Gliomas are tumors that arise from glial (supporting) cells in the brain. Gliomas that occur at the brainstem, which connects the brain to the spinal cord, tend to occur during childhood and adolescence and account for approximately 15 percent of childhood brain tumors.

These tumors tend to be quite aggressive, so the prognosis usually is not positive. While some tumors are clearly separated from surrounding tissues, most brainstem gliomas are "infiltrative," meaning that cells from the tumor grow into the surrounding tissue.

In adults, these tumors are very rare and tend to be less aggressive.

Symptoms

The most common initial symptoms associated with a brainstem glioma are

• Difficulty walking
• Headache
• Nausea
• Vomiting
• Double vision
• Trouble swallowing
• Facial weakness

Because the brainstem is a very sensitive area that is close to the structures in the brain that control blood pressure, breathing, and a number of motor and sensory functions, there is the possibility that these tumors can cause significant neurological problems. The location of these tumors also means that many children with them may experience hydrocephalus, a condition in which the flow of cerebrospinal fluid around the brain is blocked, causing an increase in pressure inside the skull that results in headache, nausea, and vomiting. Also, these tumors may grow large before symptoms begin.

Diagnosis

Imaging studies are the key component in the diagnosis of brainstem gliomas. A contrast agent is administered intravenously so neurological surgeons can visualize the tumor against the normal brain in the background.

• Magnetic resonance imaging (MRI) scans are important to help determine the relationship of the tumor to the adjacent structures.
• Computed tomography (CT) scans also are used.
• In some cases, neurological surgeons may employ an MRI scan with frameless stereotactic guidance. For this study, a contrast MRI is performed after special markers (called fiducials) are placed on the child's scalp. The fiducials are processed by a computer, which calculates the location of the tumor and creates a three-dimensional reconstruction. This image then is used at the time of surgery to help locate the tumor precisely, maximize tumor removal, and minimize injury to the surrounding brain.

Treatment

Surgery, the treatment of choice for many other types of brain tumors, usually is not used in children with brainstem gliomas because this region can be difficult to reach surgically, the tumors are close to critical areas of the brain, and they infiltrate normal tissue. However, advances in microsurgical techniques and skull base approaches are making it possible to surgically remove more of these tumors than before. Such operations are risky, and only are used in select cases, including benign slow-growing tumors and those that are clearly separated from surrounding brain tissue.

Initial treatment for a brainstem glioma may include a surgical procedure to reduce pressure inside the skull caused by hydrocephalus. If possible, tumor removal can restore the flow of cerebrospinal fluid. More often, the pressure is reduced with a shunt, an implantable tube that allows the excess fluid to drain to other parts of the brain or elsewhere in the body. Also, drugs such as corticosteroids may be given to help reduce symptoms.

Radiation therapy is the primary treatment for brainstem gliomas, but it may have adverse effects on development. Radiation therapy also will be used following surgery and some tumors may be treated effectively with stereotactic radiosurgery, which involves the use of a highly focused beam of radiation to target the cancer cells specifically and leave the surrounding brain unaffected.

Chemotherapy is not widely used in children with brainstem gliomas because its efficacy has not been established.