Diagnosis of NPH

Normal pressure hydrocephalus (NPH) can be difficult to diagnosis and a thorough and accurate diagnosis is essential for successful treatment. Several different diagnostic procedures and tests are used to diagnose the condition. A patient history and physical examination is generally considered the first step.

The goal is to document symptoms—and when they began—in order to help determine the patient's current condition. As part of this process, it's important to review the personal and family medical history.

Neuropsychological tests consist of a series of questions and tasks that can help to determine the patient's cognitive abilities (thinking and memory) and the extent of any brain impairment. These tests may be recommended before as well as after a lumbar puncture. Neuropsychological tests can also be helpful in determining whether shunt surgery may be a useful treatment option.

A CT scan (computed tomography) of the head or brain is a painless and low-risk diagnostic imaging test. A CT scan provides an image of the brain, similar to an x-ray. In some cases, a contrast agent (dye) is used to help make the images easier to read. A CT scan can help detect physical and structural abnormalities, such as areas of the brain that may be affected by the build-up of CSF pressure. In general, a CT scan is an outpatient procedure.

An MRI scan (magnetic resonance imaging) of the head or brain is another painless and low-risk diagnostic imaging test. Magnetic resonance imaging uses a strong magnetic field and radio waves to create a very detailed picture of the brain. In general, a MRI is an outpatient procedure, with the actual procedure taking about 30 to 90 minutes to complete. In some cases, the patient is given a sedative to help relieve anxiety and stress about this test. Patients with any metal inside their bodies or certain implanted devices like pacemakers may not be able to undergo MRI.

A lumbar puncture (or spinal tap) may be used to both measure the pressure of the CSF and to test whether reducing the CSF pressure actually relieves symptoms. First, a tiny sensor may be inserted in the skull to measure pressure on the brain. Then, during the actual lumbar puncture procedure, a catheter (small, flexible tube) is inserted in the lower back. The catheter allows a small amount of fluid to drain from the spinal column. The patient is then checked to see if symptoms have improved.

Risks from a lumbar puncture include headache, bleeding, and infection. Headache may occur from a couple of hours to 1 day following the lumbar puncture and is less common when the patient remains lying flat for 1–3 hours after the procedure. Patients may remain hospitalized for observation for a few hours to a few days following this test.

Other diagnostic tests may also be used to diagnose normal pressure hydrocephalus (NPH). For example, cisternography is a test that examines the rate of absorption of the CSF over a period of time. This test involves the injection of a radioactive isotope into the spinal column, usually in the lower back.

It is important to discuss possible risks and benefits with your healthcare provider before undergoing any diagnostic procedure and to adhere to all preparation and follow-up instructions. Any unusual or severe side effects, such as headache or nausea, should be reported to your healthcare provider immediately.

Publication Review By: Alan B. Ettinger, M.D.

Published: 06 May 2006

Last Modified: 28 Sep 2015