Hyperacute Posterior Circulation Ischemic Stroke: Shed DWI Light
Bibliographic record
Abstract
posterior circulation strokes (pCS) and transient ischemic attacks (tia's) account for 15-23% of all ischemic strokes/tia, 1,2 the prognosis is similar to anterior circulation in terms of persistent functional disability at three months.2,3 they have higher rate of recurrent strokes and tia 4 and yet it is Cinderella disease.Baseline national institute of health Stroke Scale (nihSS) is falsely low in patients with pCS and may influence thrombolysis decision.5 the current Canadian Best practice recommendation for Stroke Care 6 strongly recommend immediate brain and vascular imaging for all patients with suspected acute stroke patients with computed tomogram (Ct)/ Ct angiography (Cta) or magnetic resonance imaging (Mri) diffusion weighted imaging (dWi) sequence / magnetic resonance angiography (Mra).american heart association guidelines for acute stroke treatment also recommend noninvasive angiography of intracranial vessels if intra-arterial therapy is contemplated 7 but suggest non-contrast Ct (nCCt) alone is sufficient for thrombolysis decision.Both the recommendations do not distinguish anterior and posterior circulation stroke and practice pattern for imaging in acute stroke is highly variable.apparently normal nCCt and low nihSS (≤4) may exclude thrombolysis eligible pCS patients presenting in the <4.5 hours (and in selected patients up to six hours but this remains to be proven in further randomized studies 8 ).Magnetic resonance diffusion weighted imaging is better than nCCt to detect early ischemic changes in pCS and Mra would be able to diagnose vertebro-basilar artery occlusion (VBao).Computed tomogram angiography can also reliably detect VBao.But absence of visible occlusion does not always translate to good outcome in patients with early dWi lesion.9 Computed tomogram angiography source images (Si) pc-aSpeCtS ≥8 has been associated with favorable outcome in pCS albeit inconsistently.10 pc-apSpeCt≥7 on dWi has sensitivity of 0.74, specificity of 0.82 and negative predictive value of 0.95 for predicting favorable outcome in pCS 11 .a similar number for acute basilar artery occlusion is pc-aSpeCtS ≥8 on dWi. 12 further Mri perfusion weighted imaging (pWi) can also help in selection of patients for intra-arterial stroke therapies for acute basilar artery occlusion in more reliable manner then Ct perfusion.13 in a retrospective study published in the current issue of the Journal, the role of dWi lesion assessment in hyperacute pCS, as a prognostic marker for early neurological deterioration (end) and unfavorable outcome (ufo) at three months is discussed by lee et al. 14 one-third of patients with pCS presented in first six hours and thus were amenable to thrombolysis.all patients were subjected to diagnostic Mri with mean door-to-Mri time of 74±149 minutes for all patients, 30±11 minutes for moderate to severe pCS. the over-all the Canadian Journal of neurologiCal SCienCeS 139
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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 | 0.008 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.005 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.014 | 0.010 |
| Insufficient payload (model declined to judge) | 0.005 | 0.003 |
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".