Optic nerve glioma
Key points
- Gliomas are tumors that can be found in various parts of the brain.
- These tumors occur most often as a slow-growing, benign form in children and almost always occur before age 20.
- The symptoms are due to the tumor growing and pressing on the optic nerve and adjacent structures.
- A neurologic examination reveals a loss of vision in one or both eyes.
Alternative names
Glioma - optic; Optic glioma
Definition
Gliomas are tumors that can be found in various parts of the brain. They are created by the growth of abnormal cells. Optic gliomas can affect:
- One or both optic nerves - these are the nerves that carry visual information to the brain from each eye
- The optic chiasm - this is the region where the optic nerves cross each other in front of the hypothalamus of the brain
An optic glioma may also grow in conjunction with a hypothalamic glioma (a mass in the hypothalamus of the brain).
Causes, incidence, and risk factors
Optic gliomas are rare and the cause is unknown. These tumors occur most often as a slow-growing, benign form in children and almost always occur before age 20. There is a strong association between optic glioma and neurofibromatosis Type 1 (NF1).
Symptoms
The symptoms are due to the tumor growing and pressing on the optic nerve and adjacent structures. These symptoms can include:
- Vision loss in one or both eyes that leads to eventual blindness. The vision loss can be general, or it can be a decrease in the visual fields, such as a loss of peripheral vision.
- Squinting.
- Involuntary eyeball movement.
- One or both eyes may bulge outward.
The patient may show symptoms of Diencephalic syndrome, which includes delayed growth, loss of appetite and body fat, daytime sleeping and decreased memory and intellectual capacities.
Signs and tests
A neurologic examination reveals a loss of vision in one or both eyes. There may be changes in the optic nerve, including swelling or scarring of the nerve, or paleness and atrophy of the optic disk.
The tumor may extend into deeper locations of the brain. There may be signs of increased pressure within the brain (intracranial pressure). There may be signs of NF1.
The following tests may be performed:
- Head CT scan or MRI of the head - confirms the diagnosis and the exact location of the tumor
- Cerebral angiography - often not necessary, but if used, it shows a space-occupying mass
- Visual field tests - can help determine how invasive the tumor is
- Tissue removed from the tumor during surgery or CT scan-guided biopsy - examined to confirm the exact type of tumor.
Written and revised by
David Cohen, M.D.
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