Normal Pressure Hydrocephalus
What is Normal Pressure Hydrocephalus?
Normal pressure hydrocephalus is an adult onset form of hydrocephalus. It develops slowly over time and therefore differs from other types of hydrocephalus. This means that the drainage of cerebrospinal fluid (CSF) is gradually blocked, and the fluid buildup occurs slowly. It also means that symptoms often develop slowly and over a long period of time
The gradual buildup of CSF in the ventricles means that the resulting pressure within the brain may not be as much as in other forms of hydrocephalus. However, the “normal” part of the name of this condition is misleading because some patients actually do have changes in pressure (i.e., the amount of pressure is not normal).
Normal pressure hydrocephalus occurs due to a blockage in the areas where the cerebrospinal fluid (CSF) drains after exiting certain structures in the brain (ventricles). Since drainage is blocked, the amount of CSF in these structures starts to accumulate and they become enlarged. These enlarged ventricles can then compress the brain and cause damage to it.
Although normal pressure hydrocephalus can occur at age, it typically occurs in adults over 60 years of age.
Causes of Normal Pressure Hydrocephalus
Normal pressure hydrocephalus can be the result of any condition that blocks the flow of cerebrospinal fluid including:
- Head injury
- Brain tumor
- Bleeding within the brain (e.g., subarachnoid hemorrhage)
- Infection (e.g., meningitis)
- Complications from surgery.
- However many cases have no known cause.
Symptoms of Normal Pressure Hydrocephalus
Symptoms can begin slowly and be difficult to identify. It’s thought that normal pressure hydrocephalus accounts for approximately 5% of all cases of dementia.
Primary symptoms of normal pressure hydrocephalus include:
- Cognitive changes (e.g., problems with memory, the ability to think/reason, or difficulty paying attention).
- Balance/coordination problems and/or difficulty walking (e.g., shuffling the feet or difficulty when starting to walk).
- Bladder (and occasionally bowel) incontinence
- Unfortunately, these symptoms are common in elderly patients, and may have other causes.
Diagnosis of Normal Pressure Hydrocephalus
Normal pressure hydrocephalus is estimated to impact 0.5% of the population over 65 years of age. Unfortunately, its symptoms are common in elderly patients, and may have other causes. Because symptoms often develop slowly and over a long period of time, they can be mistaken as part of the normal aging process.
A physician may perform following to diagnosis normal pressure hydrocephalus:
- Medical history: Discussing medical history (including head injuries & surgeries), current symptoms, and conditions/diseases that may affect the brain.
- Physical and neurological examination: Assessing cognitive function, gait (walking) and balance. Imaging studies: Patients suspected of having hydrocephalus will undergo imaging studies (MRI or CT scan) of their head.
- Diagnostic procedures: Patients suspected of having hydrocephalus may also undergo a procedure to drain some cerebral spinal fluid. A lumbar puncture (spinal tap) will be required to accomplish this. The patient will be observed after the drainage to determine if their symptoms improve.
Treatment Options for Normal Pressure Hydrocephalus
Without treatment, symptoms often continue to get worse and can lead to death. Surgical treatment improves symptoms in many patients; however, not all patients see improvement in their symptoms. There is no way to accurately predict which patients will improve with surgery, although those with minimal symptoms generally have the best outcomes. If a patient’s symptoms improve with cerebral spinal fluid drainage, then surgery is generally recommended.