Medical Information on Brainstem Glioma

The Brain Stem

The brain stem controls our most basic functions, many of which happen without our thinking about them at all. Three structures make up the brain stem:

• The medulla controls breathing, swallowing, blood pressure and heart rate
• The pons links the cerebellum to the cerebrum
• The midbrain governs basic vision and hearing

Running down the length of the brain stem is the reticular formation, which is responsible for wakefulness or arousal. If a brain tumor distorts the reticular formation, a coma-like state is likely.

There are twelve sets of cranial nerves, one of each pair for each side of the body. Most of them originate in the brain stem. These nerves control important things like swallowing, facial movement, the senses, and neck and shoulder muscles.

Major nerves carrying information to and from the rest of the body pass through the brain stem. The nerve axons cross over in the medulla so that the left side of the brain controls the right side of the body and vice versa. Tumors on one side of the brain may well affect movement and sensation on the opposite side of the body.

*Information provided by Children's Brain Tumor Foundation

Brain Tumor: Brainstem Glioma

Definition

The brain stem consists of the midbrain, pons and medulla located deep in the posterior part of the brain. Tumors that arise along these structures are called brainstem gliomas. Most brainstem gliomas occur in the pons ("pontine gliomas"). The pontine tumors have a poorer prognosis than the less common midbrain and medullary gliomas.

Incidence

Brainstem tumors account for 10 percent of pediatric brain tumors. The peak incidence is between ages 5 and 10.

Clinical Features and Symptoms

Pontine brainstem tumors affect the cranial nerves, causing symptoms related to the nerves that supply the muscles of the eye and face, and muscles involved in swallowing. These symptoms include double vision, inability to close the eyelids completely, dropping one side of the face, and difficulty chewing and swallowing. The tumor also affects the "long tracks" of the brain, with resultant weakness of the arms or legs and difficulty with speech and walking. Symptoms usually worsen rapidly because the tumor is rapidly growing.

Tumors arising in the midbrain usually affect only the nerves supplying the eye muscles. They also block the flow of cerebrospinal fluid in the brain, causing increased pressure with headaches and vomiting. Tumors involving the medulla usually cause swallowing problems and weakness of the arms and legs.

Survival Rates

Pontine Gliomas - The patients' symptoms often improve dramatically during or after six weeks of irradiation. Unfortunately, problems usually recur after six to nine months, and progress rapidly. Survival past 12 to 14 months is uncommon, and new approaches to treating these tumors are urgently needed.

Midbrain/Medullary Gliomas - With the use of radiation therapy, these patients often to well. Long-term survival ranges from 65 to 90 percent for brain stem tumors that arise from the midbrain or medulla.

Treatment Strategies

Surgery is not generally possible because these tumors (especially pontine gliomas) are widely spread within the brain stem and can not be removed. Radiation therapy has been the main treatment approach.

*Information provided by St. Jude Children's Research Hospital