Shunting for idiopathic normal pressure hydrocephalus improved gait in randomised trials, but bleeding risk is unresolved

Design

Systematic review and meta-analysis of four randomised trials with trial sequential analysis (PROSPERO registered)

Population

224 adults aged 60 or older with idiopathic normal pressure hydrocephalus

Primary outcome

Change in gait velocity on timed assessments

Effect

SMD 0.73 (95% CI 0.45 to 1.01); positional headache OR 5.62 (1.16 to 27.18); subdural haematoma OR 4.07 (0.62 to 26.94)

This meta-analysis pooled four randomised trials (224 patients aged 60 or older) comparing immediate CSF shunting against placebo or no shunting in idiopathic normal pressure hydrocephalus. The primary outcome was change in gait speed.

Shunting improved gait velocity (SMD 0.73, 95% CI 0.45 to 1.01) and functional independence (OR 3.92), and the modified Rankin Scale fell by a mean of 0.73. Cognitive scores improved to a lesser extent (SMD 0.37 on the MMSE or MoCA). Positional headaches were more frequent with shunting (OR 5.62, 95% CI 1.16 to 27.18). The estimate for subdural haematoma was imprecise (OR 4.07, 95% CI 0.62 to 26.94), and the authors point out that the largest trial itself reported an excess of subdural bleeding.

For surgeons and referring physicians, this supports offering shunting to carefully selected patients with the gait disorder, while counselling openly about bleeding and headaches. The effect on cognition and urinary symptoms is less certain.

• Consider shunting for carefully selected patients with iNPH where gait impairment is the main problem.
• Expect the clearest gain in walking and independence, and a smaller, less certain gain in cognition.
• Counsel about positional headache and the possibility of subdural haematoma, which these trials could not exclude.
• Check local selection criteria and gait testing; this review does not define who qualifies.
• Arrange follow-up that measures gait speed so benefit is objective.

Why it matters

It gives randomised support to a surgical treatment that has long relied on observational series.

Don't overread it

Four small trials with imprecise safety estimates; it does not define who benefits or how long the benefit lasts.

The statistics, in plain English

An SMD of 0.73 is a moderate-to-large effect on gait. The subdural estimate crosses 1.0 because events were few, so it does not mean the risk is absent. Only four small trials contributed, and some used no-shunt controls rather than a placebo procedure, so patients may have known their allocation.

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