Use of alteplase from 4.5 to 9 hours in patients with ischemic stroke but with salvageable brain on perfusion imaging was superior to placebo (aRR 1.44, 95%CI 1.01-2.06; NNT = 17). Symptomatic hemorrhage was more common in the alteplase group.
Thunderclap headache (TCH) is a concerning symptom and requires diagnostic evaluation. Initial head CT w/o contrast can help detect SAH with negative LR of 0.01 if performed within 6h of headache onset. However, a head CT w/o contrast can miss other causes of TCH and may require advanced imaging and LP.
The application of the Ottawa SAH rule in this relatively small sample of patients had a 100% sensitivity for identifying SAH in the ED but a lower 95% confidence interval of 78.2. The 100% negative predictive value, with a promising 95% CI of 98.6-100%, may have been driven by the lower prevalence of SAH in this study population compared to a previous validation study.