Symptoms occur very early when posterior fossa tumors occur. 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

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.