A conversation with Søren Bache, MD, from the Neurointensive Care Unit, Department of Neuroanaesthesiology and Centre for Genomic Medicine, Rigshospitalet, University of Copenhagen, Denmark, about microRNA changes after subarachnoid hemorrhage.
Interviewed by José G. Merino, MD, Associate Professor of Neurology, University of Maryland School of Medicine.
They will be discussing the paper, “MicroRNA Changes in Cerebrospinal Fluid After Subarachnoid Hemorrhage,” published in the September 2017 issue of Stroke.
Dr. Merino: Thank you for agreeing to the interview. First, I would like you to explain some things about delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) for our readers: How common is it? How soon after SAH does it develop? How does it affect outcome after SAH?
Dr. Bache: The reported prevalence of DCI after SAH varies, but newer randomized clinical trials have found a risk of 21–38% in patients who survive the initial bleeding and aneurism-securing surgery. The variation in calculated risk may be due to discrepancies both in case definition (i.e. the numerator) and in the definition of which patients are entered into the denominator. Today, most researchers base their case definition of DCI on the criteria suggested by Vergouwen et al. (Vergouwen MD, et al. Stroke. 2010). Before this consensus work, the definition varied even more, and many used their own criteria for DCI, delayed ischemic neurological deficits (DIND) or cerebral vasospasm. However, not all patients are conscious enough to be assessed clinically for a deterioration in consciousness, and such patients may be either included or excluded in the total number of patients; hence, the variation in the denominator. Based on Vergouwen’s criteria, in our center, we found a prevalence of 23% in 450 patients admitted from 2009–12 with SAH (unpublished data). These patients all receive prophylactic nimodipine, which lowers the risk of DCI; therefore, one should expect publications from the pre-nimodipine era to report a higher prevalence of DCI (Dorhout Mees SM, et al. Cochrane Database of Systematic Reviews. 2007).
Delayed cerebral ischemia occurs a median of 6–7 days after hemorrhage, but this varies, with a typical reported range from 3 to 14 days. DCI may be reversible, but in some cases it progresses to permanent brain injury, thereby affecting outcome.