What are neuronal and mixed neuronal-glial tumors?

Neuronal and mixed neuronal-glial tumors are a group of rare tumors that occur in the brain or spinal cord. Together, your brain and spinal cord make up your central nervous system (CNS). Many of these tumors are benign (not cancerous). Benign means that the growth does not spread to other parts of the body. But these tumors can be dangerous. They can cause seizures or other problems by pressing against surrounding brain tissue.

Your brain and spinal cord contain many neurons and other supporting cells (such as glial cells). The neurons are specialized nerve cells that send messages within the CNS and the rest of your body. These neurons “talk” to each other by using chemical and electrical signals. Glial cells do not send nerve signals but carry out many other jobs in your brain, such as insulating and providing support to the neurons.

A tumor is an abnormal growth of cells. Most brain tumors come from the glial cells or other non-neuronal cells in the CNS. Neuronal tumors are a rare group of brain tumors made of abnormal neurons. Mixed neuronal-glial tumors are a rare group of brain tumors that have abnormal neuron cells along with glial cells.

Healthcare providers who specialize in examining tumor cells under a microscope normally grade them on a scale from I to IV. Grading is based on how abnormal the cells look. The cells from a grade I tumor look almost normal and grow slowly, while a grade IV tumor tends to grow very quickly.

Most neuronal and mixed neuronal-glial tumors are low grade (grade I or II) and tend to grow slowly. The cells look almost normal. Healthcare providers often remove low-grade tumors surgically.

There is one subtype of neuronal tumor that is grade III. It is called anaplastic ganglioglioma. This type tends to grow more quickly than most other neuronal tumors. It may need more aggressive treatment with chemotherapy and radiation in addition to surgery.

Overall, neuronal and mixed neuronal-glial tumors tend to be slow growing.

Some neuronal and mixed neuronal-glial tumors happen more often in children or teens than in adults. Other types (such as cerebellar liponeurocytoma) are more common in older adults. Almost any of these tumors can occur in people of any age.

What causes neuronal and mixed neuronal-glial tumors?

Experts do not yet know what causes neuronal and mixed neuronal-glial tumors to develop. Some theories suggest links to gene mutations, environmental toxins, or infections (such as by viruses). But, the possible risk factors for these tumors are not clear.

What are the symptoms of neuronal and mixed neuronal-glial tumors?

Where the tumor is located in the brain and its size determine what symptoms you may have. A neuronal or a mixed neuronal-glial tumor may cause symptoms related to the part of the brain that it grows in.

In general, symptoms may include:

• Seizures (often the first symptom)
• Headache
• Nausea and vomiting
• Dizziness and balance problems
• Trouble walking
• Eye problems
• Personality or thinking changes
• Sleepiness or inability to stay awake

How are neuronal and mixed neuronal-glial tumors diagnosed?

Healthcare providers often take a health history, asking about your recent symptoms, past health problems, and your family health history. You will need a thorough physical exam, including a nervous system exam. Your healthcare provider will likely check your coordination and reflexes and do several nervous system tests. If a healthcare provider suspects a brain tumor, they will often want to look at images of your brain. You may need:

• Biopsy of the tumor tissue to look at it for type and grade
• Blood and urine tests
• CT scans
• MRI scans of your brain and spinal cord

You may first see your primary healthcare provider and then get a referral to a specialist. This healthcare provider should be an expert in diagnosing and treating diseases of the brain, such as a neurologist, neurosurgeon, or neuro-oncologist.

How are neuronal and mixed neuronal-glial tumors treated?

The standard treatment for these tumors is to remove them surgically. In many cases, treatment may only be removing the tumor. If the tumor is in a spot where it is not possible to remove it completely, radiation therapy and chemotherapy are other options.

You can work with your care team to talk about the best treatment plan for you. You will likely need regular follow-ups with your healthcare provider, including repeated imaging tests to check whether the tumor comes back. It is very important to keep follow-up appointments so that your care team can watch for any changes.

What are possible complications of neuronal and mixed neuronal-glial tumors?

Seizures are the most common nervous system symptoms. In some cases, the tumor may be blocking drainage of the cerebrospinal fluid from your brain. This causes a buildup of fluid and increases the pressure within your brain. If this happens, you may need surgery to insert a tube to drain excess fluid and lower the pressure. After removal of the tumor, this problem often goes away.

There is a chance the tumor may grow back if you don’t have it all removed. In very rare cases, a tumor might change into a higher-grade form.

Key points about neuronal and mixed neuronal-glial tumors

Neuronal and mixed neuronal-glial tumors are rare tumors of the brain or spinal cord. These tumors include abnormal nerve cells. Some key points include:

• Most of these tumors are low grade (grade I or grade II) and tend to grow slowly.
• The first symptoms may be seizures. Headaches, nausea, or other symptoms may occur.
• Surgery to remove the tumor is often the main treatment. Radiation and chemotherapy are also options in some cases.
• Removing all of the tumor often results in a good long-term outcome.