Background: Basilar artery occlusion (BAO) is associated with high risk of disability and mortality. This study aimed to assess the prognostic value of a new radiological score: the “Basilar Artery on Computed Tomography Angiography score (BATMANs)”.
Methods: A retrospective analysis of consecutive stroke patients with a diagnosis of BAO on CT angiography (CTA) was performed. BATMANs is a 10 point CTA-based grading system. We allocated 1 point for each patent segment (proximal, middle and distal) of the basilar artery, 1 point for any patent intracranial vertebral arteries (VA), 1 point for each posterior cerebral artery (PCA) and 2 points for each posterior communicating artery (PcoM) or 1 point for hypoplastic PcoM (<1 mm diameter). Two investigators reviewed the CTA images blinded to clinical outcome. Reliability was assessed with intraclass coefficient correlation (ICC). Good outcome was defined as modified Rankin Scale≤3 at 3 months; successful reperfusion as thrombolysis in cerebral infarction 2b-3. BATMANs was externally validated and compared with the Posterior Circulation Collateral score (PC-CS).
Results: The derivation cohort (DC) included 83 patients with 41 in the validation cohort (VC). In receiver-operating-characteristic (ROC) analysis, BATMANs had an area-under-curve (AUC) of 0.81 (95%CI 0.7-0.9) in DC and an AUC of 0.74 (95%CI 0.6-0.9) in VC. BATMANs<7 was the optimal threshold for poor outcome in DC (sensitivity=84%, specificity=76%). In logistic regression adjusted for age and clinical severity, BATMANs<7 was associated with poor outcome in DC (OR 5.5, 95% CI 1.4 -21; p=0.01), in VC (OR 6.9, 95% CI 1.4-33; p=0.01) and among endovascular patients (OR 3.8, 95%CI 1.0-14; p=0.05). BATMANs was independently associated with functional outcome after adjustment for revascularization and time to treatment (OR 4.8, 95%CI 1-18; p=0.01); however, it was not associated with recanalization. Inter-rater agreement was excellent (ICC 0.85, 95% CI 0.76-0.89). BATMANs showed higher accuracy in comparison with PC-CS (p=0.03).
Conclusions: The addition of collateral quality to clot burden in BATMANs appears to improve prognostic accuracy in BAO patients.