Infratentorial Tumors - Types and Treatment

Introduction

Infratentorial tumors are those brain tumors present in the inferior region of the brain. The cerebral hemispheres are the two divided halves of the brain. Each hemisphere is divided into four lobes: the frontal lobe, the parietal lobe, the occipital lobe, and the temporal lobe. The brain is the organ that controls memory, thoughts, touch, vision, and all the regulatory functions of the human body. Brain tumors that are located in the lobes are called supratentorial tumors, and tumors located in the cerebellum or brainstem are called infratentorial tumors. Regardless of their location, brain tumors cause seizures, headaches, and problems with multitasking. Infratentorial tumors are discussed in this article.

What Are Infratentorial Tumors?

Tumors that originate in the brain are Intracranial tumors. Such tumors originating in the region inferior to tentorium cerebelli (containing the fourth ventricle, cerebellum, brain stem, and related structures) are termed infratentorial tumors. Primary tumors arising from this region commonly occur in children and show the following symptoms.

• Cranial nerve diseases.

• Vomiting.

• Headache.

• Hydrocephalus (fluid accumulation in the brain)

• Neurologic dysfunction (disorders affecting the brain and nerves).

What Are the Types of Infratentorial Tumors?

Following are the types of infratentorial tumors, of which the most important ones are explained in this article.

1. Teratoma.

2. Medulloblastoma.

3. Glioblastoma.

4. Astrocytoma.

5. Ependymoma.

6. Craniopharyngioma.

7. Choroid plexus papilloma.

What Is Medulloblastoma?

It is known as an embryonal tumor as it is formed from the remaining fetal cells after birth. It originates in the inferior (lower) part of the brain called the cerebellum.

• Causes of Medulloblastoma:
  • A change in the genes mainly causes medulloblastoma. Though not all the cases of medulloblastoma reveal the cause, most of them were caused by mutations in the genes leading to abnormal growth of cancer cells.
• Location of Medulloblastoma:
  • Medulloblastoma is mainly located in the brain's bottom part which is located behind the skull.
• Symptoms of Medulloblastoma:
  • Nausea and vomiting.
  • Headaches.
  • Double or blurred vision.
  • Extreme sleeplessness.
  • Seizures.
  • Confusion.

Medulloblastoma that is spread to the spine shows the following symptoms.

• • Change in the function of regular bowel and bladder movements.
  • Weakness in the arms.

Diagnosis of Medulloblastoma:

Medulloblastoma can occur both in children and adults. Mostly it is seen occurring in children. Diagnosis can be made using imaging techniques.

Treatment of Medulloblastoma:

The available treatment options are listed below.

• Surgery.

• Radiotherapy.

• Chemotherapy.

Surgery is the first line of treatment. Surgery helps in determining the type and characteristics of the tumor as well as removing the tumor without any harm to the patient.

Further treatments which can be added include chemotherapy and radiation. Usually, radiation is advised after the surgery has been performed. Proton beam radiation therapy is recommended to combat the problems with bone marrow and adjacent organs that can occur due to radiation exposure. Depending on the amount of tumor spread and the subtype of the tumor, chemotherapy is also advised. Clinical trials can also be a part of treatment option which includes, targeted therapy, chemotherapy, or immunotherapy drugs. A neuro-oncologist consultation is necessary to choose the best alternative treatment which is based on the patient's clinical condition, age, tumor remaining after surgery, and also the location of the tumor.

What Is Ependymoma?

One of the primary central nervous tumors (CNS) is ependymoma, which means that the tumor originates in the spinal cord or brain. A neuropathologist examines the tissue of the tumor removed during the surgery to accurately diagnose and review the tissue.

Causes of Ependymoma:

Cancer is mostly a genetic disease. Cancer is caused due to changes to genes (mutations) that control the functioning of cells. In most cancers, genes may be mutated (changed), which increases the spread and growth of cancer cells. The exact cause of ependymomas is not yet known.

Symptoms of Ependymoma:

Patients with ependymoma in the brain may have the following:

• Nausea and vomiting.

• Headaches.

• Dizziness.

Patients with ependymoma in the spine have the following symptoms:

• Back pain.

• Weakness and numbness in their legs, arms, or trunk.

• Problems with bowel and bladder movements.

• Sexual problems.

Diagnosis of Ependymoma:

Imaging techniques to visually view the tumor such as MRI(magnetic resonance imaging) scan is done. On the MRI, the tumor appears as a mass that is brighter with contrast and well-defined in its boundaries.

Treatment of Ependymoma:

Surgery is the first and best treatment approach in treating ependymoma. Surgical treatment removes as much tissue from the tumor as possible to prevent its effects from worsening.

No standard treatment for ependymoma has been implemented other than surgery. In most cases, no adjunct treatments are required after surgery. In a few cases, people require chemotherapy, radiotherapy, and immunotherapy drugs to add to a positive outcome of the surgical treatment. Based on the tumor type, patient's age, tumor size, and location, the best treatment approach is chosen to improve the condition after surgery.

Complications of Ependymoma:

Complications of long-term survivors of brain tumors present with a vast range of complications, such as the following listed below.

• Cognitive limitations.

• Neurological deficits.

• Endocrine abnormalities.

• Secondary malignancies.

• Growth abnormalities.

Long-term complications include numbness and tingling, fatigue, disturbed sleep, and pain.

What Is Pilocystic Astrocytoma?

Pilocytic astrocytoma is a type of brain tumor that occurs most commonly in childhood and is mostly present in the posterior fossa. Resection of the tumor completely usually treats the patient; however, potentially life-threatening complications can be seen associated with pilocytic astrocytomas, such as hydrocephalus and compression of the brain stem. Hence, early diagnosis and proper treatment approaches are used to cure the tumor.

Causes of Pilocytic Astrocytoma:

Mostly genetic mutations in BRAF oncogene and neurofibromatosis type 1 can cause pilocytic astrocytoma in most cases.

Management of the Pilocytic Astrocytoma:

• Surgical excision is the mainstay of treatment where the entire margins are resected keeping in mind to minimize the neurological injury. Complete resection is curative for the disease. However, as the cranial nerves and brainstem are present, it may hinder the complete tumor removal. Removal of the tumor, excluding the cyst wall, can also be recommended. If the tumor has a thick cyst wall, it is considered along with the nodule and should be removed.

• Radiotherapy is not essential. However, follow-up with consecutive imaging is appropriate. If recurrence is noticed, further resection of the tumor surgically is recommended.

• The presence of surgically unresectable tumors or the presence of malignant histology concluded the need for radiotherapy.

• SRS(stereotactic radiosurgery) is proven best for treating reoccurring tumors.

• Complications of Pilocytic Astrocytoma

Complications of pilocytic astrocytoma include

• • Hydrocephalus (managed by shunt).
  • Malignant degenerative changes.

Conclusion

Diagnosis of the infratentorial tumors forms the basis of the treatment result. Early diagnosis can make the prognosis better. Extension of life for at least a year or two is also a positive outcome in infratentorial tumors. An experienced neurooncologist has to be consulted throughout the treatment procedure. The infratentorial tumors which appear in children should be considered an emergency and diagnosed properly by the physician, and necessary treatment should be followed.