Importance of the “Rule of the Pupil” in the Modern Neuroimaging Era
Bibliographic record
Abstract
ABSTRACT: The "Rule of the Pupil" states that when aneurysms compress the oculomotor nerve, a dilated or sluggishly reactive pupil will result. In previous decades, when cerebral angiography was required to detect an intracranial aneurysm, the "Rule of the Pupil" was used to determine the relative risk of angiography and the likelihood of aneurysmal compression in patients with third nerve palsies (3NPs). Noninvasive imaging including computed tomography angiography (CTA) and magnetic resonance angiography has become readily accessible and can detect all aneurysms large enough to cause 3NPs. It is therefore recommended that all patients with 3NP undergo neuroimaging regardless of pupil status because the consequences of missing an aneurysm are high. The question therefore remains as to whether the "Rule of the Pupil" still has relevance in today's era of modern neuroimaging. We describe a 73-year-old man who developed a left complete, pupil-sparing 3NP and was found to have a paraclinoid meningioma in the left cavernous sinus. As compressive lesions are expected to impair the iris sphincter muscle, no intervention was recommended and his 3NP spontaneously improved within 3 months. We also describe a 54-year-old woman with diabetes and a complete 3NP with a dilated, nonreactive pupil. Initial CTA was reported as normal, but re-review of imaging revealed a posterior communicating artery aneurysm and immediate intervention to coil the aneurysm occurred. The "Rule of the Pupil" is still important in the modern neuroimaging era as demonstrated in cases of incidentally found lesions along the course of the oculomotor nerve and missed radiological findings.
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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 | 0.002 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.006 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.004 |
| 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".