Shunt Surgery Eases iNPH Symptoms in Older Adults

Implanting a brain shunt in older people diagnosed with idiopathic normal pressure hydrocephalus (iNPH) is effective in improving their symptoms, a randomized, double-blinded, multi-center patient trial shows.

This condition is associated with an enlargement of the brain's ventricles, the spaces where fluid to cushion the brain and spine is produced and stored. The disorder is manifested by slow gait and balance issues that increase the risk for falls, as well as difficulty thinking, memory loss, and urinary incontinence.

"If there's one thing this study does, it resolves a controversy that's been around for many, many years," said Dr. Michael A. Williams, professor of neurology and neurological surgery at the University of Washington School of Medicine in Seattle, and one of the lead authors of the study. The other lead authors are Dr. Mark G. Luciano of Johns Hopkins University, who is the principal investigator for the study, and Dr. Mark G. Hamilton of University of Calgary in Alberta, Canada.

"There've been a lot of physicians who doubt that the disorder exists or that treatment with the surgical implantation of a shunt is either effective or safe," Williams said. "Our trial puts that to rest. Our hope is that now, more neurologists, more neurosurgeons, more doctors will entertain the possibility of iNPH as a diagnosis for their patients, take them through appropriate diagnostic steps and treat them when hydrocephalus is found."

The first set of results comparing treatment and placebo groups were published today, Sept. 16, in the New England Journal of Medicine and simultaneously presented at the 150th annual meeting of the American Neurological Association in Baltimore.

The symptoms are often not attributed to normal pressure hydrocephalus, because such troubles are common in older people and could be due to many other factors. Consequently, the condition is hard to diagnose. However, if hydrocephalus significantly contributes to such symptoms, then treating it can make a big difference in patients' lives, according to these latest findings.

The average age of people with the condition is 75 years, and the older the population, the more likely they are to have normal pressure hydrocephalus. It affects about 1.5% of the population of people in their 70's, and as much as 7% of those in their 80's. The condition is diagnosed through a series of tests that include symptom evaluation, MRI brain scans, and in-hospital evaluations of response to removing some spinal fluid.

Williams noted, however, that at best, maybe only 5% to 10% of patients diagnosed with normal pressure hydrocephalus get treatment.

The Placebo-Controlled Efficacy in Idiopathic Normal Pressure Hydrocephalus Shunting (PENS) study participants, all of whom had a confirmed diagnosis, had a shunt surgically placed under general anesthesia.

The shunt is an internal drainage system. A valve goes under the skin at the side of or back of the head. A small tube from the valve is inserted into a brain ventricle, and a second tube is guided from the valve under the skin to the abdomen, where the excess cerebral fluid can drain.

The shunt used in the study can be turned on or off, and the flow adjusted, with a magnetic device placed over the valve on the scalp. Half of participants had their shunts turned on, and half had them turned off. Neither the patients nor those evaluating them knew which option they had.

In comparing the two groups, the researchers found that patients with an open shunt increased their gait velocity by more than 0.2 meter per second or double the minimum clinically meaningful difference of 0.1 meter per second. Moreover, 80% of them passed that threshold. In the group of patients with closed shunts, gait speed did not improve.

"There was very clearly a difference between the two groups on this measurement," Williams said. In addition, those with closed shunts reported more falls than did those with open shunts.

The patients were surveyed about their quality of life and ability to perform everyday activities. Those rose in the treated group and stayed the same or diminished in the placebo group.

At the conclusion of this portion of the trial, the researchers turned on the placebo group's shunts. Both groups continue to be evaluated. Additional long-term outcomes from the study are still pending, such as whether the improvements were sustained and whether MRI brain imaging can be correlated with symptom reduction.

The first phase of the study used only screening methods to check for cognitive impairment. As the study continues, researchers will use more complete assessments with neuropsychology testing. This will provide information on the range of impairments and whether they get better with treatment.

Dr. Nikolas Dasher, a neuropsychologist in the Department of Rehabilitation Medicine at UW Medicine, played a key role in assessing the efficacy of shunting for this study.

Twenty-one medical centers participated in the trial. One was in Sweden; the rest were located across the United States and Canada. Ninety-nine participants were enrolled.

"If our study has influence, we should see an increase in the number of people who are being found to have iNPH and who are getting treated," Williams said. "That's going to be a lot of improvement for the elderly population. There should be some reduction in health care costs associated with that as well."