Optic Nerve and Other Brain Tumors
Optic nerve gliomas
Optic nerve gliomas are benign (non-cancerous) brain tumors that grow on the nerves that carry vision from the eyes to the brain (the optic nerves). Optic nerve gliomas are found in approximately one in five children with NF1.
These tumors commonly arise in young children and can affect their vision. For this reason, it is important that all children with NF1 have their vision checked every year by an eye doctor (ophthalmologist) familiar with NF1. It is highly recommended that these yearly eye exams begin around one year of age and continue until children are at least ten years old.
Optic nerve gliomas are most commonly found using a specialized brain imaging test, called magnetic resonance imaging, or MRI. Baseline MRI of the brain to look for optic nerve gliomas in young children with a normal eye exam is not necessary.
Most optic nerve gliomas in children with NF1 will not continue to grow and will not cause vision problems. Thus, knowing that a child has an optic nerve glioma is not an indication to begin treatment if there are no symptoms of tumor growth. Treatment should be reserved for children whose tumors are actively growing or resulting in worsening vision.
Tumors of the hypothalmus and brainstem
In addition to tumors that grow on the optic nerves, similar tumors in children with NF1 may grow in a region of the brain called the hypothalamus.
The hypothalamus is a part of the brain that is responsible for making hormones that trigger puberty. Brain tumors that grow in the hypothalamus (hypothalamic glioma) can cause young children to begin puberty. Parents should consult a physician who is an expert in NF1 if there is hair growth under the arms or in the pubic area in girls under seven, breast development in girls younger than seven, or enlargement of the penis and testicles in boys younger than eight.
Less commonly, brain tumors in children with NF1 may grow in other parts of the brain, including a region called the brainstem. Typically, brainstem gliomas in children with NF1 do not cause medical problems. Children with this type of brain tumor should be cared for by a physician who is an expert in NF1.
Treatment of brain tumors in children with NF1 typically involves drug therapy, and not surgery or radiation. Children with NF1 who require treatment for their brain tumors should be managed by pediatric cancer specialists. Lastly, brain tumors in adults with NF1 are very rare, but occur more commonly than they do in adults without NF1.
Children with NF1 frequently will have T2 hyperintensities on magnetic resonance imaging (MRI) of the brain. They are commonly located in the optic nerve pathway, basal ganglia, cerebellum and brainstem. These bright spots are not tumors and will not develop into brain tumors. T2 hyperintensities are most commonly seen in children and disappear in adulthood.