Jan. 1, 2007

AMARILLO – Normal pressure hydrocephalus, which is thought to be a cause of dementia, can occur in people of any age but it is most common in the elderly population, said a Texas Cooperative Extension specialist.

The good news is normal pressure hydrocephalus is often a reversible or treatable disorder, said Andrew B. Crocker, Extension program specialist – gerontology health.

Normal pressure hydrocephalus is a brain disorder that occurs when the flow of cerebrospinal fluid is blocked, Crocker explained. Fluid fills up in the skull and pushes on brain tissue, causing loss of some or all brain functions controlled by the area of the brain affected.

"It is thought to account for about 5 percent of all dementias," he said.

The disorder is a form of hydrocephalus, also known as "water on the brain," which means there is too much fluid compressing the brain, Crocker said.

"It can occur without identifiable cause or it may be caused by any condition where the flow of cerebrospinal fluid is blocked," he said. "The cerebrospinal fluid is produced in normal amounts in this condition but it is prevented from being normally reabsorbed."

Crocker said when the disorder occurs, the ventricles – normally four open spaces within the brain – enlarge to accommodate the increased volume of cerebrospinal fluid. Brain tissue is damaged or destroyed because of compression by the fluid-filled ventricles.

"If there is an identifiable cause and the cause can be corrected, the symptoms may reverse or at least stop getting worse," he said. "If there is no identifiable cause, the disorder is often progressive."

Some of the identifiable causes he listed are a head injury, surgery on the brain, meningitis or similar brain and spine infections, and hemorrhage, bleeding from a blood vessel or aneurysm in the brain.

The symptoms often begin gradually and may include: changes in gait, including inability to begin walking, weakness of the legs, or a sudden fall without loss of consciousness.

Other symptoms include dementia or loss of brain functions such as movement, sensation, perception and thought processes, apathy, withdrawn behavior, impaired memory, difficulty maintaining attention, decreased spontaneity, urinary or bowel incontinence, and speech impairment.

Normal pressure hydrocephalus may be diagnosed fairly easily, Crocker said. A physical examination shows walking changes related to the damage within the brain.

Laboratory and imaging tests may include:

-- A lumbar puncture, or spinal tap, may show the pressure of fluid in the spine.

-- A computerized tomography or magnetic resonance imaging scan of the head may show changes that indicate the disorder.

Treating disorders associated with normal pressure hydrocephalus may prevent its development in some cases, Crocker said. In other cases, early treatment may prevent severe symptoms.

The goal of treatment is to improve symptoms, Crocker said. Treatment through surgery may include the insertion of a shunt that routes the fluid around the obstruction and back into the circulation.

Treatment may vary depending on the symptoms presented and the extent that symptoms are relieved by treatment, he said.

"The prognosis is poor without medical intervention," Crocker said. "The symptoms will continue to progress, and the disorder results in death. Surgical treatment improves symptoms in about 50 percent of the cases, with the best prognosis for those with minimal symptoms."

For more information on normal pressure hydrocephalus, go to the National Institute of Neurological Disorders and Stroke at http://www.ninds.nih.gov .