Ultrasound-Guided Pudendal Nerve Block at the Entrance of the Pudendal (Alcock) Canal
Bibliographic record
Abstract
BACKGROUND AND OBJECTIVES: Ultrasound-guided techniques for pudendal nerve block have been described at the level of the ischial spine and transperineally. Theoretically, however, blockade of the pudendal nerve inside Alcock canal with a small local anesthetic volume would minimize the risk of sacral plexus blockade and would anesthetize all 3 branches of the pudendal nerve before they ramify in the ischioanal fossa. This technical report describes a new ultrasound-guided technique to block the pudendal nerve. The technique indicates an easy and effective roadmap to target the pudendal nerve inside the Alcock canal by following the margin of the hip bone sonographically along the greater sciatic notch, the ischial spine, and the lesser sciatic notch. METHODS: The technique was applied bilaterally in 3 patients with chronic perineal pain. The technique described was also used to locate the pudendal nerve within Alcock canal and inject dye bilaterally in 2 cadavers. RESULTS: Complete pinprick anesthesia was obtained in the pudendal territory of the perineum in all 3 patients. Pain was effectively alleviated or reduced in all patients with no affection of the sacral plexus nerve branches. In the 2 cadavers, all 4 pudendal nerves were successfully targeted and colored. CONCLUSIONS: This new technique is based on easily recognizable sonoanatomical patterns. It probably implies no risk of sacral plexus blockade, and the pudendal nerve is anesthetized before any branches ramify from the main trunk. This promising new technique must be validated in future clinical trials.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".