Medulloblastoma is a poorly differentiated malignant brain tumor that originates in the cerebellum or posterior fossa. It occurs most frequently in children. Patients with medulloblastoma most commonly have symptoms related to increased intracranial pressure.
The common symptoms of this disease include signs of enhanced pressure on the brain, like nausea, headache, drowsiness, vomiting, coordination problems, behavioral changes and changes in the appetite. Headache usually will be present in the morning and will improve as the day passes on. Headaches will become aggressive and persistent, if the tumor is not treated in time .
The laboratory evaluation of medulloblastoma is done by complete blood count, electrolytes presence, and renal and liver function tests. Viral titers and baseline thyroid function studies are also suggested. Computerized tomography scans have a 95 percent sensitivity for detecting a brain tumor. The anatomic origin and the extent of the tumor are better exposed by magnetic resonance imaging (MRI) technique with gadolinium for the spine and head. This technique can also be performed to detect any residual tumor after the surgery. Lumbar puncture, bone marrow aspiration and biopsy are necessary to identify the late stages of the disease. Tumor subtypes may be detected by histological findings .
Treatment for this disease involves surgical removal of the tumor followed by radiation and chemotherapy. The extent of response to the treatment by the patient depends on the age of the patient at the time of diagnosis, tumor size and extent, tumor mass that can be safely removed and the metastatic disease level . Postoperative magnetic resonance imaging is performed within 48 hours. This technique has to be repeated 2 weeks after surgery. It is advised to wait for 10 to 14 days after surgery to start with radiation therapy for sufficient wound healing. Clinicians perceive that they can depend on radiation more than chemotherapy in adults, although acute side effects are seen in adults than in children .
The prognosis of this disease reported by the ‘Central Brain Tumor Registry of the United States’ was that nearly 50 to 60 percent of the adults with medulloblastoma were found alive five years after the disease was diagnosed and 44 percent were found alive 10 years after diagnosis. These figures have no relation with the differences of outcomes between the low risk and high risk groups, differences in patient characteristics and their response to the treatment. Current treatment strategies can be adopted to save 70 to 80 percent of children from the risk of medulloblastoma and see them alive after 5 years from diagnosis. Children with high-risk of this disease can be given effective therapy and the disease can be controlled in 60 to 65 percent of the patients  .
The etiology of this disease is not yet identified. Medulloblastoma has however been associated with certain conditions like neurofibromatosis, Turcot syndrome, Gorlin syndrome (nevoid basal cell carcinoma syndrome) and blue rubber-bleb nevus syndrome .
Medulloblastoma accounts for 17.2 percent of brain tumors in children and 0.7 percent of all malignant tumors in adults. Incidence of this disease is approximately 2 cases per 100,000 people, and nearly 350 cases are reported in the United States every year. The incidence of this tumor decreases with increase in age and it peaks at the age of 3 to 5 years. It is estimated that 29 percent of cases occur in people aged 20+ and the tumor rarely occurs in people aged 50+. It is found that 80 percent are diagnosed in the first 15 years of life. The data from surveillance, epidemiology and end results program has revealed that children aged below 14 years in the United States have an incidence rate of 5.7 whites and 5 blacks in a million population .
The medulloblastoma is molecularly different from embryonic tumors. It originates from primitive cells of the cerebellum. There are genetic abnormalities observed in medulloblastoma, like loss of 17p and duplication of 17q. It is also thought that abnormality in p53 gene, which is a part of chromosome 17, might lead to the development of medulloblastoma, as p53 is a tumor suppressor. Some cases have shown a better outcome due to increased expression of neurotrophin-3 receptor. Increased expression of beta catenin gene was also associated with better survival. Similarly, increased expression of ERBB2, PDGFRA, MYCC, MYCN genes was found to be associated with poor survival and greater likelihood of metastasis.
Based on the histology, medulloblastoma may be classified in five different types, the desmoplastic nodular medulloblastoma, undifferentiated medulloblastoma, anaplastic medulloblastoma, medulloblastoma with glial differentiation and medulloblastoma with neuroblastic differentiation .
Medulloblastoma is a malignant brain tumor initiated in the granular cells of cerebellum of children and has a tendency to spread over the entire central nervous system. This disease is currently classified as a primitive neuroectodermal tumor (PNET). The actual cause of medulloblastoma is not known. Early stages of medulloblastoma show signs of nonspecific headache, slight imbalance, change in the personality and fatigue. Many studies were conducted to understand the biology of medulloblastoma. Genes and chromosomes were mutated to understand their role in the disease development. There are a few rare genetic syndromes, which are thought to be increasing the risk of tumor development. As the disease stage progresses, enhanced intracranial pressure leads to severe headache .