Registry-Based Assessment of Shunt Operation Methods and Outcomes in Idiopathic Normal Pressure Hydrocephalus (RASHOMON Study): Protocol for a Multicenter Prospective Observational Cohort Study
Bibliographic record
Abstract
BACKGROUND: Idiopathic normal pressure hydrocephalus is an age-related condition characterized by cerebrospinal fluid accumulation and ventricular enlargement, leading to cognitive decline, gait disturbance, and urinary incontinence. Although shunt surgery is the primary treatment, the optimal surgical strategy remains uncertain, and procedure selection is often not tailored to individual patient characteristics. Notably, no prospective study has directly compared the 3 major shunt techniques (ie, ventriculoperitoneal, lumboperitoneal, and ventriculoatrial). OBJECTIVE: This multicenter prospective observational study will aim to generate high-quality clinical evidence by evaluating the effectiveness and safety of the 3 aforementioned surgical options in a real-world setting. METHODS: Patients suspected of having this condition will be enrolled based on characteristic symptoms and imaging findings, with a spinal tap test recommended but not mandatory. Eligible patients will undergo one of the aforementioned surgical procedures. RESULTS: On the basis of recent data from 11 collaborating institutions in Japan, we estimate enrolling 278 cases: 188 (67.6%) surgical, 100 (36%) nonsurgical, and 10 (3.6%) dropouts. Clinical outcomes will be assessed at baseline; after the tap test (if performed); and at 1 week, 3 months, and 12 months postoperatively. The analyses will explore the associations between outcomes and surgical methods, patient backgrounds, and imaging features. As of May 2025, approximately 60 participants have been enrolled from 11 institutions. Data collection is ongoing and is expected to be completed by December 2026. There will be a 1-year follow-up period. The main study results are anticipated to be published in 2028. CONCLUSIONS: Japan is well placed to lead this comparative study with its extensive experience in diagnosing and treating this disease. These findings are expected to provide practical guidance for individualized surgical decision-making and contribute to the global consensus on optimal treatment strategies. TRIAL REGISTRATION: Japan Registry of Clinical Trials jRCT1040250005; https://jrct.mhlw.go.jp/latest-detail/jRCT1040250005. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/80678.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.028 | 0.022 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.003 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.013 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".