There are many types of brain tumors, which are fundamentally divided into primary and secondary brain tumors. Primary brain tumors occur in the brain and other parts of the central nervous system (CNS). Secondary brain tumors are a result of malignant tumors in other parts of the body metastasizing (spreading) to the brain. Most secondary brain tumors are malignant.

Primary brain tumors can affect any or all of the brain cells, nerve cells in the CNS, and the meninges (the membrane surrounding the brain, and glands). The major types of primary brain tumors are gliomas and meningiomas.

Gliomas affect the glial cells that surround, insulate, and support the neurons. The different types of brain tumors affecting the glial cells are:

• Astrocytomas: These occur in a type of glial cells called astrocytes (star-shaped cells) in the cerebrum. Astrocytomas can progress from Grades I and II (low-grade) to III (high-grade anaplastic astrocytomas) and IV (malignant astrocytic glioma).
• Glioblastomas: The most aggressive type of brain tumors also affects the astrocytes. Sometimes glioblastomas are referred to as Grade IV astrocytomas.
• Oligodendrogliomas: These are most often found in a type of glial cell known as oligodendrocyte. These cells produce the fat that surrounds and protects the nerves.

Meningiomas are brain tumors that arise in the meninges – the tissue that surrounds and protects the brain. Though strictly not a brain tumor, it is classified as one, as it can affect the brain. Brain tumors are assigned Grades I to IV, as follows:

• Grade I: The tumor is benign and the cells look similar to healthy cells. The growth is gradual.
• Grade II: The tumor has turned malignant, but the cells appearance has started to change.
• Grade III: The tumor is malignant and is growing. The cell appearance is very different from normal healthy cells.
• Grade IV: The cells of the malignant tumor look abnormal and the growth has quickened significantly.

Other less common brain tumors are schwannomas (acoustic neuromas), pituitary adenomas, germ cell tumors, craniopharyngiomas, primary CNS lymphomas, and nerve sheath tumors.

The common types of tumors that spread to the brain are cancers of the breast, lung, kidney, colon, and skin.

There are numerous signs and symptoms that indicate the presence of brain tumors. In general, since the brain is affected, sensory and motor functions are impaired. Some of the symptoms are:

• Vision problems – double vision, loss of peripheral vision, and blurred vision
• Hearing problems
• Difficulty balancing, decreased muscle movement, and difficulty in maintaining posture
• Numbness, tingling, and a loss of sensation and movement in the arms and legs
• Difficulty with speech and language comprehension
• Confusion in day-to-day matters and poor reasoning and logic
• Poor memory and loss of concentration
• Decreased sense of touch and pain
• Decreased sense of space
• Behavioral changes – lower inhibitions, inappropriate social behavior, and personality changes
• Headaches that become more intense and frequent. Sometimes the pattern of headaches change over time.
• Difficulty swallowing
• Nausea and vomiting
• Blood pressure and heart rate are affected
• Seizures – especially where there is no prior history of seizures