SKULL BASE SURGERY

A brain tumor is the formation of a mass or outgrowth of cells of the brain. These tumors are enclosed within the skull that increase the intracranial pressure and cause damage to the skull and brain cells.

Brain tumors may be classified into malignant (cancerous) and benign (non-cancerous) tumors. The type of tumor determines the severity, scope of treatment and cure of the tumor.

Depending on the origin of the tumor, it can be classified as primary and secondary tumors. Primary tumors originate from the brain tissues, while secondary tumors originate from other parts of the body and affect the brain cells. These secondary tumors are also known as metastatic brain tumors.

The severity of the brain tumors depends on the size and location of the tumors. However, the rate of multiplication of cancer cells increases the risk of the condition.

Types

The common types of brain tumors include:

• Choroid plexus carcinoma: It is WHO grade-III tumor that arises from the choroid plexus of the brain. The prognosis of this tumor is very poor compared to grade-I and II choroid plexus papilloma. These tumors are predominantly found in children below 5 years of age.
• Craniopharyngioma: It is a non-cancerous tumor that nests near the pituitary stalk. Adamantinomatous craniopharyngioma, a type of craniopharyngioma is majorly found in children, while papillary craniopharyngioma, a solid tumor is predominant in the adult population.
• Pituitary tumors:  These tumors arise from the pituitary gland. Pituitary adenomas, a subtype represent approximately 10% of the brain tumors. However, pituitary carcinoma is a rare type of brain tumor.
• Pineoblastoma: It is a WHO grade-IV tumor that is a highly aggressive type of tumor. These tumors are present in the pineal gland that resembles retinoblastoma and medulloblastoma. These are also known as small round blue cell tumors.
• Meningioma: These tumors arise on the surface of the brain and spinal lying beneath the skull. These are non-cancerous tumors and may be fatal in rare cases.

Symptoms

Brain tumors may produce mild to severe symptoms that affect the functions of the brain and other parts of the body. These symptoms vary depending on the size, shape and location of the tumors.

The common symptoms of brain tumors include:

• Newer forms of headache
• Increased severity of headaches
• Nausea and vomiting
• Visual defects or visual impairment
• Loss of sensation of the hands and feet
• Reduced movement of the hands and feet
• Difficulty in maintaining balance and coordination
• Speech impairment
• Confusion
• Changes in behavioral pattern
• Hearing impairment
• Seizures

Causes

The primary brain tumors originate from the brain or the tissues present in the brain, such as meninges, pituitary gland or cranial nerves.

The secondary tumors may originate from other parts of the body and spreads (metastasis) to the brain.  These tumors usually occur in people with a history of tumors. The causes of secondary tumors may include oral, breast, lung, colon and kidney cancer.

Risk factors

The risk of brain tumors increases with the following factors:

• Age: Brain tumors affect people of all age groups. Older people are at an increased risk of developing brain tumors. However, certain types of cancers such as choroid plexus carcinoma and craniopharyngioma are observed in children.
• Exposure to radiations: Frequent exposure to radiation such as diagnostic radiations and ionizing radiation increase the risk of developing brain tumors.
• Inherited gene: Individuals with a family history of brain tumor or a genetically inherited gene are at an increased risk of developing brain tumors.

Diagnosis

The diagnosis of brain tumors include:

• Neurological examination: Monitoring the movement, coordination, vision, speech and muscle reflexes provide scope for detection of the affected part of the brain.

• Brain scan: Image scans such as magnetic resonance imaging (MRI) scan and computed tomography (CT) scan helps in detection of tumors. In certain cases, radioactive dye is injected into the veins that impart color to the brain cells enabling visibility of the tumors.
• Biopsy test:  A thin needle is inserted into the skull for the collection of the tumor cell. This test helps in differentiating cancerous tumors from non-cancerous tumors.
• Blood test: Complete blood cell count (CBC) and other laboratory parameters are performed to determine any underlying cause of brain tumors.

Treatment

Depending on the type of brain tumor and severity of the condition, brain tumors can be treated either with chemotherapy, radiation therapy or surgery.

• Chemotherapy: These agents are used to prevent the growth and spread of tumor cells that are administered by the intravenous or oral route of drug administration. The duration and the dose of the drug depend on the type of tumor cells.
• Radiation therapy: High-intensity radiations are used to kill tumor cells. These radiations are used in combination with chemotherapy for better treatment and cure of brain tumors.
• Surgery: The size and location of the tumor determine the complexity of the surgery. The tumors that are accessible can be removed easily, while only a part of the tumor is removed, when tumors lie in deeper layers of the brain. Thus, reduces the risk of brain damage.