What is an optic pathway/hypothalamic glioma?
An optic pathway glioma is a type of low-grade astrocytoma that grows in a portion of the optic pathway (optic nerve, optic chiasm, optic radiations). These tumors originate from astrocytes, which are star-shaped cells that make up the supportive tissue of the brain. Astrocytes are a type of glial cell which function to support the surrounding cells. Optic pathway/hypothalamic gliomas account for 4 percent to 6 percent of all brain tumors in children and 30 percent of all pediatric gliomas. They most often occur during the first decade of life.
What are the symptoms of an optic pathway/hypothalamic glioma?
Visual loss – either involving one eye or both eyes – is a common symptom of optic pathway gliomas. Frequently only a portion of the visual field will be affected. Other visual symptoms include proptosis (protrusion of the eye), nystagmus (bouncy eyes), or strabismus (wandering eye). An eye exam by an ophthalmologist will frequently demonstrate a pale optic nerve. Tumors that involve the hypothalamus can cause failure to thrive or obesity and precocious (early)puberty or other hormonal dysfunction. In rare instances, optic pathway gliomas can cause hydrocephalus (too much cerebrospinal fluid) resulting in symptoms of increased cranial pressure (headache, vomiting, difficulties with balance, lethargy).
How is an optic pathway/hypothalamic glioma diagnosed?
A magnetic resonance image (MRI) scan of the brain is done to further define the location of the tumor. An MRI of the spine may also be recommended due to the low possibility of metastasis (spread) of the tumor. A thorough ophthalmology exam is done to provide a good baseline evaluation. Blood is drawn for lab tests to look at the pituitary hormones, which can sometimes be affected by the tumor. The MRI appearance can often be diagnostic of an optic pathway glioma and in these cases no biopsy is needed. If the MRI is unclear regarding the diagnosis, a biopsy of the tumor is required to make the final diagnosis.
How is an optic pathway/hypothalamic glioma treated?
Surgery, chemotherapy and radiation are all effective treatments for optic pathway/hypothalamic glioma. Surgery is often required to make the diagnosis of an optic pathway/hypothalamic glioma. In most cases of optic pathway/hypothalamic glioma, the tumor extends into normal nerve fibers making it impossible to remove the tumor without causing some injury to the optic pathway or hypothalamus. In cases where all or the majority of the tumor is removed, no further treatment is required. Even after surgery, long-term control of the tumor may be necessary. If the tumor recurs after surgical resection alone, further surgery or treatment with chemotherapy or radiation may be needed.
Chemotherapy and radiation therapy are effective treatments for optic pathway/hypothalamic gliomas. The goal of chemotherapy is to stop the tumor from growing, shrink the tumor, and delay or avoid radiation therapy because of potential side effects.
While radiation is very effective for the treatment of optic pathway/hypothalamic gliomas, unfortunately it has potential long-term toxicities (cognitive impairment, secondary malignancies, and vascular injury), therefore it is typically reserved for older children or younger children who fail chemotherapy. Radiation therapy can control the tumor for the longest period of time, and in many cases it is curative.
About treatment for optic pathway/hypothalamic glioma at Children’s Hospitals and Clinics of Minnesota
Our cancer and blood disorders program consistently achieves excellent results ranking it in the top ten programs in the United States. Children’s Hospitals and Clinics of Minnesota treats the majority of children with cancer and blood disorders in Minnesota and provides patients access to a variety of clinical trials using ground-breaking new treatments. Through our renowned program, patients experience unparalleled family support, a nationally recognized pain management team, and compassionate, coordinated care.
If you are a family member looking for a Children’s neuro-oncologist, please call our clinic at (612) 813-5940.
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