What is brain tumour?
A brain tumour, like a tumour anywhere else in the body, is a result of an abnormal proliferation of cells in the brain. A primary brain tumour is one where the tumour originates from the brain cells. Secondary brain tumours are cancers originating elsewhere in the body and spreading to the brain through the blood stream. It may be mentioned that some chronic infections like tuberculosis and fungal infections often produce a tumour like moss in the brain which may mimic a cancerous lesion. A brain tumour may directly destroy brain cells or it may cause brain dysfunction by various other means.
The skull is a hard bony structure and thus provides only limited space to the structures within. Since the brain does not have any space to expand, a space-occupying tumour may be especially dangerous. Brain tumours can cause indirect damage by compressing brain tissue, inflammation of the brain (cerebral oedema) and increasing the pressure within the brain (intracranial pressure) by interfering with the circulation of brain fluid (cerebrospinal fluid or CSF).
Though most tumours are classified as 'malignant' or 'benign', brain tumours are usually classified as "high grade" or rapidly growing and "low grade" or slow growing. This is because even non-cancerous brain tumours may be life threatening since they do not have space to grow and thus endanger other parts of the brain.
What are the various kinds of tumours?
Brain tumours are basically of two kinds – those that originate from the layers covering the brain (meninges) and those that originate from the brain cells. The former are called meningiomas. They are almost always non-cancerous and are easy to remove surgically. The tumours arising from the supportive tissues of the brain are called gliomas. They are more common in adults and are more dangerous, since they are usually malignant and can often not be completely removed.
The most commonly occurring tumours in adults are gliomas, while in children, tumours usually arise near the brain stem (medulloblastoma).
What are the causes?
The exact cause of tumours is not known. However, there is a higher risk of tumours in:
Children and elderly
People with certain rare congenital abnormalities like Li-Fraumeni syndrome, tuberous sclerosis etc.
People with disorders of the immune system or auto-immune disorders like AIDS
People who are exposed to X-rays of the head
People who work in certain industries like oil refining, drug and rubber manufacturing.
What are the symptoms of tumours?
Symptoms of brain tumours are usually non-specific in the beginning. They also depend on the size and location of the tumour in the brain. The symptoms of a brain tumour may be varied since they may affect different functioning capacities of the brain. For example, a tumour that causes swelling of the brain may exhibit different symptoms than that which compresses the tissues of the brain.
Some of the common symptoms indicating a tumour in the brain are:
Frequent headaches that vary in intensity and time of the day. These headaches are usually intense in the mornings and ease out during the day.
Nausea or vomiting
Epileptic seizures or convulsions
Visual disturbances due to compression of the optic nerve or oedema of the optic disc (papilloedema)
Changes in memory functions
Changes in speech
Drowsiness and bouts of incoherence
Partial or local paralysis. Neurological deficits like weakness or paralysis of some parts of the body, loss of sensation, unsteadiness of gait (ataxia), etc.
How is it diagnosed?
The doctor first conducts a thorough physical examination of the patient and takes his medical and family history. The physical examination includes a detailed neurological examination. The latter consists of examinations for alertness, muscle strength, coordination, reflexes and response to pain. Any swelling of the eyes and visual disturbances is also ascertained.
The doctor may ask for tests like CT or MRI scan to study the tissues of the brain. These procedures help to identify any changes in the brain tissues, and outline any abnormal growth. Other tests that may be requested by the doctor are EEG, angiogram and a skull X-ray.
When should the doctor be consulted urgently?
Persistent or increasing frequency of headache specially if it is associated with vomiting, blurring or double vision, weakness of any part of the body, epileptic fits, difficulty in speaking, instability of gait. Change of behaviour, memory impairment with or without the above symptoms should also prompt expert consultation.
What is the treatment?
Depending on the type of tumour, its location, and the extent of its spread, the treatment may be surgery, chemotherapy and/or radiation therapy. These procedures may be used exclusively or in combination. Before treatment begins, patients are usually given steroid treatment to reduce brain swelling. They may also be given medication to keep the seizures (epileptic fits) under control.
Surgery - The most common form of treatment of brain tumours is removal of the cancerous mass. The neurosurgeon makes a hole in the skull and reaches the site of the tumour through that. The procedure is called craniotomy. As far as possible, the entire tumour is removed. This is usually possible to achieve in case of benign tumours like meningiomas, neuro fibromas, etc. Gliomas on the other hand, cannot be excised completely as they do not have clearly defined limits. However, the doctor is careful not to damage any vital tissues of the brain, and thus in cases where the whole tumour cannot be removed, partial removal is done. This helps to relieve the pressure within the skull and leaves a smaller portion of the tumour to be treated through radiation and/or chemotherapy.
Chemotherapy – it is the destruction of cancerous cells with the help of powerful drugs. Drugs are usually given orally or as injections into the vein.
Radiation therapy – in this high power rays are used to kill cancerous cells and prevent them from proliferating. Radiotherapy is given for a short period of time followed by a break. The period of therapy depends on the age of the patient, the site of the tumour and its size. The radiation is given with pin point accuracy, so that the surrounding healthy brain tissue is protected.
What are the side effects of treatment?
Brain tumour treatment may leave many side effects which may become less with time. Since craniotomy is a major procedure, there may be side effects like coordination difficulties, problems in comprehension and memory and personality changes. This is caused due to some damage to normal tissues surrounding the tumour.
Post surgery complications include cerebral oedema and seizures. Other side effects depend upon the location and extent of the tumour. In case there is no neurological deficit before operation, post-operatively also there should be no defect. In a large majority of cases even pre-operative deficit improves. However if tumour removed is delayed or the deficit is already severe this may not recover fully.
Side effects of radiation and chemotherapy include nausea, vomiting, weight loss, loss of hair and allergic reactions of the skin. Children who have had radiation therapy for brain tumours may have learning difficulties and visual problems. There may also be growth deficiencies in some children due to hormonal imbalance.
Some anticancer drugs may cause infertility. Women on anticancer drugs may experience menopausal symptoms like hot flashes and vaginal dryness. Some drugs may also cause kidney damage. A common condition is the formation of blood clots, usually in the leg, after the drug treatment.
What are the long term effects?
Early treatment of the tumour is necessary for better chances of recovery. The prognosis is grim for patients in whom the tumour is not completely removed. Although the inevitable is delayed with medication, survival chances are very low. The average life expectancy is about 6 months in case of a malignant tumour. In cases of benign tumours, and those which are completely removed, the prognosis is good and the patient can gain full recovery. The side effects of treatment lessen with time and the patient can resume his normal routine. Physiotherapy and rehabilitative therapy may be given to minimise the residual effects. There are various support groups that are working in the area of rehabilitation of cancer patients and they may provide the much needed support.