Many of us would recognize that memory loss, difficulty walking and incontinence are among the symptoms of Alzheimer's disease, a brain disorder that affects as many as 5 million Americans.
But it is estimated that between 2 percent and 5 percent of those diagnosed with Alzheimer's may actually be suffering from hydrocephalus, says Michael A. Williams, neurologist at Sinai Hospital of Baltimore. And in many cases, these patients can be treated and the symptoms diminished.
What is hydrocephalus?
Hydrocephalus comes from the Greek words "hydro," which means water, and "cephalus," which means head. It occurs when the spinal fluid within normal cavities inside the brain (called ventricles) builds up.
The spinal fluid, which among many other functions acts as a protective cushion for the brain, typically circulates through the ventricles and is absorbed into the blood stream. In hydrocephalus, the rate of absorption is diminished, causing the ventricles to enlarge and cause symptoms.
Is hydrocephalus a disease of the elderly?
Hydrocephalus can be congenital. Young or middle-aged adults also can present with hydrocephalus. This younger group is under-recognized because their symptoms are much more subtle. But it can also affect older adults -- those who are age 50 and over. And this is called adult-onset normal pressure hydrocephalus (NPH).
What are the symptoms of hydrocephalus in older adults?
There are three main symptoms: trouble with walking and balance, memory loss and bladder control [problems]. Those, in fact, are the three most common problems of the elderly, and while not everyone who has those symptoms has hydrocephalus, some do.
What causes the disorder?
Well, [for] most people ... we don't know. But there are things that can predispose someone to NPH such as a concussion or head injury years ago, or a brain infection like meningitis, or bleeding in or around the brain. For the most part, these are the kinds of things that family members remember and can point to.
How many elderly people are affected by it?
One estimate you will hear is that it affects about 5 percent of the Alzheimer's population. But if you are looking for a hard number, a study that we published in July (using the Medicare database of people over 65 over a five-year period from 1997 to 2001) indicated that there were about 29,000 to 30,000 patients in the United States diagnosed with NPH. But I think that number is an underestimate.
How is hydrocephalus treated?
The most common treatment is to surgically place a shunt into the brain. The shunt, a small flexible silicone tube about 1/8- of-an-inch thick, allows the excess spinal fluid to be drained out of the brain to another site in the body where it can be reabsorbed -- usually the abdomen, but sometimes the jugular vein.
In some cases, especially when the patient has virtually no symptoms or loss of function, the best thing you can do is wait and watch.
How is the disorder diagnosed?
The first step is to get a CT scan or an MRI to see if the ventricles -- or the cavities of the brain -- are larger than they ought to be. If it shows that the ventricles are enlarged and if the patient has the symptoms we talked about, then the next step is to do more testing to figure out if they are likely to respond to treatment with a shunt.
The most accurate tests involve assessing a person's response to removal of spinal fluid, which is done either with a spinal tap or by inserting a temporary drainage tube in the spinal fluid for two to three days. (During this procedure, the patient is in the hospital).
What is the outcome for those treated for NPH?
Often the most significant changes after shunt surgery, and usually the most rapid, is in their walking and balance. For example, I've seen patients who needed a wheelchair or a cane before surgery who could then walk independently afterward. But it's important to know that there is variability among patients, and not everyone has the same degree of recovery.
What is the long-term prognosis?
If they have hydrocephalus, they can get better, and they should stay better. But the caveat is that this is an elderly population, so they may experience the symptoms again over time. The problem we have is knowing whether the problems are being caused by the shunt [wearing out or not working correctly] or are now being caused by other health problems that elderly patients can have.
What happens if the condition is not treated?
It is a progressive disorder. It is very hard to predict how fast, but people can reach the point where they are wheelchair- or bed-bound, they are incontinent or the dementia is so bad they can't recognize their family.
But when I say that, I'm thinking of elderly patients who had it untreated for 20 years. Most patients we see have had symptoms for four or five years, and we're able to recognize it and reverse it. Somehow with hydrocephalus, the brain is able to come back despite such prolonged symptoms.
Learn more about hydrocephalus at baltimoresun.com/expertadvice