The Relationship Between the Duration of Acute Cauda Equina Compression and Functional Outcomes in a Rat Model
Bibliographic record
Abstract
In Brief Study Design. Immunohistochemical and behavioral study using a rat model of acute cauda equina syndrome (CES). Objective. To determine the effect of duration of extradural cauda equina compression (CEC) on bladder, sensory, and motor functions. Summary of Background Data. Cauda equina syndrome is a devastating injury treated with surgical decompression. Controversy exists regarding the optimal timing of surgery. Animal models of CES have focused on motor recovery but have not evaluated pain behavior or bladder function. Methods. A 4-mm balloon-tipped Fogarty catheter was inserted between the fifth and sixth lumbar lamina into the dorsal epidural space and inflated to compress the nerve roots at the L5 level. Maximal inflation was maintained at a constant balloon pressure of 304 Kpa for 1 or 4 hours. The catheter was inserted but not inflated in sham animals. During a 4-week period, pain behavior, bladder function, and locomotor function were assessed. Postmortem bladders and the lesion site were collected for analysis. Results. Mechanical allodynia was 2-fold greater in 1-hour CEC rats than 4-hour CEC (P = 0.002) and sham-operated (P = 0.001) rats at 4 weeks after injury. Hind limb locomotor function was not different between groups at 4 weeks after injury. Both the 1-hour and 4-hour CEC group rats retained greater volumes of urine than the sham-operated rats throughout the 4-week period (P < 0.05). At 4 weeks, bladder weight and volume were 2-fold greater in the 4-hour CEC group than in the 1-hour CEC group (P = 0.006 and P = 0.01, respectively). Histology of the bladder wall revealed an overall thinning after 4-hour CEC. Histology of the lesion site revealed a greater overall severity of injury after 4-hour CEC than after 1-hour CEC (P = 0.04) and sham operation (P = 0.002). Conclusion. Our data suggest that recovery of motor function is less affected by the timing of decompression compared with bladder function and pain behavior. Early decompression preserved bladder function but was associated with allodynia. Level of Evidence: N/A The cauda equina is vulnerable to compression injury. Rapid compression of the rat cauda equina was produced using a balloon catheter. A constant pressure of 304 Kpa was maintained for 1 or 4 hours. Sham animals had the catheter inserted but not inflated. Bladder, pain, and motor function were assessed during a 4-week period. Motor function was not affected by the timing of decompression. Early decompression preserved bladder function but was associated with allodynia.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".