What Is a Glioma?

A glioma is a brain tumor that begins in a glial cell in the brain or spinal cord. Gliomas affect all ages and are the most common type of brain tumor in adults. They are often resistant to treatment. Glial cells, the most common cellular component of the brain, surround and support neurons. Unlike neurons, glial cells can divide and multiply. When this process occurs in a rapid and uncontrolled manner, a glioma forms.

Types of Glioma

There are several types of glial cells including astrocytes, oligodendrocytes, and ependymal cells.

Each of these types of cells produce gliomas with distinct characteristics. Brain tumors are generally named and classified according to the types of brain cells from which they originate or from the location in which the cancer develops. The names of gliomas identify the type of glial cell associated with that tumor.


Astrocytomas are primary brain tumors that develop from astrocytes. Astrocytomas account for about three-fourths of all gliomas. Astrocytomas are classified by grades that reflect the degree of malignancy.

  • Grade I - Pilocytic astrocytoma: slow growing; most common in children and adolescents
  • Grade II - Low-grade astrosytoma: relatively slow growing; most common in young adults
  • Grade III - Anaplastic astrocytoma: grow rather rapidly
  • Grade IV - Glioblastoma multiforme (GBM): most malignant, fast growing, very aggressive and lethal; most common brain tumor in adults. This is the most common astrocytoma


Ependymomas are derived from ependymal cells which line the ventricles in the lower part of the brain and the central canal of the spinal cord. This is one of the most common types of brain tumors found in children.


Oligodendrogliomas develop from oligodendrocyte glial cells which form the protective myelin coatings around the nerve cells. This tumor type is considered rare and often is classified as either low-grade (grade II) or anaplastic (grade III).

Other Types of Gliomas

Mixed tumors contain a mixture of cells from different types of glial cells.

Other forms of gliomas include brainstem glioma and optic nerve glioma.

Symptoms of Glioma

The most common symptoms of gliomas include:

  • headaches
  • seizures
  • nausea or vomiting
  • changes in speech
  • changes in vision
  • problems balancing or walking
  • weakness or numbness in arms and legs

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