| Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF) in the cavities (ventricles) of the brain. Normal Pressure Hydrocephalus (NPH) is a neurological condition that occurs in adults of 55 years of age and above. In NPH, the accumulation of CSF is gradual, leading to slow enlargement of the ventricles. This, in turn, stretches the nerve tissue of the brain, causing a characteristic triad of symptoms. Diagnosis of NPH is important because it is a reversible cause of dementia and the typical walking instability associated with it can be corrected with surgery.
WHAT CAUSES NPH?
NPH can occur after a stroke, head injury, brain infection or as a result of a brain tumour. This is secondary NPH. In most cases, NPH occurs in later life with no specific attributable cause. Presently, there is no known way in preventing NPH.
WHAT ARE THE SYMPTOMS OF NPH?
Common NPH symptoms:
• Difficulty walking/balancing (Gait disturbance)
- This is usually the first and most obvious symptom. Gait problems range from mild
imbalance with a wide-based, short-stepped, slow and shuffling walk to the complete
inability to walk. Patients with NPH may have difficulties lifting their foot off the floor, trying
to take the next step, turning around and tend to turn slowly in multiple steps.
• Mild dementia (Cognitive impairment)
- This often involves a loss of interest in daily activities, forgetfulness, difficulties in handling
routine tasks and the loss of memory (of recent events).
• Problems with bladder control (Urinary incontinence)
- Patients with NPH may have bladder control difficulties such as a need to rush to the
bathroom with an increased urinary frequency. Later, it may manifest as incontinence.
HOW IS NPH DIAGNOSED?
The symptoms of NPH are similar to those in common elderly illnesses such as Alzheimer's and Parkinson's disease. Hence the early symptoms of NPH are often attributed to the normal process of ageing. The diagnosis of NPH can therefore be difficult. In many cases, symptoms can be present for months or even years before a person sees a doctor as the onset can be slow and gradual leading one to ignore or adapt to these changes. Assessment by a specialist with careful review of the symptoms, medical history, physical examination and possible diagnostic and supplementary tests are often necessary for the diagnosis of NPH.
One or more of these following investigations may be performed to diagnose NPH:
• Brain images
CT scan or MRI is often the first test performed to detect enlarged ventricles.
• High volume lumbar puncture (Spinal tap test)
This test is usually done under local anesthesia with a thin needle inserted into the spinal
fluid space of the lower back. About 40cc of CSF is extracted to see if one's walking is
temporarily improved. This is an important test for diagnosis of NPH and in prediction of the
success of surgery (a ventriculoperitoneal shunt) in gait improvement.
• Gait analysis (Walking)
This is a timed walk test where the person is watched as he or she walks 10 meters. This is usually conducted before or after the spinal tap test.
• MRI CSF flow study
This test assesses how fast CSF moves through a particular part of the brain called the
cerebral aqueduct. It is thought that high CSF flow through the aqueduct can predict
improvement in gait following CSF diversion through a ventriculoperitoneal shunt.
• Continuous lumbar drainage
A thin, flexible tube (catheter) is inserted at the lower back to drain CSF over several days.
This serves to mimic the effect of a shunt. This invasive test yields accurate results.
HOW IS NPH TREATED?
NPH generally cannot be cured but its symptoms can be controlled. Many people with the condition obtain substantial relief through a shunt operation. A shunt is an implantable device designed to drain CSF away from the ventricles in the brain. The shunt is equipped with a system of tubes that is routed under the skin from the head to a distant site where the excess CSF can be absorbed, usually the peritoneal (abdominal) cavity. The device implanted surgically is known as a ventriculoperitoneal (VP) shunt.
HOW IS THE SHUNT SURGERY PERFORMED?
The surgical procedure to implant a VP shunt is usually completed in less than an hour under general anesthesia. The patient's scalp is usually shaved or clipped short and cleansed with antiseptic. Small incisions are made on the scalp and in the abdomen to allow the surgeon to pass the shunt tubing through the fatty tissue just under the skin. A small hole is made into the skull, through which the covering of the brain (dura) is opened and a ventricular tube inserted. This tube is connected to the shunt valve which is in turn connected to a long tubing that leads to the peritoneal cavity. The patient is transferred back to the ward for careful observation immediately after surgery. On the second day after operation, most patients will be able to eat and drink, sit up in bed and start ambulating. Hospital stays usually range from 3-7 days, depending on each individual's progress. Stiches / staples are usually removed between 7-14 days after operation.
WHAT ARE THE COMPLICATIONS AND RISKS INVOLVED WITH SHUNT SURGERY?
Although shunt surgery is a relatively simple procedure, there are risks involved including those associated with any surgical procedure such as bleeding, infection and reaction to the anesthesia used during surgery. Complications may also occur days to years later due to the presence of the shunt. Fortunately, most complications can be dealt with successfully, although treatment may require additional surgery. Your surgeon will discuss with you about the risks and benefits of surgery.
It is important for patients and their families to monitor signs and symptoms resulting from a shunt complication. They should contact their doctors or go to the emergency department immediately if there is any worsening symptom:
• Double vision
• Fever
• Headache
• Irritability or drowsiness
• Nausea
• Persistent giddiness
• Redness, tenderness, pain or swelling of the skin along the length of the tube or incision
• Return of walking difficulties, mild dementia, or incontinence
• Vomiting
WHAT IS THE OUTLOOK FOR NPH PATIENTS?
With early diagnosis and treatment, symptoms of NPH can be partially or even fully reversed, with patients leading a normal life. The symptoms of gait disturbance, mild dementia and bladder control problems may improve within days of shunt surgery, or may take weeks to months. For patients who do improve, positive changes are seen in the first week in most cases, although the improvement may range from mild to dramatic. Several adjustments of the valve are often needed before the correct setting is obtained for the individual.
NPH is a progressive condition, if the symptoms are left untreated, it will worsen gradually, resulting in walking disability or dementia.
ARE THERE ANY PRECAUTIONS TO TAKE AFTER A SHUNT PLACEMENT?
The shunt placement is usually permanent. Patients will be able to live almost normal lives.
Disclaimer: This brochure is meant to be a guide only. If you are in doubt about your condition or a family member's medical condition, please consult your doctor.
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