Neurosurgery 99:50–59, 2026
This study evaluates lumbar infusion testing (LIT) as an adjunctive diagnostic tool for idiopathic normal-pressure hydrocephalus (iNPH) in a cohort of 165 patients, defining an optimal Rout threshold (≈12 mm Hg·mL−1·min−1) with good sensitivity and specificity. It reports LIT’s role in multidisciplinary decision-making, its safety, and its contribution to selecting patients for ventriculoperitoneal shunting and improving postshunt outcomes.
The authors detail standardized clinical, radiological, and hydrodynamic assessments, show outcome rates after shunting across pretest probability groups, and propose a diagnostic algorithm positioning LIT as a reproducible, low-morbidity adjunct when clinical and imaging data remain inconclusive.
Goal Evaluate lumbar infusion testing (LIT) performance to support shunt decision-making in suspected idiopathic normal-pressure hydrocephalus (iNPH), given no single reliable diagnostic test exists.
Cohort 201 referred; 165 had interpretable LIT results (mean age 79), assessed with combined clinical, radiological, and hydrodynamic workup.
Symptom profile In the 165-patient LIT cohort, gait disturbance was present in 98.8%, cognitive impairment in 86.6%, and urinary disturbances in 58.8%.
Key metric CSF outflow resistance (Rout) differed significantly across diagnostic probability groups, and the optimal cutoff was ~12 mm Hg/mL/min (AUC 0.8441), yielding 78.1% sensitivity and 74.3% specificity for shunt-response prediction.
Clinical utility (borderline cases) In patients initially classified as possible iNPH who were shunted based on LIT findings, 75.6% improved clinically.
Outcomes (high-probability cases) In the probable iNPH group, 87.1% of shunted patients showed improvement.
Safety No complications (e.g., intracranial hypotension syndrome or infection) were observed after LIT in this cohort.
Conclusion LIT is not definitive for iNPH diagnosis but is a safe, reproducible adjunct that helps in diagnostic uncertainty, supports earlier decision-making, and can help avoid unnecessary surgery when combined with clinical and radiological assessment.
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