What is normal pressure hydrocephalus (NPH)?

Normal pressure hydrocephalus (NPH) is an abnormal increase of cerebrospinal fluid (CSF) in the brain's ventricles, or cavities. NPH occurs if the normal flow of CSF throughout the brain and the spinal cord is blocked in some way, causing the ventricles to enlarge, putting pressure on the brain. NPH can occur in people of any age, but it is most common in the elderly population. It may result from a subarachnoid hemorrhage, head trauma, infection, tumor, or complications of surgery. However, many people develop NPH even when none of these factors is present. In these cases, the cause of the disorder is unknown.

Symptoms of NPH include progressive mental impairment and dementia, problems with walking, and impaired bladder control, leading to urinary frequency and/or incontinence. The person also may have a general slowing of movements or may complain that his or her feet feel "stuck." Because these symptoms are similar to those of other disorders such as Alzheimer's disease, Parkinson's disease, and Creutzfeldt-Jakob disease, the disorder is often misdiagnosed. Many cases go unrecognized and are never properly treated. Doctors may use a variety of tests, including brain scans (computed tomography [CT] and/or magnetic resonance imaging [MRI]), a spinal tap or lumbar catheter, intracranial pressure monitoring, and neuropsychological tests, to help them diagnose NPH and rule out other conditions. In September 2005, an international team of scientists developed clinical guidelines to help physicians diagnose NPH. The guidelines were published as a supplement to the journal Neurosurgery.

This Answer is based on source information from  the National Institute of Neurological Disorders and Stroke.