A landmark randomized controlled trial has definitively demonstrated that shunt surgery significantly improves mobility and reduces falls in older adults with idiopathic normal pressure hydrocephalus (iNPH), resolving decades of medical controversy about this treatment approach.
The Placebo-Controlled Efficacy in Idiopathic Normal Pressure Hydrocephalus Shunting (PENS) study, published in the New England Journal of Medicine, enrolled 99 participants across 21 medical centers in the United States, Canada, and Sweden. All participants underwent surgical implantation of programmable shunts, with half receiving functioning devices and half receiving placebo shunts that were turned off during the trial period.
Significant Mobility Improvements Demonstrated
The trial revealed striking differences between treatment groups. Patients with functioning shunts increased their gait velocity by more than 0.2 meters per second, representing double the minimum clinically meaningful difference of 0.1 meters per second. Remarkably, 80% of patients in the treatment group achieved this threshold for improvement, while those with closed shunts showed no improvement in gait speed.
"There was very clearly a difference between the two groups on this measurement," said Dr. Michael A. Williams, professor of neurology and neurological surgery at the University of Washington School of Medicine and lead author of the study.
The mobility benefits extended beyond walking speed. Patients with functioning shunts demonstrated improved balance and reported significantly fewer falls during the three-month study period. Only 25% of patients in the open-shunt group reported falling during the trial, compared with 46% of those in the placebo group.
Addressing an Underrecognized Condition
Idiopathic normal pressure hydrocephalus affects a substantial portion of the elderly population, with prevalence rates of approximately 1.5% among people in their 70s and as much as 7% of those in their 80s. The average age of affected individuals is 75 years. The condition is characterized by enlargement of the brain's ventricles and manifests through a triad of symptoms: slow gait and balance issues that increase fall risk, cognitive difficulties including memory loss, and urinary incontinence.
Despite its prevalence and potential for treatment, iNPH remains significantly underdiagnosed and undertreated. According to the study authors, only 5% to 10% of patients diagnosed with normal pressure hydrocephalus currently receive treatment, and only one in five patients who could benefit from shunt surgery are referred for evaluation.
"Diagnosis boils down to a clinical suspicion. Progressive walking difficulty, cognitive problems and urinary issues are some of the telltale signs of normal pressure hydrocephalus. Yet, it has long been underrecognized, leaving many older adults struggling with a preventable disability," said UC Davis neurosurgeon Dr. Branden Cord, who performed the shunt implantations for participants enrolled at UC Davis Health.
Resolving Medical Controversy
The study addresses longstanding skepticism within the medical community about both the existence of iNPH as a distinct condition and the effectiveness of shunt treatment.
"If there's one thing this study does, it resolves a controversy that's been around for many, many years," Williams explained. "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. Our trial puts that to rest."
The researchers hope the definitive evidence will encourage more neurologists, neurosurgeons, and other physicians to consider iNPH as a potential diagnosis for elderly patients presenting with the characteristic symptom triad.
Quality of Life and Healthcare Implications
Beyond the objective mobility measurements, patients in the treatment group reported improved quality of life and enhanced ability to perform everyday activities, while these measures remained static or declined in the placebo group. The implications extend beyond individual patient outcomes to broader healthcare considerations.
"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 noted. "That's going to be a lot of improvement for the elderly population. There should be some reduction in healthcare costs associated with that as well."
The potential impact is particularly significant given that untreated NPH can result in loss of independence, nursing home placement, and increased mortality risk.
Ongoing Research and Future Directions
Following the initial three-month placebo-controlled phase, researchers activated the shunts in the placebo group, and both groups continue to be monitored for long-term outcomes. Future analyses will examine whether the improvements are sustained over time and whether MRI brain imaging can be correlated with symptom reduction.
The study team plans to conduct more comprehensive neuropsychological assessments to better understand the range of cognitive impairments associated with iNPH and their response to treatment. The initial phase used only screening methods for cognitive assessment.
"For patients and families, the most powerful outcome of this trial is hope," Cord emphasized, acknowledging the commitment of patients who participated in this groundbreaking research that advances neurosurgical science and has the potential to change lives in tangible ways.
