Sinus pericranii in the setting of a posterior fossa pilocytic astrocytoma: illustrative case
Bibliographic record
Abstract
BACKGROUND: Sinus pericranii (SP) is a rare vascular anomaly, with an uncertain etiology. Often discovered as superficial lesions, they can be primary or secondary in nature. Herein, we report a rare case of SP in the setting of a large posterior fossa pilocytic astrocytoma associated with a significant venous network. OBSERVATIONS: A 12-year-old male presented with acute clinical deterioration in extremis with a 2-month history of lethargy and headaches. Outside plain computed tomography imaging revealed a large posterior fossa cystic lesion, probably a tumor, with severe hydrocephalus. There was also a midline small skull defect at the opisthocranion, without visible vascular anomalies. An external ventricular drain was placed with rapid recovery. Contrast imaging revealed a large midline SP emanating from occipital bone with a large intraosseous, and subcutaneous venous plexus in the midline draining inferiorly into venous plexus around the craniocervical junction. A posterior fossa craniotomy without contrast imaging could have resulted in catastrophic hemorrhage. A small modified off-center craniotomy provided access to the tumor with a gross total excision. LESSONS: SP is a rare but significant phenomenon. Its presence does not necessarily preclude resection of underlying tumors, provided that a careful preoperative assessment of the venous anomaly is undertaken.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.004 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.006 | 0.004 |
| Insufficient payload (model declined to judge) | 0.003 | 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".