Human Nervous system - Brain-Tumour-Overview

A brain tumour is a mass of abnormal tissue growing in any part of the brain. For some unknown reason, some brain cells multiply in an uncontrolled manner and form these tumours. These tumours can arise from any part of the brain, spinal cord or the nerves. Broadly these tumours can be divided into benign and malignant tumours. Benign tumours grow slowly and never spread to other parts. But as they slowly increase in size they can cause pressure on the normal brain and interfere with mental and bodily functions. Some of the benign tumours known are: meningiomas, pituitary adenoma, craniopharyngioma, epidermoid cysts, neurocytoma, haemangioma, pilocytic astrocytoma, etc. Malignant tumours or cancers are aggressive tumours that grow fast and infiltrate the surrounding brain and sometimes spread to the other parts of the brain or spine. There are various types of malignant brain tumours like High Grade Astrocytoma/Glioma, ependymoma, PNET, medulloblastoma, lymphoma, Germ cell tumours. With aggressive and timely treatment some of these can be cured.

1. Limb weakness and any abnormal sensation in the limbs can be a symptom of a tumour in certain parts of the brain especially in and around the motor or sensory cortex. Generally the opposite side is affected i.e right-sided weakness by a tumour in the left motor cortex.

2. Unsteady walking or imbalance (ataxia) may occur if the tumour is in the cerebellum or some other parts of the brain.

3. Vision may become blurred or sometimes lost if the optic nerve is compressed or swollen (Papilloedema). Sometimes a squint or double vision (diplopia) may develop if the nerves moving the eyes are affected.

4. Recent or long term memory may become weak.

5. Speech: Ability to understand (sensory aphasia) or express (motor aphasia) may be affected by tumours in certain parts of the brain. Sometimes the person is able to understand but is not able to express properly and may not get the right words.

6. Hormonal Effects: Some tumours in and around the pituitary / hypothalamus region (sellar and suprasellar region) can cause either excess or deficiency of many hormones. This may affect the growth, fertility, libido, body weight, mental functions, etc.

7. Changed behaviour, lethargy, drowsiness, and loss of consciousness are some of the other symptoms of brain tumours.

Most of the symptoms described above are non-specific and can be caused by many other diseases. A detailed history and medical examination is first done by the doctor and if a brain tumour is suspected then further tests like CT or MRI scan, angiogram, CSF test, hormonal blood test or EEG may be done.

1. CT or MRI Scan produce special X-ray pictures that show the detailed structure of the brain and spine and pick up any abnormality. To get a clearer picture, Iodine or Gadolinium contrast dyes are given intravenously. Some people can develop an allergic reaction to the iodine contrast agent and you should always tell the doctor if you have any allergies. The more expensive non-ionic contrast agents reduce the risk of allergic reaction. There is a strong magnetic field during the MRI scan and you should inform the doctor if you have any Pacemaker or metallic clip or prostheses inside your body. For these scans which take about half an hour, the patient lies down on the couch of these CT or MRI machines. The couch moves the patient through the large aperture or tunnel of these machines. The whole procedure is painless but the noise created by the MRI machines can be disturbing for some patients. During the scan the patient should not move and for small children who may move a lot, sometimes a minor anaesthesia is given.

2. Angiogram is an X-ray taken after injecting an iodine dye through catheters placed into the arteries. This shows the details of the blood supply to the tumour. For vascular malformation like AVM it is essential to plan embolisation, surgery or stereotactic radiation.

3. Cerebro Spinal Fluid (CSF) Study is done after removing the CSF from the spine by a long needle (lumbar puncture). This is done in certain tumours which have a high chance of spreading to the spine or to rule out infections or bleeding.

4. Hormonal Blood Tests are done for tumours like pituitary adenoma, craniopharyngioma, optic chiasmal or hypothalamic glioma.

5. Electroencephalogram (EEG) is occasionally done to study the pattern of seizures.

Treatment depends upon the tumour type, patient!!!s age and general condition

1. Surgery

2. Radiation Therapy

3. Chemotherapy

Surgery Surgery is generally the initial and sometimes only treatment required. The aim is to remove as much of the tumour as is safely possible. Before the operation the neurosurgeon carefully studies the CT/MRI scans. The route and type of operation is then decided after discussing the risks and benefits of this operation with the patient. Hair is completely shaved before the operation. The operation is performed after giving anaesthesia to the patient. While it is desirable to remove the tumour completely, this is not always possible if the tumour is very deep-seated or is in a very critical area. Therefore a tumour may be either completely or partially removed or only a biopsy may be taken. High-powered operating microscopes make it easier to see and remove tumours while sparing the normal brain. The operation may take many hours. The patient usually wakes up as soon as the effect of the anaesthesia wears off, but is kept in the ICU for some time to allow close observation and care. The various Neurosurgical approaches are: Craniotomy  This is the commonest approach which allows maximum tumour removal. To reach the tumour, a window is created by cutting the skull bone and after the operation this bone is replaced.  Trans Sphenoidal approach is used for removing tumours in the pituitary region by going through the nose and opening a key hole in the sphenoid sinus / base skull.  Skull Base or Craniofacial approach is used for removing tumours in and around the base of the skull. Usually a team of neurosurgeons and ENT or Head & Neck surgeons perform this operation together.  Stereotactic Biopsy is done for deep-seated or critically situated tumours where open biopsy is thought to be more risky. A CT or MRI scan is done with the patient wearing a stereotactic head frame. Using computers for accurate localisation, a needle is inserted through a small opening in the skull bone to take small piece of tumour tissue (biopsy) for pathological examination.  VP or VA Shunt operation is done when the tumour is blocking the flow of the cerebrospinal fluid (CSF). A long tube is inserted under the skin to divert the CSF flow from the brain ventricles to the peritoneal or atrial cavity. Radiotherapy Radiation Therapy or Radiotherapy (RT) is the use of penetrating X-ray or Gamma ray beams produced by the Telecobalt or Linear Accelerator machines. Radiotherapy plays a very important role in all malignant tumours and even in some benign brain tumours. Following surgery, radiation therapy targets the remaining tumour cells to prevent or delay its recurrence. Depending upon the sensitivity of different tumour types to radiation and the biological dose of radiation used, these tumours are either completely eradicated (cured) or they shrink or stabilise thus relieving symptoms. The dose, duration and technique of radiotherapy depends upon the type, size, site of the tumour and the patient!!!s age and general condition. For most tumours, only the affected part of the brain with some margins is irradiated. However for some tumours like medulloblastoma, lymphoma and germ cell tumours that have a higher risk of spread to the spine, the entire brain and spine is irradiated. Treatment Planning using head masks of thermoplastic material (ORFIT), simulator machines and planning computers help in more accurate positioning of the radiation beam for adequate coverage of the tumour while minimising the dose to the normal brain. After studying the CT / MRI scans, surgical and pathology reports, the area to be treated is decided. The path of the radiation beam is then carefully marked on the Thermoplastic mask using the simulator machines. Stereotactic radiosurgery (SRS) and radiotherapy (SRT) are special techniques of radiotherapy which have the potential to reduce the dose of radiation to normal brain and critical structures as compared to conventional radiotherapy. These techniques require a lot of manpower and high technology and are indicated in special types of tumours or conditions. We are also conducting some trials in this regard. Chemotherapy Chemotherapy is the treatment of certain types of brain tumours with cytotoxic drugs. Chemotherapy is useful for a variety of brain tumours including lymphomas, medulloblastomas, germ cell tumours, PNET and some gliomas. Commonly used drugs used for brain tumours are CCNU, BCNU, vincristine, Cisplatin, Temozolomide etc. Generally these drugs are given in combination every 4 to 6 weeks to a maximum of 6 cycles. Sometimes, if one combination of drug regimen stops working for the tumour, another drug or a combination (2nd line) may be tried. Most of the chemotherapy treatment may be administered on an OPD basis although some may require admission. Blood tests for haemoglobin, white blood count and platelets and sometimes, liver and kidney function tests are done before each cycle of chemotherapy.

In children brain tumours are the second most common cancer or tumour after leukaemia. The common childhood brain tumours include medulloblastoma, gliomas, astrocytoma, ependymoma, PNET and germ cell tumours. In most children the cause of the brain tumour is not known but in some tumours like the Optic glioma it may be due to a hereditary disease called neurofibromatosis. The effect of the tumour and its treatment on the brain function, mental and physical growth is more pronounced in children with developing brain. There is, therefore, a need for timely diagnoses, treatment and rehabilitation of these children. Fortunately, a majority of childhood brain tumours are curable with modern treatment, and with the medical resources available, these children can be restored to near normalcy. This, however, needs a multidisciplinary approach, which is expensive and rarely available under one roof. Even after completion of the hospital treatment many children require intensive rehabilitation at their homes and sometimes at special institutions. The World Health Organization had dedicated the last decade to the brain. With remarkable strides in the management of brain tumour there is a need for a foundation to provide the highest level of care to such patients and perform research into various aspects of brain tumours. Brain tumours are the commonest solid tumours in children and in our country affect thousands of young adults each year. We plan to reach out to all patients suffering from brain tumour to help them and their families through this devastating period.