Normal pressure hydrocephalus (hy dro CEPH a lus) is a form of hydrocephalus, also known as “water on the brain,” which means there is too much cerebrospinal (ce re bro SPINE al) fluid compressing the brain. In this condition, cerebrospinal fluid (CSF) is produced in normal amounts, but it is prevented from being normally reabsorbed. The ventricles, normally four open spaces within the brain, enlarge to accommodate the increased volume of CSF. The fluid-filled ventricles compress the brain tissue, damaging or destroying it. A person may lose any or all brain functions controlled by the area of the brain affected.
Normal pressure hydrocephalus (NPH) can occur in people of any age, but it is most common in older adults. It is often a reversible or treatable disorder. If there is an identifiable cause and the cause can be corrected, the symptoms may reverse or at least stop worsening. If there is no identifiable cause, the disorder is often progressive.
Risk factors include disorders that may obstruct the flow of CSF, such as head injury, brain tumor, surgery on the brain, meningitis or similar brain and spinal infections, and hemorrhage—bleeding from a blood vessel or aneurysm in the brain.
Symptoms often develop slowly over time. Early symptoms can be subtle, and they worsen gradually. The parts of the brain most affected are those that control the legs, bladder function, and mental processes. Gait disturbances are usually the first symptoms. Early symptoms may include:
- Changes in gait, including inability to begin walking
- Unsteady walking
- Weakness of the legs
- Sudden fall without loss of consciousness or other symptoms
As NPH progresses, the following symptoms may appear:
- Dementia or loss of any or all brain functions, including movement, sensation, perception, and thought processes
- No observable mood
- Apathy
- Withdrawn behavior
- Impaired memory
- Difficulty maintaining attention
- Decreased spontaneity
- Urinary or bowel incontinence
- Speech impairment
NPH is thought to account for 5 percent of all dementias. The dementia symptoms can be similar to those of Alzheimer’s disease, and the walking symptoms similar to those of Parkinson’s disease. NHP is sometimes misdiagnosed as one of those conditions. If not treated, symptoms get worse. Diagnostic workup includes a physical examination, which shows walking changes related to brain damage. Laboratory and imaging tests may include:
- A lumbar puncture or spinal tap that may show the pressure of CSF in the spine
- A computerized tomography (CT) or magnetic resonance imaging (MRI) scan of the head that may show changes that indicate NPH
NPH cannot be cured. The goal of treatment is to improve symptoms. Treatment through surgery may include inserting a long tube, called a shunt, to drain fluid from the ventricles to another part of the body, usually the abdomen, where the CSF is reabsorbed. Surgical treatment improves symptoms in about half of cases, with the best prognosis for those with minimal symptoms. Treatment will vary depending on the symptoms and the extent to which treatment relieves them. Without medical treatment, prognosis is poor—symptoms will continue to progress until the person dies.
For more information, visit the National Institute of Neurological Disorders and Stroke: http://www.ninds.nih.gov.
