Overview and Facts about Normal Pressure Hydrocephalus
Normal pressure hydrocephalus (NPH) is a disease that most commonly occurs in older patients who may have a number of underlying chronic diseases that may cause gait difficulties, dementia and urinary incontinence.
NPH is a brain disorder in which excess cerebrospinal fluid (CSF) builds up in the ventricles (fluid filled cavities in the brain). This buildup can cause thinking and reasoning issues, difficulty walking and loss of bladder control. Another name for NPH is chronic extra ventricular hydrocephalus.
NPH is often confused with other memory disorders and diseases. Because of these other underlying diseases, NPH is not always diagnosed early.
Other chronic diseases that can cause gait problems include arthritis, peripheral neuropathy (damage to the nerves in the arms and legs), dizziness related to inner ear disorders, narrowing of the spine in the neck (cervical) or low back (lumbar) regions.
Multiple strokes can also cause dementia, gait difficulty and urinary problems.
There are two main types of NPH, primary and secondary:
- Primary NPH: No obvious cause can be identified
- Secondary NPH: An identifiable cause is found, such as a history of brain tumor, history of bleeding in the brain, previous history of meningitis or history of head injury.
Research suggests that NPH may occur from a combination of factors, including poor absorption of CSF back into the blood stream or an inability of the ventricles to respond normally to other pressure changes in the body.
Signs and Symptoms of Normal Pressure Hydrocephalus
NPH is a chronic disease most typically seen in elderly patients.
- Difficulty walking
- Trouble lifting feet and moving smoothly. Patients may say their feet feel glued or stuck to the floor.
- Urinary incontinence
- Problems with thinking and memory (dementia)
Typically, problems with walking and balance appear as the first symptoms. Which symptom appears first varies from patient to patient, as well as the severity and rate of decline in health over time.
NPH may be the underlying cause for 1 of every 20 (5 percent) of patients with dementia. It is important to recognize the symptoms of NPH because unlike many other chronic forms of dementia or gait difficulty in elderly patients, this is a treatable and possibly reversible condition. Early diagnosis is important because symptoms may become irreversible as the disease progresses.
Tests and Diagnosis of Normal Pressure Hydrocephalus
Progressive gait (walking) problems with no clear cause (whether associated with urinary incontinence or dementia) may indicate NPH. Other testing includes an MRI scan of the brain to look at the size of the ventricles. A CT scan can also be used for patients who cannot have an MRI. Other tests may be ordered to exclude diseases that can have similar symptoms as NPH. If the scan shows enlarged ventricles, your neurologist or neurosurgeon will order a lumbar puncture to remove spinal fluid for testing.
Improvement in gait after this procedure may indicate that you are more likely to improve with the placement of a shunt.
Your doctor may also order a tube called a lumbar drain to drain the excess cerebral spinal fluid over a period of several days. This test requires that the patient be evaluated in a hospital with staff trained to manage these catheters to prevent complications such as infection or spinal injury. Again, improvement in gait after this procedure may indicate that you are more likely to improve with the placement of a shunt.
In addition to a neurologist and/or neurosurgeon, neuropsychologists may help with the diagnosis by analyzing specialized memory tests that help identify problem areas of memory and thinking. Neuroradiologists can also help by analyzing the brain images demonstrating enlarged ventricles and other imaging studies that may exclude other causes of gait difficulty or dementia. Physical therapists and other rehabilitation specialists can help evaluate problems with walking and mobility, especially before and after lumbar puncture or lumbar drain trials.
Treatment and Care for Normal Pressure Hydrocephalus
Diagnosis of NPH usually results in surgical treatment or the placement of a shunt. In this procedure, a shunt (a tube with a built in pressure valve) is inserted into the cerebrospinal fluid (CSF) to drain extra CSF away from the brain, thereby allowing the enlarged ventricles to decrease. The fluid is ‘shunted’ away from the brain (usually into a part of the abdomen known as the peritoneum) where the excess CSF is then easily and safely absorbed back into the body.
The most common location to place this shunt is directly into the ventricles (known as a ventriculoperitoneal (VP) shunt). Placing a shunt is a straightforward neurosurgical procedure, but it is not without risks. Among the recognized complications of this procedure are bleeding into the brain, over drainage of CSF and CSF infections. Following shunt placement, the majority of patients go home within a few days.
Rehabilitation time varies. Some patients may improve within a few days or weeks and some may need months to improve or stabilize and not show further worsening of symptoms. Usually, gait problems tend to improve more than problems with memory and thinking. Loyola University Medical Center's neurosciences department has a dedicated program with a multidisciplinary team of physicians and staff with specific interest and expertise in this disorder.
Causes and Risk Factors of Normal Pressure Hydrocephalus
NPH usually affects patients over 60 years old, and the likelihood increases as you age. NPH is often confused with other memory disorders and diseases, most commonly Alzheimer’s disease and Parkinson’s disease.
Other brain disorders can be possible causes of NPH, including:
- Head injury
- Past brain surgery
- Ruptured aneurysm
However, in most cases the cause of NPH remains unknown. It is important to see your doctor if you notice any of the signs of NPH to ensure prompt diagnosis and treatment.