studies. AJNR Am J Neuroradiol. Aug 2004;25(7):1297-8.
Listernick R, Charrow J, Greenwald MJ, et al. Optic gliomas in children with neurofibromatosis type 1. J Pediatr. May 1989;114(5):788-92. [Medline].
Hollander MD, FitzPatrick M, O''Connor SG, et al. Optic gliomas. Radiol Clin North Am. Jan 1999;37(1):59-71, ix. [Medline].
Millar WS, Tartaglino LM, Sergott RC, et al. MR of malignant optic glioma of adulthood. AJNR Am J Neuroradiol. Sep 1995;16(8):1673-6. [Medline].
Thiagalingam S, Flaherty M, Billson F. Neurofibromatosis type 1 and optic pathway gliomas: follow-up of 54 patients. Ophthalmology. Mar 2004;111(3):568-77. [Medline].
Kornreich L, Blaser S, Schwarz M, et al. Optic pathway glioma: correlation of imaging findings with the presence of neurofibromatosis. AJNR Am J Neuroradiol. Nov-Dec 2001;22(10):1963-9. [Medline].
Tumialan LM, Dhall SS, Biousse V. Optic nerve glioma and optic neuritis mimicking one another: case report. Neurosurgery. Jul 2005;57(1):E190; discussion E190.
Taylor T, Jaspan T, Milano G, Gregson R, Parker T, Ritzmann T, et al. Radiological classification of optic pathway gliomas: experience of a modified functional classification system. Br J Radiol. Oct 2008;81(970):761-6. [Medline].
Forte R, Cennamo G, Breve MA. Three-Dimensional Ultrasound of Ophthalmic Pathologies. Ophthalmologica. Jan 31 2009;223(3):183-187. [Medline].
Walrath JD, Engelbert M, Kazim M. Magnetic resonance imaging evidence of optic nerve glioma progression into and beyond the optic chiasm. Ophthal Plast Reconstr Surg. Nov-Dec 2008;24(6):473-5. [Medline].
Buffa A, Vannelli S, Peretta P. [NF1 and gliomas: the importance of the MRI]. Minerva Pediatr. Apr 2008;60(2):259-60. [Medline].
Kwon Y, Bae JS, Kim JM. Visual changes after gamma knife surgery for optic nerve tumors. Report of three cases. J Neurosurg. Jan 2005;102 Suppl:143-6.
Further Reading
Related eMedicine topics
Neurofibromatosis Type 1 (from Radiology)
Neurofibromatosis, Type 1 (from Neurology)
Optic Neuropathy, Compressive
Sudden Visual Loss (from Neurology)
Sudden Visual Loss (from Ophthalmology)
Clinical guidelines
Eye Examination in Infants, Children, and Young Adults by Pediatricians
Neurofibromatosis Type 1 in Genetic Counseling Practice: Recommendations of the National Society of Genetic Counselors
Clinical studies
Pirfenidone in Treating Young Patients With Neurofibromatosis Type 1 and Plexiform Neurofibromas
Trial to Evaluate the Safety of Lovastatin in Adults With Neurofibromatosis Type I (NF1)
Keywords
optic nerve glioma, optic pathway glioma, optic glioma, neurofibromatosis, neurofibromatosis type 1, NF-1, neurofibromatosis 1, von Recklinghausen disease, optic nerve disease, hybrid phakomatosis




Overview: Optic Nerve Glioma