A Diagnostic Dilemma

Normal Pressure Hydrocephalus Program

A Diagnostic Dilemma

We have already emphasized the importance of early diagnosis and treatment of NPH to prevent long term disability. However, many patients with dementia or gait problems and large ventricles on a brain imaging study will not improve after shunting. Performing surgery on all such patients, without further selection, can result in ineffective surgery, and more importantly other potential complications like bleeding around the brain (a subdural hematoma). Therefore selecting the patients with suspected NPH who are most likely to benefit from surgery is of the utmost importance. Most patients with suspected NPH will first undergo a lumbar puncture to measure the CSF pressure, and then drain off excess fluid, temporarily lowering the pressure. If they improve after this procedure they will usually be referred for placement of a permanent ventriculoperitoneal shunt. However, “improvement” after lumbar puncture is generally assessed subjectively, and can be very transient. There are many NPH patients who do not improve after lumbar puncture, but who could still benefit from a shunting procedure. Studies have shown that careful evaluation of patients using objective measures during prolonged CSF drainage via a lumbar drain is the most sensitive and specific way to predict which patients will improve with surgery.

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