While tumors of the nervous system may sound rare, they are in fact the most common solid tumor of childhood. They may present at any age from infancy onward. There are many symptoms which may lead to a search for a brain or spinal cord tumor. It is important to understand that many of these symptoms can mimic other far more common and benign conditions. Some of these conditions include hydrocephalus, seizures, headache disorders, infections and others to numerous to mention. The important point is to evaluate any child who is developing problems which are related to the nervous system.
Usually a neurosurgeon will not be involved in the evaluation until a radiological diagnosis of a probable tumor is made. These studies are usually ordered by the pediatrician, family practitioner or pediatric neurologist. At this point the neurosurgeon must help to determine if the abnormality on the radiographs is the cause of the child’s problems and what surgery if any should be recommended.
The surgical options are usually biopsy vs. removal of the tumor. Biopsies can be performed “open” or “closed”. Open biopsy usually implies that a small window of bone is temporarily removed from the skull to allow the surgeon to remove a small portion of the tumor under direct visualization. A closed biopsy is usually performed through a tiny hole, often no larger than an eighth of an inch. The tumor is not directly seen by the surgeon, rather a CT scan or MRI is used to determine from where the biopsy should be obtained. Prior to the CT or MRI scan, a special frame is attached to the child’s head. This is generally done with the child sedated or under general anesthesia depending on the age. This frame is seen on the scan and allows the generation of coordinates that allows the surgeon to place a probe or biopsy device anywhere in the brain with pinpoint accuracy. After surgery the frame is removed and the child typically can go home the following day.
Not all tumors should be biopsied. In fact, in pediatrics as compared to adults more tumors lend themselves to removal than biopsy alone. A brief discussion on benign vs. malignant should be made. Until now, the term tumor has been used in the very general sense without implication for prognosis. As most people are aware there are both benign and malignant tumors in the body. Unfortunately the naming of such tumors in the brain is very confusing. Most people understand benign tumors to be removable and thus curable with little chance for spread. Likewise, most people understand malignant to be highly aggressive tumors that spread throughout the body rapidly and are likely to be fatal. By and large tumors in the nervous system stay in the nervous system. Benign and malignant refer more to the rate of growth of the tumor and the degree of local invasion to the surrounding brain tissue.
To further confuse things, not all benign tumors in the brain are treatable or curable. Likewise there are malignant tumors that can be cured. One of the more crucial factors in tumors of the nervous system if their exact location in the brain. Some are in what are known as “quiet” areas. These are areas of the brain with seemingly little function. Removal of a tumor from these areas would not be expected to cause significant changes in the child’s function. Other areas are more “eloquent” and are clearly related to such functions as language, strength, sensation, coordination and vital functions such as breathing and consciousness. Clearly the risk of removing a tumor from these areas poses a greater risk to the function of the child.
In addition, remember that no matter where the tumor is located, a surgeon can never have the luxury of removing a large margin of surrounding brain to be certain that no tumor is left behind. To do so would certainly risk a major injury to the child. Despite the pessimistic sound of this discussion, there are many reasons to be optimistic. Several recent advances have greatly improved the pediatric neurosurgeon’s ability to remove almost all tumors. These include better imaging techniques, better anesthesia, better monitoring of many of the brain and spinal cord functions during surgery to avoid injuries, and lastly but not least better surgical equipment developed for specific needs and certain tumors.
Before finishing this discussion of tumors, it is important to clarify the way tumors can grow in and around the brain. Certain tumors are actually not in the brain but growing along side of the brain or its coverings. These are more often benign. Unfortunately, these type of tumors are more common in adults than in pediatrics. To use a food analogy, tumors in the brain are more like a pat of butter on toast. The same way that melted butter spreads into all the little nooks, brain tumors “infiltrate” into normal surrounding brain tissue. The only way to remove all of the butter would be to cut out some of the bread. Similarly, the only way to remove all of the viable tumor is to remove some normal tissue. The extent of infiltration and the location of the tumor would help determine the degree to which the tumor could be safely removed.
While there are those tumors that can be removed surgically for cure, there are others that can be cured with combinations of chemotherapy and or radiotherapy. After surgery and after the diagnosis is learned, the family will often meet with the surgeon and oncologist to determine if the child will require any further treatments. Often this discussion is done amongst the physicians and therapists at what is known as a “tumor board”. Here, the various options and their pros and cons are weighed in view of the child. The various treatments are very much determined by the child’s age and level of function as well as the nature of the tumor. As a general rule, radiotherapy has been the hallmark of adult brain tumor therapy. However, radiation treatments can have terrible effects to the growing immature brain. For this reason, often chemotherapy will be utilized as the initial treatment of choice for younger children. There have been many promising advances in chemotherapy for the treatment and cure of pediatric brain tumors.