A Case of Symptomatic Extra-Foraminal Lumbosacral Stenosis (“Far-out Syndrome”) Diagnosed by Diffusion Tensor Imaging
Bibliographic record
Abstract
In Brief Study Design. Case report. Objective. Diagnosis of symptomatic extra-foraminal lumbosacral stenosis using diffusion tensor imaging (DTI). Summary of Background Data. Conventional magnetic resonance imaging (MRI) has sometimes proved inadequate for evaluating symptomatic spinal nerve lesions. DTI has been developed to visualize anisotropy of nerve-fiber tracts to evaluate nerve degeneration. We report a case of nerve compression causing a far-out lesion diagnosed using DTI. Methods. A 68-year-old patient presented with an 8-month history of severe right-sided sciatica. Computed tomography and MRI showed right L5–S1 foraminal stenosis and contact of the L5 transverse process and S1 ala without canal stenosis at the L4–L5 level. We evaluated the fractional anisotropy (FA) of the right L5 spinal nerve and compared it with bilateral L3–S1 spinal nerves to determine the L5 spinal nerve compression site. Results. DTI revealed narrowing of the right L5 spinal nerve between the L5 transverse process and S1 ala. FA was significantly decreased in the right L5 spinal nerve between the L5 transverse process and S1 ala. There was no significant difference in the FA of spinal nerves between the right and left sides at L3, L4, or S1. The right L5 spinal nerve from the central spinal canal to the extra-foraminal lumbosacral lesion was exposed during surgery and found to be severely compressed by the L5 transverse process and S1 ala. Postoperatively, the patient's symptoms disappeared immediately. Conclusion. We used DTI to diagnose a symptomatic lesion as an extra-foraminal lumbosacral lesion caused by compression of the L5 spinal nerve at the foramina. Because DTI can quantitatively measure damage to nerve fibers, it may be advantageous for the diagnosis of far-out syndrome. A patient presented with severe right-sided sciatica caused by extra-foraminal lumbosacral stenosis. Diffusion tensor imaging usefully revealed narrowing of the 5 lumbar spinal nerve and a decrease in fractional anisotropy between the 5 lumbar transverse process and sacral ala, and at surgery we found the 5 lumbar spinal nerve to be severely compressed.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 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".