Optic nerve glioma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Optic nerve glioma is a slow-growing brain tumor that arises in or around the optic nerves. Optic nerve glioma may extend into the optic chiasm or hypothalamus. The majority of the optic nerve gliomas are benign but malignant gliomas of the optic nerve can occur. Optic nerve gliomas are rare. The majority of optic nerve gliomas occur in children. They are usually slow-growing and noncancerous and almost always occur before age 20. Optic nerve glioma may be classified into several subtypes based on microscopic histopathology, anatomic location, and association with neurofibromatosis type 1. Optic pathway gliomas are classified according to WHO classification into two subtypes: pilocytic astrocytoma and fibrillary astrocytoma. Optic nerve gliomas may be classified according to anatomic location into two subtypes: anterior visual pathway tumors and posterior visual pathway tumors. Based on whether or not they are associated with neurofibromatosis type 1, they may be classified into two subtypes: optic nerve gliomas associated with neurofibromatosis type 1 and optic nerve gliomas not associated with neurofibromatosis type 1. Genes involved in the pathogenesis of optic nerve glioma include BRAF-KIAA, tumor suppressor genes and chromosomes 7q34 and 17q. On gross pathology, smooth and fusiform intradural lesions are characteristic findings of optic nerve glioma. On microscopic histopathological analysis, low grade spindle shaped pilocytic astrocytes & glial filaments with the presence of numerous Rosenthal’s fibers are characteristic findings of optic nerve gliomas. There is no established cause for optic nerve glioma. Optic nerve gliomas affects females and males equally. Optic nerve gliomas commonly affects individuals younger than twenty years of age. There is no racial predilection to the optic nerve glioma.^[1] Optic nerve gliomas affects girls and boys equally. There are no established risk factors for optic nerve gliomas. Symptoms of optic nerve glioma include proptosis, unilateral or bilateral visual impairment, nystagmus, squinting, obstructive hydrocephalus and diencephalic syndrome. On head and neck CT, optic nerve glioma is characterized by variably enlarged and elongated optic nerve with kinking or buckling. On head and neck MRI, optic nerve glioma is characterized by isointense to hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI. The mainstay of therapy for optic nerve glioma is chemotherapy and radiation therapy. Chemotherapy is used in children to delay radiation therapy, and to reduce the severity of radiation therapy induced side-effects. Radiation therapy is not generally used in children less than five years of age and usually avoided in children between five and ten years of age. Radiation therapy is delayed in young children to reduce the risk of significant side- effects such as developmental and neurocognitive delay. Chemotherapy using vincristine, actinomycin D, bevacizumab, etoposide, and other agents has also been reported to be effective in patients with progressive hypothalamic/chiasmal gliomas. Surgery is not the first-line treatment option for patients with optic nerve glioma. Surgical excision is usually reserved for patients with either progressive proptosis, blindness, exophytic chiasm tumor causing mass effect, hydrocephalus, or with increased intracranial pressure.

Optic nerve glioma was first described in 1816 by Scarpa.

Optic nerve glioma may be classified into several subtypes based on microscopic histopathology, anatomic location, and association with neurofibromatosis type 1. Optic pathway gliomas are classified according to WHO classification into two subtypes: pilocytic astrocytoma and fibrillary astrocytoma. Optic nerve gliomas may be classified according to anatomic location into two subtypes: anterior visual pathway tumors and posterior visual pathway tumors. Based on whether or not they are associated with neurofibromatosis type 1, they may be classified into two subtypes: optic nerve gliomas associated with neurofibromatosis type 1 and optic nerve gliomas not associated with neurofibromatosis type 1.

Genes involved in the pathogenesis of optic nerve glioma include BRAF-KIAA, tumor suppressor genes and chromosomes 7q34 and 17q. On gross pathology, smooth and fusiform intradural lesions are characteristic findings of optic nerve glioma. On microscopic histopathological analysis, low grade spindle shaped pilocytic astrocytes & glial filaments, with the presence of numerous Rosenthal’s fibers are characteristic findings of optic nerve gliomas.

There is no established cause for optic nerve glioma.

Optic nerve glioma must be differentiated from other diseases that cause optic nerve enlargement such as optic nerve sheath meningioma, orbital pseudotumor, optic neuritis, orbital lymphomas, metastasis, fibrous dysplasia, paranasal mucocele, rhabdomyosarcoma, neurofibromatosis, perioptic haemorrhage, Erdheim-Chester disease, juvenile xanthogranuloma, medulloepithelioma, retinoblastoma, Krabbe disease, optic nerve and chiasm glioma such as germinoma and sarcoidosis, and optic chiasm glioma extending into the hypothalamus such as pituitary adenoma, craniopharyngioma, malignant astrocytoma, dermoid cyst, chordoma, colloid cyst, histiocytosis X, tuberculous granuloma, and hemangloendothelioma.

Optic nerve gliomas affects females and males equally. Optic nerve gliomas commonly affects individuals younger than twenty years of age. There is no racial predilection to the optic nerve glioma.

Common risk factor in the development of optic nerve glioma is neurofibromatosis type 1.

According to the United States Preventive Services Task Force, screening for optic nerve glioma is not recommended. It is recommended that all children with NF-1 have their vision checked every year by an ophthalmologist to screen for the development of eye tumors, including optic nerve glioma.

Most optic nerve gliomas are benign and produce slowly progressive visual loss associated with variable proptosis and anterior or posterior optic neuropathy. If left untreated, less than 5 percentage of patients with optic nerve gliomas may progress to develop blindness. Common complications of optic nerve glioma include decreased vision, blindness, growth hormone deficiency, precocious puberty, and hydrocephalus. Prognosis is generally good in most patients with optic pathway gliomas.

Symptoms of optic nerve glioma include proptosis, unilateral or bilateral visual impairment, involuntary eye ball movement, squinting, obstructive hydrocephalus and diencephalic syndrome.

Common physical examination findings of optic nerve glioma include nystagmus, strabismus, proptosis, visual impairment, afferent pupillary defect, edema and/or pallor of optic disc, torticollis and deficits of cranial nerve II.

There are no diagnostic laboratory findings associated with optic nerve glioma.

There are no electrocardiogram findings associated with optic nerve glioma.

There are no chest x ray findings associated with optic nerve glioma.

On head and neck CT, optic nerve glioma is characterized by variably enlarged and elongated optic nerve with kinking or buckling.

On head and neck MRI, optic nerve glioma is characterized by isointense to hypointense mass on T1-weighted MRI, and hyperintense mass on T2-weighted MRI.

There are no echocardiography findings associated with optic nerve glioma.

Other imaging studies for optic nerve glioma include cerebral angiography, which may show a space-occupying mass.

Other diagnostic studies for optic nerve glioma include visual field tests, biopsy, and cerebral angiography.

The mainstay of therapy for optic nerve glioma is chemotherapy and radiation therapy. Chemotherapy is used in children to delay radiation therapy, and to reduce the severity of radiation therapy induced side-effects. Radiation therapy is not generally used in children less than five years of age and usually avoided in children between five and ten years of age. Radiation therapy is delayed in young children to reduce the risk of significant side- effects such as developmental and neurocognitive delay. Chemotherapy using vincristine, actinomycin D, bevacizumab, etoposide, and other agents has also been reported to be effective in patients with progressive hypothalamic/chiasmal gliomas.

Surgery is not the first-line treatment option for patients with optic nerve glioma. Surgical excision is usually reserved for patients with either progressive proptosis, blindness, exophytic chiasm tumor causing mass effect, hydrocephalus, or with increased intracranial pressure.

Effective measures for the primary prevention of optic nerve glioma include regular eye exams in patients with neurofibromatosis type 1.

Secondary prevention strategies following optic nerve glioma include lifelong follow-up care which further includes a visit to a clinic every year for screening of tumor recurrence, management of disease complications, and management of side-effects of treatment.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Optic nerve glioma was first described in 1816 by Scarpa.

Optic nerve glioma was first described in 1816 by Scarpa.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Optic nerve glioma may be classified into several subtypes based on microscopic histopathology, anatomic location, and association with neurofibromatosis type 1. Optic pathway gliomas are classified according to WHO classification into two subtypes: pilocytic astrocytoma and fibrillary astrocytoma. Optic nerve gliomas may be classified according to anatomic location into two subtypes: anterior visual pathway tumors and posterior visual pathway tumors. Based on whether or not they are associated with neurofibromatosis type 1, they may be classified into two subtypes: optic nerve gliomas associated with neurofibromatosis type 1 and optic nerve gliomas not associated with neurofibromatosis type 1.

• Optic nerve glioma may be classified into several subtypes based on microscopic histopathology, anatomic location, and association with neurofibromatosis type 1.

Classifications of Optic Nerve Glioma
Microscopic Histopathology	Fibrillary astrocytoma(40%)
	Pilocytic astrocytoma(60%)
Association with Neurofibromatosis type 1	Optic nerve gliomas associated with neurofibromatosis type 1
	Optic nerve gliomas not associated with neurofibromatosis type 1
Anatomic location	Anterior visual pathway Orbital Intracanalicular Intracranial prechiasmal lesions.
	Posterior visual pathway Optic chiasm Hypothalamus Anterior third ventricle

• Optic pathway gliomas are classified according to WHO classification into two subtypes:

• Pilocytic astrocytoma(60%)

• Fibrillary astrocytoma(40%)

• Based on whether or not they are associated with neurofibromatosis type 1, they may be classified into two subtypes:

• Optic nerve gliomas associated with neurofibromatosis type 1

• Optic nerve gliomas not associated with neurofibromatosis type 1

Neurofibromatosis type 1 tumors are more likely to involve anterior visual pathway. Optic nerve gliomas without an association with neurofibromatosis type 1 are more frequent in the posterior visual pathway.^[1] In children diagnosed with NF-1, approximately 15% develop optic gliomas.^{[2] [3]} Twenty to forty percent of optic gliomas occur in children with NF-1.

• According to their location along the optic pathway, the two major categories are:

• Orbital
• Intracanalicular
• Intracranial prechiasmal lesions.

Most of anterior visual pathway tumors are classified as pilocytic astrocytomas and they occur most frequently in prepubertal children.^[4]

• Optic chiasm
• Hypothalamus
• Anterior third ventricle

• Most of posterior visual pathway tumors are classified histologically as pilocytic astrocytomas, and occasionally gangliogliomas.
• Hypothalamic and chiasmal lesions present at a mean age of about three years.^[5]

• About 10% of optic pathway tumors are located within an optic nerve, one third of the tumors involve both optic nerve and chiasm, another one third involves predominantly the chiasm itself, and one fourth involves predominantly the hypothalamus. 5 5% of optic nerve gliomas are multicentric.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Genes involved in the pathogenesis of optic nerve glioma include BRAF-KIAA, tumor suppressor genes and chromosomes 7q34 and 17q. On gross pathology, smooth and fusiform intradural lesions are characteristic findings of optic nerve glioma. On microscopic histopathological analysis, low grade spindle shaped pilocytic astrocytes & glial filaments, with the presence of numerous Rosenthal’s fibers are characteristic findings of optic nerve gliomas.

• Optic nerve gliomas are classified as low-grade astrocytomas.
• The majority of cases of optic nerve glioma are pilocytic.
• Tumor de-differentiation is rarely seen in younger children with optic nerve gliomas but may be observed in older children and adults.
• In rare cases, tumor may become an anaplastic astrocytoma or glioblastoma.
• About 60% of optic pathway astrocytomas are pilocytic and 40% are fibrillary.
• Hypothalamic tumors which invade the optic chiasm, show evidence of local invasion and histologically are not pilocytic in nature but they are very similar to cerebral hemisphere gliomas.
• Pilomyxoid astrocytomas are a new subgroup of optic pathway gliomas that has been defined.
• Pilomyxiod astrocytomas have different histological features and have been shown to behave more aggressively than pilocytic astrocytomas.

• Optic nerve gliomas are classified as low-grade astrocytomas.^[1]
• Sporadic pilocytic astrocytomas usually have a tandem duplication of chromosome 7q34 and associated BRAF-KIAA fusion gene.^[2][3]
• Pilocytic astrocytomas associated with neurofibromatosis type 1 lack this fusion gene.
• There is characteristic loss of neurofibromin (which is a negative growth regulator for astrocytes), and increased RAS activation in patients with optic nerve gliomas associated with NF1.^[4]
• In some pilocytic astrocytomas there is loss of allelic chromosome, suggesting that they are clonal lesions that arise from inactivation of a tumor suppressor gene.
• There is link between NF-1 gene and tumor development in optic nerve glioma, as loss of chromosome 17q (the location of NF-1 gene) has been demonstrated in some cases, even in patients without NF1 or NF2.

On tumor resection, gross pathology reveals a smooth, fusiform intradural lesion. Macroscopically, these tumors may be cystic, solid or gelatinous.

Histologically, optic nerve gliomas are identical to pilocytic astrocytomas. Typical histology of pilocytic astrocytoma consists of:

• Densely cellular areas alternating with loose cystic regions
• Immature spindle shaped pilocytic astrocytes and glial filaments
• Rosenthal fibers are common
• Eosinophilic granular bodies are seen
• Microcystic degeneration is seen
• Mitotic figures usually cannot be identified
• Microcalcifications can be seen in 50% of these tumors

Several other histological patterns of optic pathway gliomas that have been described are:

• Oligodendroglial and astrocytic proliferation
• Leptomeningeal invasion
• Reticular pattern that involves microcystic foci with mucous-like fluid
• Arachnoid hyperplasia & mucus-substance

Typical histology of pilomyxoid astrocytoma consists of:

• Pilomyxoid astrocytomas classically show a markedly myxoid matrix, with small, compact, piloid and highly monomorphous cells.
• Tumor cells are often arranged radially around vessels in a pattern that simulates the perivascular pseudorosettes seen in ependymomas.
• Tumor samples appear solid without the presence of Rosenthal fibers and eosinophilic granular bodies.
• Satellitosis of the tumor cells in the surrounding neuropil can be seen,
• Mitotic figures can be seen occasionally.
• 14% of patients with pilomyxoid astrocytomas had cerebrospinal fluid dissemination of their disease which was not recognized in patients with the pilocytic variant.

The growth pattern of tumor can be either perineural or intraneural in nature. Patients with NF1 tend to have a perineural growth pattern, whereas sporadic optic pathway glioma patients tend to have an intraneural growth pattern.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

There is no established cause for optic nerve glioma.

• There is no established cause for optic nerve glioma.
• Sporadic pilocytic astrocytomas usually have a tandem duplication of chromosome 7q34 and associated BRAF-KIAA fusion gene.^[1][2] Pilocytic astrocytomas associated with neurofibromatosis type 1 lack this fusion gene. However, it is unknown if the mutation in the BRAF-KIAA fusion gene in the setting of optic nerve glioma is the primary cause of the disease as it is in other pilocystic astrocytomas.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Optic nerve glioma must be differentiated from other diseases that cause optic nerve enlargement such as optic nerve sheath meningioma, orbital pseudotumor, optic neuritis, orbital lymphomas, metastasis, fibrous dysplasia, paranasal mucocele, rhabdomyosarcoma, neurofibromatosis, perioptic haemorrhage, Erdheim-Chester disease, juvenile xanthogranuloma, medulloepithelioma, retinoblastoma, Krabbe disease, optic nerve and chiasm glioma such as germinoma and sarcoidosis, and optic chiasm glioma extending into the hypothalamus such as pituitary adenoma, craniopharyngioma, malignant astrocytoma, dermoid cyst, chordoma, colloid cyst, histiocytosis X, tuberculous granuloma, and hemangloendothelioma.^[1]

• The major differential diagnostic considerations when an enlarged optic nerve is identified on imaging are
  • inflammatory (neuritis, infection, or pseudotumor)
  • Neoplastic,
  • Result of increased intracranial pressure.
• Distinguishing inflammatory from neoplastic processes of the nerves is difficult because both may demonstrate optic-nerve enlargement with or without contrast enhancement.
• Clinical history can then be used to determine the underlying cause.
• Unilateral involvement, no pain on extra-ocular movement, no systemic inflammatory signs at around the onset of visual loss, no additional white-matter abnormality or recurrent visual symptoms during follow-up period might support a diagnosis of optic-nerve glioma rather than optic neuritis in childhood.
• Other tumorous conditions such as lymphoma or inflammatory pseudo-tumor may be ruled in the absence of a history of painful ophthalmoplegia or a rapid deterioration of symptoms during follow-up.

Differentiating Optic nerve glioma from other diseases
Optic nerve glioma	Hemangioma, Lymphoma, Rhabdomyosarcoma, Metastases (Neuroblastoma, Leukamia, Ewing’s sarcoma), Fibrous dysplasia, Paranasal mucocoele, Meningioma, Neurofibromatosis
Optic nerve and chiasm glioma	Germinoma, Sarcoidosis
Optic chiasm glioma extending into the hypothalamus	Pituitary adenoma, Craniopharyngioma, Malignant astrocytoma Dermoid cyst, Chordoma, Colloid cyst, Fibrous dyplasia, Sarcoidosis, Histiocytosis X, Tuberculous granuloma, Hemangloendothelioma

Disease/Condition	Clinical presentation	Demographics/History	Diagnosis	Other notes
Retinoblastoma[2][3]	Retinal mass Gross examination reveals a whitish tumor with prominent vascularity Vitreous seeding in endophytic tumors exudative retinal detachment in exophytic tumor	Sporadic in 90% of the cases The median age of diagnosis is 18 months Bilateral in 70% of the cases	P/E: leukocoria Ultrasound imaging: A dome or placoid-shaped intraocular mass +/- intralesional calcification CT imaging: Presence of calcification within the tumor	Associated with 13q deletion syndrome
Coats’disease[4][5]	Yellowish appearance of leukocoria P/E: Exudative retinal detachment with vascular tortuosity and telangiectasia +/- neurovascular glaucoma Absence of calcification	Sporadic in 100% of the cases Almost always unilateral More common among boys The median age of diagnosis 5 to 9 years	P/E is diagnostic in most of the cases Ultrasound imaging: Complete retinal detachment Absence of calcification Exudative, mobile lipid material under retina	Fluorescein angiography reveals characteristic telangiectasias of small to medium-sized retinal vessels
Persistent fetal vasculature (formerly known as persistent hyperplastic primary vitreous)[5]	Presence of leukocoria in infancy which is commonly accompanied by microphthalmia Presence of retrolental fibrovascular tissue +/- secondary cataract	Sporadic in the majority of cases Always congenital (present at birth) Rarely bilateral	P/E: microphthalmia and increasedintraocular pressure Presence of elongated ciliary processes contracting into the retrolental mass Ultrasound imaging: Vitreous band from lens to optic nerve Short axial length of eyes	Bilateral cases has been accompanied byprotein C deficiency
Astrocytic hamartoma[6]	Presence of gray-yellow or translucent tumors involving the posterior pole near optic nerve	Presents at any age Some has been associated with neurofibromatosis type 1/tuberous sclerosis	P/E: A sessile shape tumor arising from the inner aspect of the sensory retina Presence of small areas of calcification/complete calcification in older patients	Reticular pattern of fine blood vessels on fluorescein angiography
Retinopathy of prematurity (ROP)[6]	Absence of calcification Presence of retinal contraction in one or both eyes	History of: Prematurity (< 32 weeks gestation) Low birth weight (< 1.5 kg/3.3 lbs) Oxygen supplementation Leukocoria is a late presentation of the disease Always bilateral	P/E: Bilateral retinal avascularity and non-perfusion in temporal peripheral retina with fibrovascular proliferation in advanced cases Ultrasound imaging: Retinal detachment with retinal bands	Short axial length of eyes
Ocular toxocariasis [6]	Presence of retinal and/or vitreous traction in approximately all of the cases	Presents at any age Mostly unilateral Ingestion of larvae leads to the infection	P/E: Presence of granuloma and retinal traction Ultrasound imaging: Peripheral mass Vitreoretinal band Traction retinal detachment Presence of eosinophils in the anterior chamber tap	Classified into three sub-types: Macular granuloma Peripheral granuloma Endophthalmitis
Familial Exudative Vitreoretinopathy (FEVR)[7]	Presents at birth The majority are asymptomatic May present with leukocoria, strabismus, and vision loss	Autosomal dominant pattern of inheritance May occur sporadically Findings include asymmetry of both eyes	P/E: Avascularity of the temporal retina with peripheral fibrovascular proliferation Fluorescein angiography: Peripheral non-perfusion of the fundus	Fundus findings are similar to retinopathy of prematurity except for the history of prematurity
Norrie’s Disease[6][8]	Presents with microcephaly, congenital blindness, deafness, and progressive neuropsychiatric illness	X-linked disorder More common in males	P/E: bilateral retinal dysplasia, sometimes with anterior segment abnormalities and microphthalmia	–
Coloboma[6]	Presents at birth Failure of the embryonic fissure to close completely results in an absence of normal retina and choroid	The majority are sporadic Congenital disorder that affects male and female equally May be unilateral or bilateral	P/E: Whitish depressed lesion of retina which is typically inferonasal and its margins may encompass the macula or optic nerve	It may be accompanied by CHARGE syndrome

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Optic nerve gliomas affects females and males equally. Optic nerve gliomas commonly affects individuals younger than twenty years of age. There is no racial predilection to the optic nerve glioma.^[1]

• Optic nerve gliomas typically present in children, and often in the setting of NF1 (10-63%).
• In adults, optic nerve gliomas do occur but are very rare and usually aggressive tumors. In such cases no association with NF1 has been found.^[2]
• Five percentage (5%) of all childhood brain tumors account for optic nerve gliomas. About 1% of all intracranial tumors are comprised of optic-nerve gliomas.^[3] It is most common in children who have the genetic condition neurofibromatosis 1 (NF1).

The incidence of NF-1 among patients of optic nerve glioma is 10-70% and the incidence of optic nerve glioma in patients with NF-1 varies from 8% to 31%.^[4]

Males and females are equally affected.

The mean age of presentation of optic nerve glioma is 8.8 years.^[5] The majority of optic nerve gliomas occur in children. They are usually slow-growing and noncancerous and almost always occur before age 20.^[2]

Age of onset of optic nerve glioma	Percentage of optic nerve glioma diagnosed
Before the age 18 months	25%
Before the age of 5	50%
Before the age of 10	75%
Before the age of 20	90%

There is no racial predilection to the development of optic nerve glioma.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

Common risk factor in the development of optic nerve glioma is neurofibromatosis type 1.

• There is a strong association between optic glioma and neurofibromatosis type 1.^{[1] [2]}
• Optic nerve glioma occurs in approximately 8% to 31% of patients with neurofibromatosis type 1.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

According to the United States Preventive Services Task Force, screening for optic nerve glioma is not recommended. It is recommended that all children with NF-1 have their vision checked every year by an ophthalmologist to screen for the development of eye tumors, including optic nerve glioma.

• According to the United States Preventive Services Task Force, screening for optic nerve glioma is not recommended. However, it is recommended that all children with neurofibromatosis type 1 have their vision checked every year by an ophthalmologist to screen for the development of eye tumors, including optic nerve glioma.
• In children with NF-1, yearly eye exams should begin around 1 year of age and continue until children are at least 10 years of age. Those with a normal eye exam, a baseline MRI of the brain to look for optic nerve gliomas is not necessary.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]

If left untreated, less than 5% of patients with optic nerve gliomas may progress to develop blindness. The clinical course of optic nerve gliomas is unpredictable.^[1] Common complications of optic nerve glioma include decreased vision, blindness, growth hormone deficiency, precocious puberty, and hydrocephalus. Prognosis is generally good in most patients with optic pathway gliomas. Most optic nerve gliomas are benign and produce slowly progressive visual loss associated with variable proptosis and anterior or posterior optic neuropathy.

• Optic nerve gliomas have an unpredictable natural history.^[2]
• The majority of the optic nerve gliomas grow slowly in a self limited manner and some of them spontaneously regress.^[3]
• If left untreated, less than 5 percentage of patients with optic nerve gliomas may progress to develop blindness. Significant visual impairment is frequently present in neurofibromatosis type 1 patients with optic nerve gliomas.^[4][5]
• These tumors demonstrate variable clinical and radiological progression. In patients with neurofibromatosis type 1, it is not unusual for these tumors to be quiescent, with little progression demonstrated over a number of years. In others, the tumors are more aggressive with extension along the optic pathways.^[6]
• Normally, the growth of the tumor is very slow, and the condition remains stable for long periods of time. However, in adults and some children, when the optic chiasm is involved, the tumor is more aggressive.
• In adults, the clinical course of an optic nerve gliomas resembles the behavior of the tumors’s histology, which is commonly a malignant glioma. Malignant optic nerve gliomas can result in rapidly progressive visual loss. Rapid onset blindness is seen in elderly and middle-aged individuals.^[7][8][9]
• Death can occur with in few months of presentation if tumor invasion into adjacent brain occurs.^[10]

Complications of optic nerve gliomas include:

• Decreased vision
• Blindness
• Hydrocephalus
• Growth hormone deficiency
• Precocious puberty

• There is nearly 90 percent survival rate for all optic pathway gliomas whether those with or without neurofibromatosis type 1.
• Children with neurofibromatosis and older children have a better prognosis.
• In patients with optic nerve gliomas associated with neurofibromatosis type 1, beter prognosis is seen.
• Spontaneous remission of the optic pathway gliomas is seen in two-thirds of children with neurofibromatosis type 1.
• Metastatic dissemination through ventriculoperitoneal shunts, malignant degeneration, and spontaneous regression have all been reported.
• Patients with chiasmal gliomas have usually less favorable prognosis.
• Patients with neurofibromatosis type 1 have appoximately twice the recurrence rate following complete excision of an intraorbital glioma as compared with patients without neurofibromatosis type 1.
• Approximately sixty percentage of children treated with chemotherapy for gliomas of the hypothalamus and optic pathways had a relapse.^[11]

Prognosis	Age at onset	Clinical features	Radiographic location
Favorable prognosis	Early childhood to adolescence	Visual loss with laterality Slowly progressive or arrested course Incidental finding in child with neurofibromatosis No symptoms of endocrine dysfunction or hydrocephalus Does not have diencephalic syndrome	Intrinsic optic nerve and/or chiasmal location
Poor Prognosis	Infancy to early childhood and adulthood	Hypothalamic symptoms and/or signs of increased intracranial pressure Severely affected vision in both eyes	Large exophytic chiasmal tumor with posterior extension Extension into third ventricle

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