Health Encyclopedia

Posterior fossa tumor

Definition

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

Causes, incidence, and risk factors

The posterior fossa is a small space in the skull, found near the brain stem and cerebellum. The cerebellum is the part of the brain responsible for movement.

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, which originate in the brain, rather than spreading from elsewhere in the body.

There are no known cause or risk factors associated with them.

Symptoms

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

Ataxia (uncoordinated gait)
Drowsiness
Headache
Imbalance
Nausea
Vomiting

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

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.

Treatment

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.

Complications

Cranial nerve palsies
Herniation
Hydrocephalus
Increased intracranial pressure

Calling your health care provider

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

References

Labuguen RH. Initial evaluation of vertigo. Am Fam Physician. Jan 15, 2006;73(1):244-251, 254.

Wilne S, Collier J, Kennedy C, Koller K, Grundy R, Walker D. Presentation of childhood CNS tumours: a systematic review and meta-analysis. Lancet Oncol. Aug 2007;8(8):685-95.

Review Date:6/10/2008
Reviewed By:James R. Mason, MD, Oncologist, Director, Blood and Marrow Transplantation Program and Stem Cell Processing Lab, Scripps Clinic, Torrey Pines, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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