Brain tumours are tumours that grow in the brain. A tumour is an abnormal growth of tissue caused by cells reproducing themselves in an uncontrolled manner.
Tumours are usually classified as benign (meaning harmless) or
malignant (meaning cancerous).
These meanings change when referring to tumours in the brain. This is because a benign tumour in an eloquent (critical area) may also cause neurological deficits and death.
Malignant tumours of the brain do not usually metastasize to areas out side the brain (spread or seed) like malignant tumours elsewhere in the body.
Another important characteristic of tumours in the brain is that they tend to affect people from all age groups and malignant brain tumours do not necessarily affect the elderly.
Benign brain tumours:
A benign brain tumour consists of benign (harmless) cells and has distinct boundaries. Surgery alone may cure this type of tumour.
Malignant brain tumours:
A malignant brain tumour made up of cancerous cells in the brain or
spinal cord. It can invade and destroy normal tissue so it cannot function properly; thereby producing neurological deficits.
Malignant brain tumours seldom metastasize outside the brain and spinal cord. [Central Nervous System (CNS)]
Tumours in the CNS may occasionally not be detected for years as they are slow growing and produce few symptoms. The bones of the skull hide brain tumours and the doctor will need to use his clinical judgment and with the help of different imaging modalities arrive at a diagnosis of a brain tumour. Scans produce pictures that suggest a particular type of tumour. However, only a sample of tumour examined under a microscope can provide an exact diagnosis.
Often, the damage done by brain tumours is due to their size. Because the skull is bone, it cannot expand to make room for even a small mass growing within it. As a result, the tumour presses on and displaces normal brain tissue. This pressure may damage or destroy delicate brain tissue. Many of the symptoms of a brain tumour are caused by this pressure. Sometimes, a tumour may cause blockage of fluid that flows around and through the brain. This blockage can also create increased pressure. Some brain tumours also cause swelling due to accumulation of fluid (edema). Size, pressure, and swelling all
create this "mass effect" which not only produces clinical symptoms but also tells us the urgency in dealing with patients suffering from brain tumours. This “mass effect” is seen on various imaging modalities that help clinicians to decide on the treatment of these tumours.
Brain Tumours may be classified into Primary and Secondary.
Tumours that start in the brain are primary brain tumours.
Secondary tumours: Metastatic brain tumours are tumours formed by cancer cells that start elsewhere in the body and spread to the brain.
Tumour names depend on where the tumour originated, its pattern of growth, and whether it is cancerous or not. The following
are some general names of tumours:
ADENOMA :- A usually benign tumour arising from a gland; for example, pituitary adenoma.
BLASTOMA :- A malignant tumour whose cells have undeveloped(embryonic) characteristics;
for example, medulloblastoma
or glioblastoma multiforme.
CARCINOMA :- A malignant tumour that arises from skin or the lining of the digestive, respiratory, and urogenital systems;
example, lung cancer (small cell carcinoma) or colon cancer (adenocarcinoma).
SARCOMA :- A malignant tumour that arises from connective tissue, blood vessels, or the lymph system;
GLIOMA :- The general name for a tumour that arises from the supportive tissue of the brain; for example, astrocytoma or oligodendroglioma. It may be benign or malignant.
Some tumours may undergo further change (mutation). A benign growth may become malignant. In some tumours, a lower-grade tumour may recur as a higher-grade tumour.
Grading Tumours :- Tumour grade indicates the degree of malignancy. Grade is based on the tumour's tendency to spread (infiltrate), its growth
rate, and its similarity to normal cells.
Tumours with distinct borders (circumscribed), considered grade I, are sometimes referred to as benign or mildly malignant.
Those tumours either do not grow or grow slowly.
Infiltrating tumours are those that tend to grow into surrounding tissue. Of the infiltrating tumours, the terms low-grade,
mid-grade, and high-grade are frequently used. However, the exact system used to grade tumours varies with each specific
family of tumours.
Tumours often contain several grades of cells. The highest or most malignant grade of cell found during microscopic
examination determines the grade, even if most of the tumour is a lower grade.
Tumour diagnosis by name and by grade is very important for both treatment and prognosis.
Click here for more information on Brain Tumour
Spinal Cord Tumors
Spinal cord tumors account for about 15% of the Central Nervous System (CNS) neoplasms. Tumors of the Spinal Cord are not common.
Incidence and Pattern
Spinal Cord tumors can be classified into:
- Extradural tumors
- Intradural extra-medullary tumors
- Intramedullary tumors
Extradural tumors are mainly bony tumors – most common in a setting dealing with cancer patients.
Eg. Metastatic tumors, Granuloma, inflammatory diseases and infective diseases.
Intradural tumors are uncommon. Most intradural tumors arise from the cellular constituents of the spinal cord and filum terminale, nerve roots or the meninges.
Common lesions are Neurofibroma, Meningioma, Hemangioblastoma, Arterio Venous Malformation (AVM), Arachnoid Cyst, Granulomas, Cysticercosis Cysts, sometimes Hydatid cysts as well.
Intramedullary tumors arise within the substance of the spinal cord.
Generally include Astrocytoma, Ependymoma, Lipomas, Arterio Venous Malformation (AVM), Granuloma, whereas sometimes Hemangioblastoma, Epidermoids, Dermoids and mixed tumors also do occur.
The ratio of intradural to extradural tumors is approximately 3 to 2.
The ratio of intramedullary to extra-medullary tumors is somewhat higher in children than in adults, approximately 30 % higher in children and 15 % in adults.
Tumors in Spinal Cord are also classified as Cervico Dorsal / Cervico Medullary / Dorsal / Lumbosacral and Conus Cauda.
Most spinal cord tumors produce symptoms and signs with a combination of local or segmental and distant features.
Age, home town, community and socio economic background, vasculature, relative size of the spinal column and other congenital or developmental features.
Modality of choice is Magnetic Resonance Imaging (MRI) with contrast.
Total excision: Often achieved in benign or well defined capsulated lesions. Examples of such tumours are neurofibroma and meningiomas
Near Total excision: When tags of tumour are left behind sometimes not evident on post operative scans but the surgeon knows that there are tumour tags left behind. This can be achieved is low grade malignant tumours such as astrocytomas or ependymomas.
Sub- total excision: When the tumour is adherent or arising from eloquent tissue or stuck to vessels which cannot be sacrificed. Sometimes there are other reasons when one cannot achieve total excision. Safety always needs to be kept at the back on the surgeons mind.
Partial Excision: any excision less than sub total should be referred as partial excision. Extensive tumours or extremely invasive tumours may be partially excised. Here the aim is to achieve reasonable decompression and a good biopsy so that adjuvant therapy can be instituted.
Biopsy: When any excision would compromise neural function then one may have to settle for a biopsy. This may also be performed when one is suspecting a medical disease such as tuberculoma however is it is safe one should try and achieve some decompression or get rid on the neural compression caused by the mass. Medical treatment or Adjuvant therapy will require to be instituted.
Difference between Extradural and Intradural extra-medullary (IDEM) tumors
Extradural Intradural extra-medullary
Radiculopathy common Radiculopathy less likely
Bowel / Bladder less Bowel / Bladder more
common involved commonly involved
Less profound weakness in benign condition as compared to IDEM
Lower limbs signs are Lower limbs signs are more
generally bilateral likely to be unilateral
Degenerative diseases Benign tumors common
Shorter history Longer history
Pathology.. Traumatic, Pathology.. Benign Neoplasm
Malignant & Degenerative
Spinal tenderness is more Spinal tenderness is less