Posterior versus anterior circulation strokes: comparison of clinical, radiological and outcome characteristics.

Background And Purpose: Physicians treating patients with posterior circulation strokes (PCS) tended to debate more on whether or not to introduce anticoagulation rather than performing investigations to identify stroke aetiology, as in patients with anterior circulation strokes (ACS). Recent findings suggest that stroke aetiologies of PCS and ACS are more alike than dissimilar, suggesting that PCS deserve the same investigations as ACS. The characteristics and current diagnostic evaluation between patients with PCS and ACS were compared.

Methods: 312 consecutive patients with first ever ACS and 93 patients with first ever PCS were prospectively analysed.

Results: Patients with ACS and PCS did not differ in terms of demographic characteristics, prevalence of vascular risk factors, diagnostic evaluation or stroke aetiology. The median National Institutes of Health Stroke Scale score was 8 in ACS and 4 in PCS (p=0.004). Brain imaging revealed more often pathological findings in ACS than PCS. The proportion of non-thrombolysed patients with a favourable clinical outcome (modified Rankin score 0-2) was similar in ACS and PCS (67.0% vs 78.4%; p=0.08). In non-thrombolysed patients, stroke severity was an independent predictor of clinical outcome both in ACS (OR 1.60, 95% CI 1.2 to 2.1; p<0.0001) and in PCS (OR 1.22, 95% CI 1.03 to 1.44; p=0.02) while age predicted poor outcome only in ACS (OR 1.11, 95% CI 1.01 to 1.22; p=0.007). In thrombolysed patients, stroke severity was the only outcome predictor in ACS (OR 1.14, 95% CI 1.04 to 1.25; p=0.004) while we identified no statistically relevant predictor of PCS outcome.

Conclusions: In PCS and ACS, baseline variables, aetiology and outcome are more alike than different.