Defining the nasopalatine line: The limit for endonasal surgery of the spine
Bibliographic record
Abstract
OBJECTIVES: The expanded endoscopic endonasal approach (EEA) to the odontoid process is performed for decompression of the brainstem and to access tumors at the foramen magnum. Caudal exposure is limited by the nasal bones anteriorly and the hard palate posteriorly. We define the line connecting these two points as the nasopalatine line (NPL) and the nasopalatine angle (NPA) as the angle between the nasopalatine line and the plane of the hard palate. STUDY DESIGN: This study was a retrospective cohort study. METHODS: Pre and post-operative computed tomographic (CT) scans of 17 patients who underwent transodontoid EEA were reviewed. The position of the odontoid and the inferior extent of the tumor and surgical dissection were compared to the NPL. Factors affecting the posterior projection of the NPL, including basilar invagination and head position, were examined. RESULTS: The mean NPA was 27.1 degrees (range 21-31 degrees ). The NPL intersects the spinal column at 8.9 mm (range -9.0-8.7 mm) above the base of the C2 body. The base of the odontoid process and the inferior extent of surgical dissection were always above this line. Both basilar invagination and head position affect the relative position of the NPL. Patients with basilar invagination demonstrated a significantly lower posterior projection of the NPL than those without (P < .01). Maximal cervical flexion afforded more caudal exposure than cervical extension. CONCLUSIONS: The NPL accurately predicts the most inferior extent of surgical dissection. Further caudal dissection may require the use of angled instruments or a transoral approach.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".