There is some concern for financial conflict of interest among guideline authors for the AHA stroke guidelines. However, just 6% (2/34) of the authors for the 2013 or 2018 AHA guidelines had industry ties related to alteplase in the year of publication. Be sure to read the more nuanced discussion.
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.