Adam S. Mednick, MD, PhD, is a neurologist at Yale-New Haven Hospital and at Hospital of St. Raphael. He is the recipient of the Compassionate Doctor Award and is the author of The Area Centralis of the Goldfish Retina. His work has also been featured in Brain Research and the Journal of Comparative Neurology. He lives in North Haven, Connecticut.

Normal Pressure Hydrocephalus

From Diagnosis to Treatment

By Adam S. Mednick

Addicus Books, Inc.

Copyright © 2013 Adam S. Mednick, M.D., Ph.D.
All rights reserved.
ISBN: 978-1-936374-96-0

Contents

Acknowledgments,
Introduction,
1 Normal Pressure Hydrocephalus: An Overview,
2 Getting a Diagnosis: General and Neurological Examinations,
3 Getting a Diagnosis: Diagnostic Tests,
4 Treatment for NPH,
5 After Your Surgery,
Resources,
Glossary,
Index,
About the Author,

CHAPTER 1

Normal Pressure Hydrocephalus: An Overview

If you’re like most people, you’ve probably never heard of the brain disorder called normal pressure hydrocephalus (NPH). This disease is more common than most people realize, however. It is rarely mentioned by the media, and few, if any, famous people have brought attention to NPH like they have with other diseases such as Parkinson’s disease and breast cancer. Consequently, NPH is little known, and, because its symptoms mimic those of other diseases, it is also often misdiagnosed and can be mistaken for Parkinson’s disease, Alzheimer’s disease, or other forms of dementia. Because the disease usually affects older individuals, symptoms are sometimes associated with “just getting older.”

Perhaps you’ve become interested in NPH because you or a loved one has been diagnosed with it. If this is the case, you may find some relief in learning about the disease — its symptoms, causes, and treatment. In many cases, the symptoms can be reversed with surgery.

What Is Normal Pressure Hydrocephalus?

NPH is a slowly developing condition in which too much cerebrospinal fluid builds up in the brain. This clear liquid circulates throughout the brain and the spine. The term “hydrocephalus” is derived from the Greek word “hydro,” which means “water,” and the word “cephalus,” which means “head.” The term literally translates to “water head.” In common terms it is sometimes referred to as “water on the brain.” NPH is considered a neurodegenerative disorder, which means that the symptoms affecting the brain gradually worsen, usually over the course of many months to years.

How NPH Develops

To better understand how NPH develops, let’s first take a brief look at the processes that occur in the brain that can lead to NPH. The human brain is bathed in a clear fluid called cerebrospinal fluid (CSF). This fluid provides nutrients to the brain and helps to cushion the brain against movement inside the skull. Cerebrospinal fluid circulates through four specialized chambers within the brain called ventricles. A group of specialized cells within the lining of these ventricles produces about one pint of this fluid per day.

After traveling through the brain, the cerebrospinal fluid circulates down through the center of the spinal cord and circulates back up toward the brain where it is reabsorbed back into the bloodstream. If the fluid is not reabsorbed properly, however, it slowly builds up within all of the ventricles, causing them to enlarge. This enlargement distorts the surrounding brain tissue and can cause permanent brain damage. It is this lack of reabsorption of fluid that causes normal pressure hydrocephalus.

It may seem confusing that the word “normal” is part of the name of a serious brain disorder. What does “normal” mean in this context? In this case, “normal” refers to the level of pressure the cerebrospinal fluid is putting on the brain. If doctors were to perform medical tests on a person with NPH to measure the pressure of the cerebrospinal fluid inside the brain, the pressure would appear normal or only slightly elevated. This is because NPH develops so slowly, over a period of months to years, that the brain is able to gradually increase its capacity to store the fluid within the ventricles. As a result, the pressure appears normal. The building pressure on the brain, however, eventually leads to the development of symptoms.

You may hear your neurologist refer to NPH as “communicating hydrocephalus.” To understand what “communicating” means in this context, you might think of it in this way: because the fluid is circulating freely through all the ventricles and the channels between them, the fluid is communicating with all parts of the brain.

There are two types of NPH. The most common type is called primary or idiopathic NPH, which means the cause for the disease is not known. About 75 percent of all NPH cases fall into this category. The other form, secondary NPH, is the result of known causes such as previous brain trauma, prior bleeding into the brain, infection, or as a result of radiation therapy for the treatment of a brain tumor. These conditions may leave scarring that interferes with the way the cerebrospinal fluid drains from the brain.

This NPH that develops later in life is called “acquired hydrocephalus.” There are other forms, including that which is present at birth. It is called congenital hydrocephalus. Another form, hydrocephalus ex vacuo, is caused by shrinkage of brain tissue rather than an excess of cerebrospinal fluid and does not cause the same debilitating symptoms.

Symptoms of Normal Pressure Hydrocephalus

With NPH, not all the symptoms appear at the same time, and some individuals may not develop all symptoms even in advanced stages. Symptoms start to occur as the build-up of cerebrospinal fluid gradually distorts brain tissues around the ventricles, particularly in the nerve fibers responsible for gait (one’s foot sequence or pattern of walking), urinary continence, and cognition. As a result, normal pressure hydrocephalus is characterized by three primary symptoms: unsteadiness in gait, or trouble walking; urinary incontinence; and cognitive difficulties, which is often referred to as dementia.

Unsteadiness in Gait

Unsteadiness in gait, or trouble walking, is typically the first symptom to develop in NPH, and it is also the most common feature of this disease. Nearly everyone with NPH develops unsteadiness. The unsteadiness in NPH is typically described as “magnetic” because it seems as if the feet are stuck to the floor. This symptom is easily recognized by family and friends. Symptoms of unsteadiness range from mild to severe and may include:

• reduction in length of stride (short, shuffling steps)

• reduction in step height

• difficulty taking steps, as if feet are stuck to the floor

• forward-leaning posture

• a wide-based gait (walking with legs farther apart than normal)

Because it can be difficult for individuals with NPH to lift their feet, they typically have problems going up stairs or curbs; they also have problems turning around and may need to take multiple, short steps to do so. The unsteadiness occurs when walking and is not associated with weakness or numbness of the legs.

Urinary Incontinence

Urinary incontinence refers to the inability to control one’s urine flow. With NPH, incontinence usually develops gradually over the course of months to years. Symptoms may include:

• urinating more frequently

• feeling an urgent need to urinate

• inability to hold urine

In severe cases, a person may become totally incontinent and require the use of a diaper. In rare cases, bowel incontinence may occur as well. Not all patients with NPH will develop urinary incontinence and in those who do, it usually begins after the onset of unsteadiness, although either symptom may precede the other. There are no characteristic features of urinary incontinence to help distinguish NPH from other disorders.

Cognitive Difficulties

Cognition refers to the process of thinking and knowing things. It includes awareness, reasoning, remembering, perception, and problem solving. Cognitive problems, or dementia, are typically the last of the three primary features of NPH to develop; they usually begin several months or years after the onset of unsteadiness and urinary incontinence. By the time dementia settles in, a person with NPH is usually in the more advanced stages of this disease. Symptoms of cognitive difficulties or dementia may include:

• forgetfulness

• loss of interest in daily activities

• short-term memory loss

• change in mood or behavior

• difficulty performing routine tasks

• difficulty in reasoning or making decisions

In the early stages of NPH, the dementia may be mild. Symptoms may include such things as forgetting where you left the car keys or forgetting someone’s name. Family and friends may attribute these symptoms to a person’s getting older rather than a sign of a serious disease. The dementia in NPH usually continues to worsen to the point where a person requires help with all daily activities.

There are no characteristic features to distinguish the dementia that comes with NPH from other forms of dementia.

Order in Which Symptoms Appear

An important distinction between NPH and other brain disorders is the order in which the symptoms appear. It is extremely important to establish the timing of the onset of the symptoms of NPH. The first symptom of NPH is almost always unsteadiness, followed by incontinence and then the gradual onset of memory problems, which may not develop for years. In NPH, unsteadiness and urinary incontinence, in either order, always occur before the onset of dementia. If an individual’s symptoms do not occur in this order, it is unlikely that he or she has NPH.

For example, one of the first symptoms of Alzheimer’s disease is memory problems; then, as a person becomes progressively mentally incapacitated, he or she may lose the ability to walk and control the bladder. With Parkinson’s disease, unsteadiness is typically one of the early symptoms, with incontinence developing later, but incontinence is usually due to the difficulty in walking to the bathroom. Furthermore, people with Parkinson’s disease usually develop tremors and have diminished arm swing when walking — neither of which is a symptom of NPH. Dementia may occur late in the development of Parkinson’s disease, usually long after the onset of other symptoms such as tremors, stiffness, and shuffling the feet when walking.

Risk Factors for NPH

The risks of developing NPH differ depending upon whether you have primary or secondary NPH. Primary NPH is a disease affecting individuals in their sixties and beyond but is more common in those who are in their seventies and eighties. Because secondary NPH occurs as a result of an underlying cause, such as brain hemorrhage, brain infection, head trauma, or radiation therapy to the brain, this form of NPH may affect individuals of any age. Primary and secondary normal pressure hydrocephalus affect both men and women equally, regardless of race or ethnicity.

How Common Is NPH?

There are no solid statistics on how many people have NPH; however, various published studies, including one from the Hydrocephalus Study Group, published in the journal Neurosurgery in 2005, estimate that as many as 350,000 Americans with dementia may have NPH. Unfortunately, only about 11,000 are being treated for the disease. The organization Alzheimer’s Disease International estimates that worldwide, 36 million people have dementia of whom 1.8 million (5 percent) may have NPH.

Treatment for NPH

There are currently no drugs to slow or reverse the symptoms of normal pressure hydrocephalus. However, some individuals with NPH may be candidates for surgery that can often reverse the symptoms or at least slow the progression of the disease. There are two forms of surgery that can be performed. The first involves placing a shunt in the brain, which is a tube that allows the excess cerebrospinal fluid to drain away. The second procedure involves creating a small hole in one of the brain’s ventricles, which also allows the excess fluid to drain away from the ventricles.

As a general rule, the longer the symptoms have been present, the less likely it is that surgery will help. This is why it is so important to get a diagnosis as early as possible — the earlier the diagnosis, the better the chance for reversing symptoms. Still, some people who have had symptoms for years can also improve with surgery. The surgical procedures for NPH are explained in chapter 4.

CHAPTER 2

Getting a Diagnosis: General and Neurological Examinations

The first part of your examination includes general and neurological exams. Your neurologist will ask about your medical history — such things as medications you’re currently taking, allergies to any medications, use of tobacco products and alcohol, pertinent family history, and social history — martial status, whether you have children, and your employment if you’re not retired.

Questions about Medical History

The neurologist will also ask questions about a variety of physical ailments. He or she will ask questions to assess:

• overall health — any changes in weight, appetite, sleep patterns; have you had fatigue, fever, chills, sweats

• eyes — visual changes, eye pain, discoloration, tearing

• ears — hearing changes or ringing in ears

• nose — runny nose or nasal congestion

• throat — trouble swallowing or pain in teeth, tongue, or gums

• cardiovascular — chest pain, shortness of breath, light-headedness

• respiratory — coughing, shortness of breath, or labored breathing

• gastrointestinal — abdominal pain, cramping, nausea, vomiting, bloating, constipation, diarrhea

• genitourinary — incontinence, frequent urination, pain during urination, menstrual irregularities

• musculoskeletal — joint or muscle pains

• skin — rashes, eczema, itching, insect or animal bites

• allergic/immunologic — allergies to foods, medications, or bee stings; any recurrent infection

• hematologic — blood in sputum, urine, or stool; anemia; easy bruising

• endocrine disorders — fatigue, intolerance to hot or cold, unexplained changes in weight, menstrual irregularities, sexual dysfunction, excessive thirst or urination

• psychiatric — depression, anxiety, or mood swings

In addition to checking for symptoms that may indicate NPH, a neurologist will be looking for others that could be signs of potentially serious illnesses. For example, someone complaining of fatigue, chest pains, and shortness of breath may need to be evaluated for cardiac or respiratory disorders. Symptoms such as frequent urination and excessive thirst may require blood-sugar testing to check for diabetes.

Physical Exam

Having asked questions about your medical history and any physical ailments, a neurologist will then perform a careful physical examination. During the physical examination, the neurologist will check vital signs such as blood pressure and heart rate. He or she will also examine your skin, head, mouth, neck, abdomen, hands, arms, legs, and feet. There are, however, no specific physical abnormalities that would indicate the presence of NPH.

Neurological Examination

The neurological examination is a complex procedure and is usually performed by neurologists and neurosurgeons. This exam consists of nine parts that assess: mental status, gait (walking ability), cranial nerves, motor strength, muscle tone, reflexes, motor coordination, sensation, and speech and language.

Note that not all of these functions are affected by NPH, but a neurologist will need to complete a thorough neurological examination to determine what is causing your symptoms, and then decide if NPH or some other disorder is likely the cause.

Although assessment of urinary incontinence is not technically part of a neurological exam, the neurologist will also ask questions about incontinence because it is a primary symptom of NPH.

Mental Status

The mental status examination is an assessment of cognitive functioning — the ability to think and know things. This assessment allows the neurologist to determine whether a patient is able to follow instructions. The neurologist often already has a good idea about the patient’s mental status at this point based on observations made while taking his or her medical history.

Various tests have been developed to determine the level of cognitive functioning if memory impairment is present. The purpose of these tests is to determine how well a person can organize thinking, prioritize goals (multitasking), plan a task, and begin and complete this task. The most common of the cognitive tests is the Folstein Mini-Mental Status Examination. It helps a neurologist quickly establish a reasonably accurate assessment of the patient’s cognitive abilities. The test usually can be completed in less than ten minutes. It contains a series of simple questions about:

• orientation — ability to answer questions such as: Where are you? What is the date?

• immediate recall — ability to recall items after a short period of time, usually five minutes

(Continues…)Excerpted from Normal Pressure Hydrocephalus by Adam S. Mednick. Copyright © 2013 Adam S. Mednick, M.D., Ph.D.. Excerpted by permission of Addicus Books, Inc..
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.