Sacral Intradural Arteriovenous Fistula Treated Indirectly by Transection of the Filum Terminale: Technical Case Report
Bibliographic record
Abstract
BACKGROUND AND IMPORTANCE: Type A intradural arteriovenous fistulae of the sacral filum terminale are rare lesions fed primarily by the distal anterior spinal artery. The artery is frequently too narrow or tortuous for endovascular obliteration, and direct surgical resection of the fistula requires an invasive sacrectomy. We present a less invasive indirect surgical approach through an L4 laminectomy and transection of the filum terminale rostral to the fistula. CLINICAL PRESENTATION: A 62-year-old man presented with a 6-month history of progressive bilateral lower extremity paresthesias and weakness and associated incontinence and impotence. Spinal magnetic resonance imaging demonstrated perimedullary flow voids. Selective spinal angiography revealed a fistula at S2-3 between the distal anterior spinal artery and an early draining vein returning cranially along the filum terminale, diagnostic of an intradural arteriovenous fistula. An L4 laminectomy and transection of the filum terminale rostral to the lesion were performed to disrupt the medullary arterial supply to the intradural fistula and outflow to the medullary venous plexus of the spinal cord. At 10-month clinical follow, up the patient had regained bowel and bladder continence, was able to ambulate with a cane, and reported subjective improvement of lower extremity paresthesias. Selective spinal angiography at 1 year demonstrated no residual arteriovenous shunt. CONCLUSION: Pathological venous hypertension of a type A intradural arteriovenous fistula of the sacral filum terminale can be treated by transection of the filum terminale at L4. This avoids posterior partial sacrectomy required for direct resection; however, subsequent clinical follow-up is necessary to monitor for reconstitution.
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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) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.004 | 0.003 |
| 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".