Recanalization of Obstructed Cerebrospinal Fluid Ventricular Catheters Using Ultrasonic Cavitation
Bibliographic record
Abstract
OBJECTIVE: Fifty percent of implanted cerebrospinal fluid (CSF) shunts fail within 2 years, primarily because of obstruction of the proximal catheter. Percutaneous techniques to reduce the morbidity of shunt revision are being developed. The authors describe the development of a device that uses ultrasonic cavitation to unblock ventricular catheters. METHODS: In collaboration with Cybersonics, Inc. (Erie, PA), we designed, built, and tested a system that produces low-frequency ultrasound (20-28 kHz). Extensional ultrasonic waves are transmitted along a tapered wire (final diameter, approximately 0.8 mm) to the tip, where cavitation is produced in a highly localized region. An in vitro model of sheep choroid plexus occluding typical ventricular catheters was developed. The device was safety tested in vivo in rat and pig brains by introducing the device into shunt catheters inserted during simulated shunt surgery. A clinical safety trial using the device to attempt to remove blocked and adherent ventricular catheters has commenced. RESULTS: In the sheep choroid plexus model, at least 90% of the occluded holes were unblocked in a few minutes, restoring normal flow. There was no adverse effect of the device within shunt catheters inserted into live animal brains. Four patients have undergone treatment with the device at open CSF shunt surgery without adverse effect, and the device seems effective at unblocking and freeing the occluded catheters. CONCLUSION: Ultrasonic cavitation produced at the end of a fine wire that is introduced percutaneously into a CSF shunt promises to be a useful technique for minimally invasive proximal ventricular CSF shunt catheter revision.
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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 | 0.000 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".