Generality
Medulloblastoma is a rare type of brain tumor that most likely originates from the undifferentiated cerebellum progenitor cells.
Belonging to the category of so-called primitive neuroectodermal tumors of the brain, it is a very rapid malignant neoplasm with a high infiltration power.
Figure: the human cerebellum.
It is more widespread in the young and affects the male sex preferably.It can involve different symptoms, depending on the size and position on the cerebellum of the tumor mass. Generally, sufferers experience headaches, vomiting, motor and coordination disorders, and vision problems.
Once the exact site of the medulloblastoma has been identified, therapy is started, which almost always consists of surgical removal of the tumor and post-surgical radiotherapy treatment.
Chemotherapy is reserved for special cases.
Brief reference to brain tumors
When we talk about brain tumors, or brain tumors or brain neoplasms, we refer to benign or malignant masses of tumor cells that affect the brain (ie an area between the telencephalon, diencephalon, cerebellum and brainstem) or the spinal cord . Together, encephalon and spinal cord form the central nervous system ( CNS ).
Fruit of genetic mutations, of which however the precise cause is not known very often, brain tumors can:
- originate directly from a cell of the central nervous system (in this case we also speak of primary brain tumors );
- derive from a malignant tumor present in other sites of the body, such as the breast (in this second case they are also called secondary brain tumors ).
Given the extreme complexity of the central nervous system and the large number of different cells that compose it, there are many different types of brain tumors: according to the latest estimates, between 120 and 130.
Regardless of their malignant power or not, brain tumors are almost always removed and / or treated with radiotherapy and / or chemotherapy, as they often cause neurological problems incompatible with a normal life.
What is medulloblastoma?
Medulloblastoma is a type of brain tumor that, according to the most recent research, would originate from the cerebellum progenitor cells; the cerebellum progenitor cells are equivalent to stem cells, therefore immature and not yet completely differentiated.
Of a highly malignant nature, medulloblastomas are the main representatives of the tumor category identified with the English acronym PNET, which in Italian means: Primitive Neuroectodermal Tumors of the Encephalon .
CEREBELLUM
The cerebellum is one of the four main structures of the brain, so it is part of the central nervous system.
Based in the postero-inferior part of the cranial cavity, it controls motor activity in all its aspects: voluntary movements, muscle tone, balance, reflex activities and visceral motility.
Moreover, it seems to be involved also in learning, language and attention skills.
Epidemiology
Medulloblastoma is a very rare brain tumor; in fact, with an annual incidence of 2 people per million inhabitants, it constitutes only 1% of all tumors of the central nervous system (NB: tumors of the central nervous system or primary brain tumors are synonymous).
Although it can also affect adults, it is a neoplasm typical of young people. Moreover, the statistics say that it is in second place in the ranking of the most common brain tumors of youth (18%) and in first place in the ranking of the most frequent malignant brain tumors that affect children.
In adults, the typical onset age is between 20 and 44; a medulloblastoma in an elderly individual is a real rarity.
With regard to juvenile juveniles and medulloblastomas, 70% of these malignancies are diagnosed in individuals under 10 years of age.
For a reason still unknown, males get sick more than females. In fact, in 62% of cases the person affected by the disease is male.
Causes
Like any malignant tumor, medulloblastoma is the result of a genetic DNA mutation able to initiate an abnormal cell division and growth process. What exactly causes this genetic mutation still remains a mystery.
RISK FACTORS
After analyzing numerous clinical cases, doctors and researchers have concluded that there are some situations - definable with the term risk factors - able to predispose to medulloblastoma.
In this case, these situations are:
- Suffering from Turcot syndrome or Gorlin syndrome . They are two congenital diseases (that is, present since birth), which determine, especially in the second case, a wide range of neoplasms.
- Being male . It has previously been seen that over half of all medulloblastoma cases are borne by male individuals.
- Be a Caucasian . Children of white skin get sick more frequently than their age of Afro-American origin.
Symptoms and Complications
One of the first effects of medulloblastoma is the increase in intracranial (or intracranial) pressure, an increase that can occur due to tumor edema and / or due to obstruction to the normal flow of cerebrospinal fluid .
The presence of high intracranial pressure causes various disorders, including:
- Headache
- Nausea and vomiting, especially in the morning
- Appetite alteration
- Listlessness
Especially at the beginning, this symptomatology often makes one think, in a completely wrong way, of migraine or some gastrointestinal problem.
As the disease progresses, the malignant neoplastic mass still increases in volume and other new symptoms and signs appear - in this case quite characteristic - as:
- Coordination deficit . The patient begins to assume strange gaits and to fall frequently.
- Vision problems, in particular diplopia, ie double vision.
- Papilledema, or edema of the optic papilla. The optic papilla, or optic disc, is the emergence of the optic nerve within the eyeball.
- Paralysis of the VI cranial nerve (or abducent nerve) and nystagmus . The VI cranial nerve is a motor nerve that regulates eye movement; nystagmus, on the other hand, is a condition characterized by the involuntary, rapid and repetitive movement of the eyes.
- Vertigo . These are due to an altered sense of balance.
- Loss of facial sensitivity .
- Changes in personality and behavior .
POSITION AND GREATNESS OF THE TUMOR
The intensity and complexity of the symptom picture can vary from patient to patient, depending on the position and size of the tumor mass.
For example, a medulloblastoma that occurs particularly close to the VI cranial nerve may result in visual disturbances more likely than a medulloblastoma not nearly as close to the same cranial nerve.
COMPLICATIONS
Being a strongly malignant tumor, medulloblastoma has a high infiltrative power. This means that, especially if it is not cured in time, it has a strong tendency to spread in the brain areas adjacent to the cerebellum and also in the spinal cord.
From the point of view of the metastasizing capacity, it rarely spreads its own neoplastic cells in other organs and tissues of the body (contrary to what one might think, given its malignancy).
WHEN TO REFER TO THE DOCTOR?
Medulloblastoma is a type of cancer that is first identified and the hopes for survival are greater .
Diagnosis
Faced with a suspected case of medulloblastoma, doctors begin their diagnostic investigations by careful physical examination and analysis of the quality of tendon reflexes .
Then they perform an ocular test and ask the patient some questions aimed at assessing mental status and cognitive abilities (reasoning, memory, etc.).
Finally, to dispel any doubts and to know the position and exact size of the tumor, they resort to specific tests such as:
- Nuclear magnetic resonance
- CT scan (or computerized axial tomography)
- Tumor biopsy
- Lumbar puncture
EXAMINATION OBJECTIVE AND TENDONS TRIMS, EYE TEST AND MENTAL-COGNITIVE EVALUATION
- The physical examination consists in the analysis of the symptoms and signs, reported or manifested by the patient. Although it does not provide any certain data, it can be very useful for understanding the type of pathology in place.
- The examination of tendon reflexes is a test that serves to assess the presence or absence of neuromuscular and coordinative disorders.
- Through an ocular test, the doctor observes the optic nerve and analyzes its involvement.
- The assessment of mental status and cognitive abilities is carried out with the intent to understand which area of the central nervous system may have developed a neoplasm. For example, finding memory disturbances would tend to suggest a neurological problem located in the temporal lobes, rather than in the parietal lobes and so on.
NUCLEAR MAGNETIC RESONANCE (RMN)
Nuclear magnetic resonance ( NMR ) is a painless diagnostic test that allows the visualization of the internal structures of the human body without the use of ionizing radiation (X-rays).
Its operating principle is quite complex and is based on the creation of magnetic fields, which emit signals capable of being transformed into images by a detector.
The magnetic resonance of the encephalon and the medulla provide a satisfactory view of these two compartments. However, in some cases, to improve the quality of the visualization, it could be necessary to inject a contrast liquid to venous level. In such situations, the test becomes minimally invasive, because the contrast liquid (or medium) could have side effects.
A classical nuclear magnetic resonance lasts about 30-40 minutes.
TAC
CT scan is a diagnostic procedure that uses ionizing radiation to create a highly detailed three-dimensional image of the internal organs of the body.
Although it is painless, it is considered invasive due to exposure to X-rays (NB: whose doses are by no means negligible compared to a normal radiograph). Furthermore, like MRI, it may require the use of a contrast agent - not without possible side effects - in order to improve the quality of the display.
A classic CT scan takes about 30-40 minutes.
BIOPSY
A tumor biopsy consists of the collection and histological analysis, in the laboratory, of a sample of cells from the neoplastic mass. It is the most suitable test if you want to go back to the exact nature (benign or malignant) and the severity of a tumor.
In the case of a medulloblastoma, sampling usually takes place during a CT scan - this allows for a highly precise collection - and requires a small but delicate head surgery.
What does the tumor look like?
At histological laboratory examination, a medulloblastoma has the appearance of a solid tumor, is gray-pink in color and has cells with little cytoplasm and a very high mitotic capacity (ie division).
LUMBAR PUNCTURE
The lumbar puncture consists in taking a sample of cerebrospinal fluid (or CSF) and in its analysis in the laboratory.
To remove the liquor, a needle is used that the doctor inserts between the lumbar vertebrae L3-L4 or L4-L5. At the insertion point, an injection of local anesthetic is obviously practiced.
The execution of the lumbar puncture is very important, since it allows to establish if the medulloblastoma has dispersed some its neoplastic cell in the liquor.
Treatment
The classic therapy of a medulloblastoma involves the surgical removal of the tumor mass, followed by radiotherapy sessions and sometimes even chemotherapy cycles.
SURGERY
The purpose of surgery is to remove all medulloblastoma or, if this is impossible, most of the tumor mass.
The quality of the removal depends on at least two factors:
- The accessible or non-accessible position of the tumor mass . A medulloblastoma located in a location difficult to reach by the surgeon can only be partially removed.
- The dispersion of the tumor mass in the remaining healthy brain mass . The more confused a tumor is in the surrounding brain tissue, the more difficult it is to remove it satisfactorily. Fortunately, medulloblastomas tend to form neoplastic masses of their own, so they lend themselves well to surgical practice.
After the operation, a complete rest phase and a physiotherapy rehabilitation phase are planned.
The first allows the patient to recover and find the energies subtracted from the operation; the second serves to recover at least in part the coordination of movements, muscular strength, the sense of balance, etc.
RADIOTHERAPY
Tumor radiotherapy is the treatment method based on the use of high-energy ionizing radiation, with the aim of destroying the neoplastic cells.
Performed after surgical removal of the medulloblastoma, it can be extended to the whole brain and to the spinal cord (if the treating physician believes that the tumor may have dispersed some of its cells in other areas of the central nervous system).
In the patient, radiotherapy involves:
- Extreme tiredness . The feeling of tiredness continues throughout the radiotherapy treatment and beyond.
- Itching and redness of the skin at the affected spot . These are two temporary side effects that resolve shortly after the treatment ends.
- Hair loss . For regrowth you have to wait 2-3 months.
CHEMOTHERAPY
Chemotherapy consists of the administration of drugs capable of killing all rapidly growing cells, including cancer ones.
In the case of medulloblastoma, doctors adopt it when they believe that the risk of a relapse (or relapse) is high or when they believe that the tumor has spread some of its cells in the rest of the body (metastasis).
In very small patients, it has been observed that the prolonged combination of radiotherapy-chemotherapy can delay the physical and cognitive development of the patient and predispose to a future second neoplasm.
For further information: Medications to cure Medulloblastoma »
Main side effects of chemotherapy
- Nausea
- He retched
- Hair loss
- Sense of fatigue
- Vulnerability to infections
OTHER CURES
If medulloblastoma causes edema around you, doctors may prescribe corticosteroid treatment before or after surgery and radiotherapy.
Corticosteroids are powerful anti-inflammatory drugs, which means that they reduce inflammation.
Prolonged use of corticosteroids can be highly damaging to the patient's health, as it can cause: indigestion, agitation, high blood pressure, diabetes, increased body weight, etc.
Prognosis
Thanks to today's treatment methods and an early diagnosis, medulloblastomas can be treated with moderate success.
A statistical study conducted in the United States has tried to calculate the survival rate of when medulloblastoma is diagnosed and treated in time and it turned out that 5 years after removal:
- The average survival (ie referred to patients of all age groups) was 62%.
- Survival, in the case of adults over the age of 20, was 57-60%.
- Survival, in the case of children aged 1 to 9, was 70-80%.
- Survival in the case of newborns was 30-50%.
LONG TERM EFFECTS OF THE THERAPY
Several research groups are trying to understand what effects radiation and / or chemotherapy can have on the hormonal activity of hypothalamus, pituitary gland and thyroid .
According to the studies carried out so far, a fair number of patients would exhibit hypothalamic, pituitary and thyroid dysfunctions, linked precisely to treatments for medulloblastoma.
