Brain Tumour:

What is a brain tumour?

A brain tumour is a new growth that occur within the brain. It can arise from the brain itself, the membrane covering the brain (meninges), the cranial nerves, or even the skull bone. Brain tumours can generally be classified into Primary brain tumours and Secondary brain tumours.

Types of Brain tumours

1. Primary brain tumours - These are tumours that originate from cells (neurons or glial cells) in the brain and have not come from another organ in the body. These tumours can be either benign (slow-growing) or malignant (fast-growing), and do not spread to other parts of the body.

(a) Benign brain tumours
These are tumours that remain in the part of the brain in which they started and do not spread into and destroy other areas of the brain. Common tumours in adults are Meningioma, Pituitary tumour, Acoustic neuroma, Ependymoma.

(b) Malignant brain tumours
These tumours can grow rapidly, by spreading into the normal brain tissue which surrounds them and causes pressure and damage to the surrounding areas of the brain. Common tumours in adults are:
  • Astrocytic tumour (some are low-grade and considered benign, others are highly malignant - glioblastoma)
  • Oligodendroglial tumour. Less common tumours are
    • Pineal gland tumour (some are benign)
    • Lymphoma
    • Germ cell tumour
2. Secondary brain tumours - These are tumours in the brain that originate from cancer in another part of the body, for example the lung or breast. They are more common than primary brain tumours and usually consist of multiple lesions when discovered.

Symptoms

Symptoms depend on the size of the tumour, location, and whether it is causing brain swelling. Some tumors may not cause symptoms until they are very large. Other tumors cause very gradual onset of symptoms.

The most common symptoms are:
  • Headaches, nausea, vomiting (Symptoms of raised intracranial pressure)
    • Headaches caused by brain tumors may:
    • Be worse when the person is sleeping or wakes up in the morning
    • Get worse with coughing or exercise
  • Weakness of an arm or leg, double vision, hearing loss (Symptoms of neurologic deficit)
  • Seizures (Symptoms of brain irritation)
  • Changes in the person's mental function, (confusion, memory loss)
  • Clumsiness, poor coordination and loss of balance, swallowing problems
Other symptoms that may occur with a pituitary tumor:
  • Abnormal nipple discharge or menses
  • Enlarged hands, feet
  • Excessive body hair
  • Facial changes
  • Obesity, lack of energy
  • Sensitivity to heat or cold
Diagnosis

The following tests are usually performed:
  • CT scan
  • MRI scan - better images, compared to CT.
  • EEG (Electroencephalogram)


CT Scan showing a brain tumour (glioblastoma) in the left temporal lobe.



MRI scan showing a large parasagittal meningioma

Treatment

Surgery - The first step in treatment is usually Surgery. The goals of treatment are:
  • Obtain tissue for histological analysis to determine the type of tumour
  • Relieve the mass effect from the tumour by reducing tumour size or removing the tumour
  • Improve symptoms and brain function.


Pre-operative MRI scan showing large 3.5 cm pituitary tumour. Patient had headaches and loss of temporal visual fields.



Post-operative MRI scan showing significant reduction in tumour size. Patient recovered her visual fields and had no more headaches.

Early treatment often improves the chance of a good outcome. If treatment is delayed, irreversible brain or neurological damage may occur.

Tumors can be difficult to remove completely by surgery alone, because the tumor can invade surrounding brain tissue. In this situation, attempts to remove the tumour may cause harm, but some debulking surgery to reduce tumour size is necessary to help to relieve symptoms.

Case Example: Patient with giant astrocytoma of the left hemisphere, causing coma and paralysis of the right arm and leg.



CT scan showing massive hemispheric tumour, causing significant midline shift to the right.



Post-operative CT scan after surgical debulking, more than 90% of tumour removed.



Picture of Craniotomy surgery scalp wound, with no hair loss.

The conscious state of the patient improved, with increased strength of right arm and leg.

Stereotactic/Image-guided surgery

An image-guidance (stereotactic) system (IGS) is sometimes used to assist the surgeon. It acts like a GPS system, so that the surgeon is able to plan the approach to the tumour and is always aware of where he is in the brain, with reference to pre-operative scans.

It ensures correct and accurate surgical approach; smaller, minimally-invasive incisions; complete surgical resections (no missed tumour).



Image-guidance system (IGS) set-up in Operating theatre.



IGS Computer monitor, showing location of surgical instruments in relation to pre-operative scans.



Detailed IGS computer monitor picture (real-time) showing surgical instrument within the tumour cyst cavity.

Intra-operative nerve stimulation and monitoring

When the tumour is close to a critical nerve (eg. facial nerve), a nerve stimulator is used during surgery to identify the nerve which may be encased by the tumour. In this way, it can be preserved.



MRI scan showing a cystic right acoustic neuroma tumour, which is very close to the facial nerve.



Picture showing electrodes in the muscles of the face, which may be paralyzed by damage to the facial nerve during surgery for acoustic neuroma.



Picture showing computer monitor which displays electrical activity in facial muscles when the facial nerve is stimulated.

Radiation therapy

When there is residual tumour after surgery, radiotherapy is used for certain tumors. This may be in various forms
  • Whole brain radiation
  • Stereotactic fractionated radiation
  • Stereotactic radiosurgery, either using gamma-knife or LINAC systems.
The decision on which form of radiation is appropriate depends on a number of factors, including:
  • Type of tumour (histology)
  • Size of tumour (gamma-knife may not be suitable for large tumours, more than 3 cm in diameter)
  • Number of tumours (metastatic tumours may be multiple)
  • Location of tumour (radiation may cause neurologic deficits)
Chemotherapy

This may be used with surgery or radiation treatment, depending on the tumour type (histology). Temozolamide has been shown to be effective in the treatment of malignant gliomas when given concomitantly with Radiation therapy.

Immunotherapy

In selected cases, antibodies to EGFR and VEGF receptors are a useful adjunct to radiation therapy and chemotherapy. They are administered to patients with malignant gliomas. These antibodies block the signals which "activate" tumour growth, thus reducing tumour progression.

Other medications used to treat brain tumors may include:
  • Corticosteroids, such as dexamethasone, to reduce brain swelling
  • Medicines such as mannitol to reduce brain swelling and pressure
  • Anticonvulsants, such as sodium valproate (Epilim) or Levetiracetam (Keppra), to reduce seizures
  • Pain medications
  • Antacids or histamine blockers to control stress ulcers

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