Hydrocephalus is a buildup of spinal fluid inside the fluid chambers of the brain. Hydrocephalus means "water on the brain."

Normal pressure hydrocephalus (NPH) is a rise in the amount of cerebrospinal fluid (CSF) in the brain that affects brain function. However, the pressure of the fluid is usually normal.

Hydrocephalus - occult; Hydrocephalus - idiopathic; Hydrocephalus - adult; Hydrocephalus - communicating; Dementia - hydrocephalus; NPH

There is no known cause for NPH. But the chance of developing NPH is high in someone who has had any of the following:

• Bleeding from a blood vessel or aneurysm in the brain (subarachnoid hemorrhage)
• Certain head injuries
• Meningitis or similar infections
• Surgery on the brain (craniotomy)

As CSF builds up in the brain, the fluid-filled chambers (ventricles) of the brain swell. This causes pressure on brain tissue. This can damage or destroy parts of the brain.

Symptoms of NPH often begin slowly. There are three main symptoms of NPH:

• Changes in the way a person walks: difficulty when beginning to walk (gait apraxia), feeling as if your feet are stuck to the ground (magnetic gait)
• Slowing of mental function: forgetfulness, difficulty paying attention, apathy or no mood
• Problems controlling urine (urinary incontinence), and sometimes controlling stools (bowel incontinence)

Diagnosis of NPH can be made if any of the above symptoms occur and NPH is suspected and testing is done.

Treatment for NPH is usually surgery to place a tube called a shunt that routes the excess CSF out of the brain ventricles and into the abdomen. This is called a ventriculoperitoneal shunt.

Without treatment, symptoms often get worse and could lead to death.

Surgery improves symptoms in some people. Those with mild symptoms have the best outcome. Walking is the symptom most likely to improve.

Problems that may result from NPH or its treatment include:

• Complications of surgery (infection, bleeding, shunt that does not work well)
• Loss of brain function (dementia) that becomes worse over time
• Injury from falls
• Shortened life span

Call your provider if:

• You or a loved one is having increasing problems with memory, walking, or urine incontinence.
• A person with NPH worsens to the point where you are unable to care for the person yourself.

Go to the emergency room or call 911 or the local emergency number if a sudden change in mental status occurs. This may mean that another disorder has developed.

Rosenberg GA. Brain edema and disorders of cerebrospinal fluid circulation. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 88.

Sivakumar W, Drake JM, Riva-Cambrin J. The role of third ventriculostomy in adults and children : a critical review. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 32.

Williams MA, Malm J. Diagnosis and treatment of idiopathic normal pressure hydrocephalus. Continuum (Minneap Minn). 2016; 22(2 Dementia):579-599. PMCID: PMC5390935 www.ncbi.nlm.nih.gov/pmc/articles/PMC5390935/.