Editors' Note: In reference to “Predicting outcome after acute basilar artery occlusion based on admission characteristics” by Drs. Greving et al., Drs. He and Li argue against a 9-hour treatment window for intra-arterial therapy, against the use of recanalization as a predictor of outcome, and for the development of prediction models for different treatment strategies. The authors respond. Drs. Li et al. comment on the new American Academy of Neurology guideline on IV immunoglobulin (IVIg) for neuromuscular disorders, pointing out where evidence is still lacking on the use of IVIg in myasthenia gravis. Robert C. Griggs, MD, and Megan Alcauskas, MD
Greving et al.1 composed a prognostic model to predict outcome of acute basilar artery occlusion (BAO). There are some problems to be resolved before utilization.
First, according to the results of the Basilar Artery International Cooperation Study (BASICS), all 31 cases with a severe deficit and 16/22 cases with a mild to moderate deficit had a poor outcome with intra-arterial therapy (IAT) when the time to treatment exceeded 9 hours.2 Should we recommend 9 hours as the time window for treating acute BAO with IAT?
Second, the BASICS results showed recanalization protected against poor outcome in IAT and IV thrombolysis (IVT) groups.2 Recanalization is an extremely important factor but is not used as a predictor in these 3 models.1
Third, did those cases with or without occlusion and presence of prodromal minor stroke get aggressive medical therapy? If they did, aggressive medical therapy might protect more cases from stroke or occlusion and prodromal minor stroke would not only be a predictive factor but also a protective factor.3
Finally, different hospitals or centers have frequently used treatment strategies for various conditions, especially in developing countries. For these reasons, different prediction models for different treatment strategies will be necessary.
Author Response:
We appreciate the interest of Drs. He and Li and response to our prognostic article.1 We agree that recanalization is an important predictor of outcome. However, our focus was on those factors available at the time of admission.
Our prediction model is meant to be used prior to the initiation of therapy. The results from the BASICS registry showed that type of treatment had no significant influence on outcome at 1 month.2 Our data do not enable any recommendations to be made with regard to the choice between IVT vs IAT in any time window.
We agree that the design of a prediction model for different treatment strategies is a high priority, but should await the results from the recently initiated BASICS trial.4 In the meantime, we recommend treating patients with BAO with IVT. Additional IAT could be considered within a time window of 6 hours from the onset of a severe deficit. Little gain is expected in the 6- to 9-hour time window, but IAT could be considered in selected cases. The 28% good outcome rate among IA-treated patients with a mild to moderate deficit suggests there is still potential gain of IAT beyond the 9-hour time window. Primary IAT should only be considered in patients with a contraindication for IVT.
- Copyright © 2012 by AAN Enterprises, Inc.
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