Normal Pressure Hydrocephalus
What is Normal Pressure Hydrocephalus?
Cerebrospinal fluid flows through large open structures-called ventricles-deep inside your brain. These fluid-filled ventricles help keep the brain buoyant and cushioned. The fluid eventually flows into closed spaces between the brain and the skull, where it's absorbed into the bloodstream.
Hydrocephalus, once called “water on the brain,” occurs when excess fluid builds up in the brain, most often because of an obstruction preventing proper fluid drainage. Keeping the production, flow and absorption of cerebrospinal fluid in balance is critical to maintaining normal intracranial pressure.
Normal pressure hydrocephalus (NPH) most often occurs in individuals over age 60. It is different than typical hydrocephalus in that it may not cause an obvious increase of pressure inside the head, but may have fluctuations in cerebrospinal fluid pressure (CSF) from high to normal to low.
Many cases of NPH have no known cause. Some cases of NPH are linked to bleeding in the brain or a blockage of CSF flow through and around the brain and spinal cord. It is believed that blockages are linked to a history of infection, stroke or head injury.
Since the symptoms of NPH are similar to those of other diseases, people with this disorder are often diagnosed with disorders such as Alzheimer's or Parkinson's disease; or the symptoms may be attributed to simple aging.
Generally, symptoms may include:
- Difficulty walking
- A change in memory and other cognitive abilities, and possible personality changes
- Problems with bladder control
All of these symptoms are not necessarily present in persons with NPH, especially in the earlier stages of the disorder.
Several forms of imaging and physiological testing are used to diagnose NPH, including:
- A thorough neurological exam
- CT or MRI imaging
- Trial removal of CFS to help determine functional improvement a shunt (drainage device) may produce
- Neuropsychological evaluation to determine if there has been cognitive decline
Treatment for NPH usually involves surgical placement of a shunt in the brain to drain excess CSF into the abdomen where it can be absorbed. This allows the brain ventricles to return to their normal size. Regular follow-up care by a physician is important in order to identify subtle changes that might indicate problems with the shunt. Endoscopic ventriculostomy also may be performed to treat NPH. In this procedure, a hole is created in the bottom, or floor, of the ventricle so that excess CSF can drain. However, this surgery is relatively new, is less commonly used, and, at this time, is associated with greater risks.
Before this procedure is performed, patients undergo a battery of neuropsychological and gait evaluations, followed by a period of intermittent lumbar drainage. This allows for a brief trial of CSF removal that mimics the drainage of an implanted shunt, and helps determine whether the patient is a good candidate for shunt placement. When shunting surgery is successful, it tends to help more with walking and bladder control than with mental decline. Overall, best surgical results are reported in patients with less than 36 months of illness duration, presence of gait abnormalities as their early symptoms, have responded favorably to a large-volume lumbar puncture, CT scan or MRI evidence of chronic hydrocephalus, and a normal CSF at lumbar puncture.
Following CFS drainage, neuropsychological and gait testing are repeated. Functional improvements reported by the patient (or patient's family) during temporary CSF drainage are a good predictor of longer-lasting improvements resulting from shunt implantation.
The symptoms of NPH usually get worse over time if the condition is not treated, although some people may experience temporary improvements. While the success of treatment with shunts varies from person to person, some people recover almost completely after treatment and have a good quality of life. Early diagnosis and treatment improves the chance of a good recovery.
What should you do?
If you (or a family member) exhibit the classic triad of NPH symptoms (difficulty walking, dementia, and bladder control problems), contact the Scott & White Neuroscience Institute. Call the Department of Neurology at 254-724-4179.