Causes

Normal pressure hydrocephalus (NPH) is a form of hydrocephalus, which means there is too much fluid pressing on the brain.

NPH can occur without a known cause, or it may be caused by any condition that blocks the flow of cerebrospinal fluid (CSF). The fluid-filled chambers (ventricles) of the brain enlarge to fit the increased volume of CSF. They press down on and damage or destroy brain tissue.

Risk factors include:

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

CSF is produced in normal amounts in these conditions, but it is prevented from being reabsorbed normally.

NPH is thought to account for about 5% of all dementias.

Symptoms

The symptoms often begin slowly.

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

• 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.

Exams and Tests

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

Treatment

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.

Outlook (Prognosis)

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.

Possible Complications

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

When to Contact a Medical Professional

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.

Alternative Names

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

References

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.

Update Date: 3/9/2012

Reviewed by: Daniel B. Hoch, PhD, MD, Assistant Professor of Neurology, Harvard Medical School, Department of Neurology, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.