Shunting for Idiopathic Normal Pressure Hydrocephalus

Dr. Margarita Fedorova discusses the effectiveness of shunting for idiopathic normal pressure hydrocephalus. 

Show citation: 

Luciano MG, Williams MA, Hamilton MG, et al. A Randomized Trial of Shunting for Idiopathic Normal-Pressure Hydrocephalus. N Engl J Med. 2025;393(22):2198-2209. doi:10.1056/NEJMoa2503109  

Show transcript: 

Dr. Margarita Fedorova:

Welcome to Neurology Minute. My name is Margarita Fedorova and I'm a neurology resident at the Cleveland Clinic. Today we're reviewing a randomized trial that provides high quality evidence for treatment we've been using for decades, shunting for idiopathic normal pressure hydrocephalus. The PENS trial, a placebo controlled effectiveness and iNPH shunting trial was published in the New England Journal of Medicine in December 2025 by Luciano and colleagues. This international multicenter study enrolled 99 patients across the United States candidate in Sweden. While idiopathic normal pressure hydrocephalus or iNPH is characterized by triad of gait impairment, cognitive decline in urinary continence, these findings can be non-specific and we mass factor in radiological findings too. Furthermore, while CSF shunting has long been the standard treatment, its effectiveness has never been rigorously confirmed in a large well-powered randomized trial. In this trial, patients with a clinical improvement in gait velocity after temporary CSF drainage were deemed eligible for shunting and randomizing the trial.

What makes this trial particularly elegant is its blending strategy. All 99 participants underwent the same surgical procedure with the same commercially available programmable shunt valve. After surgery, the valve was set either to an open functioning position or to a high resistance placebo setting. Neither patients nor assessors knew who had a working shunt. This is about as close to a true double-blind design as neurosurgery can get. The primary outcome was changing gait velocity at three months. The open shunt group improved by 0.23 meters per second on average, while the placebo group showed essentially no change in 0.03 meters per second. That's a treatment difference of 0.21 meters per second, both statistically significant and clinically meaningful. To put that in perspective, a change of 0.10 meters per second is considered the threshold for substantial meaningful change in the elderly. 80% of the open shunt group exceeded that threshold compared to only 24% of the placebo group. 

The Tenet scale, which measures gait imbalance, also showed significant improvement in the open shunt group. However, screening measures for good condition using the MoCA scale and bladder symptoms did not reach significance at three months, though tertiary outcomes for cognitive testing, quality of life and functional independence tended in favor of shunting. Importantly, falls were more common in the placebo group at 46% compared to 25% in the open shunt group. This is a meaningful safety signal given how dangerous falls are in older adults. There were also real risks with active shunting. Subdural hematomas occurred in 12% of the open shunt group versus 2% of placebo and three even required surgical intervention. Positional headaches from low CSF pressure were more common in the open shunt group at 59% versus 28%. The good news is that the adjustable valve allowed non-invasive management of many of these complications. While this trial gives us reasons to be cautiously optimistic about shunting for appropriately selected iNPH patients, it's worth noting that we only have evidence for improvement in gait and follow-up is only three months. 

Longer-term data is still being collected so we don't know yet how durable these benefits are. If you want to read more, please find the paper by Mark G. Luciano, et al. It's titled A Randomized Trial of Shunting for Idiopathic Normal Pressure Hydrocephalus published in the New England Journal of Medicine in December 2025. That's your neurology menu for today. Keep exploring and we'll see you next time.