Ask Doctor K: Hydrocephalus, or water on the brain

DEAR DOCTOR K: My father had been showing signs of dementia for a few months. We thought it was Alzheimer’s disease, but it turned out to be hydrocephalus. What is this, and how is it treated? Does it cause permanent damage?

DEAR READER: Hydrocephalus is a condition in which extra cerebrospinal fluid collects inside the brain. Cerebrospinal fluid acts as a cushion for the brain and spinal cord. It also supplies nutrients and removes waste products.

Cerebrospinal fluid flows in a space between the outer layer of the brain and the skull. It also is found in small “lakes” inside the brain called ventricles, and in a space around the spinal cord. It is the fluid surrounding the spinal cord from which doctors take a sample when they perform a “spinal tap.” The fluid is made in the brain. At about the same rate as it is made, some of the fluid leaves and enters the blood to travel elsewhere in the body.

In most people, the amount of fluid inside the ventricles remains mostly constant during adult life. In people with hydrocephalus, the ventricles expand.

Your father most likely experienced a type of hydrocephalus known as normal-pressure hydrocephalus. It can result from head trauma, bleeding in the brain or inflammation of the membrane covering the brain.

People with NPH can develop dementia; they may lose bladder control. They walk with difficulty and tend to fall.

To make a diagnosis, a doctor will use CT or MRI to look for enlarged ventricles in the brain. Next, the doctor will remove fluid with a spinal tap.

If NPH is causing the problems, removing the fluid will lead to a temporary improvement in symptoms.

To treat the condition permanently, a surgeon will implant a tube (called a shunt) that drains excess fluid from the brain. The shunt is inserted into a ventricle through a hole in the skull. It is tunneled under the skin and carries the fluid into another area of the body, where it can be absorbed. It is possible to reverse the effects of NPH, particularly if the problem is treated early. Hopefully, your father will have a good response to the treatment.