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

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 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

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 that 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, postoperative radiation treatment is also used.

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

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.

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

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

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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. 2007;8(8):685-695.