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What is Glioma of the Optic Pathway?
Known as visual pathway glioma, low grade glioma, or optic pathway glioma, it is a benign brain tumor that develops along the nerves delivering visual information from the eyes to the brain (the optic pathway). The tumor is considered benign because it grows, but does not metastasize or spread to other adjacent organs of the body. A glioma is a type of tumor originating from brain cells known as astrocytes. They are composed of the supportive network of the brain. Male and female children below 10 years old are prone to developing this tumor.
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It is still not known what causes optic pathway glioma, but a hereditary condition known as neurofibromatosis type 1 (NF-1) may result in this tumor. It is characterized by skin lesions (freckles or large lumps in the skin), changes in skin coloring (pigmentation), and growth of tumors along nerves in the skin, brain, or other organs. If a child whose tumor is less than five years old, he or she may not reveal such conditions.
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Symptoms may vary, but common symptoms associated with vision include:
- Abnormal head movements (head tilt)
- Abnormal eye movements (nystagmus)
- Difficulty seeing
- Double vision
- Blind spots
- Protruding eyes
The tumor might cause increased pressure in the head, which includes symptoms such as headache, lethargy, nausea, and vomiting.
When the tumor affects the hypothalamus in the brain, this condition might result in hormonal problems such as weight loss or weight gain, abnormal eating behavior, and early puberty. The hypothalamus is a part of the brain that helps manage the hormones in the body.
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The doctor or an ophthalmologist needs to diagnose abnormalities if he or she suspects the presence of a tumor in the child’s brain. Diagnostic procedures are important to locate and measure tumor size. They include:
Computed Tomography (CT) scan
CT scan combines a series of x-rays and a computer to generate detailed images of the brain.
Magnetic Resonance Imaging (MRI) scan
A MRI scan combines radio waves, large magnets, and a computer to generate detailed images of the brain.
This test would find out if the child has abnormal eye movements (nystagmus) and difficulty seeing. The test involves visual testing that can be applied to MRI scans to produce detailed results.
This procedure requires blood tests to examine the child’s hormones. It works well to confirm tumor presence in the hypothalamus.
An ophthalmologist evaluates and records the child’s vision when he or she undergoes a comprehensive assessment. The evaluation might be performed during and after treatment.
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Several treatment options that can help contend with this brain tumor include:
The goal of this treatment is to preserve vision by removing part of the tumor instead of removing the entire tumor. Eliminating all tumor cells by surgery is harmful because this practice would injure nerves around the eye.
Chemotherapy involves medications that prevent tumor cells from thriving. They can also shrink tumors. The doctor might recommend combining different groups of chemotherapy to combat tumor cells effectively. It is commonly injected into a vein of the child.
Radiotherapy applies radioactive substances to shrink and eradicate tumor cells. Despite being quite effective, the doctor would not suggest it in the initial treatment since radiotherapy would affect hormonal function in the child’s body.
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Gosh.nhs.uk: Optic Pathway Glioma - http://www.gosh.nhs.uk/gosh_families/information_sheets/brain_spinal_tumours_optic_pathway_glioma/brain_spinal_tumours_optic_pathway_glioma_families.html
Childrenhospital.org: Optic Pathway Glioma - http://www.childrenshospital.org/az/Site1386/mainpageS1386P0.html
Royalmarsden.nhs.uk: Optic Pathway Glioma - http://www.royalmarsden.nhs.uk/cancer-information/children/optic-pathway-glioma