A medulloblastoma is a (WHO grade IV ) malignant tumor which especially occurs in childhood. The tumor develops in the area of the back of the head from the cerebellum and grows into the surrounding tissue, such as in an adjacent ventricle, also known as the fourth ventricle .
Ventricles are cavities in the brain , which are filled with liquor. From there, the medulloblastoma can spread quickly in the surrounding healthy tissue, often in the so called brain stem.
Often the brainstem is affected by medulloblastoma. Metastases form primarily at the points that are in contact with the cerebrospinal fluid. In addition to the ventricles themselves this includes areas around the brain, the meninges and the spinal cord.
In childhood brain tumor medulloblastoma is often more common as compared to other cancers. Medulloblastoma is the most common malignant brain tumor in children . Medulloblastomas occur in most cases before the age of 15 and are most commonly found in children between five and seven years old. Boys are affected slightly more often by a medulloblastoma than girls. In adults, medulloblastoma contrast are rare : Only one out of 100 brain tumors in adults is a medulloblastoma.
Causes of Medulloblastoma
Medulloblastoma arises from immature cells embryonic that degenerate. These cells tend to grow rapidly. However, the exact causes are largely unknown.
In most cases Medulloblastoma arises spontaneously so there are no sufficient indications of a possible inheritance.
There are certain genetic changes known which are often accompanied by a medulloblastoma: So the tumor often occurs along with changes in certain chromosomes in affected cells. Perhaps it can causes disturbances in the development of the cells lead to degeneration. Why these genetic changes occur and why only some of those affected to this result in disease, is not yet known.
The risk of a brain tumor in children who have undergone radiation therapy as in case of leukemia is increased.
Symptoms of Medulloblastoma
A medulloblastoma leads to increased intracranial pressure, thereby uncharacteristic symptoms occur. This means that these complaints may also present in other diseases and often have a harmless cause. Thus in a case of medulloblastoma symptoms arise are:
- Vomiting , especially in the morning and on an empty stomach
In addition there are local symptoms, which indicate the location of the tumor. These include in infants , for example:
- Visual disturbances such as strabismus or diplopia , nystagmus
- Sensory disturbances (eg numbness or ” pins and needles “)
- Incoordination , difficulty in coordinating movements
- Gait disturbance
- Personality changes
Depending on the location and size of the tumor medulloblastoma leads to circulation and drainage disorders of the cerebrospinal fluid ( CSF ), whereby hydrocephalus (water) may occur.
From medulloblastoma cells are released that spread over the cerebrospinal fluid ( CSF ). In this way, the secondary tumors (metastases) arise in the meninges or spinal canal and cause more discomfort.
Diagnosis of Medulloblastoma
As with all brain tumor, in case of medulloblastoma in addition to the medical examination, the – imaging techniques are also important. In particular, the magnetic resonance imaging (MRI) is of great importance because with the help of MRI the doctor can see where the medulloblastoma is exactly, how big it is and how much it has spread.
In order to assess whether the medulloblastoma tumor cells are already spread in the cerebrospinal fluid (CSF) a MRI scan is also suitable. Medulloblastoma tends to metastasize in the spinal canal. For an accurate diagnosis, the physician must include this area in investigation.
If there is reasonable suspicion of a medulloblastoma, a tissue sample is surgically removed which is subjected to histological examination.As malignant cells can be located in the cerebrospinal fluid and even if there are no visible metastases in MRI doctor extract a sample of the cerebrospinal fluid and studied this in the laboratory for cancer cells.
Treatments of Medulloblastoma
The complete surgical removal of the tumor is the most important step in medulloblastoma therapy. Skull is surgically opened and diseased tissue are removed. If possible, this is carried out in micro- or laser surgical procedures in order to keep the physical discomfort to a minimum.
In addition, a treatment is carried out with radioactive irradiation, because the tumor cells are particularly sensitive to radiation.The radiation treatment is usually done after surgery. However, the side effects of radiotherapy (including developmental disorders) are found in infants therefore children younger than three to five years often alternatively receive chemotherapy . Here there are special medicines called Cytostatics is used. These are substances that block the growth of cancer cells. However, these drugs also attack healthy cells, so that side effects such as nausea , vomiting and hair loss may occur.
In some cases, initially tumor are not completely removed surgically. Doctor can use a radiation and chemotherapy to shrink the tumor and then in a second engagement completely remove the tumor.
Sometimes a medulloblastoma laid to the drainage of cerebrospinal fluid. To resolve this congestion, the surgeon places a tube system, which directs fluid to the outside a so called external drainage.
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