Stroke is the second leading cause of death worldwide following ischemic heart disease, and the fifth in the United States. The video-sharing database, YouTube, is the second most popular visited website with more than 2 billion users, thus it's increasingly being used as a medium for delivering health information. We aimed to evaluate the quality, reliability and audience engagement of stroke-related YouTube videos. In October 2019 we conducted a search on YouTube using 5 keywords: stroke, brain attack, hemorrhagic stroke, ischemic stroke and transient ischemic attack. We selected the first 30 videos from each search query for further analysis. The validated DISCERN instrument was used (a score of 0-5 per question) to assess the videos by four independent raters. We then recorded qualitative data and quantitative data for each video. After sorting through 150 stroke videos, a total of 101 unique YouTube videos met our inclusion criteria. We found that the mean overall quality of YouTube videos according to DISCERN is of fair quality. Most videos (65.3%) were uploaded by hospitals, mentioned the symptoms of stroke (66.3%), had a doctor speaking (60.4%) and contained diagrams (20.8%). YouTube is a useful source of gathering information about treatment choices for patients and their families as the quality of YouTube videos is fair. The audience engagement suggestions in our paper may help content creators improve the appeal of YouTube videos.

Previous studies on the novel Coronavirus (COVID-19) have found strong correlations between online searches and the epidemiology of the disease. Our aim was to determine if online searches for COVID-19 related to international media announcements or national epidemiology. Searches for "coronavirus" were made on Google Trends from December 31, 2019 to April 13, 2020 for 40 European countries. The online COVID-19 searches for all countries were correlated with each other. COVID-10 epidemiology (i.e. incidence and mortality) was correlated with the national online searches. Major announcements by the World Health Organization (WHO) were taken into consideration with peaks in online searches. Correlations were made using Spearman's rank correlation coefficient. Overall, the online searches for COVID-19 were not correlated with the actual incidence and mortality of COVID-19. The mean Spearman correlation for incidence was 0.20 (range -0.66 to 0.76) and for mortality was 0.35 (range -0.75 to 0.85). Online searches in Europe were all strongly synchronized with each other; a mean Spearman correlation of 0.93 (range 0.62 to 0.99). Online searches for COVID-19 in Europe are not correlated with epidemiology but strongly correlated with international WHO announcements. Our study challenges previous Google Trends studies and emphasizes the role of the WHO in raising awareness of a new disease.

Brain metastasis is a common and devastating clinical entity. Intratumor heterogeneity in brain metastases poses a crucial challenge to precision medicine. However, advances in next-generation sequencing, new insight into the pathophysiology of driver mutations, and the creation of novel tumor models have allowed us to gain better insight into the genetic landscapes of brain metastases, their temporal evolution, and their response to various treatments. A plethora of genomic studies have identified the heterogeneous clonal landscape of tumors and, at the same time, introduced potential targets for precision medicine. As an example, we present phenotypic alterations in brain metastases originating from three malignancies with the highest brain metastasis frequency: lung cancer, breast cancer, and melanoma. We discuss the barriers to precision medicine, tumor heterogeneity, the significance of blood-based biomarkers in tracking clonal evolution, the phylogenetic relationship between primary and metastatic tumors, blood–brain barrier heterogeneity, and limitations to ongoing research.