Cerebral vasomotor reactivity in reversible cerebral vasoconstriction syndrome
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Bibliographic record
Abstract
Background Altered cerebrovascular tone is implicated in reversible cerebral vasoconstriction syndrome (RCVS). We evaluated vasomotor reactivity using bedside transcranial Doppler in RCVS patients. Methods In this retrospective case-control study, middle cerebral artery (MCA) blood flow velocities were compared at rest and in response to breath-hold in RCVS ( n = 8), Migraineurs ( n = 10), and non-headache Controls ( n = 10). Hyperventilation response was measured in RCVS. Results In RCVS, Breath Holding Index (BHI) was severely reduced in seven of eight patients and 14/16 MCAs; seven of 16 MCAs showed exhausted (BHI < 0.1) or inverted (BHI < 0) vasomotor reactivity. Mean BHI in RCVS (0.23 ± 0.5) was significantly lower than Migraine (1.52 ± 0.57) and Controls (1.51 ± 0.32), p < 0.001. Triphasic velocity responses were seen in all groups. The maximum V mean decline during the middle negative phase was −15.5 ± 9.2% in RCVS, −15.4 ± 7% in Migraine, and −10.3 ± 5% in Controls ( p = 0.04). In the late positive phase, average V mean increase was 6.2 ± 14% in RCVS, which was significantly lower ( p < 0.001) than Migraine (30.5 ± 11%) and Controls (30.2 ± 6%). With hyperventilation, RCVS patients showed 23% decrease in V mean . Conclusion Cerebral arterial tone is abnormal in RCVS, with proximal vasoconstriction and abnormally reduced capacity for vasodilation. Further studies are needed to determine the utility of BHI to diagnose RCVS before angiographic reversibility is established, and to estimate prognosis.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 it