Shunting Benefits in Idiopathic Normal-Pressure Hydrocephalus: NEJM
A new clinical trial published in the New England Journal of Medicine found that among patients with idiopathic normal-pressure hydrocephalus who responded to temporary cerebrospinal fluid (CSF) drainage, shunting significantly improved gait velocity and gait/balance measures at 3 months, but showed no benefit for cognition or incontinence.
The study investigated the effects of shunting among patients carefully selected for surgery based on prior improvement in gait after temporary CSF drainage. To assess the effectiveness of the procedure, this trial was set out.
A total of 99 participants were randomly assigned to either an open-shunt group, where the device was set to allow fluid drainage at a low opening pressure (110 mm of water), or a placebo group, where the valve was set at a high pressure (>400 mm of water), essentially preventing drainage.
The primary measure of success was gait velocity 3-months after surgery. The results found that the patients’ walking speed improved by an average of 0.23 meters per second in the open-shunt group, when compared to virtually no improvement (0.03 meters per second) in the placebo group. This 0.21 m/s difference was statistically significant, illuminating that shunting has a real and measurable benefit for mobility.
On the Tinetti scale, which measures gait and balance, the open-shunt group improved by an average of 2.9 points, compared with only 0.5 points in the placebo group. However, the cognitive measure, the Montreal Cognitive Assessment (MoCA), showed only modest gains (1.3 points vs. 0.3 points), and improvements in urinary incontinence were minimal (a decrease of 3.3 points vs. 1.5 points on the Overactive Bladder Questionnaire).
While fewer falls were reported in the open-shunt group (24% vs. 46%), risks of complications were notable. Subdural bleeding occurred more often in the open-shunt group (12% vs. 2%), and positional headaches were also more frequent (59% vs. 28%). Rates of cerebral bleeding were equal in both groups (2%). Overall, this trial demonstrates that shunting offers meaningful improvements in gait speed and stability for patients with iNPH who first respond to CSF drainage, though benefits for cognition and bladder symptoms remain limited.
Reference:
Luciano, M. G., Williams, M. A., Hamilton, M. G., Katzen, H. L., Dasher, N. A., Moghekar, A., Hua, J., Malm, J., Eklund, A., Alpert Abel, N., Raslan, A. M., Elder, B. D., Savage, J. J., Barrow, D. L., Shahlaie, K., Jensen, H., Zwimpfer, T. J., Wollett, J., Hanley, D. F., & Holubkov, R. (2025). A Randomized Trial of Shunting for Idiopathic Normal-Pressure Hydrocephalus. New England Journal of Medicine. https://doi.org/10.1056/nejmoa2503109
