To evaluate the association between poor collateral circulation in patients with acute ischemic stroke (AIS) from basilar artery occlusion (BAO) and stroke outcomes.

The important role of collaterals in protecting brain from ischemia is well established in anterior circulation stroke, but less is known about the prognostic value of collaterals in posterior circulation stroke.

We conducted a retrospective study of patients presenting with AIS due to BAO between 2012-2018. Strokes were characterized acutely by NIHSS and initial posterior circulation ASPECTS score, where 1 point  was deducted for areas of early ischemic changes in thalamus, cerebellum, occipital lobe and 2 points were deducted for changes in mid brain and pons.  Collateral circulation was characterized using the  Basilar Artery on Computed Tomography Angiography (BATMAN) scoring system (deduction of 1 point  for occlusion of proximal, middle, distal basilar artery, or posterior cerebral artery and 2 points  for occlusion of posterior communicating artery, respectively). Poor collaterals were defined as BATMAN score <7. The primary outcome was modified Rankin scale (mRS) at 3 months.

A total of 14 patients met the inclusion criteria, with mean age of 65 ±21yrs; 7 (50%) were women; 11 (79%) had hypertension. Six (43%) patients had poor collaterals.  Initial NIHSS was significantly higher in patients with poor collaterals (mean NIHSS, 26±8 vs. 14±12; p=0.002). Initial ASPECTS score was lower in patients with poor collaterals (mean, 5.3±1.8 vs. 8.8±1.4; p=0.002). Three (21.4%) patients received tPA, 9 (64.3%) patients had thrombectomy and 2 (21.4%) patients had thrombectomy with stenting. Patients trended to have a greater risk of poor outcomes with worse collateral status (75.0% vs 28.6%, OR 7.5, p=0.137).

Poor collaterals may be associated with poor stroke outcomes. Follow-up studies are underway to further evaluate the utility of the BATMAN score in prognosticating stroke outcomes in patients with posterior circulation stroke.