There are various brain tumour forms that may be suitable for treatment by Gamma Knife depending on their size and location.
Glioblastoma is a primary brain tumour and belongs to a group of brain tumours known as gliomas as it grows from a type of brain cell called a glial cell. There are several different types of glial cells, astrocytes, oligodendrocytes and ependymal cells.
One of the many protocols for the treatment of glioblastoma is surgical intervention followed by chemotherapy. A post surgery MRI scan may indicate a radiosurgical boost or conventional radiation therapy. They are often more suited to the larger beams used in conventional radiotherapy, however, smaller tumours or areas of recurrence are sometimes suitable for Gamma Knife treatment. A recurrence may be treated with Gamma Knife radiosurgery.
The symptoms of glioma vary by tumour type as well as the tumour’s size, location and rate of growth.
Common signs and symptoms of gliomas include:
- Nausea or vomiting
- Confusion or a decline in brain function
- Memory loss
- Personality changes or irritability
- Difficulty with balance
- Urinary incontinence
- Vision problems, such as blurred vision, double vision or loss of peripheral vision
- Speech difficulties
- Seizures, especially in someone without a history of seizures
What are the causes
Like most primary brain tumours, the exact cause of gliomas is not known. But there are some factors that may increase your risk of a brain tumour:
- Age. The risk of a brain tumour increases as you age. Gliomas are most common in adults between 60 and 80 years old. However, they can occur at any age. Certain types of gliomas, such as ependymomas and pilocytic astrocytomas, are more common in children and young adults.
- Family history of glioma. It’s rare for glioma to run in families. But having a family history of glioma can double the risk of developing it. Some genes have been weakly associated with glioma, but more study is needed to confirm the link between these genetic variations and brain tumors.
How common are glioblastomas
Gliomas are the most commonly diagnosed of both benign and malignant primary brain tumors accounting for 45-50% of all primary brain tumours. The most common gliomas are astrocytomas, ependymomas, oligodendrogliomas and tumours with mixtures of two or more of these cell types.
Tests and procedures used to diagnose glioblastoma include:
- Neurological exam. During a neurological exam, your doctor will ask you about your signs and symptoms. He or she may check your vision, hearing, balance, coordination, strength and reflexes. Problems in one or more of these areas may provide clues about the part of your brain that could be affected by a brain tumour.
- Imaging tests. Imaging tests can help your doctor determine the location and size of your brain tumour and MRI is often used to diagnose brain tumours. Other imaging tests may include CT and positron emission tomography (PET).
- Removing a sample of tissue for testing (biopsy). A biopsy can be done with a needle before surgery or during surgery to remove your glioblastoma, depending on your particular situation and the location of your tumour. The sample of suspicious tissue is analysed in a laboratory to determine the types of cells and their level of aggressiveness.
A haemangioblastoma is a rare, slow growing brain tumour. About 2 out of 100 (2%) of brain tumours are haemangioblastomas. It starts in the cells lining the blood vessels in the brain and sometimes in the spinal cord. People with a genetic condition called von Hippel-Lindau disease have a higher risk.
Symptoms may include headaches, vomiting, problems with coordination and balance, and jerky eye movements. To find out more about the tumour, your doctor will arrange different tests. You usually have a MRI scan or a CT scan and an angiogram, which looks at the blood vessels in the brain.
Treatment depends on the size and position of the tumour and your general health. Your specialist will talk to you about the best treatment plan for you and explain the benefits and disadvantages. Radiosurgery can be used instead of or after surgery and is most often used as the main treatment for small tumours of for haemangioblastoma that has come back after treatment.
These tumours arise from abnormal growth of the pigmented melanocyte cells found within the eyeball. Beyond surgical intervention involving removal of the eye in it’s entirety, Gamma Knife treatment can be designed to control the local tumour and preserve the vision. Gamma Knife can also be used after surgery to treat any remaining tumour or recurrence.
These are hyper-vascular tumours constructed of paraganglionic tissue which grow within the jugular foramen. Their growth and location can vary as they may grow up into the middle ear or down the neck following the vagus nerve. They often arise in middle age, and have a higher incidence in women. Symptom onset is often discrete and so the tumours can be of significant size at presentation. Although the insidious nature of presentation can often cause tumours to be at the limits of what it possible with Radiosurgery, the Perfexion model of the Gamma Knife is better suited for treatment of significantly inferior tumours, either as the sole treatment or combined with surgical intervention.
Other Tumour types
Those which may be suitable for treatment with Gamma Knife include conditions such as Astrocytomas, Craniopharingiomas, Chordomas, Teratomas, Pinealocytomas, but this list is not exhaustive.
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