Normal Pressure Hydrocephalus, or NPH, is characterized by the accumulation of cerebrospinal fluid (CSF) in the brain, leading to enlarged brain ventricles. Despite the increased volume of fluid in the brain, intracranial pressure remains the same, which is why it is referred to as "normal pressure" hydrocephalus.
This condition typically presents with three characteristic symptoms: difficulty walking, urinary incontinence and loss of cognitive functions. It is most usually diagnosed in patients over 65 years of age, which is why it may be confused with dementia, however it can occur at any age.
In most cases, NPH is completely reversible. Treatment involves involves draining the accumulated CSF in the brain with a shunt and redirecting it to another area of the body for reabsorption.
Main symptoms
Normal pressure hydrocephalus usually presents with three hallmark symptoms:
1. Gait disturbance
Patients with NPH will often have an abnormal walking pattern, in which they take wide, short steps with a slight lean forward at the torso. This can make walking up the stairs or up and down slopes more difficult, and can also interfere with balance. Difficulty walking is usually the first symptom to emerge.
2. Urinary incontinence
In more mild cases, patients with NPH may experience urinary frequency or sudden urges to urinate. More severe cases of NPH may present with a total loss of bladder control.
3. Cognitive impairments
Symptoms resembling dementia, like forgetfulness, mood changes, slower thinking and difficulty making decisions may be noted in patients with NPH. Other patients may also have a lack of interest in things that may have once been pleasurable, as well as a reduced attention span and difficulty complete tasks.
These symptoms may not present all at once, and may develop from mild to moderate in severity depending on the stage of the disease.
Common causes
Normal pressure hydrocephalus can be classified into two types, depending on the cause:
- Idiopathic NPH, in which the underlying cause of increased CSF production is unknown
- Secondary NPH, in which the patient has had recent risk factors like a stroke, head injury or infection (e.g. meningitis or mumps)
In both types, excess CSF and enlarged brain ventricles are identified, while brain pressure within normal limits. However, idiopathic NPH tends to be more commonly diagnosed in older adults, while secondary NPH can affect patients of all ages.
Confirming a diagnosis
NPH may first be suspected during a clinical exam, in which a neurologist carefully assesses any abnormalities in the patient's movement, thinking and physical functioning. The doctor may then order brain imaging tests, preferably an MRI, to visualize the ventricles and determine whether they are enlarged, and to identify any fluid accumulation in the brain.
CSF flow tests or a magnetic resonance spectroscopy (MRS) can also be ordered to confirm a diagnosis.
Treatment options
Treatment for normal pressure hydrocephalus is aimed at draining the CSF to reduce ventricle size and restoring normal brain and body functioning. This can be achieved with the surgical implantation of a shunt.
This procedure involves implanting a small, flexible tube into affected ventricles to drain the CSF and divert it to another area in the body (usually the abdomen), where it can be reabsorbed. A valve inside the shunt helps to keep CSF and ventricular pressure in the brain within normal levels.
Most patients experience a notable improvement in symptoms immediately after this procedure, although many may take weeks to months to fully recover. Physiotherapy may be prescribed for patients who continue to have mobility issues even after the surgery.