A buildup of fluid in the cavities deep within the brain.

Hydrocephalus is a buildup of fluid in the cavities deep within the brain. The extra fluid puts pressure on the brain and can cause brain damage. It's most common in infants and older adults.

In infants, symptoms include a large head or a rapid increase in the size of the head. The soft spot on the top of the head may bulge. In older adults, symptoms include a loss of bladder control, memory loss and trouble with thinking skills. Older adults may shuffle when they walk and have poor balance.

Treatment is often surgery to direct the excess fluid to another part of the body. A surgeon places a tube into a ventricle or creates a hole in the bottom of a ventricle to drain excess fluid.