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.

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.

Treatment

Treatment varies with the size of the tumor and the general health of the person. The goal may be to cure the disorder, relieve symptoms, or improve vision and comfort.

Surgical removal may cure some optic gliomas. Partial removal to reduce the bulk of the tumor is feasible in many cases, which will minimize pressure-induced damage from the tumor.

Radiation therapy may be advised in some cases where the tumor is extensive and surgery is not possible. One newer technique creates a computerized 3D image of the brain and glioma, then irradiates the tumor from many directions. Another promising technique is called proton radiation therapy (PRT). In some cases, radiation therapy may be delayed because of the slow growth that this tumor typically displays.

Corticosteroids may be prescribed to reduce swelling and inflammation during radiation therapy, or if symptoms return.

Support Groups

For organizations that provide support and additional information, see blindness resources.

Expectations (prognosis)

The outlook is highly variable. Early treatment improves the chance of a good outcome. Many tumors are curable with surgery, while others return.

Normally, the growth of the tumor is very slow, and the condition remains stable for long periods of time. However, in adults and some childhood cases where the optic chiasm is involved, the tumor behaves aggressively.

Complications

• decreased vision
• blindness

Calling your health care provider

Call your health care provider if you have any vision loss, painless bulging of your eye forwards, or other symptoms of this condition.

Prevention

Genetic counseling may be advised for people with neurofibromatosis-1. Regular eye exams may allow early diagnosis of these tumors before they cause symptoms.

Illustrations

Neurofibromatosis I, enlarged optic foramen

Page Content:

Glioma - optic; Optic nerve glioma ; glioma nerve optic; optic glioma; optic nerve glioma; glioma optic pathway