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A craniopharyngioma is a tumor of the brain that commonly affects children. It grows in the area of the pituitary gland and the nerves that relay vision from the eyes to the brain (optic nerves), and frequently grows up into the base of the brain. The tumors arise from cells that in the developing embryo had helped to form the normal pituitary gland. For reasons that are not understood, these cells begin to grow on their own, producing masses that often contain both solid tissue and fluid. In children, portions of the tumor frequently have calcium deposits. The fluid ("cystic") portions of the tumors can reach very large size, and occasionally extend into both sides of the brain.
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These tumors cause symptoms in three major ways. Some children will initially have difficulties with hormonal functions since these tumors grow in or above the pituitary gland and because the pituitary gland regulates virtually all of the hormones in the body; including growth rate and the functions of the thyroid, adrenal, steroid, and sex glands. Perhaps the most common manifestation of this hormone effect is a fall-off in a normal growth rate due to a lack of growth hormone. A second form of clinical symptom is related to increased pressure within the brain. These tumors can grow up into the base of the brain, obstructing the chambers in the brain ("ventricles") through which the fluid in the brain ("CSF") circulates. This obstruction results in headache, nausea, and vomiting - all symptoms of the fluid and pressure building up inside the brain; a condition called hydrocephalus. A third, and unfortunately fairly common presentation of these tumors, is a loss of vision. Because children rarely complain about slowly developing health problems and because these tumors are located near the base of the brain where the optic nerves are located, it is possible for these tumors to put gradually increasing pressure on the optic nerves which leads to severe vision loss in one or both eyes in the peripheral or central part of the visual field. Many children will be initially diagnosed when they fail a vision test at school or when it is suddenly noted by their parents that their vision is dramatically reduced. In a personal series of patients treated at the Children's Hospital Boston over the past decade, the majority of children had diagnosed when they had symptoms because of pressure within the brain and blockage of CSF circulation. A slightly smaller percentage had visual deterioration and the smallest group had endocrine changes.
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When some children with large craniopharyngiomas are initially diagnosed, they may be quite ill with increased pressure in their brain and there really is not much time to do any special additional diagnostic testing. In this case, surgery must be carried out rapidly to reduce the brain pressure. If time is available, however, there are some tests that are helpful to the treating physicians. We believe it is worthwhile to get a standard CT scan of the brain to determine the extent of the calcium build-up within the tumor. Calcium deposits, which are not seen well on MRI, often denote areas of the tumor that may be difficult to remove and knowing location of these areas can help the surgeon plan the operation more effectively. We like to obtain endocrinologic and ophthalmologic evaluations before the surgery, since baseline evaluations of both of these areas of body function can help to predict post-operative problems and suggest management strategies to the neurosurgeon, anesthesiologist and endocrinologist caring for the child.
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There continues to be a great deal of discussion among pediatric neurosurgeons throughout the world regarding the appropriate treatment for these tumors. The two most commonly used treatment options include complete excision of the tumor surgically or partial removal followed by radiation therapy. There is no question that total removal of these tumors is perhaps the only way of guaranteeing their cure. Yet because of the nature of the tumors themselves, total removal may sometimes result in complications that affect the quality of life of the child following surgery. For example, the frequently intense scarring in the brain next to these tumors may make their removal difficult without injury to the adjacent brain. Because the brain centers near the tumor typically control not only hormonal function but also the control of appetite and emotions, any of these functions could be adversely affected if these centers are injured during an attempt at total removal of the tumor. In addition, these tumors are often quite adherent to arteries that supply blood to vital areas of the brain. If these arteries are injured during the removal of the tumor, the patient could suffer a stroke resulting in permanent paralysis or other severe neurologic deficit. The bleeding that occurs when large arteries at the base of the brain are torn may be very difficult to stop. Therefore, we believe that the surgeon must have as much information as is practicable to obtain regarding the tumor's boundaries and be able to use the utmost clinical judgment when removing the tumor in order to avoid or minimize these potential complications. Despite the most careful planning and intraoperative technical expertise, however, inadvertent injury to these vital structures can still occur.
Radiation therapy is an important part of treatment strategy in many institutions. Although these tumors are "benign," their growth can be frequently slowed or stopped by radiation therapy. Various types of radiation therapy can be employed to treat craniopharyngioma including the delivery of external beam radiation to the tumor volume or the instillation of isotopes such as radioactive phosphorus ("P32") or Yttrium directly within cystic portions of the tumor. When these treatments are employed, a skull opening must be made for either the placement of a semi-permanent tube into the cyst or to provide an avenue for the direct injection of the radioactive isotope into the cyst.
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Many children who come to the hospital with a craniopharyngioma are often very sick with pressure symptoms or visual deficits. The radiation therapy does not work quickly enough to reduce these symptoms and surgery is often required emergently to deal with the pressure of the tumor and cyst. Once radiation therapy is given, it unfortunately does not have a guaranteed cure rate and it is still possible for tumors to regrow even years after initial treatment. The radiation treatment in addition has the potential for significant long term side effects - including effects on the child's learning skills, hormonal status, and blood circulation to the brain - all because of the late damaging effects of radiation therapy to the brain of a developing child. There have been many recent advances in the technological delivery of radiation therapy, however, that may lessen the long-term likelihood of these complications. It is beyond the scope of this presentation to discuss radiation therapy and its complications in detail, but this is an issue that you should explore in detail with your child's physicians when treatment options are being reviewed. The patient's age, symptoms, preoperative hormonal status, and size and configuration of the tumor are among the many factors which need to be taken into consideration when tumor treatment is planned.
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Almost always, we attempt to remove as much of the tumor as is safely possible and, hopefully, cure the patient by removing all of it. We have been able to do this in about 65% of our operated patients. In the vast majority of children with craniopharyngiomas, the tumors grow from the pituitary stalk region; meaning that the removal of the tumor invariably results in a full and complete pituitary hormonal deficit. These children, therefore, require life-long replacement with hormones and must remain under the care of an endocrinologist throughout their growth and development. Even if surgery is completely successful in removing the tumor, there is still a possibility that the tumor could regrow from small fragments of the tumor inadvertently left behind at the operation. Some children will require reoperation to remove these recurrences.
Surgery does not sound very pleasant, but the effects of the tumor if left untreated will result in similar hormonal deficits eventually and in most cases the risks of surgery are well worth the benefits of reducing the intracranial pressure, preserving vision, and achieving a long term cure. If cysts formed by the tumor are extremely large and complex, we may drain them either as part of the initial operation or as a separate procedure using a tube directed through a hole in the skull into the cyst. Very rarely, we will utilize certain chemotherapeutic agents such as Bleomycin to slow or stop cyst growth by injecting them directly into the cyst themselves. There is relatively limited experience with this technique in North America, but there are several centers developing more experience with this technique and we have used it in a few patients in our own hospital with varying success.
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Our experience is that these children will need life-time follow-up. Although many hospitals and surgeons state their cure rate in terms of 5 or 10 year follow up, recurrences of this tumor can occur remote from surgery. In a personal series, there has been a recurrence rate of 16% even after total removal as judged by post-operative scans and the surgeon's judgment at the initial operation. For this reason, we will follow our patients yearly until ten years after surgery and then on an every two year basis indefinitely. The follow-up issues include not only the possibility of tumor regrowth, but also continued monitoring and treatment of side-effects related to radiotherapy and other adjuvant treatments. Most of our children with craniopharyngiomas are followed in the Pediatric Brain Tumor Clinic because in this clinic a continuing, ongoing relationship can be maintained with all of the specialists needed for long term follow-up including ophthalmologists, endocrinologists, neuropsychologists, neurologists, and neurosurgeons.
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For some patients, these highly focused, single-dose radiation techniques are a useful method to treat areas of tumor that cannot be successfully removed by any other means. Because these radiation modalities are intended to destroy all tissue that has been targeted, the technique is best used only for small tumor areas that are not touching structures whose function would be harmed by this type of radiation. For example, if the tumor is near or touching the brain stem or optic nerves, these treatments may not be safe. Prior radiotherapy also will affect radiation dose that can be used.
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If you have any questions, please contact us for more information.
R. Michael Scott, M.D.
Edward R. Smith, M.D.
Liliana C. Goumnerova, M.D.
Children's Hospital Boston
Department of Neurosurgery
300 Longwood Avenue
Boston, MA 02115
Phone:
617-355-6008
Email:
Michael Scott
Edward Smith
Liliana Goumnerova
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Craniopharyngioma
