Vertebrobasilar insufficiency presenting as isolated positional vertigo or dizziness: A double‐blind retrospective cohort study
Bibliographic record
Abstract
OBJECTIVES/HYPOTHESIS: Vertebral artery (VA) stenosis caused mainly by atherosclerosis accounts for up to 20% of posterior circulation strokes. Isolated positional vertigo or dizziness can be the initial presentation symptom. The objective is to compare the presence of isolated positional vertigo or dizziness in patients with evaluation of VA morphology, thrombotic stroke risk factors, and evolution of symptoms with time. STUDY DESIGN: Double-blind retrospective cohort study. METHODS: Magnetic resonance angiography reports describing the VAs of 258 patients were reviewed, and 133 were questioned and their hospital charts reviewed for positional vertigo or dizziness. Neurotologic examination was performed on 75 patients. Vestibular testing using electronystagmography was performed on 46 patients. The prevalence of thrombotic stroke factors was evaluated in all patients. Groups were compared using chi-square statistical analysis. RESULTS: A total of 72 patients with normal VAs (group A) were compared with a group of 61 patients with stenotic or hypoplastic VAs (group B). When stratifying patients for stroke risk factors, 85.7% of group B patients complaining of isolated positional vertigo on the questionnaire with at least three stroke risk factors had a vertebral artery abnormality (P = .026). A hypothesized mechanism is transient ischemic attack of the semicircular canals or vestibular nucleus during rotation and extension of the neck, which compresses a contralateral stenotic VA in patients with bilateral VA abnormalities. CONCLUSIONS: In patients complaining of isolated positional vertigo or dizziness of unexplained etiology and having at least three thrombotic stroke risk factors, we recommend a vertebrobasilar radiological evaluation for timely treatment accordingly to the results.
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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 | 0.001 | 0.003 |
| 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 | 0.000 | 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".