Cranial Anatomy - Brain Tumours

A tumour is an abnormal mass of tissue that grows on or inside the body. It is known as primary if located where its growth first started, or secondary if it began growing elsewhere in the body and metastasized, or spread, to its present location. Most primary brain tumours do not metastasize outside the brain. Inside the skull, tumours can grow almost anywhere: within brain tissue, from the meninges, or inside the ventricular system. They can be encapsulated (self-contained) or interwoven with blood vessels, nerves, or other brain structures from which they cannot be removed without devastating consequences. Metastatic tumours are usually well localised, may occur alone or in clusters, and may spread throughout much of the brain. A benign tumour usually is encapsulated, does not spread to other areas of the body, grows slowly, and often causes problems by compressing brain tissue. A malignant tumour grows uncontrollably, spreads throughout the brain, and destroys brain tissue.

What symptoms can it cause?

A brain tumour may at first cause the vague feeling of being "unwell." This may be followed by other, more specific symptoms: dull, persistent headache; nausea or vomiting; generalized weakness; vision problems. Because the left side of the brain governs the right side of the body, and vice versa, a tumour will cause specific weakness or loss of movement on the opposite side of the body. Some symptoms may be caused by the increased pressure inside the skull from brain swelling, which can temporarily be treated with a steroid medication. Because brain tissue is irritated by the tumour, the brain can temporarily "short-circuit" as its normal electrical activity is interrupted. These periods of uncontrolled brain activity can cause seizures, which may be generalised and cause contractions of all parts of the body, loss of consciousness or bladder and bowel function.The seizures may instead be of a focal nature, affecting only one arm, a leg, or part of the face. Seizures usually can be controlled with anticonvulsant medications.

How is it evaluated?

A detailed history-taking of the patient's symptoms and a physical examination are done first, followed by any of several tests, such as x-ray studies, Computerised Tomography (CT) scans, Magnetic Resonance Imaging (MRI), and angiograms. All findings are used to evaluate the patient's symptoms, determine the tumour's exact location, and provide the physician with a tentative diagnosis of the tumour type. During surgery, ultrasound imaging may be used to pinpoint the tumour's precise location and help the surgeon plan his approach for its removal. If an emergency craniotomy is required, an extensive workup may not be possible.