About Alzheimer's & Dementia
What is Normal Pressure Hydrocephalus?
Normal Pressure Hydrocephalus is a brain disorder in which excess cerebrospinal fluid accumulates in cavities of the brain (called “ventricles,”) causing cognitive challenges (with thinking and reasoning), difficulty walking and loss of bladder control.
Normal pressure hydrocephalus occurs when excess cerebrospinal fluid accumulates in the brain's ventricles. These are hollow fluid-filled chambers in the brain.
Despite the excess fluid inside these hollow fluid-filled ventricles, NPH is called "normal pressure" because a person’s cerebrospinal fluid pressure often remains normal. As brain ventricles enlarge with the excess cerebrospinal fluid, they can disrupt and damage nearby brain tissue, causing symptoms of NPH. This condition primarily affects people in their 60’s and 70’s.
What changes can I expect?
The trademark symptoms of Normal Pressure Hydrocephalus include:
- Decline in cognitive skills which includes overall slowing of thought processes, apathy, challenges with planning and decision-making, difficulties with concentration and changes in personality and behaviour.
- Difficulty walking. This is sometimes compared to the way a person walks "on a boat," with the body bent forward, legs held apart and feet moving as if they're "glued to the deck."
- Loss of bladder control, which tends to appear somewhat later in the disease than the walking challenges or cognitive changes.
How is it diagnosed?
There is no single test that can conclusively diagnose Normal Pressure Hydrocephalus. Although the symptoms of cognitive decline, walking difficulty and loss of bladder control are considered the typical signs of this disorder, not everyone with NPH will experience all of these symptoms. Brain imaging can detect enlargement of the ventricles, often with magnetic resonance imaging (MRI), and plays a key role in diagnosing NPH. Several brain disorders, including Alzheimer's disease, can cause overall brain tissue shrinkage that makes the ventricles look larger than normal. Although the ventricles are enlarged, brain tissue may not appear shrunken in NPH.
Since the symptoms of NPH may overlap with those of Alzheimer's disease and other dementias, it is recommended that a person with suspected NPH undergo examination by a neurologist experienced in evaluating brain disorders that affect movement, thinking skills and physical functions.
If symptoms and an MRI are suggestive of NPH, a large-volume spinal tap may be used to identify those who may benefit from a shunt. In this procedure, physicians remove a larger-than-normal amount of spinal fluid and then observe the person for 30 to 60 minutes to note any improvements in walking or thinking and reasoning. Most people originally suspected of having NPH do not improve following this test.
What causes Normal Pressure Hydrocephalus?
In most cases, the fluid buildup happens for unknown reasons.In some cases, normal pressure hydrocephalus is caused by other brain disorders such as hemorrhages, infections or inflammation.
What kind of treatment is available?
We do not have effective nonsurgical treatments for normal pressure hydrocephalus. Pharmaceutical drugs, such as diuretics that remove excess fluid throughout the body, have not been effective.
NPH can sometimes be treated with surgical insertion of a shunt (a long, thin tube that drains excess cerebrospinal fluid) from the brain to the abdomen. A person’s ability to walk is most likely to improve after surgery. Shunting doesn't improve symptoms for everyone with NPH and there is uncertainty about how best to identify those most likely to benefit. More research is needed to understand the prevalence of NPH, clarify the benefits of shunt insertion and identify those likely to benefit most.