The location, size and growth rate of a brain tumour determines how it affects the nervous system and the symptoms caused.
Symptoms caused by brain tumours may include:
- Headaches that gradually become more frequent and more severe
- Unexplained nausea or vomiting
- Blurred vision, double vision or loss of peripheral vision
- Gradual loss of sensation or movement in an arm or a leg
- Difficulty with balance
- Speech or hearing problems
- Personality or behaviour changes and confusion
- Seizures, especially in someone who does not have a history of seizures
Primary brain tumours originate in the brain or surrounding tissues, such as in the brain-covering membranes (meninges), cranial nerves, pituitary gland or pineal gland.
Primary brain tumours begin when normal cells acquire mutations in their DNA which causes cells to grow and divide at increased rates and to continue living when healthy cells would die. The result is a mass of abnormal cells, which forms a tumour.
In most people with primary brain tumours, the cause of the tumour is not clear. Risk factors include exposure to ionizing radiation and a family history of brain tumours.
Many different types of primary brain tumours exist. They are named by the type of cells involved. Examples include:
- Gliomas. These tumours begin in the brain or spinal cord and include astrocytomas, ependymomas, glioblastomas, oligoastrocytomas and oligodendrogliomas.
- Meningiomas. A meningioma is a tumour that arises from the membranes that surround your brain and spinal cord (meninges). Most meningiomas are noncancerous.
- Acoustic neuromas (schwannomas). These are benign tumours that develop on the nerves that control balance and hearing leading from your inner ear to your brain.
- Pituitary adenomas. These are mostly benign tumours that develop in the pituitary gland at the base of the brain. These tumours can affect the pituitary hormones with effects throughout the body.
- Medulloblastomas. These are the most common cancerous brain tumours in children. A medulloblastoma starts in the lower back part of the brain and tends to spread through the spinal fluid. These tumours are less common in adults, but they do occur.
- Germ cell tumours. Germ cell tumours may develop during childhood where the testicles or ovaries will form. But sometimes germ cell tumours affect other parts of the body, such as the brain.
- Craniopharyngiomas. These rare, noncancerous tumours start near the brain’s pituitary gland, which secretes hormones that control many body functions. As the craniopharyngioma slowly grows, it can affect the pituitary gland and other structures near the brain.
Secondary (metastatic) brain tumours result from cancer that starts elsewhere in your body and then spreads (metastasizes) to your brain.
Secondary brain tumours most often occur in people who have a history of cancer. In rare cases, a metastatic brain tumour may be the first sign of cancer that began elsewhere in your body.
In adults, secondary brain tumours are far more common than are primary brain tumours.
Any cancer can spread to the brain, but common types include breast, colon, kidney and lung cancer, and melanoma.