A Randomized Trial of Shunting forIdiopathic Normal-Pressure Hydrocephalus
The issue
In older adults with idiopathic normal-pressure hydrocephalus (iNPH), a double-blind randomized trial showed that turning a programmable shunt “on” significantly improved walking speed and balance at 3 months versus a placebo (near-closed) setting, while cognition and bladder symptoms did not measurably improve. Falls were less common with an open shunt, but subdural bleeds and positional headaches were more frequent and require monitoring. NEJMoa2503109
What do I need to know?
Investigators enrolled 99 adults (mean age ≈75) with suspected iNPH who had already shown gait improvement after temporary spinal-fluid drainage—a standard way to select good surgical candidates. Participants were randomized during shunt placement to an open setting (≈110 mm H2O) or a high-resistance “placebo” setting (>400 mm H2O). At 3 months, gait velocity rose by 0.23 m/s with an open shunt but was essentially unchanged with placebo (difference 0.21 m/s; P<0.001). Balance (Tinetti score) improved more with an open shunt (≈+2.9 vs +0.5), whereas cognition (MoCA) and urinary incontinence scores showed no significant between-group differences. About 80% of open-shunt patients achieved ≥0.10 m/s faster gait—a clinically meaningful threshold. Safety was mixed: fewer patients reported falls with the shunt “on” (24% vs 46%), but subdural hematoma/hemorrhage (12% vs 2%) and positional headaches (59% vs 28%) were more frequent and often managed by raising the valve setting. After the 3-month assessment, all shunts were opened per protocol for longer-term follow-up. NEJMoa2503109
Potential risk of iNPH (undiagnosed gait disorder in an older adult)
Recommended Actions
Ask for an evaluation for iNPH if there is slow, wide-based walking, shuffling, imbalance, urinary urgency, and progressive ventriculomegaly on brain imaging.
Discuss a standardized gait test and, when appropriate, a temporary cerebrospinal-fluid drainage (“tap test” or external lumbar drainage) to predict shunt responsiveness.
Review other causes of gait and cognitive change (Parkinsonism, neuropathy, cervical stenosis, medications).
Imminent risk (probable iNPH with improvement after CSF drainage)
Recommended Actions
Discuss programmable shunt surgery, setting expectations that gait and balance are most likely to improve; cognition and continence may not change much at 3 months.
Review bleeding risks and peri-operative plans; clarify how valve settings will be adjusted if low-pressure headaches or subdural collections occur.
Arrange early post-op follow-up to check walking speed, balance, headaches, and signs of over- or under-drainage; institute fall-prevention and physical therapy.
Confirmed disability from iNPH (substantial gait impairment affecting independence)
Recommended Actions
Proceed with shunt placement in a center experienced with iNPH selection and postoperative valve management.
Monitor closely for complications (positional headaches, subdural hygroma/hematoma); many issues can be managed noninvasively by increasing valve pressure.
Track outcomes systematically (10-meter walk time, Tinetti balance, activities of daily living) and repeat imaging if symptoms suggest over- or under-drainage.
What can I do?
Bring a brief diary of walking problems, near-falls, urinary urgency, and memory changes. Ask the team, “Am I at potential, imminent, or confirmed risk—and would a programmable shunt likely help my walking?” If surgery is planned, confirm who adjusts the valve, what symptoms should trigger a call (new headaches, confusion, or sudden imbalance), and how often gait will be re-measured in the first three months.
