Posterior fossa tumor

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Posterior fossa tumor is a type of brain tumor located in or near the bottom of the skull.

Alternative Names

Infratentorial brain tumors; Brainstem glioma


The posterior fossa is a small space in the skull, found near the brainstem and cerebellum. The cerebellum is the part of the brain responsible for movement, balance, and coordination. The brainstem is responsible for controlling vital body functions, such as breathing.

If a tumor grows in the area of the posterior fossa, it can block the flow of spinal fluid and cause increased pressure on the brain and spinal cord.

Most tumors of the posterior fossa are primary brain cancers. They start in the brain, rather than spreading from somewhere else in the body.

Posterior fossa tumors have no known causes or risk factors.


Symptoms occur very early with posterior fossa tumors and may include:

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

  • Dilated pupils
  • Eye problems
  • Face muscle weakness
  • Hearing loss
  • Loss of feeling in part of the face
  • Taste problems
  • Unsteadiness when walking
  • Vision problems

Exams and Tests

Diagnosis is based on a thorough medical history and physical exam, followed by imaging tests. The best way to look at the posterior fossa is with an MRI scan. CT scans are not helpful to see that area of the brain in most cases.

The following procedures may be used to remove a piece of tissue from the tumor to help with diagnosis:

  • Open brain surgery, called a posterior craniotomy
  • Stereotactic biopsy


Most tumors of the posterior fossa are removed with surgery, even if they are not cancerous. There is limited space in the posterior fossa, and the tumor can easily press on delicate structures if it grows.

Depending on the type and size of the tumor, radiation treatment may also be used after surgery.

Support Groups

You can ease the stress of illness by joining a support group whose members share common experiences and problems.

Outlook (Prognosis)

A good outlook depends on finding the cancer early. A total blockage in the flow of spinal fluid can be life threatening. If tumors are found early, surgery can lead to long-term survival.

Possible Complications

Complications may include:

When to Contact a Medical Professional

Call your health care provider if you have regular headaches that occur with nausea, vomiting, or vision changes.


Arriaga MA, Brackmann DE. Neoplasms of the posterior fossa. In: Flint PW, Haughey BH, Lund V, et al, eds. Cummings Otolaryngology: Head & Neck Surgery. 6th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 177.

Dorsey JF, Hollander AB, Alonso-Basanta M, et al. Cancer of the central nervous system. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2014:chap 66.

Version Info

  • Last reviewed on 2/12/2016
  • Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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