neurosurg

Brain tumours

This document is a brief overview of a large subject and is not comprehensive. There is much left unsaid so you cannot apply the information directly to your own case without discussing it with your own doctors. The purpose of this document is to give a brief explanation of brain tumours to inform patients about some of the treatments used. There is no implication of an offer of treatment nor does the author take responsibility for the outcome in patients who interpret the contents in any particular way. If in doubt, discuss the matter with your own doctors who know your case.

What is a Brain Tumour?

A brain tumour is a kind of growth that occurs in the substance of the brain. The word tumour literally means lump (from Greek language). In many ways it is a meaningless term because there are many kinds of brain tumour. Tumours may be benign or malignant. Malignant tumours may be primary or secondary.

The word benign implies that the tumour has grown from relatively normal tissues and gradually enlarges causing pressure on adjacent structures such as brain tissue, nerves or blood vessels. They exert their effects by occupying space inside the skull and if very large may raise the pressure inside the skull, causing increasingly severe and frequent headaches often associated with vomiting and maybe weakness or numbness in the limbs on one side of the body. The important point with a benign tumour is that potentially at least, it can be removed. Obviously if it has wrapped itself around vital structures, it may not be completely removable.

A malignant tumour is one which grows into adjacent structures and is a form of cancer, however the term cancer of the brain should not be used as brain tumours do not behave like malignant tumours elsewhere, in that they have local effects in the brain and only very rarely spread elsewhere in the body.

The spectrum of activity in malignant brain tumours also varies enormously. Some may run a course of 20 or more years others may cause the patient to die within months. The future for an individual patient varies considerably therefore and a patient who is told they have a brain tumour may not necessarily die quickly as much depends on the type of tumour and the treatment offered.

Secondary tumours (spread to the brain from a cancer elsewhere in the body) are a different matter and most surgeons would not operate to remove them unless there was a reasonable likelihood that it is solitary, because it would achieve very little when the patient has many such tumours.

What symptoms do they cause?

Unlike a stroke which happens suddenly, a tumour exerts its effects gradually. The symptoms appear slowly and there are many clinical pictures depending on where the tumour is and what its nature is.

Epilepsy may be the first symptom in a proportion of patients. Usually this begins out of the blue and the type of epilepsy is focal or grand mal.

There may be headaches. The typical headache due to raised pressure in the head is worse in the morning, worse with bending forwards, straining and maybe coughing. All these symptoms just mean increased pressure in the head and that of course can be due to many things other than a brain tumour. Usually the headache becomes more severe and more frequent with the passage of time and that may be a clue to the possibility of the diagnosis.

There may be a gradual onset of numbness or weakness in an arm or leg or both as the tumour presses on the parts of the brain that control movement or sensation.

There may be personality change. For example a person who is normally easy going and happy becomes depressed and morose. There may be difficulties with remembering things or performing tasks that are usually easily carried out. A neat and tidy person may become unkempt or unwashed.

There may be visual difficulties because the tumour can cause such raised pressure in the head that this can affect the optic nerves that are important for vision. All this sounds very frightening to the average person who has any of the above symptoms but it is not the individual symptoms themselves that raise the suspicion of a tumour but the gradual progression or more than one of the above.

Diagnosis

The diagnosis depends on the story of the illness, examination of the patient and special investigations. Taking a history and examining the patient are beyond the scope of this information leaflet.

The common tests may include a skull x-ray, CT-scan or MRI scan.

On a skull x-ray there may be signs of raised pressure in the head or areas where the skull bone has worn away because of the pressure of the tumour. With the advent of modern scans however it is unlikely that diagnosis will depend upon a simple x-ray.

CT-scan is an investigation which uses x-ray density to build up a picture of the skull and brain using a computer to put the information together. It shows the bone and brain and the normal fluid spaces inside and you can tell if something is causing pressure or displacement of structures.

CT scan of brain

By injecting an iodine based substance into a vein in the arm, the tumour can be seen as the injected substance appears in the tumour itself. This lighting up of the tumour is called contrast enhancement.

A more state-of-the-art investigation is MRI. This test depends on using radio waves to affect a magnetic field in such a way that an image can be created which shows all the tissues which contain water and some other elements. As different tissues in the head contain different amounts of water, it demonstrates different tissues very well. Bone contains the least water and therefore is the least visible. Brain fluids (Cerebrospinal fluid) can be made to look very bright. A contrast enhanced picture can be made by using an injection of a substance called Gadolimium.

MRI scan of brain

Treatment

Much depends on the nature of the tumour. Once the tumour has been diagnosed on the scan, the surgeon will decide what the next step should be. Although one can hazard a pretty good guess about what kind of tumour it may be, the only way to be 100% sure is to take a small sample of the tumour to be examined by a neuropathologist (biopsy). In some cases a wait and watch policy can be adopted with further scans being carried out after an interval to see if the tumour changes in size, but this is unusual.

In most tumour patients a powerful steroid drug is given to relieve irritation in the surrounding brain. This can be very effective but the effects are temporary and side-effects to the treatment are common if the steroid is given long term.

The safest course is likely to be a biopsy which can be done in a number of ways:

1. Burr hole biopsy

A small hole is made in the skull bone and brain surface is exposed. A blunt needle-like probe can then be inserted and a piece of tumour removed for examination. This is quite a small procedure but does carry with it a small risk of bleeding inside the head which might even require surgery to sort out.

2. Craniotomy

This is an operation that requires a flap of skull bone being cut with a special kind of saw and a direct approach is made to see the tumour and take a piece of it. The pathologist who examines the specimen rings back to say what kind of tumour it is. The surgeon can then decide whether the tumour can be removed and whether it is in the patient’s best interests to do so.

After removing the tumour or obtaining a biopsy the final definitive report is obtained from the pathologist and prognosis can tentatively be given.

There are many ways that modern technological improvements may make the surgery easier or more accurate. A special frame can be put on the patients head before scanning and one can use markings on the frame to guide one when doing the operation (stereotactic surgery).

A similar technique can be used but without the frame using a special computer model that allows very accurate localisation of the tumour (computer navigation).

Additional Treatment

It is not possible to remove malignant tumours completely with surgery. The main reasons for operating are to make the diagnosis and to relieve high pressure in the head.

To treat any remaining tumour it would be necessary to give either radiothereapy (a kind of high powered x-ray beam) or chemotherapy (injection of tumour killing drugs).

Radiotherapy is used to make any remaining malignant tumour cells stop growing. Very rarely in specific kinds of tumour it may melt away but not in most cases. How long the radiotherapy will work for varies according to the type of tumour and also individual variations in the patient so when the patient asks “how long have I got?” the odds are that the doctor will be wrong whatever figure he selects. In either event the doctor’s job is to keep the patient in as good condition for as long as possible but if quality of life is becoming poor, many doctors at that stage may advise cessation of active treatment.

Another technique for giving radiotherapy is also available called ‘stereotactic radiosurgery’. This technique uses a stereotactic frame placed on the patient’s head and shines the radiotherapy beam through a special mask. The mask has small holes in so the beam is directed only to the area the beam is focused on. Usually 68 beams are used and this is carefully worked out to be finely focused on the tumour area, the rest of the brain only receiving a small dose of the beam. This is a kind of super concentrated radiotherapy which is safe and relatively non-traumatic but is most useful only in small tumours or possibly in secondary tumours spread to the brain (of small size).

Chemotherapy in brain tumours is rather disappointing. In a few cases it can be helpful but the scope is limited and it serves mainly as a short term treatment in the majority of brain tumours. Certain types of unusual tumours such as Lymphoma may respond well however. There is constant research going on to find chemotherapeutic agents that can get rid of tumours but so far none are shown to be very effective.

Outcome

What happens to the patient at the end of all this treatment and investigation? The truth in most cases of malignant tumour is that the illness will shorten the patient’s life. It would be inaccurate to say by how much life is shortened as it varies so much from patient to patient and from tumour to tumour. All surgeons with this condition will have the experience of a fiercely malignant tumour where the patient is alive ten or fifteen years after diagnosis and the converse is also true. The majority of patients with very malignant tumours however experience re-growth requiring further treatment within only a short time. The best hope for such patients is to rely on their surgeon to make the right decisions for their case weighing up quality of life and the possibility of multiple operations or other treatments as time goes by. The aim as mentioned above is to ensure that the patient has as long as possible and as good a quality of life as the disease allows.