Treatment and Prognosis
Children with brain tumors should be seen at a multi-disciplinary medical center, staffed with the following: pediatric neurosurgeon, pediatric neuro-oncologist, pediatric hem-onc, pediatric neuro-radiolgoist, and a pediatric neuropsychologist. All too often children with brain tumor are not treated at centers that have the experience to handle all aspects of the disease.
The treatment and prognosis depends on the type, grade, and location of the tumor. Type and location are explained above paragraphs. The grade of the tumor indicates the degree of malignancy: its tendency to spread, its growth rate, and its similarity to normal cells when viewed under a microscope. Tumors with distinct borders are considered "grade I", are sometimes referred to as benign or mildly malignant. These tumors either do not grow or grow very slowly. Infiltrating tumors are those that tend to grow into surrounding tissue. Of the infiltrating tumors, the terms low-grade, mid-grade, and high-grade are frequently used. A "high grade" tumor is considered highly malignant. However, the exact system used to grade tumors varies with each specific family of tumors.
Brain tumors are treated with surgery, radiation, and chemotherapy. Depending on the type of tumor and the promptness of diagnosis.
Surgery.
The purpose of surgery is to remove as much of the tumor as possible, to establish an exact diagnosis, to determine the extent of the tumor, and sometimes to provide access for other treatments, such as implants or radiation. As mentioned above, some tumors are inaccessible to the neurosurgeon.
Chemotherapy - and how it works?
Chemotherapy drugs act on DNA- the genetic material found within each cell. The drugs alter the ability of tumour cells to copy their DNA and reproduce.
All cells follow a regular pattern of growth called the cell cycle. The cycle consists of five successive steps, or phases. Each cell that completes the cycle reproduces itself as two new cells. The two cells produce four new cells, four cells produce eight cells , and so on.
In order for a cell to produce normal cells, it must complete specific jobs during each phase of the cell cycle. Each cell must make proteins and enzymes needed to fuel its reproductive process, then duplicate and separate its set of chromosomes. A cell that spends to much or too little time in a phase might not successfully complete the job of that phase. For example, a cell might produce too many proteins or not enough enzymes. The abnormal cell continues along the cell cycle. Each abnormal cell is capable of producing two new abnormal cells. Those two cells produce four abnormal cells, four produce eight, until there are enough abnormal cells to form a mass or lump-called a tumour. Chemotherapy is effective when it stops abnormal cells from going through the cell cycle.
Actively dividing cells are the most vulnerable to chemotherapy. Most tumour cells and some normal cells fall into that category. The effect of chemotherapy on normal cells causes unwanted side-effects. Chemotherapy is usually given in cycles, and the cycles are repeated over a specific period of time. The cycle schedule is designed to allow sufficient time for effected normal cells to recover between treatments.
Definition of Neutropenic- This is when there is a reduction in the number of Neutrophils. The most likely cause of this is the Chemotherapy treatment. A Neutrophil is an important type of white blood cell used for fighting infection. When a child has a reduction in the number of Neutrophils then they are Neutropenic.
Radiotherapy
Radiotherapy is the treatment of cancer and other diseases with high energy (ionizing) radiation. Ionizing radiation damages or destroys cells in the area being treated making it impossible for the cancer cells to continue to grow and multiply. Most radiotherapy is delivered from the outside of the body (external beam radiotherapy) usually in the form of high energy X-rays or sometimes as Gamma rays. For certain cancers a radioactive implant can be placed next to the tumour inside the body (internal radiotherapy). As radiotherapy can damage normal cells as well as cancer cells there can be potential side effects, these may depend on the radiotherapy dose, site's of treatment, age and other factors.
Gamma Knife Surgery
The Gamma-Knife is not a knife in the conventional sense, but uses a focused array of 201 intersecting beams of gamma radiation to treat lesions within the brain. The technique was invented by a Swedish neurosurgeon, Professor Lars Leksell and provides an alternative method of treatment for a number of conditions, for which open neurosurgery may be either not practicable or carry a high risk of complications.
Within the central body of the Gamma Knife there is an array of 201 separate cobalt sources and each of these produces a fine beam of gamma radiation. The sources are evenly distributed over the surface of the hemispherical source core so that each beam is directed at a common focal spot at the center. The resultant intensity of radiation at the focus is extremely high whilst the intensity only a short distance from the focus is very low . This enables a high dose of radiation to be delivered to the abnormal tissues whilst sparing the adjacent healthy brain tissue.
Stereotactic Radiosurgery
Radiosurgery is a surgical procedure in which narrow beams of radiation are targeted to a volume of tissue within the brain. This highly focused and destructive dose of radiation is given in a single session and avoids potentially harmful radiation to surrounding brain structures. Stereotaxis refers to an accurate targeting technique for intracranial structures (such as brain tumors) using an external reference frame fixed to the head. Modern imaging by CT and MR technology and computer advances has made stereotaxis a very potent aid in brain tumor diagnosis and treatment. Since 1968, non-invasive Gamma Knife radiosurgery for the treatment of brain tumors and vascular malformations has enjoyed incredible success. More than 65,000 patients have been safely treated with focused gamma rays worldwide.
Radiosurgery differs from conventional radiation therapy in several respects. With standard external beam radiation therapy techniques, tumors and much or all of the surrounding brain are treated to the same dose of radiation. The radiation dose is given in small increments over several weeks to allow normal brain tissue to recover from its effect, while tumor tissue is less likely to recover. Ultimately, the brain can absorb only a maximal dose of radiation, beyond which no further treatment is advisable. There is increasing evidence that over long periods of time, high doses of radiation are harmful to normally functioning brain. The technique of Gamma Knife radiosurgery, however, treats only the abnormal tissue. This treatment occurs in a single session, without significant radiation to adjacent brain. There is no evidence that radiosurgery has led to the development of other malignant tumors since the introduction of the GK more than 25 years ago.
Stereotactic techniques can also be used to accurately aim fractionated doses of gamma rays or x-rays to a target; administering the treatment in small doses over days to weeks. This technique is a compromise between radiosurgery and conventional radiotherapy and is termed stereotactic radiotherapy.
What Brain Disorders Can Gamma Knife Radiosurgery Treat ?
Modern brain imaging with CT and MR techniques and sophisticated computers allow GK radiosurgery for many tumors, vascular abnormalities, and pain problems which are now treated by open surgery. The results of treatment are very beneficial in most cases, optimistic in others, and under going continuing evaluation in all cases.
Stereo tactic Needle Aspiration
Stereo tactic needle biopsy: A biopsy in which the spot to be biopsies is located three-dimensionally, the information is entered into a computer, and the computer calculates the information and positions a needle to remove the biopsy sample.
Angiogram Or Arteriogram
After injection of a contrast material into a deep artery, x-rays follow the flow of the material through the blood vessels of the brain. This test usually requires prior sedation, as it can be uncomfortable. The angiogram shows the position of the blood vessels near the tumor and the extent of the tumor's blood supply. (vascularity)
MRI angiography will be available at many medical centers in the near future. This will, to a great extent, replace invasive arteriography.
Shunt
Some patients with Brain Tumors develop increased intracranial pressure (IICP). To relieve the pressure, a shunt procedure to drain excess or blocked fluid might be required.
A shunt is a narrow piece of flexible tubing (called a catheter) which is inserted into a ventricle in the brain. The other end of the tubing is threaded under the scalp toward the neck, then, still under the skin ,threaded to another body cavity where the fluid is drained and absorbed. The body cavities used for drainage are the right atrium of the heart and, more commonly, the abdominal cavity.
A system shunt includes:
a ventricular catheter, which can be detected by x-ray.
an optional reservoir, which allows access to the cerebrospinal fluid (CSF), and can be used to test the shunt device.
a longer catheter , leading to the drainage area.
a valve system, which permits CSF flow in a single direction only (away from the brain).
When compared to other Brain Tumor Surgery, the surgery to implant a shunt is relatively minor. A small burr hole is drill in the skull through which the catheter is threaded into a ventricle. The shunt valve is tested and then inserted under the scalp. A small incision is made in the abdomen or the chest, depending on which cavity is used for the drainage. The other end of the catheter is threaded under the skin to the cavity and then fastened.
Shunts might be temporary-left in place until the brain tumor is surgically removed : or they may be permanent. Shunts are often left in place even after successful surgery.
Following shunt insertion many patients, particularly children, show dramatic improvement within days. In others, symptoms might remain for a period of several weeks.
Shunts will require revision or replacement if they are blocked, disconnected, displaced, or if they become infected and do not respond to antibiotic treatment. The need for a shunt revision is not uncommon.