What is Surgical Neuro-Oncology?
Brain tumours are one of the most frequently managed conditions
by neurosurgeons. This subspecialty is known as surgical neuro-oncology.
Surgical Neuro-Oncology at Precision Neurosurgery
At Precision Neurosurgery we provide expert care of patients with
benign and malignant tumours of the brain.
The most up-to-date imaging techniques are utlilised in order
to clearly define the location and extent of the 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 tumour
using contemporary neurosurgical strategies.
The most common brain tumours treated are primary brain tumours
(gliomas), metastases (tumours that have arisen elsewhere in the
body and spread to the brain), and meningiomas (usually benign
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 amenable 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. 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 possess
some 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, and the brain stem. The pituitary
gland sits at the base of the brain. The brain is surrounded
by a tough lining, the dura (or dura matter), and is protected
by the skull bones.
Each part of the brain performs certain functions. Whilst we now
understand a great deal about the way the brain works, much remains
unknown.
The cerebral hemispheres are composed of four lobes (frontal,
temporal, parietal, and occipital).
The frontal lobes participate in a variety of functions, including:
Personality
Social skills and behaviour
Mood and emotions
Judgment, reasoning, and decision-making
Initiative
Planning
Memory
Movement
Smell
Speech
The temporal lobes are important for:
Speech and understanding
Memory
Hearing
Emotions
The parietal lobes are behind the frontal lobes, and function
in:
Sensation to touch, temperature and pain
Integration of multiple types of sensory information
Telling left from right
Calculation
Reading and writing
The occipital lobes sit at the back of the cerebral hemispheres,
and are the main area of the brain responsible for vision.
The cerebellum is an important structure for:
Balance
Speech
Control of movements (co-ordination)
Walking
The brainstem is the structure which connects the brain to the
spinal cord. It is critical for:
Breathing
Heartbeat
Blood pressure
Swallowing
Eye movements
Walking
The pituitary gland is connected to the brain, and releases hormones
which are important for:
Energy
Body weight
Growth
Fertility
Fluid balance
What are the most common types of brain tumours?
Brain tumours may 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 elsewhere).
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 metastases’.
The most common types of brain tumours are described below.
1. Metastases
These tumours grow in the brain after tumour cells spread there
from cancers in other parts of the body.
The most common types of cancer that spread to the brain are
lung, breast, bowel and kidney cancer, as well as melanoma.
These tumours usually occur in the brain tissue itself, but
may arise in the lining of the brain or the skull.
They may be treated with significant impact using a combination
of surgery or radiosurgery, radiotherapy, and frequently chemotherapy.
2. Gliomas
Gliomas arise from the supporting cells of the brain tissue.
Most are known as astrocytomas, but other types include oligodendroglioma
and ependymoma.
Astrocytomas are primary brain tumours arising from cells known
as astrocytes. They are classified into 4 grades:
Grade 1 is benign, and is also known as pilocytic astrocytoma.
Grade 2 (‘low-grade gliomas’), are not very
aggressive, however may become aggressive with time.
Grade 3 astrocytomas (‘anaplastic astrocytomas’)
are more aggressive than low-grade gliomas.
The most aggressive astrocytomas are Grade 4 (‘glioblastoma
multiforme’).
Astrocytomas may be treated with surgery, radiotherapy, and/or
chemotherapy.
3. Meningioma
Meniongiomas are tumours arising from the lining of the brain
(the meninges).
Most are benign and curable, causing symptoms by direct pressure
on the brain. A small proportion are aggressive, invading the
brain and other surrounding structures, and may not be curable.
Most meningiomas are treated with surgery, however some require
radiotherapy or radiosurgery.
4. Lymphoma
Primary central nervous system lymphomas arise from the white
blood cells, part of the body's immune system.
They are treated, after a biopsy has confirmed the diagnosis,
with chemotherapy and/or radiotherapy.
Like cerebral metastases, they are not curable, but modern
treatment can make a big difference to the length and quality
of life.
5. Acoustic Neuromas (‘Vestibular
Schwannomas’)
These are usually benign tumours arising from the cells lining
the hearing and balance nerves at the base of the brain.
They may cause dizziness, ringing in the ears (tinnitus), hearing
loss, as well as weakness of one side of the face.
Acoustic neuromas are treated with surgery or radiosurgery.
6. Pituitary Tumours
These tumours arise from the pituitary gland, an important gland
at the base of the brain, behind the bridge of the nose.
They may present with visual problems, hormonal disturbance
(weight loss or gain, hair loss or gain, lethargy, menstrual
irregularities, milk secretion from the breasts, poor libido,
infertility), or headaches.
They are usually benign, and many can be treated without surgery.
What are the 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 are common.
Confusion may occur.
Personality changes
Emotional instability
Speech problems. Difficulty talking or understanding speech
may occur.
Weakness of an arm, leg or both
Balance and coordination problems
Lethargy
Vision problems
What signs will your neurosurgeon look for?
You will be examined, depending upon your symptoms, for the following
problems:
Changes in the size and reaction of your pupils
Drowsiness
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?
A brain CT scan is the usual initial investigation that most patients
will have had before being referred to a neurosurgeon.
The following investigations may then be ordered:
1. MRI Brain
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.
2. Magnetic resonance spectroscopy
(MRS)
MRS gives information about the likely chemical composition of
the tumour, and therefore its probable diagnosis. It can be done
at the same time as the MRI in some institutions.
3. 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 frequently useful in differentiating
between a recurrent tumour and the effects of radiotherapy, both
of which may look identical on MRI.
4. 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.
5. CT Chest, Abdomen 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 frequently 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.
A biopsy is a surgical procedure where a piece of the tumour
is taken and sent to a neuropathologist 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.
1. 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.
2. Surgery
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.
3. Stereotactic Radiosurgery (‘Gamma
Knife Surgery’)
Radiosurgery is an alternative to surgery for small (<3cm)
tumours located in deep structures. 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.
4. Radiotherapy
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.
5. Chemotherapy
Many tumours are responsive to specific drug cocktails.
a) Patients with metastatic tumours and lymphoma are most commonly
treated with chemotherapy.
b) A relatively recent development in the treatment of aggressive
gliomas has been the introduction of an oral medication, Temazolamide,
which has been shown to improve survival in these patients.
c) Gliadel wafers are often implanted in the brain following
surgery for malignant gliomas. These release a chemotherapeutic
medication directly into the brain.
6. Other
A number of other techniques some of which remain experimental,
have been used to treat brain tumours. These include brachytherapy
and photodynamic therapy.
You should discuss your particular situation with your neurosurgeon
to determine which of these are appropriate in your case.
