Brain Stem Glioma in Childhood

Brain Stem Glioma in Childhood

What is the Brain Stem?

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The brain stem is located at the back of the neck and is the lowest part of the brain, connecting it to the spinal cord. It controls essential bodily functions, such as muscle movement, coordination, heartbeat, breathing, and sensory activities. The brain stem consists of three parts:

• Midbrain: Located in the middle part of the brain.
• Medulla Oblongata: Connects the brain to the spinal cord.
• Pons: Found between the medulla oblongata and the midbrain.

What is Brain Stem Glioma?

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Brain stem glioma is a type of central nervous system (CNS) tumor that forms when cells in the brain stem grow uncontrollably, forming a mass. These tumors may or may not be cancerous, but most are highly aggressive and spread quickly. Due to its location, surgery is often challenging, making treatment complex. Brain stem gliomas are most commonly seen in children between the ages of 5 and 10.

Statistics

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While specific data for India is unavailable, in the United States, about 3920 children are diagnosed annually with CNS tumors, of which 13% are brain stem gliomas. Most of these occur in the pons area of the brain stem, around 75%.

Risk Factors

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Though the exact cause of brain stem glioma in children is unknown, certain genetic conditions may increase the risk:

• Li-Fraumeni syndrome
• Neurofibromatosis type 1
• Nevoid basal cell carcinoma syndrome
• Tuberous sclerosis complex
• Turcot syndrome

Symptoms

• Double vision
• Inability to close the eyes properly
• Facial drooping
• Difficulty chewing or swallowing
• Weakness in the arms or legs, trouble walking
• Difficulty speaking
• Headaches
• Vomiting

Diagnosis

• MRI
• CT Scan
• Biopsy: A small portion of the suspected tumor is removed for examination under a microscope.

Stages
Unlike other cancers, brain stem gliomas do not follow the traditional TNM staging system. Instead, they are classified based on their appearance and behavior under a microscope.

Grades

• Diffuse Brain Stem Glioma: The most common and aggressive type, spreading rapidly, often through the pons and other parts of the brain. These are high-grade tumors.
• Focal Brain Stem Glioma: Found in only one area, typically in the midbrain or medulla. These are low-grade, less aggressive tumors.
• Recurrent Brain Stem Glioma: Tumors that return after treatment.

Treatment

Radiation Therapy
This is the most commonly used treatment for brain stem gliomas. High-energy radiation is directed at the tumor to destroy cancer cells. However, radiation may affect the growth of a child’s brain, so alternative treatments are sometimes explored first.

Chemotherapy
Chemotherapy is not typically used as a sole treatment for brain stem gliomas but is often given before, during, or after radiation therapy. The drugs can help shrink or slow the growth of the tumor. Common chemotherapy drugs used include:

• Cisplatin
• Vincristine

Side effects of chemotherapy may include:

• Fatigue
• Infections due to low blood cell counts
• Hair loss
• Nausea and vomiting
• Loss of appetite
• Diarrhea

These side effects often improve after chemotherapy ends.

Targeted Therapy
This treatment uses drugs designed to target specific genetic mutations or proteins that help cancer cells grow. In brain stem gliomas, medications like:

• Dabrafenib (Tafinlar)
• Trametinib (Mekinist)
may be used in specific cases. These drugs attack the cancer cells without harming normal cells as much.

Surgery
Surgery is usually only an option for focal brain stem gliomas, where the tumor is confined to a smaller area and can be safely removed. For diffuse brain stem gliomas, surgery is generally not possible due to the tumor’s location and extent of spread.

Follow-up for Brain Stem Glioma in Childhood
After completing treatment for brain stem glioma, regular follow-up appointments are essential to monitor for recurrence and manage any side effects. These follow-ups include:

• Physical exams
• Blood tests
• Imaging tests such as MRIs or CT scans to check for tumor regrowth

Regular monitoring ensures that any recurrence or new symptoms can be addressed promptly. Follow-up also helps manage long-term side effects, such as those from radiation therapy, which may affect a child’s growth and development.

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