Brain Tumor

Brain Tumor



Definition of Brain Tumor

Brain Tumors are defined as abnormal growth of cells inside the cranium, an Intracranial Neoplasm. These tumors are formed due to uncontrolled and abnormal division of cells in different parts of the brain involving different cells.

In the Brain itself, cells that are involved are usually

  • Neuronal cells.

  • Meningeal cells.

  • Glial cells.

Glial cells are actually the non neuronal cells of the brain with supporting functions like scaffoldings. These cells include:

  • Oligodendrocytes: Its tumor is called Oligodendroglia.

  • Astrocytes. The tumor of these cells is known as Astrocytoma. A stage 4 astrocytoma is known as Glioblastoma Multiforme, a highly invasive and fatal cancer having a higher metastatic property. It can spread via corpus callosum to the both of the hemispheres of the brain. That’s why it is sometimes known as Butterfly Glioma.

  • Schwann cells: These cells form myelin sheath in the peripheral nervous system. Tumor of these cells is called Schwannoma.

  • Ependymal cells: These cells surround the capillary tufts present in the ventricles of the brain and are associated with the production of cerebrospinal fluid inside the ventricles. The tumor of these cells is called Ependymoma.

Eyes are considered as the projections of human brain. Actually its retinal part is the derivative of the Diencephalon, one of the precursor parts of the brain. So, the tumor of retinal cells, called retinoblastoma, is normally included in the brain tumors. Brain meanings are formed of meningeal cells that may sometimes undergo malignant transformation leading to the formation of a tumor called Meningioma. Moreover, the pituitary gland present inside the brain may develop pituitary adenomas with of different cells present inside the pituitary presenting the different symptoms.

Cancers of other organs can also spread brain tumors. Such tumors are called Metastatic Tumors.

Brain tumor of any sort is serious and life threatening. The reason for it is that they perform invasive and infiltrative character in limited space of intracranial cavity.

Brain tumors can be of following two types.

  • Malignant

  • Benign

These two types are entirely different from other cancerous or noncancerous neoplasms of body. Malignancy of tumor depends upon type, size, location and state of development of tumor.

Detection of brain tumor is carried out by diagnostic tools, which are directed into the intracranial cavity. This detection is carried out when tumor causes unexplained symptoms. Primary location of brain tumors in children and adults are respectively given below.

  • Children: In Posterior Cranial Fossa.

  • Adults: Two thirds of Cerebral Hemispheres

Cause of Brain Tumor

Different kinds of chemicals, heavy elements and exposure to ionizing radiations are the causes of cancers. Vinyl chloride and Asbestos are the common environmental factors that cause brain tumors. Other causes for brain tumors are as follows.

  • Mutations of Tumor Suppressor Genes

  • Inherited diseases that include Von Hippel-Lindau syndrome, multiple Endocrine Neoplasia and Neurofibromatosis type 2

  • Exposure to chemicals

  • Hormones abnormalities.

  • Occupational Factors.

However, mobile phone radiations are classified by WHO on IRAC scale in Group 2B that refers it possibly carcinogenic ability.

Signs and Symptoms of Brain Tumor

Signs and symptoms of brain tumors depend upon two factors i.e.

  • Tumor size

  • Tumor location

Brain tumors in different parts of the brain cause different neurological symptoms. Brain tumors mostly cause behavioral changes in the affected people. So, when the symptoms of patients suffering with brain tumors become apparent to people around them that is the first step in diagnosis of the tumor and its treatment. Symptoms of Primary and Secondary brain tumors are alike that are divided into three main groups as follows.

  • Intracranial Hypertension:

Symptoms occurring first are due to increased intracranial pressure. Tumors that have Edema (perifocal swelling) lead to increased intracranial hypertension. The common signs and symptoms of this condition are as follows.

  • Headaches

  • Vomiting associated with Nausea

  • Altered state of Consciousness that include Coma or Somnolence

  • Papilledema

Small tumors obstruct the passage of Cerebrospinal Fluid causing signs of intracranial hypertension. Intracranial hypertension also causes Herniation (displacement) in the following parts of brain that causes fatal brainstem compression.

  • Cerebral Tonsils

  • Temporal Uncus

Intracranial hypertension leads to the increase in the size of the skull.

  • Dysfunction:

Tumor location and the damage it causes to surrounding brain structures following types of Focal Neurologic symptoms can occur in patient.

  • Cognitive and Behavioral impairment that includes impair judgment, memory loss, lack of recognition and spatial orientation disorders.

    • Personality and emotional changes

    • Hemiparesis

    • Hypoesthesia

    • Visual field Impairment

    • Facial Paralysis

    • Double vision

    • Dizziness

 

  • Irritation:

Irritation includes the following.

  • Abnormal pain

  • Weariness

  • Tremors

  • Epileptic seizures

Primary brain tumors don’t show any apparent symptoms for years. Many uncertain symptoms like headaches, weariness and vomiting can be mistaken for Gastritis. Pain is felt usually on outside of skull not in brain. Brain outer surface has no nerves to transmit pain signals to brain’s pain center. That is why secondary symptoms explained earlier should alert patient for diagnosis.

 

Risk Factors for Brain Tumor

Possible risk factors for development of a Brain Tumor in a person are as follows.

  •   Age:

Chances of brain tumors are more in children than adults; however person of any age can be at risk.

  • Gender:

Generally men are more at risk factor for developing brain tumors than women. Peculiar brain tumor common in women is Meningioma.

 

  • Home and work exposures:

There is risk factor for developing brain tumor upon exposure with everyday home products although there is no possible link for this evidence. These home and office exposures are as follows.

  • Pesticides

  • Oil products

  • Rubber

  • Vinyl Chloride

 

  • Family history:

5% of brain tumors are associated with the following genetic factors.

  • Li-Fraumeni syndrome

  • Neurofibromatosis

  • Nevoid Basal Cell Carcinoma syndrome

  • Turcot syndrome

  • Von Hippel-Lindau disease

 

  • Previous Cancers:

Brain tumor risk is increased if as a child person suffered from cancer. People who had suffered from Leukemia or Non Hodgkin Lymphoma also are at risk for developing brain tumors.

  • Exposure to infections, allergies and viruses:-

  • People exposed to following virus are at risk for developing brain tumors.

  • Epstein-Barr virus (EBV) increases risk of Central Nervous System Lymphoma. This virus also causes Mononucleosis.

  • Cytomegalovirus (CMV) is found in brain tumor tissues.

 

  • Electromagnetic fields:

Electromagnetic fields which increase the risk for developing brain tumors are as follows.

  • Energy from power line

  • Cell phone use

 

  • Race and ethnicity:

White people are likely to develop Gliomas but less likely to develop Meningioma than black people. Europeans are twice likely to develop brain tumors than Asians.

 

  • Ionizing radiation:

Previous treatment of brain or head with ionizing radiation like X-rays can be a possible risk factor for developing brain tumors.

 

  • Head injury and seizures:

Serious head trauma is associated with Meningioma but not with Glioma. Seizures are associated with brain tumors. It is not known if seizures increase risk for brain tumors, if brain tumors cause seizure or if the anti medication for seizure increase the risk factor for developing brain tumor.

 

  • N-nitroso compounds:

Dietary N-nitroso compounds increase the risk factors for developing brain tumors in both children and adults. Dietary N-nitroso compound are formed with Nitrites in body. Nitrites are found in the following products.

  • Cured meat

  • Cigarette smoke

  • Cosmetics

 

  • Exposure to nerve agents:

Nerve agents used in wars increase the risk for brain tumor development in soldiers.

People suffering with allergies like Eczema, Asthma and Hay fever have low risk for developing brain tumors especially Gliomas. This is due to increased immune system activity.  

Diagnosis of Brain Tumor

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Complete medical history and physical examinations are carried out for diagnosing brain tumors. Most of the brain is separated by Blood-Brain-Barrier (BBB). Tracers can reach tumors if BBB is disrupted. In addition to physical test and medical history a series of tests are also performed for diagnosing brain tumors by detecting BBB disruption. These tests are as follows.

  • Angiogram is a procedure in which a dye is inserted into the blood vessels supplying the brain. This helps to detect specific tumors.

  • Bone scan is a test to detect tumors and bone abnormalities. The procedure involves injecting a dye that is absorbed by bone tissues. This helps in taking X-ray.

  • Computed Tomography Scan (CT scan) is a procedure for diagnosing through imaging. It involves a combination of X-rays and computer technology for producing Slices (horizontal and vertical cross sectional images) of body. This procedure is more detailed than X-rays as it detail image of any body part.

  • Functional Magnetic Resonance Imaging (FMRI) is a procedure for mapping functional area of patient’s brain. This test provides guidance and navigation precision during surgery. It maximizes tumor resection and minimizes weakness, blindness and speech loss.

  • Magnetic Resonance Imaging (MRI) is a diagnostic procedure which produces detail images of a body part through the combination of large magnets, radio frequencies and computer.

  • MR SPECT is the most effective method for detecting brain tumors which other tests might neglect. A non-invasive test providing results in real time while decreasing needs for Biopsies and surgeries.

  • Stereotactic Biopsy is a test for obtaining a specimen of tumor, which are then analyzed by neuropathologist. Main purpose of biopsy is confirmation for diagnosis. This minimal invasive approach is used to obtain diagnosis before Craniotomy or a large procedure. This test has three stages i.e.

    • Interpretative examination of fresh tissues

    • Microscopic examination of prepared tissues

    • After genetic analysis follow up examination of prepared tissues

Prevention from Brain Tumor

Until now there is no known way to prevent brain tumors. As more about their causes is known more will be the ways to prevent them.

Secondary brain tumors whose origin is in other organs can be prevented. For example avoiding tobacco products minimize Lung cancer risk which In turn decreases the chance for Lung Cancer Cells to ever appear in brain. For prevention against brain tumors a person should take some following steps.

  • Avoid smoking

  • Excess use of alcohol

  • Minimum consumption of processed meat

  • Use hands-free for listening calls on cell phones

There is still little knowledge on prevention against brain tumors. A healthy lifestyle is the best yet known prevention against brain tumors.   

Treatment of Brain Tumor

Treatment for brain tumors depend upon their size, location, type and as well as patient age and health. There are three main treatments for brain tumors.

  • Surgery

  • Radiation Therapy

  • Chemotherapy

Before the treatment to reduce swelling of brain tissues can commence, patient is given corticosteroid drugs. Combination of treatment like Surgery and Radiation Therapy is often used.

Surgery:

Most preferred course of action for treating brain tumors is their surgical removal. The surgery is known as Craniotomy. Meningiomas at the base of skull can be surgically removed by minimally invasive approach. Pituitary Adenomas can be surgically removed by minimal invasive approach through Nasal cavity and Skull base. This approach is called Tans Nasal, Trans Sphenoidal approach.  Craniotomy (opening of skull) is performed for removal of large Pituitary Adenomas. Person undergoing brain surgery can suffer Epileptic Seizures.

Radiation Therapy:

The procedure is to kill tumor cells without harming normal brain tissues. Depending on tumor, 10 to 30 treatments of radiations are used. This gives improved results and longer survival rates for patients. There are two types of radiation therapy i.e.

  • Radiosurgery; method to use computerized calculations for focusing radiations at site of tumor. It in course of action minimizes radiation dose to surrounding brain. It is primary treatment technique for many tumors.

  • Radiotherapy; it is used in place of, resection of brain tumor. Forms of Radiotherapy include following:

    • External Beam Radiation

    • Brachytherapy

    • Stereotactic Radiosurgery such as Gamma Knife and Cyberknife.

Radiotherapy is common for treatment of secondary Brain Tumors. For preventing the risk of future secondary brain tumors, Whole Brain Radiotherapy Treatment (WBRT) is performed.

Chemotherapy:

It is a treatment in which drugs are administered in patients for killing tumor cells. The treatment is generally performed for children instead of radiation to avoid negative effects on developing brain. The treatment is based on tumor’s type, extent of cancer and patient’s overall health. Radiation therapies and surgery is preferred because of the treatments following results.  

  • Toxicity

  • Side effects of drugs

  • Uncertain outcome

Other treatment of brain tumor is a Shunt. It is not a cure instead it only reduces hydrocephalus caused by blockage of Cerebrospinal Fluid. This results in reliving symptoms of brain tumors. Other treatments still under research are as follows.

  • Gene therapy

  • Focused radiation therapy

  • Immunotherapy

  • Novel Chemotherapies