Brainstem glioma

Alternative names 
Infratentorial brain tumors; Posterior fossa tumor

Posterior fossa tumor is an abnormal growth located in or near the posterior fossa (a depression on the interior, back portion of the base of the skull, near the cerebellum part of the brain).

Causes, incidence, and risk factors

Most tumors of the posterior fossa are primary brain cancers, which originate in the brain, rather than spreading from elsewhere in the body.

They have no known cause or risk factors associated with them.


Symptoms occur very early with posterior fossa tumors. The posterior fossa itself is a small, confined space, and any growth there can block the flow of spinal fluid and cause increased pressure on the brain and spinal cord. The symptoms of increased intracranial pressure include:

  • Nausea  
  • Vomiting  
  • Headaches  
  • Drowsiness  
  • Ataxia (uncoordinated gait)  
  • Imbalance

Symptoms from posterior fossa tumors also occur when the tumor damages local structures, such as cranial nerves. Symptoms of cranial nerve damage include:

  • Hearing loss  
  • Visual field deficits  
  • Eye deviations  
  • Unsteadiness when walking  
  • Facial muscle weakness  
  • Dilated pupils  
  • Taste disturbances  
  • Loss of sensation of part of the face

Signs and tests

Diagnosis is based on thorough history and physical examination, followed by imaging tests. The best way to look at the posterior fossa is with an MRI.

Posterior craniotomy (open brain surgery) or stereotactic biopsy (using special instruments to get a small piece of the tumor) can be used to obtain tissue for diagnosis.

Tumors of the posterior fossa usually require surgical removal, even if they are benign (noncancerous). This is because of the delicate structures in the area which can be compressed by any abnormal growth and the frequency of symptoms associated with the tumors.

Most tumors of the posterior fossa are surgically removed. Occasionally, depending on the type of tumor and the size of it, post-operative radiation treatment is also used.

Support Groups
The stress of illness may be eased by joining a support group whose members share common experiences and problems.

Expectations (prognosis)
Prognosis depends on early detection. Complete obstruction to the flow of spinal fluid causes herniation and death. If tumors are recognized before this point, surgery is associated with good, long-term survival.


  • Increased intracranial pressure  
  • Hydrocephalus  
  • Herniation  
  • Cranial nerve palsies

Calling your health care provider
Call your health care provider if you notice consistent headaches that are accompanied by nausea, vomiting, or visual changes.

Johns Hopkins patient information

Last revised: December 2, 2012
by Arthur A. Poghosian, M.D.

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