Childhood Medulloblastoma - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Childhood medulloblastoma is the most prevalent malignant brain tumor in children. The risk categorization for these cancers is separated into standard and high-risk categories based on age at diagnosis, surgical resection extent, and metastatic characteristics. A multimodality treatment strategy involving surgery, chemoradiation, and adjuvant therapy is employed to treat this tumor.

What Is Childhood Medulloblastoma?

The most frequent type of malignant brain tumor in children is medulloblastoma, which forms mainly in the cerebellum. Children with medulloblastoma are often treated with craniotomy, tumor removal, radiation therapy, and chemotherapy. Treatment for children with hydrocephalus may also include ventriculostomy or shunt implantation.

How Is Childhood Medulloblastoma Categorized?

The World Health Organization grades tumors on a scale of one to four, with grade one being the least aggressive and grade four being the most aggressive. Grade four medulloblastomas are recognized for their rapid growth and ability to spread to other locations. According to the World Health Organization (WHO) 2007, histopathology is critical in categorizing the following tumor subtypes.

1. Traditional medulloblastoma.

2. Nodular desmoplastic medulloblastoma.

3. Medulloblastoma with nodules.

4. Medulloblastoma with giant cells.

5. Medulloblastoma anaplastic.

6. Melanocytic medulloblastoma.

7. Medullomyoblastoma.

Where Is the Occurrence of Childhood Medulloblastoma?

On computerized tomography or magnetic resonance imaging, medulloblastomas usually appear as solid, contrast-enhancing masses in the posterior fossa. The majority arise in the region of the vermis of the cerebellum and can occupy the fourth ventricle and compress the brainstem. Medulloblastomas tend to emerge from the cerebellar hemispheres in teenagers and young adults.

What Are the Signs and Symptoms of Childhood Medulloblastoma?

Children usually present with posterior fossa lesions and manifest cerebellar symptoms, including:

1. Truncal ataxia (difficulty walking).

2. Disturbances of gait.

3. Intracranial hypertension.

4. Obstruction of cerebrospinal fluid (hydrocephalus).

5. Lethargy.

6. Headaches.

7. Vomiting.

8. Diminished ability to control bowel and bladder function.

9. Back pain.

With the onset of clinical symptoms, neuroimaging should be obtained. The symptoms of pediatric medulloblastomas differ depending on the child's age. However, hydrocephalus affects the majority of children and newborns with medulloblastomas. The increasing tumor and hydrocephalus might increase intracranial pressure, resulting in characteristic symptoms such as severe headache, nausea and vomiting, and lethargy.

What Is the Cause of Childhood Medulloblastoma?

The etiology of medulloblastomas in children is unknown. The vast majority of medulloblastomas in children develop on their own and are more common in boys than girls. Certain genetic disorders, such as Gorlin, Turcot, and Li-Fraumeni syndromes, increase a child's likelihood of developing pediatric medulloblastomas.

A genetic defect on chromosome 17 is seen in about half of all children with medulloblastomas. In addition, some cancers also have mutations on chromosomes 1, 7, 8, 9, 10q, 11, and 16. The relationship between these genetic anomalies and the four subtypes is currently being researched.

How Is Childhood Medulloblastoma Diagnosed?

A physical examination is undertaken to discover a child's complaints, and a neurological exam is performed to detect further symptoms related to brain function. The sense of smell, motor function, swallowing, hearing, feeling, eye movements, balance, and coordination are all evaluated during this assessment. Imaging tests confirm the diagnosis if a brain tumor is suspected.

Magnetic Resonance Imaging (MRI) - It is the recommended imaging test because it visualizes the spinal cord, where juvenile medulloblastomas can metastasize. Children must be closely watched since the sedatives supplied may increase intracranial pressure.

Biopsy - Although imaging tests may imply a brain tumor, a biopsy during surgery is required to establish if the cancer is genuinely medulloblastoma.

Genetic Testing - It is performed on tumor tissue samples to determine if the tumor is in group three or four.

Lumbar Puncture - A lumbar puncture can assess whether the pediatric medulloblastoma has spread via the cerebrospinal fluid. This surgery, however, may be dangerous for youngsters with elevated pressure inside the skull. Therefore, lumbar puncture is typically avoided until the medulloblastoma has been removed and the pressure has returned to normal.

Bone Scan - A bone scan is frequently performed on children with bone discomfort and medulloblastomas to detect bone metastases.

What Is the Treatment for Childhood Medulloblastoma?

The current standard of care for children with medulloblastomas is to divide them into standard-risk and high-risk groups. They are classified as high risk if the child has:

1. Positive lumbar cerebrospinal fluid cytology.

2. More than 1.5 centimeters of residual illness.

3. Local or diffused metastases.

People with standard risk are treated with craniospinal irradiation followed by local boost and concurrent and adjuvant chemotherapy. People at high risk undergo equal treatment with larger doses of craniospinal irradiation. In addition, children under three commonly get postoperative high-dose chemotherapy with stem cell harvesting and autologous stem cell transplant to postpone the cognitive adverse effects of radiation.

Surgery - Surgical resection is a critical component of therapy. Depending on the location and size of the tumor, an external ventricular shunt or third ventriculostomy may be required as an emergency treatment before tumor resection to reduce intracranial pressure caused by fluid circulation obstruction at the foramina of Lukscha, foramina of Magendie, or the aqueduct of Sylvius. Due to scarring of the cerebrospinal fluid channels, around 20 to 30 % of patients require a permanent ventriculoperitoneal shunt.

The intimate proximity of medulloblastoma to the fourth ventricle and occasionally the brainstem increases the risk of morbidity. Yet, competent pediatric neurosurgeons are typically able to altogether remove the tumor without causing significant morbidity. The degree of surgical resection is best determined by a post-operative MRI (magnetic resonance imaging) scan (within 48 hours after surgery) determines the degree of surgical resection.

However, a small quantity of tumors visible to the operating surgeon's sight is below the resolution limitations of modern scanners. Therefore, it can be left behind, and a thorough conversation with the neurosurgeon and reading the operational report is vital in therapy.

What Are the Complications of Surgery in Childhood Medulloblastoma?

The complications of surgery are as follows:

1. Infections.

2. Fluid leak.

3. Pseudomeningocele (abnormal collection of cerebrospinal fluid).

4. Direct neurosurgical manipulation.

5. Posterior fossa mutism syndrome.

6. Significant cerebellar impairments.

7. Dysmetria (lack of coordination of movement).

8. Hypotonia (low level of muscle tone).

9. Paresis (numbness of muscles).

10. Mood depression.

Conclusion

The operative report's perspective is critical in treatment planning. For example, people with postoperative residual tumors reduced to less than or equal to 1.5 centimeters are eligible for a second surgery. In addition, the importance of genetic risk associated with partial resection competes with the risk of biological problems. Therefore, a near-total resection, if less hazardous, may be preferable to an entire gross resection.