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 scan. CT scans are usually not helpful.

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