Normal Pressure Hydrocephalus – Slow and Steady Pressure… Loses the Race

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You may or may not know someone with dementia, but you are most certainly familiar with it – this common disease currently affects 36 million people worldwide. It is a clinical condition in which a patient suffers a decline in mental functioning, and in a preponderance of cases, this process progresses into an inevitable debilitating disease. Yet, many people are unaware of the fact that some types of dementia are reversible. An example of this is Normal Pressure Hydrocephalus (NPH), a syndrome characterized by a triad that includes dementia, difficulty walking, and urinary incontinence. Unfortunately, the presenting symptoms of NPH are similar to those found in many other clinical scenarios witnessed in the elderly population, oftentimes making it difficult to discern the right diagnosis. Patients who undergo prompt treatment for NPH have a 60% chance of clinical improvement. Quick recognition of the signs and symptoms related to this disease enables an earlier intervention and creates a greater probability of a life changing treatment.

In order to understand NPH, we must first learn some basic cerebral physiology. The brain and spinal cord are surrounded by CSF (cerebrospinal fluid), a liquid that acts as a regulator of cerebral blood flow. It is produced within the ventricles (cavities in the brain), runs through the brain and spinal cord, and eventually drains into specialized tissue cells known as arachnoid. Scientists have determined that patients with NPH have damage to the arachnoid tissue and, consequently, the CSF is not adequately absorbed. Gradually, the excess CSF causes a localized increase in pressure over the brain tissue leading to the clinical syndrome. [However, the overall brain pressure does not increase, hence the name “normal pressure” hydrocephalus]. The injury to the arachnoid tissue can occur when a patient suffers brain trauma, intracranial bleeds, infections, cancer, or an inflammatory process. The typical triad seen in the clinical manifestation of NPH involves: A) dementia, characterized by a decrease in attention and concentration abilities, in addition to a general sense of apathy; B) gait abnormalities, in which patients take short steps and have a marked decrease in their stride; and C) urinary incontinence. The diagnostic process involves a cognitive examination and radiographic imaging studies such as CT scans and MRI’s. NPH is treated with a ventricular shunt, a device inserted into the brain (via surgery) designed to remove the excess fluid.

As with any surgical procedure, ventricular shunts incur some complications. For example, patients can develop headaches (due to over drainage of CSF), intracranial bleeds, infections, seizures, or they can have a mechanical device failure requiring shunt replacement. Of note, patients who decide to undergo surgery should have this done within 6 months of the onset of symptoms, as studies have shown better outcomes in this particular subset of patients. So, for anyone with an elderly grandparent, friend, or neighbor who has received a diagnosis of dementia, consideration of the other two classic symptoms may lead to a swift diagnosis of NPH. Your concern and inquisitiveness just might make all the difference in whether someone gets a second chance at their old life.

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