WHAT IS A BRAIN TUMOUR?
Brain tumours can be broadly defined as any tumour or growth occurring in the brain tissue, its lining, the skull, or its associated glands (pituitary or pineal glands). Brain tumours may either be "primary" (arising from the brain, its lining, or the pituitary or pineal glands) or "secondary" (spreading to the brain or skull from somewhere else in the body). Primary tumours may either be benign (less aggressive, do not invade or destroy surrounding tissues) or malignant (aggressive, destructive, aka brain cancer). Almost all secondary tumours are malignant (having spread to the brain from cancers elsewhere in the body), and these are known as 'metastases' or 'cerebral or brain metastases'.
Surgical neuro-oncology at Precision Brain, Spine and Pain Centre
At Precision Brain, Spine and Pain Centre, our neurosurgeons provide expert care of patients with benign (non-cancerous) and malignant (cancerous) brain tumours. We use the most up-to-date brain scans and other imaging techniques in order to clearly define the location, extent and likely nature of the brain tumour.
Our expertise in functional brain mapping and stereotactic surgical techniques permits us to accurately localise the abnormality, either for the purpose of obtaining a biopsy or in order to excise the brain tumour using contemporary neurosurgical strategies.
The most common brain tumours that we treat are primary brain tumours (gliomas), metastases (tumours that have arisen elsewhere in the body and spread to the brain), and meningiomas (usually benign brain tumours arising from the lining of the brain). Some tumours are located in regions where they cannot be safely removed using traditional neurosurgical techniques. In many cases these may be responsive to stereotactic radiosurgery, which does not involve an operation. This is done using a stereotactic head frame, an advanced computerised planning station, and a radiosurgery delivery system (typically a linear accelerator or Gammaknife). The patient is hospitalised for several hours and in most cases only one treatment session is required. In order to understand the way that brain tumours affect individuals, the surgical approaches to treat these tumours, and the potential side-effects associated with such treatment, it is useful to have a basic understanding about the structure and function of the human brain. This is summarised in the following section.
How is the brain organised?
The brain is composed of two cerebral hemispheres (the largest structures), the cerebellum (at the back of the brain), and the brain stem. The pituitary gland, which releases important hormones into the bloodstream, sits at the base of the brain, just beneath the optic nerves which control vision. The brain is surrounded by a tough lining, the dura (or dura matter), and is protected by the skull bones.
The cerebral hemispheres are composed of four lobes (frontal, temporal, parietal and occipital)
The frontal lobes play a part in a variety of functions, including:
- Personality, social skills and behaviour
- Mood and emotions
- Judgment, reasoning, and decision-making
- Initiative and planning
The temporal lobes are important for:
- Speech and understanding
The parietal lobes are behind the frontal lobes, and play a role in:
- Sensation to touch, temperature and pain
- Integration of multiple types of sensory information
- Telling left from right
- Reading and writing
The occipital lobes sit at the back of the brain, and are the main area of the brain responsible for vision.
The cerebellum, below the occipital lobes, is an important structure for:
- Control of movements (co-ordination)
The brainstem is the structure which connects the brain to the spinal cord. It is critical for:
- Blood pressure
- Eye movements
The pituitary gland is connected to the brain, and releases hormones which are important for:
- Body weight
- Fluid balance
What are the most common types of brain tumours?
The most common types of brain tumours are listed below.
What are the most common symptoms of brain tumours?
Many brain tumours do not cause any symptoms until they are very large. Some, however, produce obvious problems at quite a small size. The most common symptoms are:
- Headaches. These are usually worse in the morning.
- Seizures or convulsions (epileptic fits). These may also result in weakness, numbness, loss of consciousness or temporary confusion.
- Nausea or vomiting -this is usually worse in the morning
- Memory loss. Trouble thinking and remembering and feeling confused
- Personality changes
- Emotional instability
- Speech problems –(difficulty talking or understanding speech)
- Weakness of an arm, leg or both
- Balance and coordination problems
- Vision problems
What signs will your neurosurgeon look for?
Depending on your symptoms, you will be examined for the following problems:
- Changes in the size and reaction of your pupils
- Memory and other problems of mental functioning
- Speech disturbance
- Weakness of the limbs and/or face
- Balance and co-ordination problems
- Evidence of hormonal insufficiency or excess
How are tumours investigated?
Before being referred to a neurosurgeon, most patients will have had a brain CT scan.
Your neurosurgeon may then order further investigations such as:
MRI Brain Scan
This gives much more detail than a CT scan, and is important for surgical planning. It may also detect smaller tumours that may be missed with CT.
Magnetic Resonance Spectroscopy (MRS)
MRS gives information about the likely chemical composition of the tumour, and therefore its probable diagnosis. In some facilities this can be done at the same time as the MRI.
Positron Emission Tomography (PET) and Single Photon Emission CT (SPECT) Scans
These give information about the blood flow and metabolic activity of a mass within the brain. They are useful in distinguishing between a recurrent tumour and the effects of radiotherapy, both of which may look identical on MRI.
Cerebral Angiography/CT Angiogram (CTA)/Magnetic Resonance Angiogram (MRA)
These may be helpful where a tumour looks very vascular, or where a diagnosis of a vascular malformation or aneurysm is being considered.
CT Chest, absomen and pelvis/nuclear medicine bone scans/breast ultrasound or mammogram
These scans help to pick up tumours elsewhere in the body. This process of "staging" is usually important in deciding the best way to manage brain metastases.
How is a definite diagnosis made?
A definite diagnosis is generally made with a biopsy of the tumour.
What is a biopsy?
A biopsy is a surgical procedure where a piece of the tumour is taken and sent to a pathologist who examines it under a microscope using special staining techniques.
Biopsies can be done either via a small hole in the skull (stereotactic biopsy), or via a window of bone which is removed and then replaced (open biopsy via craniotomy).
Whilst performing a biopsy does carry some risks (including bleeding, stroke, seizures and mortality), it is very important to know exactly what type of tumour is being dealt with. It is also critical to confirm that the lump or mass is, in fact, a tumour.
Often the tumour is removed at the time of biopsy (‘excisional biopsy’), but in cases where the diagnosis is unclear, a biopsy may be followed several days or weeks later by more definitive treatment.
What are the treatment options available?
A number of treatment options are available for brain tumours.
No active treatment
In some patients, particularly the very elderly, extremely unwell, or those with very advanced tumours, the most sensible option is to do nothing apart from giving steroid medications to reduce the swelling around the tumour or tumours. This is known as palliative care.
Surgery is the mainstay of therapy for most brain tumours. Generally the aim is to remove as much of the tumour as possible without disrupting surrounding brain regions. In some cases this is not possible, and a partial removal may be advocated. Surgery is often followed by radiotherapy.
Radiosurgery is an alternative to surgery for many small (<3-4cm) tumours. It uses focused X-ray beams to preferentially damage tumour cells, whilst leaving normal brain tissue relatively untouched. Your neurosurgeon should discuss this option with you and make the appropriate arrangements if warranted.
Radiotherapy is a well-established therapy for certain brain tumours. Some tumours, such as melanoma, do not respond well to this however. Radiotherapy may be given to the entire brain (whole brain radiotherapy), or may be given to a specific region of the brain. It is usually fractionated (given in multiple small doses over several weeks). Radiotherapy may be used alone or in combination with surgery or chemotherapy. One of the problems with radiotherapy to the entire brain is the frequent development of dementia in long-term survivors.
A number of other techniques, some of which remain experimental, have been used to treat brain tumours. These include brachytherapy and photodynamic therapy.
Many tumours are responsive to specific drug cocktails. Patients with metastatic tumours and lymphoma are most commonly treated with chemotherapy.
The treatment of aggressive gliomas often includes an oral medication, Temazolamide, which has been shown to improve survival in these patients.
Gliadel wafers are occasionally implanted in the brain following surgery for malignant gliomas. These release a chemotherapeutic medication directly into the brain.
What's right for you?
You should discuss your particular situation with your neurosurgeon to determine which of these are appropriate in your case. Our neurosurgeons
are also happy to offer second opinions.