Hydrocephalus is a build-up of fluid inside the skull, which leads to brain swelling. Hydrocephalus means "water on the brain."

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

Hydrocephalus - idiopathic; Hydrocephalus - adult; Hydrocephalus - communicating; Extraventricular obstructive hydrocephalus

NPH may be caused by:

• Any condition that blocks the flow of cerebrospinal fluid (CSF)
• No known reason

As CSF fluid 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.

You are more likely to get NPH if you have:

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

NPH is thought to play a role in some types of dementia.

The symptoms often begin slowly.

A person needs to have three symptoms to be diagnosed with normal pressure hydrocephalus:

• Headache
• Changes in the way a person walks: difficulty when beginning to walk (gait apraxia), feet held wider apart than normal, shuffling of the feet, unsteadiness
• Slowing of mental function: forgetfulness, difficulty paying attention, apathy or no mood
• Problems controlling urine (urinary incontinence), and sometimes controlling stools (fecal incontinence)

Sudden falls without a loss of consciousness or other symptoms (drop attacks) may occur early in the illness.

Note: Many of these symptoms are common in the elderly, and may be caused by other conditions.

An examination shows walking (gait) changes related to the pressure placed on parts of the brain. Deep tendon reflexes may be increased in the lower legs.

Tests include:

• Lumbar puncture (spinal tap) with careful testing of walking before and after the spinal tap
• Head CT scan or MRI of the head

The treatment of choice is surgery to place a tube called a shunt that routes the excess CSF out of the brain ventricles. This is called a ventricoperitoneal shunt.

Some patients improve a lot after this surgery, but many do not. Walking is the symptom most likely to improve. No specific symptoms or test results can accurately predict which patients are most likely to get better after surgery.

See: Dementia - homecare for information about taking care of a loved one with dementia.

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

Surgical treatment improves symptoms in a percentage of patients. People with minimal symptoms have the best outcome.

• Complications of surgery (infection, bleeding)
• Dementia that becomes worse over time
• Injury from falls
• Shortened life span

Call your health care provider if:

• You or a loved one is having increasing problems with memory, walking, and 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 the local emergency number (such as 911) 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: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann; 2008:chap 63.